INFORMATION TO USERS While th e m o st advanced technology has been used to photograph and reproduce th is manuscript, th e quality of the reproduction is heavily dependent upon the quality of the material submitted. For example: • M anuscript pages may have indistinct print. In such cases, the beBt available copy has been filmed. • M anu scrip ts may n o t always be complete. I n such cases, a note will indicate th a t it is not possible to obtain m issing pages. • Copyrighted m aterial may have been removed from the manuscript. In such cases, a note will indicate the deletion. Oversize m aterials (e.g., maps, drawings, and charts) are photographed by sectioning th e original, beginning at the upper left-hand corner and continuing from left to rig h t in equal sections w ith small overlaps. Bach oversize page is also film e d a s o n e e x p o s u r e a n d is a v a i la b l e , fo r a n additional charge, as a standard 35m m slide or as a 17”x 23” black and white photographic print. M ost p h o to g r a p h s r e p r o d u c e a c c e p ta b ly on p o s itiv e microfilm or microfiche b u t lack th e clarity on xerographic copies made from the microfilm. For a n additional charge, 35mm slides of 6”x 9” black and w hite photographic prints are available for an y ph otog raphs or illu s tra tio n s t h a t cannot be reproduced satisfactorily by xerography. 8707163 M estey-V illam H , V ivian M. DIPLOPODA OF A MICHIGAN BEECH-MAPLE FOREST: ECOLOGY AND SEASONAL ACTIVITY Michigan State Universiiy University Microfilms International 300 N. Zeeb Road, Ann Arbor, Ml 48106 POPULATION Ph.D. 1986 I PLEASE NOTE: In all c a se s this material h a s been filmed in the b est possible w ay from th e available copy. Problem s encountered with this d o cu m en t have been identified here with a ch eck mark V . 1. Glossy photographs or p a g e s _____ 2. Colored illustrations, pap er or p rin t_______ 3. Photographs with dark background 4. Illustrations are p o o r c o p y _______ 5. P ages with black marks, not original c o p y ______ 6. Print shows through a s th ere is text on both sides of p a g e _______ 7. Indistinct, broken or small print on several pages 8. Print exceeds m argin req u irem en ts______ 9. Tightly bound co p y with print lost in s p in e _______ 10. 11. f f Computer printout p ages with indistinct print_______ P ag e(s)____________lacking w hen material received, a n d not available from school or author. seem to b e missing in numbering only as text follows. 12. Page(s) 13. Two pages num bered 14. Curling and wrinkled p ages 15. Dissertation con tain s p ages with print at a slant, filmed a s received 16. . Text follows. Other University Microfilms International DIPLOPODA OF A MICHIGAN BEECH-MAPLE FOREST POPULATION ECOLOGY AND SEASONAL ACTIVITY by V iv ia n M e s te y -V illa ra il A THESIS S u b m it te d t o M ic h ig a n S t a t e U n i v e r s i t y in p a r t i a l f u l f i l l m e n t of th e re q u ire m e n ts f o r th e degree of DOCTOR OF PHILOSOPHY D e p a rtm e n t o f Z o o lo g y ABSTRACT DIPLOPODA OF A BEECH-MAPLE FOREST: POPULATION ECOLOGY AND SEASONAL ACTIVITY By V iv ia n M e s te y -V illa m il The p r e s e n t s t u d y a s s e s s e d some a s p e c t s o f p o p u l a t i o n d e n s i t y , v e r t i c a l an d h o r i z o n t a l d i s t r i b u t i o n , a n d a c t i v i t y o f t h e d o m in a n t d i p l o p o d s p e c i e s o f B ak er w o o d l o t , a b e e c h - m a p l e f o r e s t , i n M i c h i g a n . F i e l d w ork was f o c u s e d o n q u a n t i t a t i v e s a m p l i n g o f l e a f l i t t e r , o rg a n ic l a y e r an d A h o r i z o n . P i t f a l l t r a p s w e re u s e d t o a s s e s s s e a s o n a l a c t i v i t y d u r i n g two c o n s e c u t i v e y e a r s ( 1 9 8 4 - 1 9 8 5 ) . Of s i x d i p l o p o d s p e c i e s c o l l e c t e d i n t h e s t u d y a r e a o n l y t h r e e w ere common en o u g h f o r q u a n t i t a t i v e a n a l y s i s : O p h y lu lu s p i l o s u s ( N e w p o r t ) , P o ly d e s m u s l n c o n s t a n s L a t z e l , and P o ly z o n iu m b l v i r g a t u m (W ood). O p h y l u l u s p i l o s u s was t h e d o m in a n t s p e c i e s . V e r t i c a l m i g r a t i o n and d i s t r i b u t i o n o f t h e l i f e sta g e s o f 0. p i l o s u s was a f f e c t e d by c l i m a t i c p a r a m e t e r s s u c h a s s e a s o n a l t e m p e r a t u r e an d p r e c i p i t a t i o n . D i f f e r e n c e s i n t h e s e two p a r a m e t e r s among y e a r s a l s o a f f e c t e d p o p u l a t i o n d e n s i t y o f t h e s p e c i e s . O p h y lu lu s p i l o s u s c a n o v e r w i n t e r i n a n y s t a g e ( s m a l l j u v e n i l e , ju v e n ile or a d u lt), e x c e p t p r o b a b l y a s e g g s , w h ic h a r e l a i d d u r i n g s p r i n g an d sum m er. A d u l t s w ere common i n s p r i n g a n d w ere p r e s e n t i n e v e r y s o i l l a y e r . I n m a t u r e s t a g e s w ere m o s t common, d u r i n g summer and fa ll, i n 0 an d A h o r i z o n s . The h o r i z o n t a l d i s t r i b u t i o n o f t h e d o m i n a n t s p e c i e s c o u l d n o t be r e l a t e d t o t h e am ount o f l i t t e r o r i t s m o i s t u r e c o n t e n t . D a ta fr o m p i t f a l l t r a p s showed d i f f e r e n t a c t i v i t y p e a k s f o r e a c h s p e c i e s . O p h y lu lu s p i l o s u s was m a i n l y a c t i v e i n s p r i n g , P . l n c o n s t a n s d u r i n g summer an d P . b i v i r g a t u m I n t h e f a l l . A d u l t s w ere t h e m o st a c t i v e s t a g e i n e v e r y s p e c i e s , and b o t h s e x e s w e re e q u a l l y a c t i v e , in d i c a ti n g t h a t a c t i v i t y peaks o f each s p e c ie s corresponded to t h e i r m a ttin g se a so n . To my h u s b a n d , f a m i l y a n d f r i e n d s ii ACKNOWLEDGEMENTS I w i s h t o t h a n k t h e members o f my g u i d a n c e c o m m it te e : D r. R i c h a r d S n i d e r , D r. Max H e n s l e y , a n d D r. D o n ald S t r a n e y , D e p a r tm e n t o f Z o o lo g y , a n d D r. P e t e r M urphy, D e p a r tm e n t o f B o ta n y an d P l a n t P a t h o l o g y f o r t h e i r a s s i s t a n c e i n t h e c o u r s e o f t h i s stu d y . To my m a j o r p r o f e s s o r , D r. R e n a t e S n i d e r , I e x p r e s s s i n c e r e a p p r e c i a t i o n f o r h e l p i n g me d u r i n g t h e p r e p a r a t i o n of th is d isse rta tio n . I a l s o w i s h t o t h a n k t h e U n i v e r s i t y o f P u e r t o R ic o f o r t h e i r f i n a n c i a l s u p p o rt th ro u g h o u t th e s e y e a r s . V ery s p e c i a l t h a n k s t o my f a m i l y , f r i e n d s an d my h u s b a n d , W aldo, f o r t h e i r p a t i e n c e , l o v e an d u n d e r s t a n d i n g . iii TABLE OF CONTENTS L i s t o f T a b l e s ................................................................................................................. Page vl L i s t o f F i g u r e s .......................................... . ................................... v ii PART I - INTRODUCTION .......................................................................................... 1 PART I I - MATERIALS AND METHODS .................................................................... 7 1. D e s c r i p t i o n o f t h e s t u d y a r e a ........................................................ 7 2. S a m p lin g m e t h o d s . ........................................................................................ 7 2 .1 . 2 .2 . 2 .3 . 2 .4 . 2 .5 . 2 .6 . PART I I I 1. Q u a d r a t s a m p l i n g ....................................................................... P i t - t r a p p i n g ................................................................................ C l a s s i f i c a t i o n o f l i f e s t a g e s ...................................... S o i l m o i s t u r e d e t e r m i n a t i o n ............................................ L i t t e r m ass d e t e r m i n a t i o n ................................................ T e m p e r a t u r e and p r e c i p i t a t i o n ....................................... 8 10 14 15 15 15 RESULTS AND DISCUSSION .................................................................. 16 P h y s i c a l p a r a m e t e r s ................................................................... 1 .1 . 1 .2 . 1 .3 . D a i l y t e m p e r a t u r e s .................................................................. D a i l y p r e c i p i t a t i o n ............................................................... S u b s t r a t e m o i s t u r e .................................................................. 16 16 21 ........................................................................ Leaf l i t t e r 0 l a y e r ................... A l a y e r .................................................................................... 21 23 23 A) B) C) 1 .4 . 16 L i t t e r c o v e r ............................................................................ 23 2. S p e c i e s d o m in a n c e ..................................................................................... 25 3. P o p u l a t i o n d e n s i t y .................................................................................. 29 4. P o p u l a t i o n s t a g e s t r u c t u r e ............................................................... 32 5. S p a t i a l d i s t r i b u t i o n o f t h e d o m in a n t s p e c i e s ................... 36 5 .1 . 5 .2 S e a s o n a l h o r i z o n t a l d i s p e r s i o n .................................... H o r i z o n t a l d i s t r i b u t i o n and l i t t e r m a s s ................ iv 36 38 6. V e r t i c a l d i s t r i b u t i o n o f t h e d o m in a n t s p e c i e s ............... 46 6 .1 . S e a s o n a l d i s t r i b u t i o n ......................................................... 46 6*2. S ta g e -sp e c ific d is trib u tio n .......................................... 46 S m a ll j u v e n i l e s ............................................... J u v e n i l e s .............................................................. A d u l t s ..................................................................... 46 54 56 ....................................................................... 57 T o t a l num ber o f i n d i v i d u a l s c a p t u r e d .................... S t a g e - s p e c i f i c a c t i v i t y .................................................... S e a s o n a l a c t i v i t y p a t t e r n s ............................................. 57 59 61 At s p e c i e s l e v e l .............................................................. At s t a g e l e v e l ................................................................... S e x -re la te d d iffe re n c e s in a d u lt sta g e . . . . 61 68 70 A .l) A .2) A . 3) 7. S urface a c t i v i t y 7 .1 . 7 .2 . 7 .3 . A) B) C) C .l) C .2 ) C .3 ) PART IV - O p h y l u l u s p i l o s u s .......................................... P o ly d esm u s l n c o n s t a n s ................................ P o ly z o n iu m b i v i r g a t u m ..................... 75 76 76 SUMMARY AND CONCLUSIONS .............................................................. 78 BIBLIOGRAPHY ......................................................................................... 82 v LIST OF TABLES Table Page 1. I n t e r - t r a p d i s t a n c e s ....................................... 12 2. C h a r a c t e r i s t i c s o£ d e v e l o p m e n t a l s t a g e s u s e d t o c l a s s i f y O p h y iu lu s p i l o s u s .................................................................. 13 C h a r a c t e r i s t i c s o f d e v e lo p m e n ta l s t a g e s used to e s t a b l i s h c a t e g o r i e s f o r P o ly d esm u s l n c o n s t a n s .................. 14 4. A v e ra g e d r y m ass o f f o r e s t f l o o r (g /m ) .................................. 24 5. P e r c e n t o f t o t a l num ber f o r t h e t h r e e s p e c i e s s t u d i e d i n B ak er w o o d lo t e a c h s e a s o n .............................................................. 26 S easonal v a r ia tio n s in average p o p u la tio n d e n s ity fro m t h e t h r e e s p e c i e s s t u d i e d i n B a k e r w o o d lo t ............... 30 S t a g e - s p e c i f i c a v e r a g e number o f 0 . p i l o s u s p e r s q u a r e m e t e r f o r e a c h s e a s o n .............................................................. 33 V a r ia n c e / m e a n r a t i o t e s t p a r a m e t e r s f o r l a r g e s a m p le s f ro m t h e 0 ^ p i l o s u s p o p u l a t i o n ......................................................... 37 V a lu e s o f r f o r l i n e a r r e g r e s s i o n t e s t b e tw e e n l i t t e r m ass and num ber o f 0 . p i l o s u s .................................... 45 S e a s o n a l v e r t i c a l d i s t r i b u t i o n o f a v e r a g e number o f 0 . p i l o s u s p e r s q u a r e m e t e r ................................................................ 48 11. S p r i n g v e r t i c a l d i s t r i b u t i o n o f a v e r a g e num ber o f 0 . p i l o s u s p e r s q u a r e m e t e r by s t a g e s ........................................ 50 12. Summer v e r t i c a l d i s t r i b u t i o n o f a v e r a g e num ber o f 0 . p i l o s u s p e r s q u a r e m e t e r by s t a g e s ....................................... 52 1 3 . F a l l v e r t i c a l d i s t r i b u t i o n o f a v e r a g e num ber o f 0 . p i l o s u s p e r s q u a r e m e t e r by s t a g e s ....................................... 53 3. 6. 7. 8. 9. 10. 14. S t a g e d i s t r i b u t i o n o f t o t a l number o f p i t - f a l l t r a p p e d i n d i v i d u a l s ( a l l s p e c i e s c o m b in e d ) ........................... 60 15. T o t a l num bers c a p t u r e d o f e a c h s p e c i e s ............................................ 69 16. T o t a l nu m b e rs o f m a le s and f e m a l e s c a p t u r e d ................................ 71 vi LIST OF FIGURES Figure 1. Page A p p r o x im a te q u a d r a t s a m p l i n g l o c a t i o n s i n ............................................................................................. B ak er w o o d lo t 9 2. P r o f ile of c o l l e c t i n g cups used in p i t - t r a p p i n g . . ............ 11 3. D a i l y a i r t e m p e r a t u r e s (NWS) - y e a r 1 ......................................... 17 A. D a i l y a i r t e m p e r a t u r e s (NWS) - y e a r 2 ......................................... 18 5. D a i l y p r e c i p i t a t i o n (NWS) - y e a r 1 ................................................ 19 6. D aily p r e c i p i t a t i o n (NWS) - y e a r 2 ................................................ 20 7. M o istu re i n % o f d ry w e ig th o f l i t t e r , 0 a n d A l a y e r s i n B a k e r w o o d lo t.......................................................... 22 S e a s o n a l f l u c t u a t i o n s i n p e r c e n t o f t o t a l num bers f o r th e th r e e s p e c ie s o f d ip lo p o d s s tu d ie d in B a k e r w o o d lo t I n y e a r 1 ............................................................................ 