A l m, A 32 ma .44 0": ‘.\ \. ‘4 L. “n.2, o .w'fi ‘34:!“ . {L a.:\ 7V5 Hf , lwn‘xa’m: 49“?» 555,93 3. w “2:! ‘1 J M“ 7’- M V ‘du ' ‘3: " 444.23 2-“ an.“ ... "‘7‘? 4....k' v‘-\,..Iur . vs 1444' . a ‘I ‘ ’0‘. win m...u..’1-.-} \- 0-4 \m‘ as. {”7“ flat: . ’4’. Wage-2» ‘ 3??“‘55‘ v;; u: L :5.“ 4 .n “for“ gun «Rn " - fir IEE-‘ffl‘f 4:;er - _._. WW 4 4 Wm- «Maya-fi'w .nr-u . . ~. 3» . 5 ‘ _ _ _ t...“{:;.x,g~‘ WE wzxfia . '.L.., 1.0.01. n‘ < J ‘ 4 4“-,\v-_ 1 ‘,h-V;VI;,‘ 511:...“ . “(-7". 1. -- . 4 M 4. .. WHEN“ fimf; film“ I; A "’L '0‘?" X—J-s'ug 9"? ' - x;- e .5" W3; ‘ " " ‘ ‘ ' £4 2“ 1‘2" K‘f“ “‘av ¥ wg' “525;:3; ‘ :4“ v: ...u .A‘ ’h‘u u: m: min» 4“"... \ . 44 Ilfliilii'lilflilifliiilifiiiflfiiiilfllit'fliififil 3 1293 00877 2406 This is to certify that the thesis entitled Vegetation Responses to Prescribed Burning in a Mature Red Pine Stand presented by Sandra J. Henning has been accepted towards fulfillment of the requirements for M.S. degree in ForeStry Major profekss/or Date 2/14/92 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution ————.——.M . .._... ._ . . .._ _...#¥ ‘ LIBRARY 1 t Michigan State UnhenIty PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before one due. DATE DUE DATE DUE DATE DUE MSU Is An Affirmative ActiorVEquel Opportunity Institution cha-oi w" VEGETATIVE RESPONSES TO PRESCRIBED BURNING IN A MATURE RED PINE STAND BY Sandra J. Henning A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Forestry 1992 ABSTRACT VEGETATIVE RESPONSES TO PRESCRIBED BURNING IN A MATURE RED PINE STAND BY Sandra J. Henning Prescribed burning techniques were explored in a red pine (Pinus resigosa) plantation in northern lower Michigan to promote wildlife, timber, and recreational benefits. Three experimental blocks were divided into four treatment plots which were burned every 2, 5, and 10-years, with one plot serving as a control. Overstory and understory woody and herbaceous vegetation were measured most recently in 1991, six years after the study began. Results indicate that prescribed burning, if done properly, will not adversely effect the overstory. Burning had no significant effects on total herbaceous cover or on herbaceous species richness. However, it did effect species composition. Frequent burning reduced the total number of woody stems present, and had a large impact on species composition. Those species able to respond to fire were primarily vegetative sprouters, with a larger percentage of seeders present as time between burn intervals increased. Initial findings indicate that burning at long intervals under a thinned red pine stand will enhance wildlife, recreation, and timber objectives. ii ACKNOWLEDGEMENTS Many people have contributed.their time and effort in the initiation and continuity of this study. I would personally like to recognize Don Dickmann, my major professor, who was responsible for making this study a reality. I feel fortunate to have had a major professor with a background in fire and siviculture, and one who could match my academic interests in those areas with a hands-on project. My committee members, Karen.Potter-Witter and.Bud.Hart, have also been supportive in my educational goals and I thank them for their help in preparing this thesis. Thanks also go out to the Department of Natural Resources and the staff of the Pigeon.River Country State Forest, who have been instrumental in project continuity; In addition, I*would like to thank.those who.have previously worked on this project and were responsible for initial plot layout and data collection. Finally, I would like to recognize Brian Palik who helped me considerably. I sincerely thank him for his time and for showing an interest in my work. iii List of Tables. . . TABLE OF CONTENTS List of Figures. . . . . . . . . . . . . . . . Introduction. . . . Statement of Problem. Background. . Objectives and Hypotheses of the Study Methods. . . . . . Experimental Site. Fire Schedule. Sampling Design . Data Analysis. Results and Discussion: Overstory. . . Ground Vegetation. Woody Understory Density. Species Richness - Woody Understory. Woody Understory Composition. Conclusions and Recommendations. Appendix: List of References. iv Completed ANOVA's for entire study. 14 LIST OF TABLES Table 1. Stand & Stock Table for Red 2. Stand & Stock Table for Red 3. Stand Table for Red Pine in Number of Trees per Hectare 4. Stock Table for Red Pine in Pine in Block A. Pine in Block B. Block C; Mean and per Acre. . Block C; Mean Gross Cu. Meters/Hectare and Cu. Ft./Acre. . 5. Overstory Characterisitics for Blocks A, B, and C. . . . . 6. Effects of Burning Intervals on Total Percent Cover and Species Richness of Herbaceous Ground Vegetation. . . . .. . . . 7. Effects of Burning Intervals on Percent Coverage of Various Understory Species in a Mature Red Pine Stand . . 8. Species with Greater than 1% Ground Coverage, Averaged by Treatment. . . . 9. Effects of Burning Interval on Density (stems/ha) of the Woody Understory in a Mature Red Pine Stand. 10. Effects of Burning Interval on Average Species Richness (no. of species) in the Woody Understory of a Mature Red Pine Stand. . . . 11. Effects of Burning Intervals on Density (stems/ha) of Various Woody Understory Species in a Mature Red Pine Stand. . . . . 12. Ranking of Species Importance, Averaged by Treatment. . . . 