27 Seasonal f lu c tu a tio n s f o r th e th re e s p e c ie s B a k e r w o o d lo t i n y e a r 28 8> 9. 10. 11. 12 . 13. 14 . i n p e r c e n t o f t o t a l nu m bers of d ip lo p o d s s tu d ie d in 2 S e a s o n a l d i s t r i b u t i o n o f s t a g e s i n t h e 0^_ p i l o s u s p o p u l a t i o n i n 1 9 8 4 -1 9 8 5 ........................................................................ 34 S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r m ass and number o f p ilo s u s d u rin g s p r i n g y e a r 1.... ................................................................................................. 39 S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r m ass a n d num ber o f p ilo s u s d u rin g s p r i n g y e a r 2 .................................................................................................. 40 S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r m ass and num ber o f 0j>_ p i l o s u s d u r i n g summer y e a r 1 .................................................................................................. 41 S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r mass a n d num ber o f 0 . p ilo s u s d u rin g summer y e a r 2 .................................................................................................. 42 15 . S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r m ass and number o f ^ p i l o s u s d u r i n g f a l l y e a r 1 ...................................................................................................... A3 S c a t t e r d i a g r a m s f o r r e g r e s s i o n a n a l y s i s b e tw e e n l i t t e r mass and number o f 0 ^ p i l o s u s d u r i n g f a l l y e a r 2 ...................................................................................................... AA Seasonal v e r t i c a l d i s t r i b u t i o n o f 0. p ilo su s s t a g e s ( a v e r a g e t f / m e t e r )... .............. A7 V e r tic a l d i s t r i b u t i o n of 0 ^ p ilo s u s sta g e s i n p e r c e n t o f t o t a l f o r e a c h s e a s o n .................................... A9 19. S e a s o n a l f l u c t u a t i o n s i n p i l o s u s a c t i v i t y ................................... 62 20. Seasonal fluctuations in 63 21. S e a s o n a l f l u c t u a t i o n s i n P. b i v i r g a t u m a c t i v i t y 1 6. 17 . 18. InconBtans activity ....... ................. 6A Maximum and minimum t e m p e r a t u r e s on t r a p p i n g d a y s w i t h maximum d i p l o p o d a c t i v i t y and on d a y s p r e c e d i n g th e m , y e a r 1 (198A) ..................................................................................... 66 23* Maximum and minimum t e m p e r a t u r e s on t r a p p i n g d a y s w i t h maximum d i p l o p o d a c t i v i t y and on d a y s p r e c e d i n g th e m , y e a r 2 ( 1 9 8 5 ) ..................................................................................... 67 22. 2A. 25. 26. S easo n al f l u c t u a t i o n s in th e a c t i v i t y of 0 . p i l o s u s a d u l t s ( b y s e x e s ) ............................................................ 72 S easo n al f l u c t u a t i o n s in th e a c t i v i t y of P . l n c o n s t a n s a d u l t s ( b y s e x e s ) ...................................................... 73 S e a so n a l f l u c t u a t i o n s i n th e a c t i v i t y of P . b i v i r g a t u m a d u l t s ( b y s e x e s ) ........................ 7A viii I. INTRODUCTION The D i p l o p o d a , commonly known a s m i l l i p e d e s o r t h o u s a n d - l e g g e r s , a r e a n e n t i r e l y t e r r e s t r i a l g r o u p o f more t h a n 7 , 5 0 0 d e s c r i b e d s p e c i e s ( B a r n e s , 1 9 8 0 ) . They a r e fo u n d t h r o u g h o u t t h e w o r l d , e s p e c i a l l y i n t h e warm an d humid t r o p i c s , b u t a l s o i n a l l t e m p e r a t e r e g i o n s e x c e p t t h e m o st a r i d . M i l l i p e d e s a r e fo u n d up t o t h e snow l i n e and down t o t h e s e a l e v e l (W illia m s and H e fn e r, 1 9 2 8 ) . They l i v e u n d e r n e a t h s t o n e s , b a r k , l o g s , among l e a v e s an d i n t h e s o i l , c o n s u m in g l e a f l i t t e r an d o t h e r o r g a n i c d e b r i s a n d t h e r e b y c o n t r i b u t i n g t o t h e f o r m a t i o n o f hum us. A num ber o f s p e c i e s a r e c a v e i n h a b i t a n t s , o t h e r s a r e t r e e d w e l l e r s , and a few a r e com m ensal i n a n t n e s t s , b u t m o st a r e f r e e l i v i n g (B arnes, 1980). A l th o u g h D ip lo p o d a a r e v e r y w e l l d i s t r i b u t e d , n o t much i s known about t h e i r n a tu ra l h is to r y , life c y c l e s , and p o p u la tio n d e n s i t i e s . T h e r e a r e many p u b l i c a t i o n s on t h e m i l l i p e d e f a u n a o f N o r th A m eric a and E u r o p e , b u t m o s t o f t h e s e p a p e r s d e a l w i t h t h e taxonom y an d m o rp h o lo g y o f t h e g r o u p . The f i r 3 t s c i e n t i s t t o i n v e s t i g a t e A m e ric a n D ip lo p o d a was Thomas Say ( 1 8 2 1 ) who d e s c r i b e d 13 s p e c i e s , o f w h ic h h a l f s t i l l s t a n d g e n e ric a lly . B o llm an ( 1 8 9 3 ) p u b l i s h e d t h e f i r s t c a t a l o g u e o f N o r t h A m e ric a n m i l l i p e d e s . A s e c o n d was w r i t t e n by C h a m b e r lin ( 1 9 4 7 ) . The m o st r e c e n t c h e c k l i s t was made by C h a m b e r lin a n d H offm an ( 1 9 5 8 ) . F a u n i s t i c s t u d i e s h a v e b e e n p u b l i s h e d f o r o n l y f o u r s t a t e s : O hio ( W i l l i a m s and H efner, 1 9 2 8 ) ; M ic h i g a n ( J o h n s o n , 1 9 5 2 , 1 9 5 3 ) ; New Y ork ( B a i l e y , a n d f o r some a r e a s o f N o r t h C a r o l i n a ( S h e l l e y , 1978). 1 9 2 8 ); 2 P o p u la tio n s t u d i e s t h a t a tte m p t t o d e te rm in e d e n s i t y , age s t r u c t u r e , a n d v e r t i c a l o r h o r i z o n t a l d i s t r i b u t i o n a r e few i n n u m b er. E a r l y s t u d i e s w e re made i n Denmark, by B o r n e b u s c h ( 1 9 3 0 ) , who r e c o r d e d p o p u l a t i o n s o f u p t o 160 m i l l i p e d e s / m 1 i n d e c i d u o u s w o o d la n d s . Van d e r D r i f t ( 1 9 5 1 ) e s t i m a t e d a d e n s i t y o f 80 j u l l d s / m * ( m a i n l y C y l i n d r o l u l u s p u n c t a t u s ( L e a c h ) ) i n a b e e c h wood w i t h raw humus i n H o l l a n d . B lo w er and G a b b u tt (1 9 6 4 ) d e s c r i b e d th e p a p u l a t i o n s t r u c t u r e o f C y l i n d r o l u l u s la te strla tu B ( C u r t i s ) , C y l i n d r o l u l u s p u n c t a t u s , O p h y lu lu s p i l o s u s ( N e w p o r t , 1 8 4 2 ) , a n d l u l u s s c a n d i n a v i u s L a t z e l i n Devon Oak Wood i n E n g lan d , b u t co u ld n o t e s tim a te p o p u la tio n d e n s it y b ecau se th e y o n ly s a m p le d l i t t e r . D e n s i t y a n d s u r f a c e - a c t i v i t y o f d i p l o p o d s w ere a l s o r e c o r d e d by B lo w er ( 1 9 6 9 ) i n a n E n g l i s h w o o d la n d w h ere he s a m p le d s o i l and l i t t e r . S e v e r a l s c i e n t i s t s h av e I n v e s t i g a t e d t h e v e r t i c a l d i s t r i b u t i o n o f m i l l i p e d e s . Bocock and H e a t h ( 1 9 6 7 ) s t u d i e d t h e f e e d i n g a c t i v i t i e s i n s o i l o f G lo m e ris m a rg in a ta ( V i l l e r s ) i n r e l a t i o n to i t s v e r t i c a l d istrib u tio n . Dowdy ( 1 9 4 4 ) w o rk ed on t h e i n f l u e n c e o f t e m p e r a t u r e on v e r t i c a l m ig ra tio n of in v e r te b r a te s In h a b itin g d if f e r e n t s o i l ty p e s. P e i t s a l m i ( 1 9 7 4 ) i n v e s t i g a t e d t h e v e r t i c a l o r i e n t a t i o n an d a g g r e g a t i o n o f P r o t e r o i u l u s f u s c u s (AM S t e i n ) . And D a v i e s , H a s s a l l a n d S u t t o n ( 1 9 7 7 ) d e s c r i b e d t h e v e r t i c a l d i s t r i b u t i o n o f l s o p o d s an d d i p l o p o d s i n a d u n e g r a s s l a n d a t E a s t Y o r k s h ir e , E n g lan d . Some E u r o p e a n r e s e a r c h e r s ( M i l l e r , 1974; B lo w e r, 1974a; Sakwa, 1974) h a v e shown t h a t d i p l o p o d d i s t r i b u t i o n c a n be r e l a t e d n o t o n l y t o a v a ila b le food, but a lso , t o l e a f l i t t e r d e p t h , a r e a t o p o g r a p h y and 3 o t h e r f a c t o r s s u c h a s h u m i d i t y a n d t e m p e r a t u r e . V ery few r e p o r t s on v e r t i c a l d i s t r i b u t i o n a r e p u b l i s h e d f o r N o r t h A m e ric a . M ic h ig a n D ip lo p o d a h a v e b e e n i n v e s t i g a t e d by J o h n s o n ( 1 9 5 2 , 1 9 5 3 ) , Kane ( 1 9 8 1 ) a n d S n i d e r ( 1 9 8 0 ) . J o h n s o n r e c o r d e d 16 s p e c i e s n o t p r e v i o u s l y known fro m t h e s t a t e . The a u t e c o l o g y o f some o f t h e 31 s p e c i e s r e p o r t e d t o o c c u r i n M ic h i g a n i s known ( J o h n s o n , 1 9 5 2 ) . Many o f t h e s e s p e c i e s a r e h ard w o o d f o r e s t i n h a b i t a n t s and c a n be f o u n d a l l o v e r th e s t a t e . L a tz e l, S n i d e r ( 1 9 8 0 ) s t u d i e d t h e b i o e c o l o g y o f P o ly d e s m u s l n c o n s t a n s 1884, an d K ane ( 1 9 8 1 ) w o rk ed on t h e s y s t e m a t l c s , m o r p h o lo g y , and n a t u r a l h i s t o r y o f P o ly x e n u s l a g u r u s ( L i n n e ) . The p r e s e n t i n v e s t i g a t i o n d e a l s w i t h s p e c i e s c o m p o s i t i o n , v e r t i c a l d i s t r i b u t i o n , a n d a c t i v i t y o f t h r e e D ip lo p o d a s p e c i e s I n a m a p l e - b e e c h f o r e s t on t h e M ic h i g a n S t a t e U n i v e r s i t y M i c h i g a n . The campus i n E a s t L a n s i n g , s t u d i e d s p e c i e s w e r e : t h e j u l i d O p h y lu lu s p i l o s u s , t h e p o ly d e s m id P o ly d e s m u s i n c o n s t a n B an d F o ly z o n iu m b i v i r g a t u m (Wood) 1864, w h ic h i s th e o n ly r e p r e s e n t a t i v e o f th e c o lo b o g n a th fa m ily P o ly z o n iid a e i n M ic h ig a n ( J o h n s o n , 1952). O p h y l u l u s p i l o s u s h a s b e e n s t u d i e d by B low er and G a b b u t t ( 1 9 6 4 ) , B low er ( 1 9 7 0 , 1 9 7 4 a ) , M i l l e r ( 1 9 7 4 ) a n d B low er and M i l l e r ( 1 9 7 4 ) i n E n g l a n d . T h e s e a u t h o r s f o u n d t h a t 0 . p i l o s u s was one o f t h e m o st common j u l i d s a s s o c i a t e d w i t h l e a f l i t t e r , w h e re i t c o n t r i b u t e s t o l i t t e r d e g r a d a t i o n . O p h y lu lu s p i l o s u s i s a s e m e l p a r o u s s p e c i e s w h ic h upon r e a c h i n g m a t u r i t y , d i e s , u n l i k e m o st B r i t i s h j u l i d s w h ich become m a t u r e , b r e e d an d and s u r v i v e f o r s e v e r a l y e a r s ( B l o w e r , 1 9 6 9 ) . Compared t o o th e r B ritis h j u l i d s , f o r e x am p le Z u lu s s c a n d i n a v i u s w h ic h n e e d s 3 y e a r s 4 to m a tu re , 0 . p i l o s u s re a c h e s m a tu r ity in 2 y ears* I t h as been su g g e ste d ( B l o w e r , 1 9 69 ) t h a t t h i s t y p e o f n e o t e n i c c o n t r a c t i o n o f t h e l i f e h i s t o r y has c o n f e r r e d on th e s p e c i e s th e a b i l i t y to su c c e e d a s a c o l o n i s t . O p h y lu lu s p i l o s u s h a s s p r e a d o v e r t h e w o r ld and now d o m i n a t e s e x o t i c f a u n a s ( B lo w e r , 19 69 ). I n E u r o p e 0 . p i l o s u s i s fo u n d fro m t h e B r i t i s h I s l e s , w h e re i t i s t h e s e c o n d m o s t f r e q u e n t l y r e c o r d e d s p e c i e s ( B lo w e r , 1 9 8 5 ) , t o C e n t r a l E u r o p e , N o r t h e r n I t a l y , Y u g o s l a v i a and b o t h t h e E u r o p e a n p l a i n s a n d C a r p a t h i a n r e g i o n s o f t h e S o v i e t U n io n ; b u t i t h a s n o t b e e n r e c o r d e d fro m F i n l a n d , F r a n c e and B elg iu m ( B lo w e r , 198 5 ). I t h as a l s o been d e s c r i b e d fro m New Z e a la n d by Dawson ( 1 9 5 8 ) a n d J o h n s ( 1 9 6 2 , 1 9 6 7 ) . I n N o r t h A m erica 0 . p i l o s u s h a s b e e n s t u d i e d by J o h n s o n ( 1 9 5 2 , 1 9 5 3 ) , who d e s c r i b e d i t s m o rp h o lo g y and d i s t r i b u t i o n w i t h some n o t e s on i t s a u t e c o l o g y and n a t u r a l h i s t o r y . He r e p o r t e d 0 . p i l o s u s f o r t h e f i r s t t i m e i n M ic h i g a n a n d r e c o r d e d i t fro m 41 l o c a l i t i e s . J o h n s o n ( 1 9 5 2 ) a l s o c h a r a c t e r i z e d i t a s a n i n h a b i t a n t o f U lm u s-A cer a s s o c i a t i o n s i n Ingham C o u n ty (w h e r e t h e p r e s e n t s t u d y t o o k p l a c e ) . The s p e c i e s h a s a l s o b e e n r e p o r t e d fro m Ohio ( W i l l i a m s a n d H e f n e r , 1 9 2 8 ) , New J e r s e y , P e n n s y l v a n i a , Q uebec ( C h a m b e r l i n , 1 9 4 7 ) , Nova S c o t i a , V i r g i n i a , T e n n e s s e e , and t h e A p p a l a c h i a n s ( C h a m b e r lin and H o ffm an , 1 9 5 8 ) . I t t h u s seem s t h a t 0 ^ p i l o s u s i s fo u n d i n r e g i o n s c h a r a c t e r i z e d by t e m p e r a t e d e c id u o u s f o r e s t s ( M i l l e r , 1974). P o ly d e s m u s l n c o n s t a n s , l i s t e d by J o h n s o n ( 1 9 5 2 ) a s P . c o r i a c e u s P o r a t , i s c o n s i d e r e d a P a l e a r c t i c s p e c i e s fo u n d i n m o st E u r o p e a n c o u n t r i e s and t h e S o v i e t U n ion ( B lo w e r , 1 9 8 5 ) . I t was i n t r o d u c e d t o t h e 5 U n ite d S t a t e s , C anada and I c e l a n d ( B lo w e r , 1985) an d I s w i d e l y s p r e a d . I n t h e U n i t e d S t a t e s i t h a s b e e n r e p o r t e d fro m New Y ork ( B a i l e y , 1 9 2 8 ) , I n d i a n a ( a s 0 . t e s t i by B o llm a n , 1 8 8 7 ) , Ohio ( W i l l i a m s and H e f n e r , 1 9 2 8 ) , M a s s a c h u s s e t s , D e la w a re ( C h a m b e r l i n , 1 9 4 7 ) ; fro m N ew foun dland t o New E n g l a n d , O re g o n , B r i t i s h C olum b ia ( C h a m b e r lin and H e f n e r , 1928) and fro m 14 l o c a l i t i e s i n M ic h ig a n by J o h n s o n ( 1 9 5 2 , 1953) who d e s c r i b e d I t a s an i n h a b i t a n t o f g r a s s l a n d s i n Ingham C o u n ty . P olyd esm us l n c o n s t a n s was i n t e n s e l y s t u d i e d by S n i d e r ( 1 9 8 0 , 198 1, 19 84a) who d e s c r i b e d i t s e c o l o g y and l i f e cy cle. P o ly z o n iu m b i v i r g a t u m a n e n d em ic N o r t h A m eric an s p e c i e s i s t h e l e a s t w e l l known o f t h e t h r e e s t u d i e d s p e c i e s . I t was f i r s t d e s c r i b e d by Wood ( 1 8 6 4 ) a n d l a t e r by Cook and Loomis ( 1 9 2 8 ) . I t h a s b e e n r e p o r t e d fro m T e n n e s s e e (Cook a n d L o o m is, 1928; B a i l e y , 1 9 2 8 ) , Ohio ( W i l l i a m s and H efner, 1928; Dowdy, 1944; J o h n s o n , 1 9 5 2 ) , an d M ic h ig a n ( B o ll m a n , 1888, 1893; C h a m b e r lin , 1914; J o h n s o n , 1 9 5 2 ) . J o h n s o n ( 1 9 5 2 ) c h a r a c t e r i z e d P. b i v i r g a t u m a s a n i n h a b i t a n t o f U lm u s-A cer a s s o c i a t i o n s i n Ingham C o u n ty . The p r i m a r y o b j e c t i v e s o f t h e p r e s e n t r e s e a r c h w e r e : 1) t o s t u d y t h e com m unity s t r u c t u r e and d o m in an ce r e l a t i o n s h i p s o f t h e D ip lo p o d a f a u n a i n a b e e c h - m a p le f o r e s t ; 2 ) t o q u a n t i f y t h e s e a s o n a l p o p u l a t i o n d y n a m ic s o f t h e d o m in a n t s p e c i e s O p h y lu lu s p i l o s u s i n th e stu d y s i t e ; 3) t o s t u d y t h e i n f l u e n c e o f m o i s t u r e and t e m p e r a t u r e on t h e s p a t i a l d i s t r i b u t i o n o f t h e d o m in a n t 6 sp e c ie s' l i f e s t a g e s ; and 4) to d e s c r ib e th e a c t i v i t y p a t te r n s of 0 ^ p i l o s u s , P . l n c o n s t a n s an d b iv irg atu m d u rin g s p rin g , summer a n d f a l l * To a c c o m p l i s h t h e a b o v e , d a t a w e re c o l l e c t e d i n t h e f i e l d fro m A p r i l t o O c to b e r o f two c o n s e c u t i v e y e a r s ( 1 9 8 4 - 1 9 8 5 ) . A s p e c ts o f d ip lo p o d b io lo g y l i s t e d above have been o n ly s u p e r f i c i a l l y s t u d i e d in N o r t h A m e ric a . I n p a r t i c u l a r , no s t u d i e s o f t h e v e r t i c a l d i s t r i b u t i o n o f m i l l i p e d e s a r e i n e x i s t e n c e . The p r e s e n t s t u d y a s s e s s e d t h o s e a s p e c t s . 7 II. 1. MATERIALS AND METHODS D e s c rip tio n o f th e stu d y a re a The s t u d y s i t e was l o c a t e d i n B a k e r w o o d l o t , a b e e c h - m a p le w o o d lo t I n Ingham C o u n ty on t h e campus o f M ic h i g a n S t a t e U n i v e r s i t y . The w o o d lo t c o m p r i s e s 30 h a w i t h A cer s a c c h a ru m M a r s h , d o m i n a n t , f o l l o w e d by FagUB g r a n d i f o l i a E h r h . m ixed w i t h Q u e rc u s r u b r a L . a n d F r a x i n u s a m e r i c a n a L. A re a t o p o g r a p h y c o n s i s t s o f low h i l l s i n t e r s p e r s e d w ith pronounced d e p r e s s i o n s , among w h ic h f o u r p o n d s a r e f o u n d . T h i s s t u d y t o o k p l a c e a r o u n d t h e l a r g e s t p o n d , e n c o m p a s in g a p p r o x i m a t e l y 1 ha i n a r e a . D i f f e r e n t ty p e s o f s o i l o c c u rre d in Baker w o o d lo t. In d e p r e s s io n s t h e s o i l c o n s i s t e d o f m o d e r a t e l y d r a i n e d loam w i t h pH b e tw e e n 5 . 7 t o 6 .5 , an d a p p r o x i m a t e l y 9X o r g a n i c m a t t e r . H i l l s o i l s w ere more v a r i a b l e , w e l l d r a i n e d s a n d y lo a m s p r e d o m i n a t i n g w i t h pH 6 . 2 t o 6 . 6 , a n d a p p r o x i m a t e l y 6% o r g a n i c m a t t e r ( S n i d e r , covered w ith l e a f l i t t e r , its 1 9 8 0 ) . S o i l was a l w a y s t h i c k n e s s v a r y i n g s e a s o n a l l y . Fond s i z e a l s o v a r ie d w ith th e s e a s o n , b ein g l a r g e s t d u rin g s p rin g tim e a f t e r s n o w m e lt and s m a l l e s t d u r i n g A u g u s t , t h e d r y s e a s o n . 2. S a m p lin g m e th o d s A t o t a l o f 14 s a m p l i n g d a t e s w e re s e l e c t e d d u r i n g y e a r 1 ( 1 9 8 4 ) and 13 d u r i n g y e a r 2 ( 1 9 8 5 ) , e a c h s e t s p a n n i n g t h e m onths fro m A p r i l t o O c t o b e r . C o l l e c t i o n d a t e s i n e a c h y e a r w e re o r g a n i z e d i n t h r e e g r o u p s . T h e s e c o r r e s p o n d e d a p p r o x i m a t e l y t o t h e s p r i n g , summer an d f a l l 8 s e a s o n s . A l l c o l l e c t i o n d a t e s b e tw e e n A p r i l 1 and J u n e 21 w ere c l a s s i f i e d a s " s p r i n g " , b e t w e e n J u n e 22 a n d A u g u s t 21 a s " su m m e r" , and b e tw e e n A u g u st 22 and O c t o b e r 31 a s " f a l l " . 2 .1 . Q u ad rat sam p lin g Ten g e n e r a l s a m p le l o c a t i o n s , a p p r o x i m a t e l y 10 -1 5 m a p a r t and s u r r o u n d i n g a s m a l l p o n d , w ere s e l e c t e d ( F i g u r e 1 ) ; w i t h i n e a c h a 25cm x 25cm s a m p le o f t h e f o r e s t f l o o r w as t a k e n ra n d o m ly a t 2 w eek i n t e r v a l s . E ach s a m p le was d i v i d e d i n t o 3 s u b s a m p l e s : 1) The l e a f l i t t e r ( I X ) w h ic h was t h e u p p e r p o r t i o n o f t h e f o r e s t f l o o r m o st r e c e n t l y d e p o s i t e d i n c l u d i n g l e a v e s , t w i g s , b r a n c h e s , e tc . 2 ) The o r g a n i c l a y e r , o r 0 l a y e r ( 0 L ) , w h ic h c o n s i s t e d o f deco m p o se d a n d p a r t l y deco m po sed o r g a n i c m a t t e r , raw humus, w e l l d e l i m i t e d fro m t h e m i n e r a l s o i l . 3) The u p p e r l a y e r o f t h e A h o r i z o n (AL) w h ic h was t h e z o n e of p r o n o u n c e d d e c o m p o s i t i o n and h u m i f i c a t i o n , i n w h ic h o n l y few p l a n t re s id u e s a re re c o g n iz a b le . A t o t a l o f 30 s u b s a m p le s w e re o b t a i n e d p e r d a t e , c o n s i s t i n g o f a l l t h e l e a f l i t t e r p r e s e n t i n t h e q u a d r a t , t h e o r g a n i c l a y e r , an d t h e A l a y e r . The am ount o f s o i l c o l l e c t e d i n t h e A h o r i z o n v a r i e d fro m q u a d r a t t o q u a d r a t d e p e n d i n g on i t s n a t u r a l l y o c c u r r i n g d e p t h a t a g iv e n sam p lin g p o i n t . S am p les w e re i n m e d l a t e l y p l a c e d i n p l a s t i c b a g s and t r a n s p o r t e d to t h e l a b o r a t o r y i n a foam c o o l e r t o a v o i d o v e r - h e a t i n g . Even th o u g h 9 \ \ N. 4 N t POND V — •— F i g u r e 1. A p p ro x im a te q u a d r a t s a m p l i n g l o c a t i o n s i n B aker w o o d lo t. trail 10 T u l l g r e n h e a t e x t r a c t i o n i s commonly u s e d t o e x t r a c t o r g a n is m s fro m s o i l an d l i t t e r s a m p l e s , i t was n o t u s e d i n t h i s s t u d y . D u rin g p r e lim in a r y e x p e rim e n ts dead m i lli p e d e s , e s p e c i a l l y sm a ll j u v e n i l e s , w e re fo u n d i n s i d e r o l l e d l e a v e s a n d s e e d s a f t e r e x t r a c t i o n was c o m p le te d * M o re o v e r , w i t h t h i s method i t was i m p o s s i b l e t o f i n d eg g c a s e s . Hand s o r t i n g o f s a m p l e s w a s , t h e r e f o r e , p r e f e r e d . A l l s e e d s , wood a n d l e a v e s w e re c a r e f u l l y i n s p e c t e d u n d e r a p o w e r f u l m a g n i f y i n g g l a s s . M i l l i p e d e s w e re p r e s e r v e d i n 95% e t h a n o l a l c o h o l , w i t h g l y c e r i n a d d e d , and c l a s s i f i e d by s p e c i e s , 2 .2 . 2% l i f e s t a g e , an d s e x . P it-tra p p in g S u r f a c e a c t i v i t y o f m i l l i p e d e s was d e t e r m i n e d by t h e p i t f a l l t r a p m e th o d . T r a p s c o n s i s t e d o f a l a r g e , p e r m a n e n t l y e m p la c e d o u t e r c u p , and a s n a p - i n f u n n e l t o g u i d e t h e c a t c h i n t o t h e i n n e r c o l l e c t i n g cup ( F i g u r e 2 ) . The r im o f t h e o u t e r cup was f l u s h w i t h t h e s o i l s u r f a c e . Tw enty t r a p s w ere d i s t r i b u t e d a r o u n d t h e pond a t i n t e r v a l s o f a p p r o x i m a t e l y 10 m e t e r s . D u rin g t h e s e c o n d y e a r s e v e n o f t h e t r a p s w ere r e l o c a t e d b e c a u s e i n c r e a s e d pond s i z e t h r e a t e n e d t o f l o o d them . S a m p lin g t o o k p l a c e e v e r y o t h e r week fro m A p r i l t o O c to b e r d u r i n g 1984 and 1 9 8 5 . T r a p s w ere a c t i v a t e d f o r a p e r i o d o f 24 h o u r s , a n d t h e c a t c h was p r e s e r v e d i n 95% e t h a n o l w i t h 2% g l y c e r i n . D u rin g t h e f i r s t y e a r e t h y l e n e g l y c o l was u s e d a s t r a p p i n g medium i n t h e i n n e r c u p s . I n t h e s e c o n d y e a r a n i m a l s w ere l l v e - t r a p p e d an d p r e s e r v e d l a t e r a t t h e l a b o r a t o r y . The d i s t a n c e b e tw e e n t r a p s a t t h e en d o f t h e s e c o n d y e a r i s d e s c r i b e d i n T a b l e 1. 11 in n e r cup OU TE R CUP Table 1. Inter-trap distances. Traps Distance (meters) 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10 10-11 11-12 12-13 13-14 14-15 15-16 16-17 17-18 18-19 19-20 20-1 9 .0 2 1 5 .2 7 1 6 .9 2 1 1 .3 1 7 .6 8 1 0 .8 5 8 .5 0 9 .4 5 9 .1 1 9 .0 5 1 0 .1 4 9 .2 6 7 .3 8 7 .7 7 1 1 .0 3 8 .2 0 1 2 .1 9 1 3 .2 5 1 1 .7 9 1 5 .2 4 * * * * * * * * h * * * Traps that were moved from their original position after first year. 13 Table 2. Characteristics of developmental stages used to classify Ophyiulus pilosus. Stage SJ # podous segments # apodous segments I to V 4 22,23 2 7,8 JU VI to IX 29,30 44 6,7 2,3 AD IX 45,40 to XI 51,54 (males) 3 3,4 (females) 2 Data taken from Slower and Miller (1974). 14 2*3. C la s s ific a tio n of l i f e M illip e d e l i f e sta g e s s t a g e s w ere c l a s s i f i e d by c o u n t i n g t h e t o t a l number o f bo dy s e g m e n t s a C a t e g o r i e s e s t a b l i s h e d f o r 0 . p i l o B u s w e r e : s m a l l j u v e n i l e s ( S J ) , j u v e n i l e s ( J U ) , a n d a d u l t s (AD). T a b l e 2 shows t h e r a n g e o f s e g m e n t n u m b e rs w i t h l e g s ( p o d o u s ) and w i t h o u t l e g s ( a p o d o u s ) p re s e n t in each of th e se c a te g o r ie s . PolydesmuB i n c o n s t a n s w e re a l s o lum ped a s s m a l l j u v e n i l e s , J u v e n i l e s , an d a d u l t s , e n c o m p a s s in g a t o t a l o f e i g h t d e v e l o p m e n t a l s t a g e s . T a b l e 3 shows how t h e y w e re o r g a n i z e d f o r t h e p u r p o s e o f t h i s stu d y . T ab le 3. C h a r a c t e r i s t i c s o f d ev elo p m en tal s ta g e s used to e s t a b l i s h c a t e g o r i e s f o r P o ly d esm u s i n c o n s t a n s . C ateg o ry In sta r T o tal # of se g m e n ts SJ I * II III 7 9 12 JU IV V VI V II 15 17 18 19 AD V III 20 * l a r v a l stad iu m D ata t a k e n fro m S c h u b a r t ( 1 9 3 4 ) 15 S m a ll j u v e n i l e s o f P. b i v l r g a t u m w e re r a r e l y f o u n d , b u t when t h a t was t h e c a s e t h e y w ere s h o r t e r t h a n 2 mm. J u v e n i l e s c o n s i s t e d o f a n im a ls w ith l e s s t h a n 29 s e g m e n t s . A d u l t s p o s s e s s e d 30 t o 60 s e g m e n t s . 2 .4 . S o il m o istu re d e te rm in a tio n On e a c h d a t e , 10 s a m p l e s o f e a c h l a y e r w ere p l a c e d i n t i g h t l y co v ere d c o n t a in e r s 6 .5 cm h i g h by 9 cm d i a m e t e r . S am ples w ere w et w e ig h e d , d r i e d i n a 24°C o v e n f o r o ne week o r u n t i l no f u r t h e r w e i g h t l o s s o c u r r e d , an d w e ig h e d a g a i n . P e r c e n t m o i s t u r e o f e a c h l a y e r was o b t a i n e d by u s i n g t h e f o l l o w i n g e q u a t i o n : % M o i s t u r e - 100 x (Wet w e i g h t - Dry w e i g h t ) / Cry w e i g h t 2 .5 . L e a f l i t t e r m ass d e t e r m i n a t i o n The 10 l e a f l i t t e r s u b s a m p le s o b t a i n e d on e a c h d a t e w ere u s e d t o d e t e r m i n e l e a f l i t t e r m ass a f t e r a l l a n i m a l s , t w i g s , s e e d s , an d p i e c e s o f wood h ad b e e n rem o v e d . The l e a v e s w ere p l a c e d i n p a p e r b a g s , d r i e d i n a 2 4 ° C o v en f o r one w eek, and r e - w e i g h e d . 2 .6 . T e m p e r a t u r e and p r e c i p i t a t i o n T e m p e r a t u r e and p r e c i p i t a t i o n d a t a w ere o b t a i n e d fro m t h e U .S . D e p a r tm e n t o f Commerce N a t i o n a l W e a th e r S e r v i c e (N .W .S .) i n E a s t L an sin g . 16 III - 1. RESULTS AND DISCUSSION P h y s ic a l p a ra m e te rs 1 .1 . D ally te m p e ra tu re s Maximum an d minimum t e m p e r a t u r e s r e c o r d e d by t h e N a t i o n a l W e a th e r S e r v i c e d u r i n g t h e two y e a r s o f s t u d y a r e p r e s e n t e d i n F i g u r e s 3 , 4 . Low t e m p e r a t u r e s w e re r e p o r t e d a t t h e b e g i n n i n g o f t h e s t u d y d u r i n g b o t h y e a r s . H ow ever, warmer t e m p e r a t u r e s w ere o b t a i n e d e a r l i e r i n A p r i l o f y e a r 2 . I n a d d i t i o n many more w arm er d a y s w ere o b s e r v e d I n y e a r 2 ( e . g . 4 d a y s w i t h t e m p e r a t u r e s ab ove 2 0 *C i n y e a r 1 , an d 12 d a y s f o r y e a r 2 ) . D u rin g mid-May o f y e a r 1, more c o l d d a y s and t e m p e r a t u r e s b e lo w z e r o w ere r e c o r d e d . Summer t e m p e r a t u r e s w ere w arm er i n y e a r 1 t h a n i n y e a r 2 , many m ore d a y s w i t h t e m p e r a t u r e s a b o v e 2 6 .4 °C w ere r e p o r t e d ( e . g . , 21 d a y s I n J u n e , y e a r 1, and 8 d a y s i n y e a r 2 ) . The h i g h e s t t e m p e r a t u r e s r e c o r d e d f o r b o t h y e a r s o c u r r e d I n J u l y ( 3 3 . 0 *C y e a r 1 an d 3 2 . 4 " C y e a r 2 ). The warm p e r i o d was p r o l o n g e d u n t i l t h e b e g i n n i n g o f S e p te m b e r ( b o t h y e a r s ) . F a l l t e m p e r a t u r e s w ere v e r y s i m i l a r t o t h o s e o b t a i n e d I n sp rin g . 1 .2 . D a lly p r e c i p i t a t i o n D a i l y p r e c i p i t a t i o n r e c o r d e d by t h e N a t i o n a l W e a th e r S e r v i c e i s p r e s e n t e d i n F i g u r e s 5 and 6 . Snow was r e c o r d e d e a r l y i n A p r i l d u r i n g b o t h y e a r s , h o w ev er more snowy d a y s w ere r e p o r t e d f o r y e a r 2 . O nly i n • - # ua k u u u *-* umiuu 35- O TRAPS 0 QUADRATS TEMPERATURE C°C> 30- 25- 20- 15- 10 - 5 - 0- -5 DATES FIGURE 3. DAILY AIR TEMPERATURES, NATIONAL WEATHER SERVICE, EAST LANSING STATION, YEAR 1 (1984). UASUUU imuuu 0 TRAPS D QUADRATS TEMPERATURE (°C) 30- 20- 13- 10 - 8- 0- -3 FIGURE 4. DAILY AIR TEMPERATURES, NATIONAL WEATHER SERVICE, EAST LANSING STATION, YEAR 2 (1985). • PREEPTTMIOH ♦ SNOW/FROST o TRAPS a QUADRATS PRECIPITATION (CENTIMETERS) &000 4500 4000 1000 — 1500 1.000— OJ500 no DATES FIGURE 5. DAILY PRECIPITATION, NATIONAL WEATHER STATION, EAST LANSING STATION, YEAR 1 (1984). 6.000 • pREOPtunm + SNOwymsr o 0 TRAPS QUADRATS PRECIPITATION (CENTIMETERS) 5.000 4 .5 0 0 4 .0 0 0 3.500 3 .0 0 0 2 .5 0 0 2.000 1 .5 0 0 - 0.500 0.000 DATES FIGURE 6. DAILY PRECIPITATION, NATIONAL WEATIIER STATION, EAST LANSING STATION, YEAR 2, (1985). 21 y e a r 1 d i d s n o w f a l l o c c u r w e l l i n t o t h e m onth o f A p r i l , I n y e a r 2 p r e c i p i t a t i o n i n t h e fo rm o f r a i n was o b s e r v e d e a r l i e r i n t h e s p r i n g , h o w e v e r , more p r e c i p i t a t i o n d a y s w ere r e c o r d e d f o r y e a r 1. A t o t a l r a i n f a l l o f 4 4 . 