13. Total Percent Cover of Herbaceous Vegetation by Burning Interval and Block. . Page . 15 .16 .17 . 22 .25 . 31 .36 . 42 .46 .59 Table 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. Species Richness of Herbaceous Vegetation by Burning Interval and Block. . . . . . . Total Percent Ground Cover of Mosses and Lichens by Burning Interval and Block. . . Total Percent Ground Cover of Grasses by Burning Interval and Block. . . . . . . . Total Percent Ground Cover of Black Cherry by Burning Interval and Block. . . . . . . Total Percent Ground Cover of Rubus Spp. by Burning Interval and Block. . . . . . . Total Percent Ground Cover of Brackenfern by Burning Interval and Block. . .. . . . Total Percent Ground Cover of Red Pine by Burning Interval and Block. . . . . . . Total Stems per Hectare by Burning Interval and Block. Total Stems per Hectare by Burning Interval and Block, 0.109 cm. 0 O O O O 0 Total Stems per Hectare by Burning Interval and Block, 2-5.9 cm. 0 e e e e e Total Stems per Hectare by Burning Interval and Block, Species Richness in by Burning Interval Species Richness in by Burning Interval Species Richness in by Burning Interval Species Richness in by Burning Interval 6-9.9 cm. . . . . . . the Woody Understory and Block. . . . . . the Woody Understory and Block, 0-1.9 cm. . the Woody Understory and Block, 2-5.9 cm . the Woody Understory and Block, 6-9.9 cm . Total Stems per Hectare of Black Cherry by Burning Interval and Block. . . . . . Total Stems per Hectare of Red Maple by Burning Interval and Block. . . . . . . vi Page .62 .65 .67 .68 .69 .70 .71 .72 .73 .74 .75 Table 31. Total Stems per Hectare by Burning Interval and 32. Total Stems per Hectare by Burning Interval and 33. Total Stems per Hectare by Burning Interval and 34. Total Stems per Hectare by Burning Interval and 35. Total Stems per Hectare by Burning Interval and of Birch Block. . of White Block. . of Beech Block. . of Aspen Block. . of Choke Block. . vii Page 77 78 79 80 81 LIST OF FIGURES Figure 1. Experimental Design. . . . . . . . . . . . . . . . . 2. Average Percent Ground Cover, by Treatment. . . . . 3. Average Percent Ground Cover, by Treatment and Species. . . . . . . . . . . . . . 4. Total Stems per Hectare by Treatment. . . . . . . . 5. Total Stems per Hectare by Size Class and Treatment. 6. Stems per Hectare by Treatment and Species. . . . . viii 24 35 .37 45 INTRODUCTION statement of Problem Today, the forests of the Lake States contain over 486,000 hectares (1.2 million acres) of red pine (mug regingga), an important component of the timber resource in this region (Schone et. a1 1984). In addition, nearly 1/4 of these stands in Michigan are 40 years and older (Dickmann et a1. 1986). Red pine plantations, however, have often been criticized as being poor wildlife habitat, especially overstocked plantations. Because timber, wildlife, and recreation are key management objectives on state and federal lands in Michigan, and red pine represents a large component of our forests, it is important to»employ proper silvicultural management in this type. This argues for management of red pine to improve wildlife habitat and aesthetics, especially when confronted with the lack of conifer species alternatives for timber due to the jack pine budworm and white pine blister rust. 0n better soils, especially following thinning, middle- aged red pine stands develop a dense hardwood or mixed hardwood-conifer understory. The understory competes with the pine for water, nutrients, and space. Moreover, as the understory matures, wildlife browse is reduced, as are accessibility and aesthetics. One technique for managing the understory in pine stands is prescribed burning (Methven and Murray 1974, Mobley et. al 1973, Van‘Wagner 1965). Prescribed burning is a silvicultural tool that is commonly used 2 throughout the southern pine and western conifer regions (Wade and Lunsford 1989, Walstad et al. 1990). In the Lake States however, prescribed burning under pine is*virtually’unknown as an operational practice (Dickmann 1991). Many managers are unsure of its effects and lack experience in its use. In addition, selecting proper fire conditions can be a problem because of the unpredictable weather in Michigan. Until underburning in red pine can be demonstrated to be safe, and data on specific effects in stands growing on Michigan soils are produced, this practice will not become an operational part of forest land management in the Lake States. This study investigates the effects of management of the understory in a wide-spaced, mature red pine plantation with prescribed burning. Background Immediately after regeneration, and then following the first thinning, the total understory of a red pine stand is available for the production of game food plants and shrubs, and for hunting, without affecting the timber crop (Miller 1964). Prescribed burning can serve to manipulate understory vegetation, to the advantage of wildlife habitat, aesthetics, and timber management. Control of stand density and composition are the principal means by which timber and wildlife habitat needs are coordinated (Miller 1964). Red maple (Agerg rubrum), grasses, and. brackenfern (Pteridium agui 1i num) ; the most common plants found under wide-spaced red 3 pine; are favored forage species for deer at certain times