4 2 cm was o b t a i n e d f o r t h e s t u d y p e r i o d o f y e a r 1 an d 5 8 .8 3 cm f o r y e a r 2 . As shown i n F i g u r e 5 r a i n was n o t ev en ly d i s t r i b u t e d th ro u g h o u t y e a r 1 as i t was i n y e a r 2 ( F i g u r e 6 ) . The d r y e s t and w a rm e st p e r i o d was o b s e r v e d d u r i n g summer o f y e a r 1 (1 2 * 3 4 cm o f r a i n ) , w h ere 4 r a i n y d a y s w ere r e c o r d e d i n J u n e , 9 i n J u l y , and 5 i n A u g u s t. The h i g h e s t a c c u m u l a t i o n o c c u r e d i n J u n e , w i t h a t o t a l o f 0 .4 5 7 2 cm. I n summer o f y e a r 2 r a i n was e v e n l y d i s t r i b u t e d ( F i g u r e 6 ) a n d t h e w a rm e s t d a y s w ere a l w a y s p r e c e d e d by r a i n . A f t e r t h e warm an d d r y summer, s e v e r a l r a i n y d a y s w ere r e c o r d e d e a r l y i n S e p te m b e r and i n O c t o b e r . D u rin g f a l l o f y e a r 1, few more d a y s w ere r e p o r t e d w i t h a t o t a l o f 1 5 .2 7 cm. H ow ever, i n y e a r 2 t h e t o t a l am ount o f p r e c i p i t a t i o n i n t h e f a l l was 2 1 .3 6 cm. 1 .3 . S u b s tra te m o istu re A v e ra g e p e r c e n t m o i s t u r e o f l e a f l i t t e r , 0 l a y e r and A l a y e r i s p re s e n te d i n F ig u re 7. A) Leaf l i t t e r : The l e a f l i t t e r was t h e l e a s t humid l a y e r i n b o t h y e a r s e x c e p t b e tw e e n w eeks 11, an d 13 o f y e a r 1, w h ere many r a i n y d a y s w ere r e c o r d e d a f t e r th e d r y e s t p e rio d of th e y e a r . M o i s t u r e p e a k s o f l i t t e r shown i n F i g u r e 7 c o r r e s p o n d t o d a y s o f AVERAGE PERCENT MOISTURE 22 70 LEAF UTTER 0 - LAYER A - LAYER 60 50 40 20 10 - A p ril Hay June Ju ly A ug. S e p t. O ct (a ) SAMPLING DATES tlO-n SO BO PERCENT MOISTURE 100 AVERAGE 30- A p ril May June Ju ly (b) SAMPLING DATES A ug. S e p t. O ct FIGURE 7 . MOISTURE IN % OF DRY WEIGHT, OF LITTER, 0 AND A LAYERS IN BAKER WOODLOT. 23 h ig h p r e c i p i t a t i o n in b o th y e a r s . The d r i e s t c o n d i t i o n s w e re o b s e r v e d b e t w e e n w eeks 4 a n d 9 o f y e a r 1 and w eek s 3 t o 7 i n y e a r 2 , t h e s e p e r i o d s c o r r e s p o n d s t o t h e d r y s e a s o n o f e a c h y e a r . The d r y n e s s o f t h e l e a f l i t t e r e n d e d e a r l i e r i n . y e a r 2 (w eek 8) t h a n i n y e a r 1 (w eek 1 1 ) . B) £ la y e r: The 0 l a y e r w eek s o f y e a r 2 . was t h e m o st humid l a y e r d u r i n g y e a r 1 an d i n a few A v e ra g e p e r c e n t m o i s t u r e was v e r y s i m i l a r a t t h e b e g in n in g o f b o th y e a r s , b u t d i f f e r e d th ro u g h o u t th e rem a in in g s e a s o n s . I n y e a r 1 t h i s p a r a m e t e r o s c i l l a t e d m ore t h a n i n y e a r 2 , w h ere p r e c i p i t a t i o n was e v e n l y d i s t r i b u t e d . Y e a r 2 showed a d r a m a t i c i n c r e a s e i n a v e r a g e p e r c e n t m o i s t u r e d u r i n g w eek 7 (108%) and week 10 (1 0 5 % ). I n y e a r 2 t h e 0 l a y e r was n o t o n l y more m o i s t i n t h e summer b u t a l s o d u rin g f a l l . C) A^ l a y e r : The r e s u l t s s im i la r to th o s e o b ta in e d f o r t h e A l a y e r d u r i n g y e a r 1 w ere v e r y f o r t h e 0 l a y e r . T h i s was a l s o t h e c a s e f o r y e a r 2 e x c e p t i n week 7 , w h e re no i n c r e a s e i n t h e a v e r a g e p e r c e n t a g e o f m o i s t u r e was o b s e r v e d . 1 .4 . L i tt e r cover T a b l e 4 s u m m a riz e s a v e r a g e l i t t e r m a s s /m 4 i n B aker w o o d lo t f o r each s e a s o n . L i t t e r c o v e r d im in ish e d c o n s id e r a b ly d u rin g y e a r 2, b e in g 24 Table 4. Average dry mass of forest floor litter (g/m1 ) SEASON YEAR 1 YEAR 2 Spring 545.28 328.37 Summer 409.12 258.68 Fall 325.72 256.11 25 o n l y a b o u t 2 / 3 o f t h e am o unt r e c o r d e d f o r s p r i n g o r summer o f y e a r 1 a n d a b o u t 3 / 4 t h e am ou nt i n t h e f a l l o f t h a t same y e a r . The h i g h e s t l i t t e r m ass was r e c o r d e d i n s p r i n g , d e c r e a s i n g s l o w l y t to w ard s f a l l . S p r i n g l i t t e r m ass i n y e a r 2 was v e r y s i m i l a r t o t h e am oun t o b t a i n e d i n f a l l o f t h e p r e v i o u s y e a r . The l i t t e r m ass was s m a l l e r i n summer an d f a l l o f y e a r I , an d a l m o s t t h e same f o r b o t h s e a s o n s i n y e a r 2. 2. S p e c i e s d o m in a n c e S i x D lp lo p o d a s p e c i e s o c u r r e d i n t h e s t u d y s i t e . T h e s e w ere P s e u d o p o ly d e s m u s s e r r a t u s (S ay ), 1821; A n i u l u s v e n u s t u s (W ood), 1864; D i p l o l u l u s c a e r u l e o c i n c t u s (W ood), 1864; 0 . p i l o s u s ; P . i n c o n s t a n s , and P . b i v i r g a t u m . O nly o n e s p e c im e n o f A^ v e n u s t u s a n d I)^ c a e r u l e o c i n c t u s , a n d two s p e c i m e n s o f P. s e r r a t u s w e re c o l l e c t e d d u r i n g t h e two y e a r s . B e c a u s e o f t h e low f r e q u e n c y o f o c c u r r e n c e o f t h e s e t h r e e s p e c i e s , s p e c i e s d o m in a n c e was a s s e s s e d u s i n g o n l y d a t a on 0 ^ p i l o s u s , P. I n c o n s t a n s , and b iv irg a tu m . To s e a s o n a l l y a s s e s s s p e c i e s d o m i n a n c e , t h e p e r c e n t o f t h e t o t a l num ber o f i n d i v i d u a l s c o l l e c t e d i n B a k e r w o o d l o t was co m p u ted f o r e a c h s p e c i e s ( T a b l e 5 , F i g u r e s 8 and 9 ) . O p h y i u l u s p i l o s u s was t h e m o st common s p e c i e s d u r i n g y e a r 1 and i n t h e s p r i n g and f a l l o f y e a r 2 . D u r in g summer o f y e a r 2 i t was s u r p a s s e d by j \ _ i n c o n s t a n s . The a p p a r e n t p o p u la tio n peak of i n c o n s t a n s , h o w e v e r , was d u e t o 61 h a t c h i n g s r e c o v e r e d fro m a s i n g l e s a m p le ( a s e v i d e n c e d by t h e l a r g e SE) a n d i s t h u s a som ew hat b i a s e d e s t i m a t e . Table 5 . Percent of total number for the three species studied in Baker woodlot each season. (a) YEAR 1 SPECIES 0. pilosus P. inconstans P. bivirqatum SPRING SUMMER FALL 93.26% 3.70% 3.04% 90.00% 6.67% 3.33% 89.51% 5.59% 4.90% TOTAL 91.53% 4.91% 3.56% (b) YEAR 2 SPECIES O. pilosus P. inconstans P. bivirqatum SPRING SUMMER FALL 91.18% 4.41% 4.41% 40.00% 56.36% 3.64% 86.26% 10.99% 2.75% TOTAL 75.93% 20.56% 3.57% FIGURE 8. SEASONAL FLUCTUATIONS IN PERCENT OF TOTAL NUMBERS FOR THE THREE SPECIES OF DIPLOPODS STUDIED IN BAKER NOODLOT IN YEAR 1. YEAR 1 — 80*- 60- — OF to. 40- — PERCENT TOTAL DIPLOPODS 1 = 3 Q. PILOSUS E23 P. INCONSTANS 1 0 0 - mm P. BIVIRGATUM 20- — n 7 3 - 86 r^ i vm 2 - 93 2 *40 SPRING rrm ...- 5 4 .0 0 4 *00 SUMMER 2 *00 5 1 .2 0 3 .2 0 FALL 2 .3 0 in d ./n 2 FIGURE 9. SEASONAL FLUCTUATIONS IN PERCENT OF TOTAL NUMBERS FOR THE THREE SPECIES OF DIPLOPODS STUDIED IN BAKER WOODLOT IN YEAR 2. YEAR 2 BO- 60- PERCENT OP TOTAL DIPLOPODS I I 0. PILOSUS EZa P. INCONSTANS 1 0 0 - Imm P. BMRGATUM 20 - AVERAGE DENSITY 3 3 .0 7 1 .6 0 S P R IN G 1 .6 0 1 7 .6 0 2 4 .8 0 SUMMER 1 .6 0 8 3 .7 3 ^ 0 .6 £ 2 .6 7 in d ./m 29 3. P o p u la tio n d e n s ity P o p u l a t i o n d e n s i t i e s o f t h e t h r e e common s p e c i e s a r e p r e s e n t e d i n T a b l e 6 an d F i g u r e 8 an d 9 . E a c h a v e r a g e r e p r e s e n t s t h e e x p e c t e d num ber o f i n d i v i d u a l s ( a l l s t a g e s c o m b in e d ) /m l ( a l l l a y e r s c o m b in e d ) d u r i n g a c o l l e c t i o n d a t e . O p h y iu lu s p i l o s u s showed t h e h i g h e s t p o p u l a t i o n d e n s i t y i n a l l s e a s o n s o f y e a r 1 an d i n s p r i n g a n d summer o f y e a r 2 . D u r in g y e a r 1 t h e maximum d e n s i t y was o b s e r v e d d u r i n g s p r i n g ( 7 3 . 8 6 m i l l l p e d e s / m * ) ■ H ow ever, i n y e a r 2 t h e maximum d e n s i t y was o b t a i n e d i n t h e f a l l ( 8 3 . 7 3 m i l l i p e d e s / m * ') . P o ly d esm u s I n c o n s t a n s was m o st a b u n d a n t i n summer o f y e a r 2 , w i t h a n e s t i m a t e d 2 4 . 8 0 m i l l i p e d e s / m * ’, and o c c u r r e d i n v e r y low n u m b e rs t h r o u g h o u t y e a r 1. The low d e n s i t y d u r i n g summer o f y e a r 1 was p r o b a b l y d u e t o a h o t and d r y summer ( S e c t i o n 1 ) . B low er ( 1 9 6 9 ) h a s s u g g e s t e d t h a t low nu m bers o r c o m p le te a b s e n c e o f P o ly d esm u s d u r i n g summer c a n r e s u l t fro m v e r y d r y c o n d i t i o n s . P o ly z o n iu m b i v i r g a t u m showed t h e l o w e s t p o p u l a t i o n d e n s i t y i n a l l s e a s o n s , e s p e c i a l l y d u r i n g y e a r 2 . The maximum d e n s i t y o b t a i n e d f o r t h i s s p e c i e s was 2 . 8 0 m l l l i p e d e s / m 1 i n f a l l o f y e a r 1. P o p u l a t i o n s t u d i e s o f o t h e r j u l i d s i n E u ro p e show d e n s i t i e s s i m i l a r t o t h o s e o b t a i n e d f o r 0 ^ p i l o s u s i n t h e p r e s e n t s t u d y . Van d e r D r i f t ( 1 9 5 1 ) f o u n d d e n s i t i e s o f 80 m i l l i p e d e s / m p u n c t a t u s an d I u I ub f o r C y lin d ro iu lu s s c a n d i n a v i u s i n a B eech wood w i t h raw hum us. H o w ev er, B low er ( 1 9 7 0 ) r e p o r t e d v e r y h i g h p o p u l a t i o n d e n s i t i e s f o r B r i t i s h f o r e s t s on l i m e s t o n e , r a n g i n g fro m 350 t o 650 m i l l i p e d e s / m 4 Table 6 . Seasonal variations in average population density from the three species studied in Baker woodlot ( + S .E . ) a (a) YEAR 1 SPECIES 0. pilosus P. inconstans P. bivirqatum SPRING 73.86 ± 10.85 2.93 + 1.11 2.40 + 0.83 SUMMER 54.00 + 16.15 4.00 + 1.64 2.00 + 1.30 FALL TOTAL 51.20 + 9.43 3.20 + 1.54 2.B0 + 1.39 61.71 + 6.67 3.31 + 0.79 2.40 + 0.65 FALL TOTAL tb) YEAR 2 SPECIES 0. Dilosus P. inconstans P. bivirqatum SPRING 33.07 + 7.90 1.60 t I.35 1.60 + 0.98 SUMMER 17.60 ± 4.09 24.80 + 24.39 1.60 + 0.96 83.73 + 24.71 10.67 + 4.15 2.67 + 1.73 40.00 + 7.15 10.83 + 7.58 1.85 + 0.67 31 r i s i n g t o 800 m i l l i p e d e s / m 1 a t t i m e s o f j u v e n i l e e m e r g e n c e . S ev e n ty -fiv e p e rc e n t o f th e se w ere j u l i d s l i k e 0 . p i l o s u s a n d I . s c a n d i n a v l u s . B lo w er a n d M i l l e r (1 9 7 4 ) f o u n d t h a t 0 . p i l o s u s showed f o u r tim es h ig h e r d e n s i t i e s th a n o th e r j u l i d s such a s I . s c a n d in a v lu s. I n a d d i t i o n , when s p e c i e s o f d i f f e r e n t o r d e r s w e re c o m p a re d , j u l i d s a l w a y s e x h i b i t e d t h e h i g h e s t a b u n d a n c e . B low er ( 1 9 7 0 ) , f o r i n s t a n c e , r e p o r t e d n u m b e rs /ra z o f 58 l u l u s , 38 P o ly d e s m u s a n d 6 T a c h y p o d o l u l u s a t E r n o c r o f t w o o d s. A bundance e s t i m a t e s o b t a i n e d f o r I n c o n s t a n s an d b iv irg a tu m w e re much s m a l l e r t h a n t h o s e r e p o r t e d by S n i d e r ( 1 9 8 0 , 1 9 8 4 a) and J o h n s o n ( 1 9 5 2 ) . S n i d e r ( 1 9 8 4 a ) e s t i m a t e d 450 i n d i v i d u a l s o f P. i n c o n s t a n s / m 2 i n A p r i l b u t d e n s i t i e s g e n e r a l l y d i d n o t e x c e e d 200 i n d i v i d u a l s / m 1 i n d e p r e s s i o n s a n d 5 t o 74 i n d i v i d u a l s / r a 3, i n u p l a n d a r e a s o f Baker w o o d lo t. E s tim a te d d e n s i t y ra n g e s i n u p la n d a r e a s ( S n i d e r , 1 9 8 4 a ) w e re s i m i l a r t o t h o s e o b t a i n e d f o r P^_ i n c o n s t a n s i n t h e p r e s e n t s t u d y ( T a b l e 6 ) . C o n d i t i o n s i n t h e s e a r e a s may h a v e b e e n s i m i l a r t o t h e h o t / d r y c l i m a t e o f 1 9 8 4 - 8 5 , w h ic h c o u l d b e p a r t l y r e s p o n s i b l e f o r low d e n s i t i e s . The m o st I m p o r t a n t c a u s a t i v e f a c t o r may h a v e b e e n i n t e n s i v e c o l l e c t i n g a c t i v i t y p r i o r t o 1 9 8 4 . D u rin g a n e x p e r i m e n t i n w h ic h d l p l o p o d s w e re o f f e r e d a s p r e y t o c a r a b i d b e e t l e s ( S n i d e r , 1984b), s e v e r a l t h o u s a n d i n d i v i d u a l s o f P . I n c o n s t a n s w e re removed f r o m t h e B a k e r w o o d lo t p o p u l a t i o n . S l i g h t l y i n c r e a s i n g a b u n d a n c e i n 1985 ( y e a r 2 o f t h e p r e s e n t s t u d y ) may h a v e r e p r e s e n t e d t h e b e g i n n i n g o f p o p u l a t i o n reco v ery . 32 G iv e n t h e known h i s t o r y o f p o p u l a t i o n d e p l e t i o n ( S n i d e r , 1984b) p r i o r t o t h i s s t u d y , d o m in a n c e r e l a t i o n s h i p s w i t h i n t h e d i p l o p o d com m unity o f B a k e r w o o d l o t ( T a b l e 6) may w e l l c h a n g e i n f u t u r e y e a r s ; e v e n t u a l l y t h e y may r e t u r n t o t h e " u n d i s t u r b e d ” s t a t e c h a r a c t e r i s t i c o f th e s i t e , i n w h ic h P . i n c o n s t a n s becom es d o m i n a n t ( S n i d e r , 1980) o r c o - d o m i n a n t w i t h (h_ p i l o s u s . J o h n s o n ( 1 9 5 2 ) r e p o r t e d d e n s i t i e s f o r P o ly z o n iu m b i v i r g a t u m i n S o u t h e r n M ic h ig a n f o r e s t s o f 30 t o 40 i n d i v i d u a l s / m 1. A c c o r d in g t o t h i s a u t h o r , P . b i v i r g a t u m a b u n d a n c e was g e n e r a l l y lo w e r i n N o r t h e r n f o r e s t s , b u t no n u m b e rs w ere g i v e n . P o p u la tio n s ta g e s t r u c t u r e S t a g e - s p e c i f i c d e n s i t i e s w ere com p uted f o r e a c h s e a s o n o n l y f o r t h e d o m in a n t s p e c i e s , 0 . p i l o s u s , i n o r d e r t o s t u d y s t a g e - r e l a t e d seasonal flu c tu a tio n s. The s t a g e s t r u c t u r e o f 0^_ p i l o s u s i s p r e s e n t e d i n T a b l e 7 and F i g u r e 1 0. O p h y i u l u s p i l o s u s i s a s e m e l p a r o u s s p e c i e s w h ic h l i v e s f o r two y e a r s ( B lo w e r an d M i l l e r , 1984). I t s l i f e c y c le s t a r t s w ith sm all j u v e n i l e s h a t c h e d a t t h e en d o f s p r i n g o r summer and e n d s a f t e r t h e y m a t u r e a n d r e p r o d u c e d u r i n g t h e i r s e c o n d summer. I n t h e p r e s e n t s t u d y , s m a l l j u v e n i l e s showed a n i n c r e a s e i n n um b ers fro m s p r i n g ( o v e r w i n t e r e d i n d i v i d u a l s ) t o f a l l i n b o t h y e a r s . T h i s i n c r e a s e was c a u s e d by h a t c h l i n g s e n t e r i n g t h e p o p u l a t i o n a t t h e end o f s p r i n g and summer, t h i s was o b s e r v e d d u r i n g b o t h y e a r s . S m all j u v e n i l e s showed a d e n s i t y Table 7. Stage-specific average number of 0. pilosus per square meter for each season ( ± S.E.). (a) YEAR 1 STAGE SPRING SUMMER FALL Small juveniles Juveniles Adults 2.66 + 36.80 t 34.40 + 1.91 8.15 5.94 30.80 + 11.40 16.00 + 4.17 7.20 + 2.43 40.80 ± 4.00 + 6.40 ± 8.37 1.25 1.97 Total 73.86 ± 10.85 54.00 t 16.15 51.20 ± 9.43 (b) YEAR 2 STAGE SUMMER SPRING FALL Small juveniles Juveniles Adults 3.20 + 12.27 ± 17.60 f 1.65 4.72 4.11 4.40 t 3.20 + 10.00 ± 1.98 1.83 2.90 20.27 ± 7.89 5B.13 + 16.76 5.33 + 2.34 Total 33,07 + 7.90 17.60 + 4.09 83.73 + 24.71 100 - N SMALL JUVENILES 9 0 - E Z2 JUVENILES * 8 0 - CEO ADULTS 70- % OF TOTAL * 60u 50- .p- * 40* 30- 20 10 0 SPRING SUMMER (1 984) FAIL SPRING SUMMER 2 FALL (1 9 8 5 ) FIGURE 1 0 . SEASONAL DISTRIBUTION OF STAGES IN THE 0 . PILOSUS POPULATION IN 1 9 8 4 -1 9 8 5 . 