of the year (Rogers et al 1981). Correctly handled, prescribed burning should benefit game by increasing herbaceous growth and providing new sprout growth.of woody plants (Little 1952). Frequent (5 - 10 year intervals), low intensity fires may kill aerial portions of any hardwood vegetation, and thus promote low coppice growth, which provides wildlife browse (Rouse 1988). Sprouts of many species are favored foods of white- tailed deer (Perala 1974). Buckmann (1964) found close relationships between wildfire and the maintenance of high populations of white-tailed deer or sharp tailed grouse. Sprouts occasionally form on standing live trees but sprouting is most vigorous after the bole is felled or killed, such as by fire (Perala 1974). Also, in areas valued for recreation, fire can.make a stand more accessible as well as more visually pleasing. The success of prescribed burning in controlling woody plants and grass under a stand of trees depends upon the presence of an overstory resistant to damage by fire and an understory easily destroyed by fire (Buckmann 1964). Red pine is a species ideally suited for intermediate stand.management: it grows well over'a wide range of stocking densities (Berry 1984); diameter growth responses to thinning are excellent (Lundgren 1981); and from small sawtimber size onwards, it is adapted.to the use of prescribed.burning in the understory (Van Wagner 1970) . To increase recreation and wildlife objectives, stocking densities below what might be considered optimum for timber production could be adopted 4 (Dickmann 1991). Heavy thinnings, to 16 - 21 square meters per hectare (7O - 90 square feet per acre), combined with prescribed burning to maintain a low understory, produces valuable, large diameter trees as well as a plant layer that is utilized by wildlife. A thorough review of the multiple-use benefits and techniques of prescribed burning in red pine stands was prepared by Dickmann (1991). Objectives and Hypotheses of the study (Dickmann 1990) Objectives 1. Quantify the extent and composition of the understory in once thinned red pine stands growing on good quality sandy loam soil. 2. Assess the effects of spring prescribed fires in red pine stands on overstory characteristics and understory composition and development. 3. Determine the feasibility and effects of repeated prescribed burns at 2, 5, and 10-year intervals on understory composition and development as compared to no burning. 4. Provide conclusions and recommendations on burning intervals in relation to timber and wildlife objectives. Hypotheses 1. Thinning red pine stands on good soils stimulates the development of a diverse and extensive understory of herbaceous and woody plants. 5 2. Low-intensity prescribed fires will have little effect on the overstory in mature red pine stands. 3. Burning at long intervals will hold back the development of the woody understory in thinned red pine stands, but will have little effect on the extent and diversity of the herbaceous understory. 4. Repeated burns at short intervals will reduce both the extent and.diversity of the herbaceous and woody understory in thinned red pine stands. Fire intolerant species will die out, whereas certain fire stimulated species will increase in abundance. METHODS Experimental site The study site was located in the Pigeon River Country State Forest in northern lower Michigan; T33N, R1W, section 25. The forest is known for its game habitat; with white- tailed deer, elk, snowshoe hare, turkey, and ruffed grouse being most prominent. The study area is approximately a 61 hectare (150-acre) plantation which was established in 1931 with a mixture of red, white (Pings strobus), and jack pine (Pinus banksiana) seedlings. In 1970, all white and jack pine were thinned out, leaving an average residual basal area of 10 square meters per hectare (40 square feet per acre), an understocked condition for this species. This is a productive site for red pine; the Emmet sandy loam soils produce a site index of 20 meters (65 feet) at 50 years of age. During the summer of 1983, three experimental treatment blocks were established (Blocks A, B, and C), which varied in size from 6-8 hectares (15-20 acres). Blocks A, B, and C were then divided into 7, 7, and 8 plots (experimental units), respectively. Overstory density varied, with Block A the heaviest at 24 square meters per hectare (104 square feet per acre) and Block C the lightest at 13 square meters per hectare (58 square feet per acre). Block C had the most dense understory, followed by Block A and Block B. Block B was recently thinned, accounting for its low stem density. Each plot was randomly assigned a spring burning treatment with a fire frequency of 2, 5, or 10 years. One 7 plot in each block was designated as a control for comparison purposes, except in Block C where there were two control plots“ ‘Within.each.plot, two transects were established which ran on a north-south compass line. Along each transect in Blocks A.and B, five subplots or points were randomly assigned for measurement purposes. Six subplots were set out along each transect in Block C. Each point was permanently marked with a metal stake. Figure 1 depicts the overall experimental design and treatment layout of each block. Fire Schedule Spring burning has taken place more