35 d e c r e a s e fro m f a l l o f y e a r 1 t o s p r i n g o f y e a r 2 . T h i s d e c r e a s e was c a u s e d by m o l t i n g o f t h i s c a t e g o r y t o t h e J u v e n i l e c a t e g o r y a t t h e end o f f a l l an d I n e a r l y s p r i n g . The j u v e n i l e p o r t i o n o f t h e p o p u l a t i o n showed a p r o g r e s s i v e d e c r e a s e i n d e n s i t y fro m s p r i n g t o f a l l o f y e a r 1 . The ju v e n ile d e c r e a s e was c a u s e d by m o l t i n g o f i n s t a r s V I I I and IX t o a d u l t . T h e s e new a d u l t s r e p l a c e d t h e t w o - y e a r - o l d a d u l t s d u r i n g t h a t t i m e . I n a d d i t i o n , u n fa v o ra b le w e ath e r c o n d itio n s caused e s t i v a t i o n in th e p r e v a i l i n g s t a g e s and an a p p a r e n t p o p u la tio n d e c r e a s e . The p o p u l a t i o n i n y e a r 2 showed a n i n c r e a s e fro m t h e p r e v i o u s f a l l , a g a i n c a u s e d by new j u v e n i l e s e n t e r i n g t h e p o p u l a t i o n . A f t e r t h e v e r n a l i n c r e a s e o f y e a r 2 , a d e c r e a s e was o b s e r v e d i n t h e summer, a g a i n a t t r i b u t a b l e t o c l i m a t i c c o n d i t i o n s . H o w ever, t h e p o p u l a t i o n showed a l a r g e d e n s i t y i n c r e a s e i n t h e f a l l , p r o b a b l y c a u s e d by a h i g h e r s u r v i v o r s h i p o f e s t i v a t i n g i n d i v i d u a l s ( s m a l l j u v e n i l e s an d j u v e n i l e s ) w h ic h now r e - a p p e a r i n t h e u p p e r s o i l h o r i z o n and a r e now s a m p le d f o r t h e f i r s t t i m e . I n a d d i t i o n some o f t h e s m a l l j u v e n i l e s ( i n s t a r V) m o l t e d t o j u v e n i l e s . The l a r g e s u r v i v o r s h i p was p r o b a b l y c a u s e d by m o i s t e r c o n d i t i o n s d u r i n g t h i s summer. The p r e s e n c e o f f e w e r s m a l l j u v e n i l e s an d m ore J u v e n i l e s c o u l d be i n d i c a t i v e o f a f a s t e r d e v e l o p m e n t t h a n i n t h e p r e v i o u s y e a r (B lo w e r ( 1 9 7 4 a ) ; B lo w er and M i l l e r ( 1 9 7 4 ) ) . The e f f e c t s w ere s u b t l e , h o w e v e r , m o st j u v e n i l e s c o l l e c t e d a t t h e end o f f a l l o f b o t h y e a r s w e re i n s t a r s V I I , V I I I , and IX , o v e r w i n t e r i n g a s s u c h . T h i s c o n f i r m e d d a t a g i v e n by B low er and M i l l e r (19 7 4 ) f o r th e B r i t i s h I s l e s . 36 The a d u l t s u b p o p u l a t l o n was m o s t a b u n d a n t i n s p r i n g , d e c r e a s i n g c o n s i s t e n t l y to w ard s f a l l > A ll tw o -y ea r a d u l t s a p p a r e n tly d ie d a f t e r r e p r o d u c i n g d u r i n g summer. A d u l t s c o l l e c t e d i n t h e f a l l w e re young a d u l t s w h ic h w ould m a t u r e t h e f o l l o w i n g s p r i n g . 5. S p a t i a l d i s t r i b u t i o n o f t h e d o m in a n t s p e c i e s 5 .1 . Seasonal h o riz o n ta l d is p e rs io n The v a r i a n c e / m e a n r a t i o th e p o p u la tio n d is p e r s io n o f te s t (E llio t, 1973 ) was u s e d t o e v a l u a t e p i l o s u s i n c o m p a r is o n w i t h a P o i s s o n s e r i e s . T h r e e s a m p le g r o u p s w e re c o n s i d e r e d , one p e r s e a s o n ( y e a r s and l a y e r s c o m b in e d ) , u s i n g a l l q u a d r a t d a t a fro m a g i v e n s e a s o n . B eca u se t h e num ber o f s a m p l e s was l a r g e , a g r e e m e n t w i t h t h e P o i s s o n m od el was t e s t e d w ith th e s ta n d a r d norm al v a r i a b l e : d - V w h e re V r e p r e s e n t s d e g r e e s o f f r e e d o m an d ')(*’ i s t h e v a r i a n c e / m e a n r a t i o p r o p o s e d by E l l i o t ( 1 9 7 3 ) . R e s u l t s a r e d e t a i l e d i n T a b l e 8 . As a l l v a l u e s o f d w e re much l a r g e r t h a n 2 . 5 8 , a g r e e m e n t w i t h a P o i s s o n s e r i e s was r e j e c t e d a t t h e 99% p r o b a b i l i t y l e v e l . T h i s i m p l i e s t h a t t h e p o p u l a t i o n was n o t d i s t r i b u t e d ran d o m ly . A ch ec k w ith th e g o o d n e s s - o f - f i t co n firm ed th e se r e s u l t s . The e x t r e m e l y h i g h v a l u e s o f d ( T a b l e 8 ) i n d i c a t e t h a t t h e d i s p e r s i o n o f t h e p o p u l a t i o n was s t r o n g l y a g g r e g a t e d . A y 1 t e s t f o r g o o d n e s s - o f - f i t w ith th e n e g a t iv e b in o m ia l d i s t r i b u t i o n gave p o s i t i v e r e s u l t s f o r s p r i n g d a t a . B e c a u s e o f d i f f e r e n t s a m p le s i z e s , a Table 8 . Variance/mean ratio test parameters for large samples from the 0, pilosus population. Data from both years were combined. SEASON n X/sample S* X* d DISPERSION Spring 120 3.34 22.59 804.85 24.73 aggregated Summer 80 2.24 17.08 602.37 22.18 aggregated Fall 70 4.07 38.98 660.84 24.65 aggregated * d is normally distributed N(0,1) and Prob(d > 2.58) = 0.0049 38 c o m p a r is o n o f t h e r e l a t i v e d e g r e e o f c l u m p in g b e tw e e n s e a s o n s was n o t p o s s i b l e . I t c a n be a s s u m e d , h o w e v e r, t h a t t h e d i s t r i b u t i o n o f 0 . p i l o s u s g e n e r a l l y c o n fo rm e d t o t h e n e g a t i v e b i n o m i a l . The a g g r e g a t e d d i s t r i b u t i o n o f 0 ^ p i l o s u s , a s w e l l a s o f o t h e r d ip lo p o d s ( S n id e r , 1 9 8 0 ) , c a n be i n p a r t r e l a t e d t o o v i p o s i t l o n h a b i t s . B low er an d M i l l e r ( 1 9 7 4 ) f o u n d t h a t one f e m a l e o f 0 . p i l o s u s c a n l a y an a v e r a g e o f m ore t h a n 72 e g g s . Eggs a r e l a i d i n m a s s e s a n d n ew ly h a t c h e d i n d i v i d u a l s h a v e v e r y low m o b i l i t y , t h u s c l u s t e r i n g t h e p o p u l a t i o n . 5 .2 . H o r i z o n t a l d i s t r i b u t i o n and l i t t e r mass A p o s s i b l e r e l a t i o n s h i p b e tw e e n t h e s p a t i a l d i s t r i b u t i o n o f 0 . p i l o s u s an d l e a f l i t t e r m ass was a s s e s s e d by l i n e a r r e g r e s s i o n f o r e a c h season. S c a t t e r d i a g r a m s o f l i t t e r m ass a n d num ber o f i n d i v i d u a l s i n e a c h q u a d r a t a r e p r e s e n t e d i n F i g u r e s 11 t o 16 f o r s p r i n g , summer, and fa ll. The p a r a m e t e r r z was u s e d t o v a l i d a t e t h e l i n e a r m o d e l. The s m a l l v a l u e s o f t h i s p a r a m e t e r ( T a b l e 9) i n d i c a t e d l a c k o f f i t w i t h t h a t m o d e l. I n p a r t i c u l a r , l e s s t h a n 8% o f t h e v a r i a b i l i t y i n number o f i n d i v i d u a l s p e r s a m p le i n y e a r 1 and l e s s t h a n 13% i n y e a r 2 c o u l d be e x p l a i n e d by l i n e a r r e g r e s s i o n . A lth o u g h r 1 was somewhat h i g h e r i n summer o f y e a r 1 and f a l l o f y e a r 2 , no s i g n i f i c a n t l i n e a r r e l a t i o n s h i p b e t w e e n t h e am ount o f l e a f l i t t e r and t h e d e n s i t y o f p i l o s u s became ap p a re n t. F i g u r e s 11 t o 16 i l l u s t r a t e t h i s l a c k o f c o r r e l a t i o n b e tw e e n d e n s i t i e s an d l i t t e r m a s s , an d no a d d i t i o n a l r e g r e s s i o n m o d e ls w e re FIGURE 11. SCATTER DIAGRAMS FOR REGRESSION ANALYSIS BETWEEN LITTER MASS AND NUMBER OF O. PILOSUS DURING SPRING YEAR 1. • SPRING - YEAR 1 y= 3 . 8 1 1 + O.OlOx NUMBER OF INDIVIDUALS PER SAMPLE 25* r = 0.0L2H3 20- 15• * 9 • « 105- • • a a • 9 • « 9 •a * • - 0- r 10.0 1 • • • •• I • * « « • • •! • • 1* T I ' l A—I f f ! —I—1—I—1—1—I - I 1"1—1—I—r i r i r " i 20.0 30.0 4 0 .0 5 0 .0 UTTER MASS (GRAMS) 60.0 i i'"i • • i “i ■ i ■ i t 7 0 .0 8 0 .0 FIGURE 12. SCATTER DIAGRAMS FOR REGRESSION ANALYSIS BETWEEN LITTER MASS AND NUMBER OF 0. PILOSUS DURING SPRING YEAR 2. SPRING - YEAR 2 y= 0.1*12 + O.OBUx r = 0 .2 5 2 9 8 M 0. 20 & : 01 1 Q 2 Q - Z fe 1 0 G * to 3 13 Z 5- 5.0 15.0 2 5.0 3 5 .0 UTTER MASS (GRAMS) 45.0 5 5 .0 65.0 FIGURE 13. SCATTER DIAGRAMS FOR REGRESSION ANAI.YS1S RETWF.F.tt LITTER MASS AMD 7 :u OF O. IMI.OSUS PUR IHU SUMMER YEAR 1. 30 SUMMER - YEAR 1 NUMBER OF INDIVIDUALS PER SAMPLE y= - 1 . 3 2 1 + 25- 0 .l85x r = 0.U9396 20- 15- 10 - 5- 0- 5.0 15.0 2 5 .0 3 5 .0 UTTER MASS (GRAMS) 55 .0 65 .0 7 5 .0 FIGURE 14. SCATTER DIAGRAMS FOR REGRESS IOH ANALYSIS BETWEEN LITTER MASS AND NUMBER OF O. PILOSUS DURING SUMMER YEAR 2. SUMMER - YEAR 2 0 .2 6 0 + 0 .0 5 5 x r = 0 .2 5 1 9 9 6- NUMBER OF INDIVIDUALS PER SAMPLE y= 0- 0 .0 10.0 20.0 LITTER MASS (GRAMS) 30.0 40 .0 FIGURE 15. SCATTER DIAGRAMS FOR REGRESSION ANALYSIS BETWEEN LITTER MASS AND NUMBER OF O. PILOSUS DURING FALL YEAR 1. FALL - YEAR 1 y= 1.221* + 0 .0 9 7 * y a. i r= 0.3 3 0 0 0 . - IS ,0 Q. a ; Q £ - lu o 5- n fii cn 3: =3 Z 0- 5.0 15.0 3 5 .0 UTTER MASS (GRAMS) 55.0 7 5 .0 FIGURE 16. SCATTER DIAGRAMS FOR REGRESSION ANALYSIS BETWEEN LITTER HASS AND NUMBER OF O. PILOSUS DURING FALL YEAR 2. 30FALL - YEAR 2 y= - 1 .2 5 7 + 0 . 398x r= 0 . 6 2 U9 8 in ftl 2 0 D. Q n 15- 2 0.0 10.0 20.0 5 0 .0 UTTER MASS (GRAMS) 60.0 Table 9. Values of r l for linear regression test betveen litter mass and number of 0. pilosus. SEASON YEAR 1 YEAR 2 Spring 0.0016 0.0640 Summer 0.2440 0.0635 Fall 0.1089 0.3906 Annual 0.0800 0.1300 46 t r i e d on t h e d a t a . An e x p e c t e d d i r e c t p r o p o r t i o n a l i t y b e tw e e n l i t t e r m ass and num bers o f 0 . p i l o s u s c o u l d n o t be c o n f i r m e d . A b r i e f e v a l u a t i o n o f p o t e n t i a l r e l a t i o n s h i p s b e tw e e n l i t t e r m o i s t u r e and p o p u l a t i o n d e n s i t y was e q u a l l y i n c o n c l u s i v e . The d i s t r i b u t i o n o f t h e s p e c i e s a p p e a r e d t o be a f u n c t i o n o f o t h e r , p o s s i b l y i n t e r a c t i n g p a r a m e t e r s ( e . g . t e m p e r a t u r e , am ount o f woody d e b r i s , o r e v e n A h o r i z o n c h a ra c te ristic s). 6* V e r t i c a l d i s t r i b u t i o n o f t h e d o m in a n t s p e c i e s 6 .1 . Seasonal d i s t r i b u t i o n D a ta p r e s e n t e d i n F i g u r e 17 and T a b l e 10 show t h a t l e a f l i t t e r was c o n s i s t e n t l y th e l e a s t p o p u la te d l a y e r d u rin g b o th y e a r s , e x c e p t d u rin g f a l l o f y e a r 2 . M ost o f t h e m i l l i p e d e s w e re p r e s e n t i n t h e A h o r i z o n d u r i n g s p r i n g and f a l l a n d i n t h e 0 l a y e r d u r i n g summer o f y e a r 1 an d 2. 6 .2 . S ta g e -sp e c ific d is tr ib u tio n A .l) S m a ll j u v e n i l e s No s m a l l j u v e n i l e s w e re fo u n d d u r i n g s p r i n g ( b o t h y e a r s ) i n t h e l e a f l i t t e r ( F i g u r e s 17 a n d 18 a n d T a b l e 1 1 ) . The few s m a l l j u v e n i l e s c o l l e c t e d w e re o v e r w i n t e r i n g fo r m s ( s t a d i a s IV and V) and w e re fo u n d i n t h e A l a y e r (100%) d u r i n g y e a r 1 an d fro m t h e 0 (6 6 .5 6 % ) a n d A l a y e r ( 3 3 .4 4 % ) i n y e a r 2 ( F i g u r e 1 8 ) . A dverse w e a th e r c o n d i tio n s a t th e b e g in n in g of each y e a r ( S e c tio n 1) may h a v e c a u s e d a b s e n c e o f t h e s t a g e i n l e a f l i t t e r , fo rc in g i t to 45 40 35 EZZJ ADULTS E Z 3 JUVENILES SMALL JUVENILES YEAR 1 ( 1 9 8 4 ) YEAR 2 ( 1 9 8 5 ) AVERAGE # / METER ■ 20 15 ♦aV 10 5 Mm ite 1 m 0LAYERS ^ SEASONS ± ® Spring Summer O A Fal I LL O 4 T” a Spring FIGURE 17. SEASONAL VERTICAL DISTRIBUTION OF 0 . PILOSUS STAGES (AVERAGE # / METER1) O ^ Summer O Fal I A Table 10, Seasonal vertical distribution of average number of 0, pilosus per square meter + S.E. (percent of season total). LAYER s YEAR 1 p R I LL OL AL 18.40 + 5.29 25.86 + 7.71 29.60 ± 5.88 G TOTAL 73.86 t 10.85 S U M M t?l E LL OL AL 9.60 ± 8.02 23.20 ± 6.30 21.20 + 5.74 R TOTAL 54.00 ± 16.15 F A L LL OL AL 4.40 + 2.43 21.20 ± 5.45 25.60 + 5.92 TOTAL 51.20 + 9.43 M ft % (24.93) (35.00) (40.07) YEAR 2 % 9.33 ± 3.51 11.74 ± 2.63 12.00 ± 4.02 (28.21) (35.51) (36.28) 33.07 ± 7.90 (17.78) (42.96) (39.26) 3. 20 ± 1.64 7.60 + 2.56 6.80 ± 2.49 • (18.18) (43.18) (38.64) 17.60 ± 4.09 ( 8.59) (41.41) (50.00) 31.47 ± 15.20 17.60 + 6.29 34.66 + 9.55 u T 83.73 ± 24.71 (37.59) (21.02) (41.39) YEAR 2 1 SEASON S SU F 1 S SU S SU ttS cq 00 AVERAGE/m2 ^ to to $ F S SU F CO O r- C\j ^ 00* CO IO PERCENT OF SEASON TOTAL 100----------------- S SU O 2 F O ^ C\| ^ CO K t o S SU F to O 2 I I VO II A LAYER Z Z a 0 LAYER s» m Small J u v e n i l e s LEAF LITTER Juveniles Adults FIGURE 18. VERTICAL DISTRIBUTION OF 0 . PILOSUS STAGES IN PERCENT OF TOTAL FOR EACH SEASON. Table 11. Spring vertical distribution of average number of 0. pilosus per square meter by stages ± S.E. (percent of season total). LAYER YEAR 1 % YEAR 2 % SJ LL OL AL 0.00 + 0.00 0.00 + 0.00 2.66 + 1.91 Total 2.66 t 1.91 ( 0.00) ( 0.00) (100.0) 0.00 + 0.00 1.07 + 0.75 2.13 + 1 .49 ( 0.00) (33.44) (66.56) 3.20 + 1.65 JU LL OL AL 6.67 + 2.47 14.93 + 6.65 15.20 + 3.85 Total 36.80 + 8.15 LL OL AL 11.73 ± 3.38 10.94 + 2.03 11.73 + 2.97 Total 34.40 ± 5.94 (18.13) (40.57) (41.30) 2.66 + 1.71 4.54 + 1.32 5.07 + 2.30 (21.68) (37.00) (41.32) 12.27 + 4.72 AD (34.10) (31.80) (34.10) 6.67 t 2.19 6.13 + 2.32 4.80 + 1.71 17.60 + 4.11 (37.90) (34.83) (27.27) 51 r e m a in i n t h e s o i l . S e v e r a l a u t h o r s ( D a v is e t a l , 1977; Dowdy, 1944 and Bocock and H e a t h , 1967) fo u n d t h a t d i p l o p o d s r e m a in d eep i n t h e s o i l d u r i n g u n f a v o r a b l e w e a t h e r c o n d i t i o n s ( w i n t e r and summer) and t h e i r v e r t i c a l m i g r a t i o n i s a c t i v a t e d by t e m p e r a t u r e . ■ Warm e a r l y summer t e m p e r a t u r e s p r o b a b l y t r i g g e r e d m i g r a t i o n o f o v e rw in te rin g in d iv id u a ls ( i n s t a r s IV an d V) a n d o f new ly h a t c h e d i n d i v i d u a l s ( I n s t a r s I I and I I I ) fro m t h e A l a y e r t o t h e u p p e r s o i l and l e a f l i t t e r ( F i g u r e 18 and T a b l e 1 2 ) . Warmer s u r f a c e t e m p e r a t u r e s ( S e c t i o n 1 . 