or less according to schedule. Burns in the two-year treatments have been completed four times, in 1985, 1987, 1989, and 1991. Burns in the five-year treatments have been completed twice, one in 1985, and one in 1990. A single burn was completed in the ten-year treatments in 1985, and a second burn is scheduled for 1995. Very little information regarding weather conditions and fire factors for the prescribed burns, which were conducted by the Department of Natural Resources (DNR), are available. The burns have varied in intensity and in the degree to which the understory vegetation was affected. Most burns were moderate in intensity. Techniques of burning also differed; some burns were backfired and others perimeter ignited. It is hoped that better communications between the Michigan State Forestry Department and the DNR.are kept in the future to ensure fire information is recorded and passed on, memo ”I III JIIII III 38 ."2. NS .Wu Wv a .cuqaoa asucoamuodxm I A 853... TI . . u , .. . a sue a a; a A . “umv.ew a .. _ ,/, a goo—m \s 4 . .l . t c _ u .\ // - . . h - . w _ u A ~ 4 .mw; . — \‘I/ ‘ Via—fl: . a: To .3 .r __ \ < sue—a ./ . __ Z /. _. / ._ . __ xv A // . m Esaom .m~ =o_suom .amua z emcee .gutoz mm a.gm=:oh datacoc 32:3...— temxnm e was: toot 35.5 I _ . xoobé ”NH” 33.3.: .5on e 325 possum 7% 28.. .3595 33a 3235 segue: coco 35:5 a 9 and that proper firing techniques are also used (i.e. strip headfires). Headfires should be used because they are often less damaging than backfires; the heat is carried upward more rapidly and high temperatures are not as long sustained near the ground (Smith 1986). It is also very important to keep in mind the length of time elapsed since each of the plots was last burned. When measurements were taken, six growing seasons had elapsed since the 10-year plots were burned, one4growing season since the 5- year burns, and zero for the two-year burns, with measurements taken in the same year as these plots were burned- Therefore, the results indicate the effects of fire after a growing period of 2-months, 1-year, and 6-years since the last burn; not 2, 5, or 10-years, respectively. Sampling Design The vegetation on each plot was divided into three strata for measurement purposes: ground vegetation consisted of all vascular plants less than 1.4 meters in height (4.5 feet); woody understory was all woody plants more than 1.4 meters in height and less than 10 centimeters (4 inches) in diameter; while overstory comprised all trees over 10 centimeters in diameter, most of which was red pine. Ground vegetation was measured at each sampling point along every transect. Frequency and percent cover of all species were estimated using one square meter circular subplots randomly located along each transect, which 10 themselves were randomly located within each burning compartment. A rope 56.4 centimeters (1.85 feet) long was centered on each plot center (the stake) for data collection. Each species of ground vegetation falling within that radius as well as percent cover of each species within the circular subplot was recorded” Ground vegetation could then be characterized by relative frequency and percent cover. Blocks A and B had 10 ground vegetation measurement subplots per treatment, while Block C had 12. Each of those subplots became a permanent measuring point and a basis for gathering all data. Woody’ understory’ was assessed. at two sample points randomly chosen along transect lines using a 147 square meter subplot. A rope, 14.8 meters long, running north and another rope, 9.9 meters long, running east from the plot center stake were used to lay out the sampling area. All woody understory species more than 1.4 meters tall and less than 10 centimeters in diameter were recorded into three different diameter size classes: 0-1.9 cm, 2-5.9 cm, and 6-9.9 cm (0-0.75 in., 0.75- 2.3 in., and 2.3-3.9 in.). Woody understory vegetation could then be characterized by frequency and density from a total of four measurements per treatment. Overstory measurements were taken at the point along each transect where woody understory subplots were measured. A. relaskop with a basal area factor of 10 was used to determine basal area and tally trees. Each tally tree’s diameter at breast height was measured with a diameter tape, and a 11 relaskop was used to determine merchantable height in 2.4 meter sticks (8 feet) to a 10 centimeter top (4 inches). This protocol resulted in two overstory measurement points per treatment. Overstory data was then entered into the inventory program INVENPRO (an inventory processor for the Lake States) to create stand and stock tables for each block. Because the major objective of this study was to assess the vegetative responses to prescribed burning, a complete inventory of the area was completed in 1984, prior to the first fire. Post-burn measurements have been made in three different years, starting in 1985. The second set of measurements were taken in 1988, and the third in 1991. Each time data was collected after August 1. Data from each block was totaled and averaged by treatment for recording and analyzing purposes. In instances where 3plot stakes ‘were 'vandalized or missing, an attempt was made to relocate that point at it’s original location as identified in the original data sheets. It is safe to assume that relocated points were not in their exact original position. IBlock.B was completely reset in both 1988 and 1991, most points being in slightly different locations. In addition, this block was recently thinned to its ‘present. density; making' comparisons. between. data of different years very difficult. Therefore, 1991 data was used for the principle comparisons and findings of this paper, except where noted. 12 Data Analysis Total percent cover of ground vegetation by treatment and species was computed. Because data was expressed in percentages, an arcsin transformation was done to normalize the data. Analyses of variance (ANOVA’s) were conducted on the transformed values, and F-max tests were performed to ensure that variances were homogeneous. However, graphs and tables which depict percent cover report original percentages, and standard errors are based on those original percentages. In all cases where separation of means were performed, the orthogonal method was used. This method was used to compare means in three different ways: 1) the 2 and 5-year treatments against the 10-year treatment and control, 2) the 10-year treatment vs. the control, and 3) the 2-year treatment vs. the 5-year treatment. It was assumed that these tests were based on a two-sided hypothesis, and appropriate significance values were used. Due to the low number of replicates and heterogeneous nature: of the experimental blocks, a significance value of 20% was deemed acceptable when separating means for the entire study. A significance value of 10% was acceptable for all analyses of variance. F-max tests were performed on original data collected for the woody understory. It was found that the variances were not homogeneous, and therefore, transformation of the data was necessary. For all data relating to stems per hectare (by totals, size class, and species), transformations took the form of ln(x+1), where x = the original value. It was 13 necessary to add one to each number before transforming due to the presence of zeros in the original data sets. Subsequent F-max tests were performed and variances were found to be homogeneous. Analyses of variance were then conducted on transformed values. Again, all tables and figures report original values with means and standard errors based on that original data. Complete ANOVA’s for the entire study may be found in the Appendix of this document; the reader should refer to them when necessary. RESULTS AND DISCUSSION Overstory Stand and stock tables for Blocks A, B, and C are presented as Tables 1, 2, 3, and.4. Block A was most dense at 24 square meters per hectare (104 square feet per acre), followed by Block B at 68 and Block C at 60 square feet per acre. Only Block C had species in the overstory other than red pine which were greater than 10 cm (4 inches) in4diameter. A t-test was performed which showed that Block A was significantly different from Blocks B and C in terms of density. Block B and Block C were not significantly different. Obviously, these differences in stocking will have some effect on species composition and understory stocking of the woody understory and herbaceous ground cover. To describe the effects of prescribed burning on the overstory is not a primary objective of this study. However, some important points regarding this stratum must be discussed. In general, the prescribed burns which were conducted had few adverse effects on the overstory. Some problems did exist with overstory mortality at the initiation of the study. Where fires burned very hot and slash concentrations after initial thinnings were high, some mortality occurred; e.g. Block A, plot 7 and Block B, plot 1. However, as the DNR burning crews became more experienced and after slash concentrations were diminished, the fires became much more predictable. I could find no evidence of overstory mortality related to any recent burns. 14 15 Table 1. Stand and Stock Table for Red Pine* in Block A Dbh Mean Number of Trees Volume** (cm.) (in.) per ha. per acre cu. meters/ha cu.ft./acre 28 11 5 2 1.3 19 31 12 20 8 9.3 133 33 13 22 9 13.4 192 36 14 40 16 26.8 383 38 15 32 13 25.8 369 41 16 40 16 35.1 502 43 17 15 6 16.2 231 46 18 20 8 21.1 301 48 19 2 1 1.7 24 51 20 5 2 6.3 90 53+ 21+ 2 1 4.3 62 Total 203 82 161.4 2306 (+-16.7) (+-239) Basal Area 24 104 Table 2. Stand and Stock Table for Red Pine* in Block B Dbh Mean Number of Trees . Volume** (cm.) (in.) per ha. per acre cu. meters/ha cu.ft/acre 33 13 7 3 4.1 58 36 14 10 4 6.3 90 38 15 15 6 12.5 178 41 16 37 15 35.5 508 43 17 32 13 33.4 477 46 18 15 6 19.3 276 48 19 2 1 2.0 28 Total 119 48 113.0 1615 (+-7.9) (+-113) Basal Area 15.6 68 * : The overstory of Blocks A and B contained only red pine **: Species specific volume equations from Hahn (1984) 16 Table 3. Stand Table for Red Pine in Block C; Mean Number of Trees per Hectare and (per acre). Dbh (cm.) (in.) Red Pine Sugar Maple White Pine Total 15 6 12 (5) o 0 12 (5) 28 11 5 (2) 0 0 5 (2) 31 12 2.5 (1) 0 2.5 (1) 5 (2) 33 13 7 (3) 0 0 7 (3) 38 15 5 (2) 2 (1) o 7 (3) 41 16 25 (10) 0 0 25(10) 43 17 12 (5) o 0 12 (5) 46 18 17 (7) 0 0 17 (7) 48 19 12 (5) 0 0 12 (5) 51 20 7 (3) o 0 7 (3) Total 104.5 (43) 2(1) 2.5 (1) 109(45) Basal Area 13.3 (58) .2 (1) .2 (1) 14 (60) Table 4. Stock Table for Red Pine in Block C; Mean Gross Cu. Meters/Hectare and (Cu. Ft./Acre) (without bark)* Dbh (cm.) (in.) Red Pine Sugar Maple White Pine Total 15 6 1.2 (17) o o 1.2 (17) 28 11 .6 (9) 0 0 .6 (9) 31 12 1.3 (18) 0 .7 (10) 2.0 (28) 33 13 4.3 (61) o o 4.3 (61) 38 15 2.1 (30) .3 (4) 0 2.4 (34) 41 16 20.4 (291) 0 o 20.4(291) 43 17 11.7 (167) 0 0 11.7(167) 46 18 18.2 (260) o 0 18.2(260) 48 19 13.5 (193) 0 o 13.5(193) 51 20 9.2 (132) 0 0 9.2(132) 53+ 21+ 1.5 (22) 0 0 1.5(122) Total 84 (1200) .3 (4) .7 (10) 85 (1214) +-12 (+-172) * : Species specific volume equations from Hahn (1984). 