3 ) and m ore a v a i l a b l e f o o d c r e a t e d f a v o r a b l e c o n d i t i o n s t h a t w ere n o t p r e s e n t b e f o r e . B low er an d M i l l e r (1 9 7 4 ) r e p o r t e d t h a t a t l e a s t one m onth was n e c e s s a r y f o r th e f i r s t i n d i v i d u a l s o f sta d iu m I I I t o a p p e a r i n th e f i e l d . I n d i v i d u a l s c o l l e c t e d fro m s o i l s a m p le s (A l a y e r ) m ust h a v e em erged fro m eg g s l a i d d u r i n g A p r i l , May and t h e b e g i n n i n g o f J u n e . I n a p r e l i m i n a r y s t u d y , 32 s m a l l j u v e n i l e s an d s e v e r a l e g g s w ere fo u n d i n s i d e an a c o rn i n th e l e a f l i t t e r . T h i s may i n d i c a t e t h a t t h e s p e c i e s l a i d i t s eggs n o t o n ly in th e s o i l b u t t h a t i t used o th e r r e s o u r c e s as w e l l . The p r e s e n c e o f e g g s an d i n s t a r s I I I i n a l l l a y e r s a l s o i n d i c a t e d t h a t summer was t h e h a t c h i n g s e a s o n f o r 0 ^ p i l o s u s . S m a ll j u v e n i l e s w ere d i s t r i b u t e d o v e r a l l h o r i z o n s d u r i n g f a l l . In y e a r 1 m o st w ere fo u n d i n t h e 0 and A l a y e r b u t i n y e a r 2 t h e y p r e f e r r e d th e le a f l i t t e r ( F i g u r e 18 an d T a b l e 1 3 ) . E a r l y o n s e t o f c o l d t e m p e r a t u r e s d u r i n g f a l l o f y e a r 1 ( F i g u r e 3) may h a v e c a u s e d m i g r a t o r y m ovements t o l o w e r s o i l l a y e r s . D u rin g t h i s s e a s o n 48.04% o f t h e s m a l l j u v e n i l e s ( i n s t a r s IV and V) w e re i n t h e 0 Table 12. Summer vertical distribution of average number of 0. pilosus per square meter by stages ± S.E. (percent of season total). LAYER YEAR 1 % YEAR 2 % LL OL AL 8.40 + 7.62 12.00 ± 4.92 10.40 ± 3.69 (27.27) (38.96) (33.77) 1.60 + 1.12 0.40 ± 0.40 2.40 + 1.67 (36.36) ( 9.09) (54.55) Total 30.80 ± 11.40 SJ 4.40 1.98 JU LL OL AL Total 0.80 ± 0.56 6.40 t 1.88 8.80 + 2.86 ( 5.00) (40.00) (55.00) 0.00 ± 0.00 2.40 + 1.77 0.80 ± 0.56 ( 0.00) (75.00) (25.00) 3.20 ± 1.83 16.00 ± 4.17 AD LL OL AL 0.40 + 0.40 4.80 ± 2.23 2.00 + 1.02 Total 7.20 + 2.43 ( 5.56) (66.67) (27.77) 1.60 ± 0.96 4.80 + 2.00 3.60 ± 1.67 10.00 ± 2.90 (16.00) (48.00) (36.00) Table 13. Fall vertical distribution of average number of 0. pilosus per square meter by stages ± S.E. (percent of season total) LAYER YEAR 1 % YEAR 2 % LL OL AL 4.40 + 2.43 19.60 t 5.23 16.80 + 4.21 (10.78) (46.04) (41.18) 12.80 + 6.25 2.67 ± 1.55 4.80 + 2.56 (63.15) (13.17) (23.68) Total 40.80 ± 8.37 SJ 20.27 + 7.89 JU LL OL AL 0.00 ± 0.00 1.60 ± 0.77 2.40 + 1.08 Total 4.00 + 1.25 LL OL AL 0.00 ± 0.00 0.00 + 0.00 6.40 ± 1.97 Total 6.40 ± 1.97 ( 0.00) (40.00) (60.00) 17.60 ± 8.69 12.80 + 5.11 27.73 + 8.12 (30.28) (22.02) (47.70) 58.13 + 16.76 AO ( 0.00) ( 0.00) (100.0) 1.07 ± 1.07 2.13 + 1.67 2.13 ± 1.27 5.33 ± 2.34 (20.08) (39.96) (39.96) 54 l a y e r an d 41.18% w e re i n t h e A. l a y e r . T h i s m i g r a t o r y movement p r o b a b l y c o n t i n u e d u n t i l t h e end o f f a l l when t h e a n i m a l s s t a r t e d h i b e r n a t i n g . D u r in g f a l l o f y e a r 2 m o s t s m a l l j u v e n i l e s w e re c o l l e c t e d fro m le a f l i t t e r ( 6 3 .1 5 % ) , i n d i c a t i n g t h a t t h e s t i m u l i c a u s i n g v e r t i c a l m i g r a t i o n i n y e a r 1 w e re n o t y e t p r e s e n t a t t h e t i m e . Downward m ig ra tio n p ro b ab ly o c c u rre d l a t e r in th e s e a so n . Some r e s e a r c h e r s (Dowdy, 1944; D a v ie s e t a l , 1977) h a v e fo u n d t h a t many i n v e r t e b r a t e s move downward when t h e t e m p e r a t u r e f a l l s c r i t i c a l le v e l, b e lo w a t h e t h r e s h o l d b e i n g a r o u n d 4 - 7 aC (Dowdy, 194 4, a n d Bocock a n d H e a t h , 1967) o r 4 -9 °C ( D a v i e s e t . a l . , 1 9 7 7 ) . I n t h e p r e s e n t s t u d y s i m i l a r t e m p e r a t u r e s w ere r e p o r t e d e a r l y i n f a l l o f y e a r 1 (S e c tio n 1 .1 ). A .2) Ju v e n ile s J u v e n i l e s w e re f o u n d i n a l l h o r i z o n s i n t h e s p r i n g o f b o t h y e a r s ( F i g u r e s 17 and 18 an d T a b l e 1 1 ) . The m a j o r i t y o f i n d i v i d u a l s o c u r r e d i n t h e A h o r i z o n (41.30% i n y e a r 1 a n d 41.32% i n y e a r 2 ) and i n t h e 0 l a y e r (40.57% i n y e a r 1 a n d 37% i n y e a r 2 ) . I t I s n o t known why t h i s s t a g e was p r e s e n t i n a l l l a y e r s d u r i n g A p r i l ( b o t h y e a r s ) , reg ard less o f c o l d t e m p e r a t u r e s o r t h e p r e s e n c e o f snow . I t i s p o s s i b l e t h a t j u v e n i l e s respond to d i f f e r e n t te m p e ra tu re s t i m u l i th a n sm a ll j u v e n i l e s . F o llo w in g a su b z e ro w i n t e r , te m p e r a tu r e s above 5 . 5 ' C r e c o r d e d i n M arch a n d e a r l y A p r i l ( S e c t i o n 1 . 1 ) , t h i s may h a v e t r i g g e r i n g upw ard m o b i l i t y . Dowdy ( 1 9 4 4 ) f o u n d t h a t t e m p e r a t u r e s b e tw e e n 3 . 3 ° C an d 7 . 1 5 ®C i n f l u e n c e d u p w ard m ovem ents i n s o i l w ere 55 in v e r t e b r a t e s d u rin g s p r in g . D u r in g summer o f b o t h y e a r s f e w e r j u v e n i l e s w ere c o l l e c t e d m a in ly fro m t h e 0 l a y e r (40% i n y e a r 1 and 75% i n y e a r 2 ) , a n d A h o r i z o n s (55% i n y e a r 1 a n d 25% i n y e a r 2 ) ( F i g u r e 18 and T a b l e 1 2 ) . P r e s e n c e o f j u v e n i l e s i n s o i l d u r i n g summer o f b o t h y e a r s may be i n d i c a t i v e o f u n fa v o ra b le c o n d itio n s in th e le a f l i t t e r . D r y n e s s and summer h e a t ( S e c t i o n 1) c o u l d h a v e t r i g g e r e d downward m i g r a t i o n and e s t i v a t i o n o f j u v e n i l e s i n o r d e r t o s u r v i v e t e m p e r a t u r e s t r e s s . The num ber o f s u r v i v o r s w ould d e p e n d on t h e i n t e n s i t y o f t h e s e c l i m a t i c c o n d i t i o n s ( L e v l n g s an d W in d s o r , 1 9 8 5 ) . I t h a s b e e n known ( O ' N e i l l , 1969; L e w is , 1 9 7 1 a , 1971b, 1974) t h a t t h e a n n u a l m o lt i n some m i l l i p e d e s c o r r e s p o n d e d t o t h e p e r i o d when t h e f o r e s t f l o o r became d r y . At t h i s tim e m i l l i p e d e s b u rro w e d i n t o l o g s ( O ’N e i l l , 1969) o r m i g r a t e d down i n t o t h e s o i l , b u i l d i n g t h i c k w a l l e d m o l t i n g c h a m b e rs and e n t e r i n g d i a p a u s e t h r o u g h t h e d r y s e a s o n ( L e w i s , 1 9 7 4 ) . T h e s e a r e m e ch an ism s w h ic h p r o t e c t t h e p o p u l a t i o n d u r i n g c l i m a t i c s t r e s s , p a r t i c u l a r l y i n t r o p i c a l r e g i o n s ( L e w is , 1974). D e s s i c c a t i o n i s one o f t h e m o st i m p o r t a n t fo rm s o f s t r e s s t o w h ic h m i lli p e d e s a r e s u b je c t in t h e i r n a t u r a l h a b i t a t ( O 'N e i ll, 1969). A f t e r a n u n f a v o r a b l e summer, j u v e n i l e s r e m a in e d i n t h e A h o r i z o n (60%) an d 0 l a y e r (40%) d u r i n g f a l l o f y e a r 1 , b u t o c u r r e d i n a l l s o i l h o r i z o n s (47.70% i n t h e A h o r i z o n , 30.28% I n t h e l e a f l i t t e r , and 22.02% i n t h e 0 l a y e r ) d u r i n g f a l l o f y e a r 2 ( T a b l e 1 3 ) . The b e h a v i o r o f j u v e n i l e s i n t h e f a l l o f b o t h y e a r s was t h u s v e r y s i m i l a r t o t h a t e x h i b i t e d by s m a l l j u v e n i l e s d u r i n g t h e same s e a s o n . 56 A .3 ) A d u lts A d u l t s w ere f o u n d I n a l l h o r i z o n s d u r i n g s p r i n g o f b o t h y e a r s ( F i g u r e s 17 an d 18 an d T a b l e 1 1 ) . T h i s s u g g e s t e d t h a t a d u l t s s t a r t e d t h e i r p o s t - h i b e r n a t i o n a c t i v i t y v e r y e a r l y i n t h e s p r i n g . S m a ll j u v e n i l e s d e n s i t i e s ( F i g u r e s 17 a n d 18) a n d p r e s e n c e o f e g g s i n d i s s e c t e d f e m a l e s e a r l y i n t h e summer i n d i c a t e d t h a t s p r i n g was t h e re p ro d u c tiv e season f o r th e s p e c ie s . A s u b t l e p r e f e r e n c e f o r l e a f l i t t e r i n b o t h y e a r s (34.1% i n y e a r 1 and 37.9% i n y e a r 2) s u g g e s t e d t h a t s u r f a c e - a c t i v l t y i s b e n e f i c i a l t o th e s p e c i e s . I t g iv e s th e a d v a n ta g e o f a tw o -d im e n s io n a l r a t h e r th a n a t h r e e - d i m e n s i o n a l h a b i t a t t o s e a r c h f o r a m a te and a l s o o f f e r s a r i c h e r s o u r c e o f fo o d t h a n t h e s o i l ( L e w i s , 1 9 7 4 ) . F i g u r e s 17 an d 18 a l s o show , h o w e v e r , th a t an d 31.8% i n 0 l a y e r a d u l t s w e re common i n t h e s o i l (34.1% i n A h o r i z o n d u r i n g y e a r 1 , and 27.27% i n A h o r i z o n a n d 34.83% in th e 0 la y e r d u rin g y e a r 2 ). A f te r th e s p r in g re p r o d u c tiv e s e a s o n , ex ten d ed i n t o th e b e g in n in g o f summer, s u r v i v i n g a d u l t s ( S e c t i o n 4 ) m i g r a t e d i n t o t h e s o i l . 1, 66.67% w e re f o u n d in le a f l i t t e r In y ear i n t h e 0 l a y e r , 27.77% I n t h e A h o r i z o n and 5.56% ( T a b l e 1 2 ) . I n y e a r 2 , 48% w ere p r e s e n t i n t h e 0 l a y e r , 36% i n t h e A h o r i z o n a n d 16% i n t h e l e a f l i t t e r . The d r y , warm summer o f y e a r 1 may h a v e c a u s e d more p r o n o u n c e d v e r t i c a l m i g r a t i o n i n o r d e r t o s u r v i v e t h e d r y s e a s o n . The l a r g e body s i z e o f a d u l t s a l l o w s them t o s u r v i v e d e s s i c a t i o n b e t t e r t h a n s m a l l e r s t a g e s ( L e w i s , 1 9 7 4 ) . H ow ever, th e y can n o t s u r v iv e ex trem e c o n d i t i o n s , b e c a u se th e y la c k th e a b i l i t y 57 t o c o n s t r u c t p r o t e c t i v e m o l t i n g c h a m b e rs ( L e w is 1 9 7 1 a , 1 9 7 1 b , 1 9 7 4 ) . Even i n t h e t e m p e r a t e c o n d i t i o n s o f B a k e r w o o d l o t , many d e a d a d u l t s w ere fo u n d d u r i n g h a n d c o l l e c t i n g . A d u l t s c o l l e c t e d a t t h e end o f summer w ere p r o b a b l y yo un g a d u l t s , h a v i n g m o l t e d fro m j u v e n i l e t o a d u l t a t t h a t tim e ( S e c t i o n 4 ) . The few a d u l t s w h ic h s u r v i v e d t h e summer w ere p r e s e n t i n t h e A l a y e r (100%) d u r i n g f a l l o f y e a r 1 and i n e v e r y h o r i z o n (39.96% i n A h o r i z o n , 3 9 . 9 6 i n t h e 0 l a y e r and 2 0 .0 8 i n t h e l e a f l i t t e r ) d u r i n g f a l l y e a r 2 ( T a b l e 1 3 ) . F a l l v e r t i c a l d i s t r i b u t i o n p a t t e r n s w e re t h u s s i m i l a r f o r a l l l i f e s t a g e s . Young a d u l t s w ould o v e r w i n t e r i n t h e A h o r i z o n , m i g r a t i n g t o t h e u p p e r s o i l an d l e a f l i t t e r t o r e p r o d u c e t h e fo llo w in g s p rin g . 7. S urface a c t i v i t y 7 .1 . T o t a l num ber o f i n d i v i d u a l s c a p t u r e d C a t c h e s fro m a l l 20 t r a p s w ere a d d e d t o o b t a i n f r e q u e n c i e s f o r e ac h sa m p lin g d a t e , b e c a u se c o n s id e r i n g i n d i v i d u a l t r a p s d id n o t g iv e a d d i t i o n a l i n f o r m a t i o n . The m ost a b u n d a n t s p e c i e s was 0 . p i l o s u s . The o t h e r two s p e c i e s w e re s c a r c e , a c c o u n t i n g f o r a b o u t 1 /5 o f t h e t o t a l . t o t a l o f 472 i n d i v i d u a l s w ere A c a p t u r e d i n y e a r 1 . Among t h e s e , 78% ( 3 6 8 ) w e re 0 . p i l o s u s , 17% ( 8 3 ) w ere P . i n c o n s t a n s an d 5% ( 2 1 ) P . b i v i r g a t u m . I n y e a r 2 , 206 i n d i v i d u a l s w ere c a p t u r e d . O p h y iu lu s p i l o s u s a c c o u n t e d f o r 87% ( 1 7 9 ) o f t h e t o t a l , P . i n c o n s t a n s f o r 6% ( 1 3 ) a n d P. b i v i r g a t u m f o r 7% ( 1 4 ) . The h i g h p e r c e n t a g e s o b t a i n e d f o r 0 . p i l o s u s 58 i n d i c a t e d t h a t t h i s s p e c i e s was t h e m o st a c t i v e , a n d c o n f i r m e d i t s d o m i n a n t p o s i t i o n i n t h e com m unity ( S e c t i o n 2 . 1 ) . A s i m i l a r d i s t r i b u t i o n h a s b e e n r e p o r t e d f o r t h e B r i t i s h I s l e s ( B l o w e r , 1979) w h e re p i l o s u s was t h e d o m i n a n t s p e c i e s i n s e v e r a l f o r e s t s s t u d i e d . The num ber o f i n d i v i d u a l s o f a l l s p e c i e s t r a p p e d i n y e a r 1 was d o u b l e t h e t o t a l num ber f o r y e a r 2 . T h i s d e c r e a s e i n y e a r 2 may h a v e b e e n t h e r e s u l t o f a r e d u c t i o n i n p o p u l a t i o n d e n s i t y c a u s e d by summer d r o u g h t, y e a r 1 sa m p lin g a c t i v i t i e s (e .g ., t r a p p i n g and hand c o l l e c t i n g ) and p o s s i b l y by p r e d a t i o n . Q u a n t i t a t i v e p o p u l a t i o n d a t a a l s o showed a m arked r e d u c t i o n i n p o p u l a t i o n d e n s i t y fro m y e a r 1 t o year 2. S i m i l a r r e d u c e d c a t c h e s w e re d e s c r i b e d by F a i r h u r s t ( 1 9 7 9 ) who d o c u m e n te d a d e c r e a s e i n t h e num ber o f i n d i v i d u a l s t r a p p e d a f t e r t h e f i r s t y e a r . He p o i n t e d o u t t h a t t h i s was r e l a t e d t o a d e c r e a s e i n p o p u l a t i o n s i z e d u e t o o v e r - t r a p p i n g and n o t t o p e r i o d i c p o p u l a t i o n o u t b r e a k s a s r e p o r t e d by B arlo w ( 1 9 5 7 ) . The e f f e c t o f p r e d a t o r s on m i l l i p e d e a c t i v i t y and d e n s i t y h a s n o t b e e n t a k e n i n t o c o n s i d e r a t i o n by many a u t h o r s , b u t a n e f f e c t i v e p r e d a t o r ca n p o t e n t i a l l y i n f l u e n c e p o p u la tio n d e n s i t y . S n id e r (1984b) fo u n d t h a t c a r a b i d an d s t a p h y l i n i d b e e t l e s c o u l d l i v e on a m i l l i p e d e d i e t i n l a b o r a t o r y e x p e r i m e n t s , and w ere c a p a b l e o f c o n s u m in g l a r g e n u m b e rs o f d i p l o p o d s p e r d a y . S n i d e r ( 1984b) r e p o r t e d t h a t a l l s t a g e s o f P^_ i n c o n s t a n s w e r e s u c e p t i b l e t o s e v e r a l s p e c i e s o f p r e d a c e o u s b e e t l e s . A d u lt O p h y lu lu s p i l o s u s w e re a l s o o f f e r e d a s p r e y by S n i d e r ( 1 9 8 4 b ) , b u t t h e r e i s no d o u b t t h a t t h e y c a n e a t j u v e n i l e s a n d s m a l l 59 j u v e n i l e s a s w e ll ( p e r s o n a l o b s e r v a tio n s ) * These in m a tu re s ta g e s te n d t o c l u s t e r so t h a t , one b e e t l e c o u l d d e c i m a t e a w h o le c l u s t e r i n a s h o r t p e r io d o f tim e . 7 .2 . S ta g e -sp e c ific a c tiv ity S t a g e - s p e c i f i c c a t c h e s a r e shown i n T a b l e 14. C a t c h e s o f s m a l l j u v e n i l e s w ere i n f r e q u e n t , r e p r e s e n t i n g o n l y 1% o f a l l i n d i v i d u a l s c o l l e c t e d i n y e a r s 1 a n d 2 , and a t t r i b u t a b l e t o low m o b i l i t y o f t h e s t a g e . F i t - t r a p p i n g i s n o t a good m ethod t o c o l l e c t s m a l l j u v e n i l e s , n o t e v e n d u r i n g summer a n d f a l l when t h e y a r e more a b u n d a n t . A d u l t s w e re m o s t a c t i v e , c o n s t i t u t i n g 89% o f t h e t o t a l i n y e a r 1 a n d 83% i n y e a r 2. O th er a u t h o r s have found t h a t s m a ll j u v e n i l e s a r e in d e e d re la tiv e ly in a c tiv e . S n i d e r ( 1 9 8 1 ) r e p o r t e d t h a t f i r s t i n s t a r s o f P. i n c o n s t a n s showed a t e n d e n c y t o a g g r e g a t e n e a r t h e em pty eg g c h a m b e r. I n t h e p r e s e n t s t u d y , s m a l l j u v e n i l e s n e a r em pty ch a m b e rs w ere fo u n d i n le a f l i t t e r ( s e e S e c t i o n 6 . 