17 Table 5. Overstory Characteristics for Blocks A, B, and C. Basal Area Average Diameter Volume 2 2 3 3 m /ha ft./acre (cm.) (in.) m/ha ft./acre Block A 24.0 104 42.4 16.7 161.4 2306 Block B 15.6 68 41.6 16.4 113.0 1615 Block C 14.0 60 43.4 17.1 109.0 1214 18 Mature red pine is tolerant of understory fires and many authors have had successful results with underburning. Niering (1970) conducted a study in which burning was done with no mortality to the overstory. In fact, studies done with red pine have failed to show any adverse effect of underburning on overstory tree growth, provided excessive crown scorch is avoided (Alban 1977, Methven and Murray 1974) Red pine is essentially a fire-adapted species (Van Wagner 1970) and several factors will determine if fire injures or kills a tree. Those factors include lethal temperature, season, bark characteristics, size and vigor of the tree, and specific fire characteristics (Rouse 1988). A few comments about each of those factors discussed by Rouse (1988) follows: Season - In spring, the forest floor litter layer is winter cured and dry, whereas the fermentation and humus layers are moist" ‘Wildfires spread quickly in red.pine stands during this season, yet they burn shallowly, causing little damage to the soil or roots. Different burning seasons have been recommended for different burning objectives; spring burning is addressed here because it is generally a more reliable season for burning in the Lake States. In addition, only spring burns were conducted for the present study; no fall burns were possible due to improper weather conditions. Lethal temperature - Researchers have shown that when living tissue reaches 64 degrees Celcius (147 degrees Farenheit), it dies almost instantaneously. Red pine is well 19 known for its ability to produce thick bark which, because of its insulating qualities, enables the stem of mature trees to withstand fire. Needles, however, can quickly reach lethal temperature if they are in the convection column of a hot surface fire (Dickmann 1991). Fire characteristcs - Greater fire intensity means that more energy is directed at the tree so the probability of injury increases. The intensity of a flaming front can be estimated from flame length" iMethods to estimate both rate of spread and flame length in the field.have been devised (Simard et al. 1989). Size and Vigor - Until a red pine is around 18 meters tall (60 feet) (approximately 50 years old), either the basal cambium or crown can be killed. After the tree reaches this height, the bark is thick enough to protect the cambium from all but the most extreme fires and the majority of the crown is far above the flames. Although tall trees are still susceptible to crown damage, they may survive even though 75- 85% of their original crown was scorched (Van Wagner 1970). Van Wagner (1970) found that the crowns of pine stands maintain maximum flammability up to heights of around 18 meters (60 feet), and thereafter the possibility of crown fire is lessoned by the increasing height of the open trunk space. Crown fires in mature red pine stands are, thus, a rare occurrence. The usual limitation to the survival of red pine in a surface fire is its susceptibility to crown scorch by hot gas rising above the flames (Van Wagner 1970). Burning on 20 cool days can minimize scorching (Dickmann 1991). Low intensity fires of no more than 0.6 meter (2 feet) flame heights cause little or no scorching and the risk of a crown fire is slight. An average energy release of less than 165 kcal/sec.-m (200 Btu/sec.-ft.) will leave mature red pine crowns untouched (Van Wagner 1970). Ground Vegetation It would appear that there is a difference between treatments when comparing total percent cover (Figure 2) . However, upon examining Table 6, no significant differences were found after conducting an analysis of variance. 'This may be due to the low sample size and large variability between experimental units. Block C had the largest percent cover, followed by Blocks A, and B. These differences between blocks probably affected treatment values. Block C had the most open canopy, accounting for a high ground cover percentage, whereas Block B had been recently logged, probably accounting for a relatively lower percentage of ground cover. In any event, total percent ground cover varied anywhere from 35% to 55% between treatments. Due to the scattered distribution of the vegetation, no definite relationship to burning frequency could be determined. Species richness of ground vegetation, which may be defined as the total number of different species found in a certain treatment, was also examined. No significant 60 50 40 30 percent ground cover 21 2 years 5 years 10 years burn interval Figure 2. Average Percent Ground Cover, control by Treatment 22 Table 6. Effects of Burning Intervals on Total Percent Cover and Species Richness of Herbaceous Ground Vegetation* Burning Interval 2 years 5 years 10 years control Percent Cover 35.8 42.4 55.9 35.3 (8.7) (12.0) (13.4) (6.8) Species Richness 21 19 23 22 (No. of spp.) (2.5) (4.0) (2.6) (3.5) *: Treatments were not significantly different. Standard errors are shown in parentheses. 