2 ) . B low er and M i l l e r ( 1 9 7 4 ) r e p o r t e d t h a t i n s t a r I I o f 0 . p i l o s u s c o u l d w a lk o u t fro m t h e eg g c a p s u l e b u t w ere re la tiv e ly in a c tiv e . I n s t a r I I I , w h ic h i s t h e n o r m a l s t a g e f o r t h i s s p e c i e s t o l e a v e t h e n e s t , w e re a l s o n o t v e r y a c t i v e . The f o u r s m a l l j u v e n i l e s t r a p p e d i n y e a r 1 a n d t h e two i n y e a r 2 w e re a l l t h i r d in sta rs. H ig h f r e q u e n c y o f a d u l t s i s p r o b a b l y r e l a t e d t o t h e f a c t t h a t m i l l i p e d e s a c t i v e l y s e a r c h f o r m a te s an d o v i p o s i t i o n s i t e s 1 9 71b, 1 974; B a rlo w , 1958; B a n e r j e e , (L ew is, 1967a). I t a p p e a rs t h a t a d u l t s Table 14. Distribution among stages of pit-fall trapped individuals (all species combined). STAGE Small juvenles Juveniles Adults YEAR 1 YEAR 2 4 2 47 32 421 172 61 move t o t h e s u r f a c e I n s e a r c h o f m a t e s , g i v i n g them t h e a d v a n t a g e o f s e a r c h i n g I n a tw o - d i m e n s i o n a l r a t h e r t h a n a t h r e e - d i m e n s i o n a l h a b i t a t . A ls o t h e s o i l s u r f a c e p r o v i d e s a r i c h e r s o u r c e o f fo o d th a n th e s o i l b u t has th e p o t e n t i a l d isa d v a n ta g e of a llo w in g in c re a s e d p r e d a t i o n (L e w is, 1971b). 7 .3 . Seasonal a c t i v i t y p a tte r n s A) At s p e c i e s l e v e l : D a ta f o r b o t h y e a r s ( F i g u r e s 19t o 2 1 ) showed an a c t i v i t y p e a k for e a c h s p e c i e s . I n 0 . p l l o s u s i t o c u r r e d i n A p r il- M a y w i t h t h e h i g h e s t num b ers c a p t u r e d e a r l y i n May; P. i n c o n s t a n s was m o st a c t i v e i n J u n e - J u l y , w ith a d i s t i n c t p eak i n Ju n e ; P. b iv ir g a tu m a c t i v i t y peaked in S e p te ra b e r-O c to b e r. I t i s s i g n i f i c a n t t h a t none o f th e s e peaks o v e rla p p e d , i n d i c a ti n g s e a s o n a li ty of re p ro d u c tiv e b eh av io r ( a c t iv a t e d by t e m p e r a t u r e o r p r e c i p i t a t i o n ) and t h e p o s s i b i l i t y o f s p e c i a l i z a t i o n to av o id i n t e r s p e c i f i c c o m p e titio n f o r re s o u rc e s d u rin g a g iv e n se aso n . B low er ( 1 9 7 9 ) r e p o r t e d t h a t when two s p e c i e s ( 0 . p i l o s u s and M ic ro c h o rd e u m a s c u t e l l a r e ( R i b a u t ) ) w ere a t t h e i r h i g h e s t b io m a s s s i m u l t a n e o u s l y , t h e y w ou ld n e e d m o st o f t h e i r fo o d a t t h e same ti m e and p r e s u m a b l y c o n c e n t r a t e d on d i f f e r e n t f o o d i t e m s . I f t h e same r e s o u r c e was u s e d by two o r m ore s p e c i e s t h e maximum b io m a s s o f e a c h s p e c i e s w o uld b e r e a c h e d a t d i f f e r e n t t i m e s , t h e r e b y a v o i d i n g c o m p e t i t i o n te m p o ra lly . 0. PILOSUS YEAR 1 ( 3 6 8 ) YEAR 2 ( 1 7 9 ) 75- 50- # OF INDIVIDUALS 1GO- 25- su FIGURE 19. SEASONAL FLUCTUATIONS IN O. PILOSUS ACTIVITY. S = SPRING SU = SUMMER F = FALL P. INCONSTANS # OF INDIVIDUALS 28 •-- < YEAR 1 ( 8 3 ) * - ■ YEAR 2 ( 1 3 ) - 1 6 - 12 - 8- FIGURE 20. SEASONAL FLUCTUATIONS IN P. INCONSTANS A C T IV IT Y . S = SPRING SU = SUMMER F = FALL § OF INDIVIDUALS P. BIVIRGATUM 12 YEAR 1 (21) YEAR 2 (1 4 ) - 8 - 4- su FIGURE 21, SEASONAL.FLUCTUATIONS IN P. BIVIRGATUM ACTIVITY. S = SPRING SU = SUMMER F = FALL 65 R e l a t i o n s h i p w ith te m p e ra tu re and p r e c i p i t a t i o n : B arlo w ( 1 9 5 8 ) m a i n t a i n e d t h a t t e m p e r a t u r e an d p r e c i p i t a t i o n i n i t i a t e d s p r i n g a c t i v i t y an d g o v e r n e d i t s te rm in a tio n l a t e r i n th e y e a r . A c c o r d in g t o t h i s a u t h o r t e m p e r a t u r e was a p p a r e n t l y more i n f l u e n t i a l i n ch an g in g a c t i v i t y . In th e p re s e n t stu d y , t h i s r e l a t i o n s h i p was i n v e s t i g a t e d by a n a l y z i n g d a t a fro m t h e two c o l l e c t i o n d a y s w h ic h y i e l d e d t h e h i g h e s t n u m b e rs . The t e m p e r a t u r e r a n g e f o r t h e s e d a y s i s p r e s e n t e d i n F i g u r e s 2 2 , a n d 2 3 . D a ta f o r b o t h y e a r s i l l u s t r a t e t h e m arked p r e f e r e n c e o f 0 . p l l o s u s f o r c o o l e a r l y s p r i n g t e m p e r a t u r e s an d o f P . b i v i r g a t u m f o r m o d e r a te e a r l y f a l l t e m p e r a t u r e s . T e m p e r a t u r e s d u r i n g t h e p e r i o d s o f maximum a c t i v i t y f o r b o t h s p e c i e s w ere somewhat s i m i l a r , b u t t h e r e was no o v e r l a p i n t h e a c t i v i t y p a t t e r n s ( F i g u r e s 19 an d 2 1 ) . The r e l a t i o n b e tw e e n t e m p e r a t u r e an d a c t i v i t y o f i n c o n s t a n s was l e s s c l e a r . D u r in g y e a r 1 t h e s p e c i e s was more a c t i v e when t h e t e m p e r a t u r e s r a n g e d fr o m 1 1 .5 5 t o 3 1 .3 5 ° C ( F i g u r e 2 2 ) . I n y e a r 1 a s m a l l a c t i v i t y p e a k was a l s o o b s e r v e d a t t h e b e g i n n i n g o f t h e t r a p p i n g p e r i o d ( F i g u r e 2 0 ) , b u t t h i s may h a v e b e e n t r i g g e r e d by t h e f r e s h l y d l g g i n g - i n o f t h e new t r a p s . I n y e a r 2, t r a p s fro m y e a r 1 w ere r e u s e d , e l i m i n a t i n g d i g g i n - i n e f f e c t s . The o n l y a c t i v i t y p e a k r e c o r d e d i n y e a r 2 o c u r r e d a t t h e b e g i n n i n g o f t h e t r a p p i n g p e r i o d ( F i g u r e 2 0 ) . T h is was p r o b a b l y c a u s e d by my a c t i v i t i e s i n t h e a r e a . No o t h e r p e a k was o b s e r v e d , p o s s i b l y d u e t o t h e s m a l l num ber o f i n d i v i d u a l s t r a p p e d d u rin g y ear 2. P e r c e n t o f t o t a l number f o r e a c h s p e c i e s . ~ 1 35 _ 205f 16% «------1------ r ■ — SAMPLING DATE - 7— - PRECEDING DATE t1 1 1 1 3 2 1 % 1---------------- >---------------- 1------------------<— 30% — 36% 33% i --------------1-----------------1 ----------------1---------------- 1------------------1------------ 1------------------1 ----------------■---------------- 1 YEAR 1 TEMPERATURE (°C ) 30- 25- T i T I I 1 I |I I1 I !II 4 f < I ' >0- 5- ! , ' ! ' ! ; ! ' I !I - ! 1 I 1 i ' ! • 1 1 ! ! 4 I n 0-5-1 0 -1 ' 5/2 I | 5/16 ' 1------1------ 1------ 1------ i 6/13 1--------1-------1----- j-------- ,-----,------- ,------ 6/27 9/IB 9/5 Dates P. P i l o s n g P. i n c o n s t a n s R biviraatiim FIGURE 2 2 . MAXIMUM AND MINIMUM TEMPERATURES ON TRAPP I^G ^A Y ^T iOTHMAXIMUM DIPL0P0D ACTIVITY AND ON DAYS PRECEDING THEM, YEAR 1 ( 1 9 8 4 ) . P e r c e n t o f t o t a l num ber f o r e a c h s p e c i e s . 31 % 19* 40 84% 0.76% — SAMPLING DATE 35 — PRECEDING DATE 43% i 14% 1------1 — i— ------r YEAR 2 TEMPERATURE (°C) 30 25 20 T 15 i ( 1 I i i i i i T 10 5 T 0 I A -5 -1 0 5 /3 4 /1 9 4 /3 5 /1 7 9 /2 2 9 /1 6 D a te s — P f losiJg gjnconstans P. bi v i r o a t u m FIGURE 2 3 . MAXIMUM AND MINIMUM TEMPERATURES ON TRAPPING DAYS WITH MAXIMUM DIPLOPOD ACTIVITY AND ON DAYS PRECEDING THEM, YEAR 2 ( 1 9 8 5 ) . 68 B) At_ s t a g e l e v e l : S t a g e - s p e c i f i c a c t i v i t y f o r a l l s p e c i e s i s sum m arized i n T a b l e 15. The few s m a l l j u v e n i l e s t r a p p e d i n y e a r s 1 and 2 w ere fo u n d d u r i n g f a l l and w ere a l l ()•_ p i l o a u s . No s m a l l j u v e n i l e s o f i n c o n s t a n s o r P. b i v i r g a t u m w ere c o l l e c t e d . F a l r h u r s t (1 9 7 9 ), i n h i s s tu d y o f P. i n c o n s t a n s , o n ly tr a p p e d f o u r s m a l l j u v e n i l e s d u r i n g t h e e n t i r e s t u d y an d was u n a b l e t o d e d u c e t h e s p e c i e s ' l i f e h i s t o r y by t h e s e m e an s. B lo w er (1 9 6 9 ) fo u n d t h a t s m a l l j u v e n i l e s o f o t h e r p o ly d e s m i d s a l s o r a r e l y f e l l i n t o t r a p s . P o ly z o n iu m b i v i r g a t u m i s t h e l e a s t known o f t h e t h r e e s p e c i e s . No s m a l l j u v e n i l e s w e re t r a p p e d d u r i n g t h e s t u d y ; t h e a d u l t s t a g e was t h e m o st a c t i v e ( T a b l e 1 5 ) . I t was fo u n d t h a t P. b i v i r g a t u m p r e f e r r e d d e c a y i n g wood a n d a r e a s o f a b u n d a n t , humid l e a f l i t t e r , c o n f i r m i n g o b s e r v a t i o n s by J o h n s o n ( 1 9 5 2 ) . Among j u v e n i l e s , 59% ( 2 8 ) o f t h e t o t a l i n y e a r 1 and 19% ( 1 9 ) o f th e t o t a l i n y e a r 2 w ere c o l l e c t e d i n t h e s p r i n g ; 35% ( 1 6 ) o f y e a r 1 and 19% ( 6 ) o f y e a r 2 t o t a l s w ere c o l l e c t e d i n t h e summer and 6% ( 3 ) y e a r 1 and 22% ( 1 2 ) o f y e a r 2 w ere c o l l e c t e d i n t h e f a l l . O phyiuluB p i l o s u s j u v e n i l e s a c t i v e i n t h e s p r i n g r e p r e s e n t e d i n d i v i d u a l s h a t c h e d t h e p r e v i o u s y e a r . A l l i n d i v i d u a l s t r a p p e d w ere i n s t a r s V I I , V I I I an d IX a n d became s e x u a l l y m a tu r e d u r i n g s p r i n g an d e a r l y summer. Q u a n t i t a t i v e d a t a a l s o showed a h i g h f r e q u e n c y o f j u v e n i l e s i n s p r i n g and a d e c r e a s e to w a r d s summer. A c c o r d in g t o B low er an d M i l l e r (1 9 7 4 ) 0 . p i l o s u s j u v e n i l e s o v e r w i n t e r a s i n s t a r s V I, V I I and V I I I . L a b o r a t o r y s t u d i e s by t h e s e of 69 Table 15. Total numbers captured of each species. 20 4 INCONSTANS 1 1 I 2 23 SJ P. 0 0 0 0 0 0 0 0 1 7 B 4 14 57 42 27 6 7 S 10 13 11 5 TOTAL BIVIRGATUM 0 0 0 0 0. a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 154 0 a (b) 7 0 0 0 0 0 0 0 0 0 SJ 4 0 0 0 0 »> 29 34 55 12 15 4 3 2 0 0 0 0 0 0 0 2 0 0 0 0 0 t 3 1 t 0 7 0 0 0 0 0 5 1 5 0 0 0 0 0 0 Year 1 1 t_ I C AO 0 17 2 1 1 O 0 0 0 0 1u 1 c 1 7 1 1 I ■ TOTAL 0 0 l (. I C 3 19 3 17 30 13 28 12 26 7 19 2 16 22 2 16 a i < 1 APR APR MAY MAY MAY JUN JUN JUL JUL AUG AUG SEP SEP SEP OCT OCT 47 421 76 39 325 SJ 33 41 91 59 0 4 OATE 7 2 13 3 1 2 5 0 4 2 0 5 0 3 a 0 0 P. 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PILOSUS AO 0 0 0 0 0 0 0 0 0 0 a 3 0 1 0 33 40 91 59 8 30 19 10 4 6 5 3 5 7 5 0 . SJ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 2 13 2 1 2 3 0 4 2 0 5 0 1 0 (a) AO 0 1 0 0 5 27 23 1 VI 1 TOTAL TOTAL 0IV IR G A TU M 3 0 0 1 0 0 2 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 3 a i P. SJ JU O 1 < 1 3 4 2 16 30 13 27 11 25 1 16 5 18 2 25 INCONSTANS SJ OATE APR APR MAY MAY MAY JUN JUN JUL JUL AUG AUG SEP SEP OCT OCT P. 1 1 1 1 PILOSUS 1 c. 1 c 0. 0 0 1 0 0 0 1 a 0 0 0 0 0 0 0 0 0 0 0 0 7 6 a Year 2 0 0 0 o Q 0 0 0 0 □ 0 0 JU 0 0 0 0 0 O' 1 0 0 o 0 0 0 » 0 0 AO SJ JU AO 2 2 0 0 0 0 0 0 a 0 0 0 0 2 0 0 0 a 10 0 1 1 0 7 1 0 a 0 0 5 1 8 0 0 35 34 55 13 15 4 3 3 0 0 0 0 2 5 1 2 12 2 32 172 o 0 0 0 0 0 0 0 0 0 0 2 s 1 70 a u t h o r s showed t h a t m a le s c o u l d r e a c h s e x u a l m a t u r i t y a t I n s t a r IX (tw o m o n th s a f t e r t h e p r e s e n c e o f l n s t a r V I I ) . H o w ev er, m a le s w h ic h r e a c h e d s e x u a l m a t u r i t y a t i n s t a r X s p e n t a l a r g e am ount o f tim e i n m o u l t i n g ch am bers* They a p p e a r e d a t t h e same ti m e a s t h e f e m a l e s , w h ic h c o u l d r e a c h s e x u a l m a t u r i t y o n l y a t i n s t a r X ( 1 0 - 1 3 m o nth s w e re n e e d e d t o reach th a t i n s t a r ) . O v e r w i n t e r e d j u v e n i l e s o f P ^ i n c o n s t a n s fo u n d i n s p r i n g w e re i n s t a r s V, VI and V I I , and w o uld become s e x u a l l y m a tu r e by t h e e n d o f s p r i n g an d t h r o u g h summer* Q u a n t i t a t i v e d a t a showed a l a r g e r num ber o f P . i n c o n s t a n s j u v e n i l e s i n t h e s p r i n g t h a n i n summer. L ittle i s known a b o u t ^ b i v i r g a t u m and t h e e x t r e m e l y low f r e q u e n c y o f j u v e n i l e s t r a p p e d d u r i n g t h i s s t u d y ( T a b l e 15) made i t I m p o s s i b l e t o d ra w c o n c l u s i o n s . The a d u l t s t a g e was t h e m ost a c t i v e i n a l l s p e c i e s s t u d i e d d u r i n g a l l s e a s o n s , an d t h e r e f o r e was t h e d e t e r m i n a n t o f t h e a c t i v i t y p a t t e r n s o f a l l s p e c i e s shown i n F i g u r e s 19 to 21. C) S e x -re la te d d iffe re n c e s in a d u lt a c t i v i t y i S e x -s p e c ific a c t i v i t y fre q u e n c ie s f o r each sp e c ie s a re p re se n te d i n T a b l e 1 6, a n d F i g u r e s 24 t o 2 6 . B oth s e x e s w e re e q u a l l y a c t i v e i n a l l s p e c i e s . I n y e a r 1 , 52% ( 2 2 0 ) o f a l l a d u l t s w e re m a le s and 48% ( 2 0 1 ) f e m a l e s . I n y e a r 2 , 44% ( 7 6 ) o f t h e t o t a l w e re m a le s an d 56% ( 9 6 ) w e re f e m a l e s . The p r o n o u n c e d a c t i v i t y p e a k s o f e a c h s p e c i e s o c u r r e d i n b o t h s e x e s ( F i g u r e s 2 4 - 2 6 ) a n d w ere d i r e c t l y p e rio d s. r e l a t e d to re p ro d u c tiv e 71 Ta b l e 16. T o t a l n u m b e r s of m a l e s 0. PILO SU S cf OATE APR APR MAV MAV MAV JUN JUN JUL JUL AUG AUG SEP SEP OCT OCT 3 4 2 16 30 13 27 11 25 1 16 5 16 2 25 P. INCONSTANS Cf _? — P. and fema l e s c a p t u r e d . B IV IR G A TU M 9 19 12 36 18 4 18 12 6 3 5 1 3 3 2 4 0 0 0 a 4 9 14 7 0 1 0 0 0 0 0 18 9 10 2 0 0 0 0 0 0 177 146 35 41 or Cf — —■ 0 0 0 0 0 0 □ 0 0 0 0 2 5 1 0 0 t 0 0 14 28 53 41 4 12 7 4 1 1 4 0 2 5 1 1 a) 0. P ILO S U S P. Y ear INCONSTANS 0 0 a 0 i 0 0 a 0 0 0 5 3 3 0 — —— TOTAL TOTAL 8 12 9 14 26 S3 41 B 21 21 11 1 2 4 2 7 6 1 19 13 36 18 6 36 21 16 5 5 1 8 6 5 4 — 220 — - 201 1 . P. B IVIR G A TU M TOTAL OATE APR APR MAV MAV MAY JUN JUN JUL JUL AUG AUG SEP SEP SEP OCT OCT 3 19 3 17 30 13 28 12 26 7 19 2 16 22 2 16 TOTAL 7 19 22 11 6 0 3 a 0 0 0 0 0 0 0 0 22 15 33 1 9 4 0 2 0 0 a 0 0 0 0 0 68 86 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 (b) 1 0 o 0 0 4 0 0 1 0 0 0 0 0 0 a 0 0 0 0 0 0 3 1 0 2 0 □ 0 0 0 0 Year 2 ■I 0 0 0 0 0 0 0 0 0 0 0 2 2 0 0 a 19 22 27 15 33 11 2 6 0 9' 4 3 1 0 a 0 0 0 0 0 2 o o a 3 2 2 2 0 0 76 96 1 72 YEAR 523 < Q > § 4440-| 363228- Z 24~. O 204 Sfc 1612-1 su a • - « MALES(6 3) a - * FDJALES(BG) YEAR 2 32 3 28- I 2*^ 1 Z 20 - ' (b) FIGURE 24. SEASONAL FLUCTUATIONS IN THE ACTIVITY OF 0. PILOSUS ADULTS (BY SEXES). 73 INDIVIDUALS 16- # OF YEAR 1 8- 12 - 4- a YEAR 2 < Q > Q Z u. o (b) FI G U R E 25. S E A S O N A L F L U C T U A T I O N S IN T H E A C T I V I T Y OF P. INCONSTANS. A D U L T S (BY SEXES). 74 • MALES (8 ) « - i FEMALES( \ 2 ) // OF INDIVIDUALS YEAR 43- Q Z lu O 2- =te (b) FIGU R E 26. S E A S O N A L F L U C T U A T I O N S IN T H E A C T I V I T Y OF .P. B I V I R G A T U M A D U L T S (B Y S E X E S ) . 75 B a n e r j e e ( 1 9 6 7 a ) r e p o r t e d t h a t t h e ti m e when t h e l a r g e s t num ber o f d i p l o p o d s w ere c o l l e c t e d I n p i t f a l l t r a p s c o i n c i d e d w i t h t h e i r b r e e d i n g p e r i o d , when a d u l t s became a c t i v e i n s e a r c h f o r m a te s an d s u i t a b l e s i t e s f o r o v ip o sitio n > C .l) O p h y lu lu s p i l o s u s More m a le s ( 1 5 9 ) t h a n f e m a l e s ( 1 0 9 ) o f 0 . p i l o s u s w ere c a p t u r e d d u r i n g t h e s p r i n g o f y e a r 1, b u t more f e m a l e s ( 2 6 ) w ere c a p t u r e d i n t h e summer ( m a l e s ■ 3 ) . I n s p i t e o f t h e f e w e r c a p t u r e s o f y e a r 2 more f e m a l e s ( 8 4 ) t h a n m a le s ( 6 5 ) w ere fo u n d i n t h e s p r i n g o f t h a t y e a r * B oth s e x e s showed a p e a k o f a c t i v i t y d u r i n g s p r i n g ( F i g u r e 24 ) w h ic h I s t h e r e p r o d u c t i v e s e a s o n f o r t h i s s p e c i e s . Blow er an d M i l l e r ( 1 9 7 4 ) r e p o r t e d t h a t 0 . p i l o s u s e g g s w e re l a i d b e tw e e n A p r i l and J u n e . The r e l a t i v e s i z e s o f e a c h p e a k c a n be r e l a t e d t o t h e r e l a t i v e d e n s i t i e s o f e a c h s e x . T h i s was i n d e e d t h e c a s e i n y e a r 2 when q u a n t i t a t i v e d a t a showed a 1 : 1 . 8 m a l e : f e m a l e r a t i o i n t h e s p r i n g ( t r a p d a t a showed a 1 : 1 . 3 r a t i o ) . R e l a t i v e d o m in a n c e o f m a le s t r a p p e d i n t h e s p r i n g o f y e a r 1 ( 1 . 4 : 1 r a t i o ) was n o t i n c o r r e s p o n d e n c e w i t h t h e q u a n tita tiv e d ata r a t i o ( 1 : 1 . 2 ) b u t t h e d i f f e r e n c e i s n e g l i g e a b l e when s t a n d a r d e r r o r s a r e c o n s i d e r e d . Blow er an d M i l l e r (1 9 7 4 ) a l s o fo u n d s e x r a t i o s o f a p p r o x i m a t e l y 1:1 i n o v e r w i n t e r i n g 0 . p i l o s u s , b u t d i d n o t a s s e s s a c t i v i t y sex r a t i o s . In th e p r e s e n t s tu d y , th e s e r a t i o s d i f f e r e d s l i g h t l y fro m t h e d e n s i t y s t a n d a r d s . A d e c l i n e i n a c t i v i t y o f 0^_ p i l o s u s a d u l t s a t t h e end o f summer i s e v i d e n t fro m F i g u r e 2 4 . B low er and M i l l e r ( 1 9 7 4 ) fo u n d t h a t t h i s 76 s p e c ie s s u f f e r e d a h ig h m o r t a l i t y o f o l d e r s t a d i a i n t h e i r second y e a r , f i n i s h i n g t h e s p e c i e s ' l i f e c y c l e . The few a c t i v e a d u l t s d u r i n g f a l l ( T a b l e 16 and F i g u r e 2 4 ) w e re p r o b a b l y yo ung a d u l t s ( s e e s e c t i o n 6 . 2 ) . C .2 ) P o ly d esm u s i n c o n s t a n s The h i g h e s t a c t i v i t y o f in c o n sta n s a d u lts in y e a r 1 o ccu rred b e tw e e n l a t e May a n d l a t e J u l y ( F i g u r e 2 5 ) . B oth s e x e s w e re a c t i v e a t t h e same t i m e . The nu m bers o b t a i n e d d u r i n g y e a r 2 w ere v e r y s m a l l ( T a b l e 1 6 ) , b u t m ost o f t h e t r a p p e d i n d i v i d u a l s w ere f e m a l e s . No a c t i v i t y t r e n d c o u l d be o b s e r v e d i n t h a t y e a r . The m a in p e a k o b t a i n e d f o r P^_ i n c o n s t a n s d u r i n g y e a r 1 c o r r e s p o n d e d t o t h e r e p r o d u c t i v e s e a s o n o f t h e s p e c i e s . T h i s was s u p p o r t e d by t h e p r e s e n c e o f eg g s i n f e m a l e s d i s s e c t e d d u r i n g t h i s s t u d y and by S n i d e r ( 1 9 8 4 a ) who r e p o r t e d e g g s l a i d i n May and J u n e ( w i t h a p e a k o f egg p r o d u c t i o n p r o b a b l y i n J u n e ) . An a p p r o x i m a t e 1 :1 s e x r a t i o i n t r a p p e d a d u l t s was c h a r a c t e r i s t i c o f y e a r 1 ( y e a r 2 d a t a w e re i n c o n c l u s i v e ) , s i m i l a r t o s e x r a t i o s o f f i e l d - c o l l e c t e d i n d i v i d u a l s r e p o r t e d by S n i d e r ( 1 9 8 4 a ) . A d r o p i n a c t i v i t y o f P._ i n c o n s t a n s a d u l t s was o b s e r v e d a t t h e end o f J u l y ( F i g u r e 2 5 ) . T h i s c a n be r e l a t e d t o t h e f a c t t h a t in co n stan s I s a s e m e l p a r o u s s p e c i e s i n w h ic h no i n d i v i d u a l s s u r v i v e beyond t h e summer b r e e d i n g s e a s o n ( S n i d e r 19 8 0 , 1 9 8 1 ) . C .3 ) P o ly z o n iu m b i v i r g a t u m H i g h e s t a c t i v i t y o f a d u l t s o c c u r r e d d u r i n g S e p te m b e r an d e a r l y 77 O c t o b e r , s i m u l t a n e o u s l y i n b o t h s e x e s ( F i g u r e 2 6 ) . A p p ro x im a te 1 :1 s e x r a t i o s w ere o b ta in e d d u r in g t h i s p e r i o d . J o h n s o n ( 1 9 5 2 ) o b s e r v e d m a le s and f e m a l e s i n c o p u l a t i o n d u r i n g May, w h ic h s u g g e s t s t h a t s p r i n g i s t h e r e p r o d u c t i v e s e a s o n f o r P. b iv i r g a tu m . U n lik e t h e o t h e r s p e c ie s d is c u s s e d p r e v io u s l y , t h e r e a p p e a r e d t o be no c o r r e l a t i o n b e tw e e n h i g h a c t i v i t y and r e p r o d u c t i v e b eh av io r in th i s s p e c ie s . 78 IV. SUMMARY AND CONCLUSIONS The p h y s i c a l p a r a m e t e r s o f t e m p e r a t u r e , p r e c i p i t a t i o n , s o i l m o i s t u r e , and l i t t e r c o v e r w ere d i f f e r e n t i n e a c h s t u d y y e a r . Y e a r 1 was c h a r a c t e r i z e d by a c o o l e r s p r i n g t i m e , a d r i e r and w arm er summer, and a s l i g h t l y more humid f a l l when com pared t o y e a r 2 . I n y e a r 2 t h e e f f e c t o f warm t e m p e r a t u r e s was p r o b a b l y b u f f e r e d by p r e c i p i t a t i o n . F u r t h e r m o r e , l i t t e r c o v e r was g r e a t e r i n y e a r 1. T h ese p a r a m e t e r s , t o g e t h e r w i t h t h e im p a c t o f s a m p l in g a c t i v i t i e s i n t h i s a n d p r e v i o u s s t u d i e s , may h a v e a f f e c t e d t h e s e a s o n a l p o p u l a t i o n d e n s i t i e s each y e a r . Y ear 1 d e n s i t i e s f o r P . b i v i r g a t u m w ere h i g h e r t h a n y e a r 2 . p i l o s u s , P . i n c o n s t a n s and O p h y iu lu s p I I obub showed t h e h i g h e s t d e n s i t y d u r i n g y e a r 1 and i n s p r i n g and f a l l o f y e a r 2 . P o ly d e s m u s i n c o n s t a n s o u tn u m b e re d 0^_ p i l o s u s i n summer o f y e a r 2 . The d e n s i t i e s r e p o r t e d f o r P ^ i n c o n s t a n s an d _P;_ b i v i r g a t u m i n t h i s s t u d y w ere t h e l o w e s t e v e r r e c o r d e d i n M ic h ig a n . Dominance a n a l y s i s d e m o n s t r a t e d t h a t 0^_ p i l o s u s was t h e d o m in a n t s p e c i e s i n B aker w o o d l o t . S ta g e s t r u c t u r e a s s e s s m e n t o f 0^_ p i l o s u s showed t h a t i t s s m a l l j u v e n i l e s u b p o p u l a t i o n i n c r e a s e d c o n s i s t e n t l y fro m s p r i n g t o f a l l d u r i n g b o t h y e a r s . T h i s i n c r e a s e was c a u s e d by n ew ly h a t c h e d i n d i v i d u a l s e n t e r i n g t h e p o p u l a t i o n a t t h e end o f s p r i n g and summer. The j u v e n i l e s t a g e was m ost a b u n d a n t i n s p r i n g o f y e a r 1 (o v e rw in te re d i n d i v i d u a l s ) and f a l l o f year2. In s u b p o p u l a t i o n d e c r e a s e d fro m l a t e s p r i n g t o f a l l , y ear 1 th e ju v e n ile but in y ear 2 a d e c r e a s e was o b s e r v e d o n l y fro m s p r i n g t o summer. I n b o t h y e a r s t h e 79 d e c r e a s e was c a u s e d by m e ta r a o r p h ic c h a n g e s i n i n s t a r s V I I I an d IX and by u n f a v o r a b l e w e a t h e r c o n d i t i o n s t h a t i n d u c e d e s t i v a t i o n and t h u s a n a p p a r e n t d e c r e a s e o f t h e p o p u l a t i o n . The l a r g e i n c r e a s e o f t h e j u v e n i l e s u b p o p u l a t i o n d u r i n g f a l l o f y e a r 2 was p r o b a b l y c a u s e d by h i g h e r s u r v i v o r s h i p d u r i n g summer due t o f a v o r a b l e w e a t h e r c o n d i t i o n s . The a d u lt p o p u la tio n reached i t s maximum d e n s i t y d u r i n g s p r i n g ( b o t h y e a r s ) , d i m i n i s h i n g c o n s i s t e n t l y to w a r d s f a l l . T h i s d e c r e a s e was c a u s e d by d e a t h o f m o s t t w o - y e a r a d u l t s a t t h e end o f t h e i r r e p r o d u c t i v e p e r i o d i n t h e summer. The few a d u l t s c o l l e c t e d d u r i n g f a l l w e re p r o b a b l y yo u n g a d u l t s . I t was fo u n d t h a t 0^_ p i l o s u s s t a g e s f o l l o w e d a s e a s o n a l p a t t e r n i n t h e i r v e r t i c a l d i s t r i b u t i o n . H o r i z o n p r e f e r e n c e s o f t h e s p e c i e s w e re i n f l u e n c e d by t e m p e r a t u r e an d p r e c i p i t a t i o n . The l e a f l i t t e r was l e a s t p o p u la te d , i n d i c a t i n g th e s p e c i e s 's s tr o n g e r p r e f e r e n c e f o r th e s o i l la y e rs. The fe w s m a l l j u v e n i l e s c o l l e c t e d i n t h e s p r i n g w ere fo u n d i n t h e A l a y e r i n y e a r I a n d i n t h e 0 and A l a y e r i n y e a r 2 . D u r in g t h e summer t h i s s t a g e was f o u n d i n e v e r y l a y e r b u t more p r e d o m i n a n t l y i n t h e 0 and A l a y e r i n y e a r 1 a n d i n t h e A and l e a f l i t t e r in y e a r 2. F a l l p r e f e r e n c e s w ere v e r y s i m i l a r t o t h e summer d u r i n g y e a r 1, b u t i n y e a r 2 m o s t o f t h e s m a l l j u v e n i l e s w e re i n t h e l e a f litte r. The p r e s e n c e o f s m a l l j u v e n i l e s i n t h e l e a f l i t t e r d u r i n g summer a n d f a l l o f y e a r 2 c o u l d b e a n i n d i c a t i o n o f a d e q u a t e m o i s t u r e c o n d i t i o n s due t o h i g h e r a n d more e v e n l y d i s t r i b u t e d p r e c i p i t a t i o n . J u v e n i l e s w e re p r e s e n t i n t h e l e a f l i t t e r , 0 l a y e r and A l a y e r 80 d u r i n g t h e s p r i n g o f b o t h y e a r s , h o w e v e r , m o st i n d i v i d u a l s w ere fo u n d i n t h e A l a y e r . D u rin g summer o f y e a r 1 m o st j u v e n i l e s w ere i n t h e A l a y e r f o l l o w e d by t h e 0 l a y e r b u t t h e r e v e r s e s i t u a t i o n was o b s e r v e d i n y e a r 2 . D u r in g f a l l o f b o t h y e a r s t h i s s t a g e a l s o showed a s t r o n g e r p re fe re n c e f o r th e A la y e r . A d u l t s w ere p r e s e n t i n a l l s t r a t a , w i t h a s t r o n g e r p r e f e r e n c e f o r t h e A l a y e r i n y e a r 1 and f o r t h e 0 i n y e a r 2 . They w e re a l s o p r e s e n t i n e v e r y s t r a t a d u r i n g t h e summer show ing a s t r o n g e r p r e f e r e n c e f o r t h e 0 l a y e r f o l l o w e d by t h e A. D u rin g f a l l o f y e a r 1 a d u l t s showed a s t r o n g e r p r e f e r e n c e f o r t h e A l a y e r , w h i l e t h e y w ere p r e s e n t i n a l l s t r a t a d u rin g y e a r 2. The v a r i a n c e / m e a n r a t i o t e s t f o r t h e h o r i z o n t a l d i s t r i b u t i o n o f t h e d o m in a n t s p e c i e s showed t h a t t h e 0±_ a g g r e g a t e d . T h i s c l u s t e r i n g te n d e n c y i s p i l o s u s p o p u l a t i o n was t y p i c a l o f t h e D ip lo p o d a and c a n be r e l a t e d t o t h e i r o v i p o s i t i o n h a b i t s . A r e g r e s s i o n a n a l y s i s r e v e a l e d no d i r e c t r e l a t i o n s h i p b e tw e e n l i t t e r m ass and t h e num ber o f 0 . p i l o s u s i n a s a m p l e . S i m i l a r r e s u l t s w ere o b t a i n e d when a n a l y z i n g t h e r e l a t i o n s h i p b e tw e e n s o i l m o i s t u r e and d e n s i t y . The s p a t i a l d is tr ib u tio n of 0. by t h e j o i n t e f f e c t s of v a r io u s p a ra m ete rs such a s te m p e ra tu re , p re c ip ita tio n , p i l o s u s was p r o b a b l y a f f e c t e d t y p e o f s u b s t r a t e , m o i s t u r e and l i t t e r c o v e r . P i t f a l l t r a p d a t a showed t h a t 0 ^ p i l o s u s was t h e m o st s u r f a c e - a c t i v e s p e c i e s i n B ak er w o o d l o t . A c h a r a c t e r i s t i c p e a k o f h i g h s u r f a c e - a c t i v i t y was do cu m en ted f o r e a c h s p e c i e s . T h ese p e a k s o c c u r e d i n s p r i n g f o r (K_ p i l o s u s , summer f o r P;_ i n c o n s t a n s and f a l l f o r , 81 b i v i r g a t u m . The p r e s e n c e o f e g g s i n d i s s e c t e d f e m a l e s o f 0 ^ p i l o s u s and P . i n c o n s t a n s a n d o f s m a l l j u v e n i l e s i n t h e f o l l o w i n g s e a s o n may I n d i c a t e t h a t t h e s e a c t i v i t y p e a k s w ere r e l a t e d t o r e p r o d u c t i o n . BIBLIOGRAPHY BIBLIOGRAPHY B a i l e y , J .W . 1928* The C h il o p o d a o f New Y ork S t a t e w i t h n o t e s on t h e D i p l o p o d a . N.Y. S t a t e Mus. B u l l . 2 7 6 : 5 - 5 0 . B a k e r , A.N. 1974. Some A s p e c t s o f t h e Econom ic I m p o r t a n c e o f M i l l i p e d e s . Symp. Z o o l . S o c . L ond. 3 2 : 6 2 1 - 6 2 8 . B a n e r j e e , B. 1 9 6 7 a . D i u r n a l and S e a s o n a l V a r i a t i o n s i n t h e A c t i v i t y o f th e M illip e d e s C y lin d ro iu lu s p u n c ta tu s (L each ), T a c h y p o d o iu lu s n l g e r ( L e a c h ) and P o ly d e s m u s a n g u s t u s L a t z e l . O ik o s 18: 1 4 1 -1 4 4 . B a n e r j e e , B. 1 9 6 7 b . S e a s o n a l C hanges i n t h e D i s t r i b u t i o n o f t h e M i l l i p e d e C y l i n d r o i u l u s p u n c t a t u s ( L e a c h ) i n D ec a y in g Logs an d S o i l . J . Anira. E c o l . 3 6 : 1 7 1 -1 7 7 . B a r n e s , R.D . 1980* I n v e r t e b r a t e Z o o lo g y , 2nd e d . , P h i 1 1 . 1089 p p . S aunders C o lle g e , B a r lo w , C.A . 1957 . A F a c t o r i a l A n a l y s i s o f D i s t r i b u t i o n i n T h r e e S p e c i e s o f D i p l o p o d s . T i j d s c h r . V. E n t . , 100: 3 4 9 -4 2 6 . B a rlo w , C.A . 1958 . D i s t r i b u t i o n and S e a s o n a l A c t i v i t y i n T h re e S p e c i e s o f D i p l o p o d s . A r c h . N e e r l . Z o o l . 1 3: 1 0 8 -1 3 3 . B h a t t a c h a r y y a , G.K. & J o h n s o n , R.A. 1977. S t a t i s t i c a l C o n c e p ts and M e th o d s . J o h n W ile y and S o n s , N.Y. 639 p p . B lo w e r, G . J . 1955 . M i l l i p e d e s and C e n t i p e d e s a s S o i l A n im a ls . I n : S o i l Z oolog y 1 3 8 - 1 5 1 . K e v a n , D.K. McE. Ed. L ondon: B u t t e r w o r t h . B lo w e r, G . J . 1956 . Some R e l a t i o n s B etw een M i l l i p e d e s an d t h e S o i l . S ix ie m e C o n g r. I n t . S c i . S o l . , P a r i s 3 : 1 6 9 - 1 7 6 . B lo w e r, G . J . 1 9 6 9 . Age S t r u c t u r e o f M i l l i p e d e P o p u l a t i o n i n R e l a t i o n t o A c t i v i t y a n d D i s p e r s i o n . P u b i s . S ystem A s s o c . 8 : 2 0 9 - 2 1 6 . B lo w e r, G . J . 1970. The M i l l i p e d e s o f a C h e s h i r e Wood. J . Z o o l . L ond. 160: 455-496. B lo w e r, G . J . 1 9 7 4 a . 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