23 differences were found between treatments (Table 6). Species richness ranged from 19 different types of vegetation in the 5-year treatment to 23 species in the 10-year treatment. According to this analysis, burning had no effect on species richness of ground vegetation. Although burning did not have significant effects on total percent ground cover or species richness, it did appear to effect species composition and importance (Figure 3) . Those species which appear to be most affected by burning include mosses and lichens, MAE spp. , grasses, brackenfern and black cherry (Ergngs sergtin§)- A significant difference between treatments existed at the 5% error level for coverage of mosses and lichens (Table 7) . Significant differences were found between percent ground cover of short-rotation.fires (2-year and 5-year intervals) as compared to fires with a longer rotation (10 years) or no fire at all; the percentage of mosses and lichens increased as time between burns increased (Figure 3). There was also a significant difference between one burn and no burn at all, as seen when comparing the 10-year treatment to the control (Table 7) . However, no significant difference existed between the 2-year and 5-year treatments. Burning’s net effect on mosses and lichens was to reduce their abundance. Mosses and lichens decreased from approximately 9% cover in the control to 4% in the 10-year treatment to about 2% in the 2 and 5- year treatments. There appears to be an obvious pattern between burning 24 ’4’4’4‘D Z/fifll/Zgfiy/IIZZZZZ/la werewerewewewewe. W‘r.» Vfi/IfiZ/ZIZ/ fierereweeewewereweweweweren 7‘" N’NFNFNFNFNF‘. I/I/I/Ia. 72% ”one?“ .OLOLOMOI ........ 2543/25 L1 Lr 0 5 0 1 .960 «e own—96 IS)- grass red pine black cherry QZ-years S-years 4” IO-years @wntrol brackenfern moss/lichen rubus Average Percent Ground Cover, by Treatment and Species Figure 3 . 25 Table 7. Effects of Burning Intervals on Percent Coverage of Various Understory Species in a Mature Red Pine Stand.* Burn Interval (years) Species 2 5 10 control Moss and 2.2 a 2.0 a 4.3 b 9.1 c Lichens (0.46) (0.96) (1.3) (1.5) Grasses 4.4 a 12.7 a 16.9 a 3.8 a (2.6) (5.6) (8.9) (1.2) Black 1.6 a 1.5 a .26 b 0.5 b Cherry (0.41) (0.26) (0.12) (0.25) Rubus spp. 7.4 a 6 a 9.5 a 2.8 a (3.4) (1.7) (5.0) (0.4) Brackenfern 10.9 a 6.8 a 14.1 a 5.0 a (5.7) (3.8) (11.3) (4.4) Red pine 0.6 a 1.8 b 1.7 c 1.6 c (0.5) (1.3) (0.9) (0.8) *: Means followed by the same letter are not significantly different (p <= 0.2) using the orthogonal test. Standard errors shown in parentheses. 26 frequencies and grass cover (Figure 3) . However, differences between treatments were not conclusive upon analysis of variance. However, I think it is safe to conclude that burning, especially at 5 or 10-year intervals, stimulates grass growth. Other authors have reported similar findings. For example, Luppino (1984) found that grasses occurred more frequently and covered more area in burned sections than in unburned sections in a similar study in the same area. Ahlgren (1979) found that grass seeds were more abundant in burned areas than in unburned areas in a Minnesota study. Burning stimulates the growth of grasses (Ffolliott et. al. 1977, Lewis et al. 1982, Pearson et al. 1972, White 1983) and may also benefit wildlife by increasing production of grass seeds (Ahlgren and Ahlgren 1960). Buell and Cantlon (1953) found that the herbaceous layer increases in cover with increasing frequency of burning; much of the increase in cover was contributed by grasses. Frequent burning causes the development and maintenance of a comparatively lush undergrowth of herbs, often with grasses as the dominant species. Fire stimulates perennial herbs, grasses, and ferns to root sucker and sprout vigorously. Fire also can stimulate flowering, especially in monocots such as lillies and grasses (Trabaud 1987). There were detectable differences between treatments in black cherry ground cover (Table 7). Separation of means showed only a significant difference when comparing the 2- and 5-year treatments against the 10-year treatment and the 27 control, however. Coverage ranged from approximately 0.3% and .5% in the control/10 year treatment to about 1.5% in the 2- year/S-year treatments. This would indicate that black cherry responds to more frequent burning intervals (2-year and 5- year) than to longer rotations of fire or no fire at all. Black cherry is one of the few woody species that is being recruited in areas having 2-year and 5-year interval fires; total stems per hectare for these two treatments is made up mostly of black cherry stems. Black cherry stems per hectare were also high in the control, but not nearly as important as in the 2-year and 5-year treatments. Obviously, fire will dictate species composition and importance. Seeds of fire- adapted species can sprout after fire and compete effectively, whereas in the control plots, these same species are outcompeted for light, space, and nutrients. Again, although there may be a trend, no detectable differences existed between treatments in terms of Rub—us coverage (Table 7). Looking back at Figure 3, however, it would appear that burning increased.ggbu§ coverage. Coverage was lowest in the control (2.8%) and reached.a high in the 10- year burn treatment (9.5%). The fact that fire increased abundance of 3% species, especially red raspberry, is supported in the literature. Raspberry vegetatively sprouts and fruits heavily after fire (Ahlgren 1979). Luppino (1984) also found raspberry occurring more frequently and covering more area in burned versus unburned areas. Red raspberry typically increases dramatically after fire (as cited by 28 FEIS). In addition to vigorous sprouting, raspberry is also capable of forming dense thickets after disturbance. Although it ‘vigorously invades and. colonizes disturbed. sites, it decreases as canopies close (as cited by FEIS). In addition, seed may persist in the soil for many years until conditions for germination are favorable. Most sprouting shrubs appear to have great longevity owing to their extensive underground parts (Abrahamson 1984). Brackenfern was also a large component in many treatment plots. Although there appears to be a trend in its coverage, which is similar to that of Rubus, no significant differences were detected between treatments. However, there were differences between experimental blocks, which may have masked the responses expected from brackenfern. This was most likely due to data from Block B, in which virtually no brackenfern was recorded in any of the plots. Looking back at Figure 3, brackenfern coverage (although not significant) was highest in the 10-year treatment (14%) , and lowest in the control at 5 % coverage. This would suggest that brackenfern responds to fire, a fact which is supported in the literature. Brackenfern is known to be a competitive plant that invades disturbed areas. Brackenfern, another species which vegetatively reproduces, appears to require soil sterilized by fire for spore germination (as cited by FEIS). Brackenfern is considered a fire adapted species throughout the world (as cited by FEIS) and repeated fires favor its growth. It’s deeply buried rhizomes sprout vigorously after fires, before 29 most competing vegetation is established. In the burned compartments, brackenfern was, other than grasses, the most widespread species in the understory. There were significant differences between treatments in red pine cover (Table 7). This was especially true in relation to frequency of the prescribed fires. A separation of means test showed significant.differences between the 24and S-year treatment. vs. the 10-year 'treatment and control. Significant differences also existed between the 2-year treatment and the 5-year treatment, but not between the 10- year treatment and the control. Red pine coverage was lowest in the 2-year treatments at less than 1%, and relatively similar in other treatments at approximately 2% (Figure 3). Frequent burns kill the small, unprotected red pine seedlings. In fact, only a very small portion of these seedlings are being recruited into the woody understory, and none at all into the overstory. Woody stems per hectare was greatest in the control plots. Burning of any kind seems to discourage red pine recruitment, not regeneration. In fact, until a red pine is approximately 50 years old, fire can be lethal (Rouse 1988). Although red pine can depend on fire for producing mineral seedbeds necessary for regeneration, fires of more than moderate intensity during the first 50 years would likely destroy the whole stand (Van Wagner 1970). In addition to differences between treatments, there were also differences between experimental blocks. Red pine seedlings were highest in Block B and lowest in Block C. This could be due to the 30 lower stocking density in Block B, and also to the fact that fires in Blodk B burned hotter, thus creating more mineral soil ideally suited for regeneration. Other species which were tested for differences included red maple, sugar maple (Age; saccharum), and hawkweed (W) (Table 8). No significant differences between treatments were found for any of these species. Maples will be discussed extensively in the woody understory results, but were not much of a factor in the ground vegetation, representing greater than 1% coverage only in the control plots. Correctly handled, prescribed burning should benefit game by increasing herbaceous growth (Little 1952). During the first three post-fire growing seasons, vigorous growth of herbs and shrubs can. be expected, especially aster and raspberry (Ahlgren 1976). Ahlgren also stated that in a Minnesota study herbs and shrubs of early post-fire years gradually declined and that 13 years after fire, major plants included the herbs big-leafed aster (Aster macropnyllus) , false lily-of—the-valley (Maianthemum canadense), and wild sasparilla (Aralia nudicaulis). In addition, species with seeds that are wind disseminated after fire germinated in soil from burned areas only (Ahlgren 1979). Repeated fires can substantially increase overall understory richness (White 1983). Presumably, the continued application of prescribed fire would favor the most vigorous hardwood and shrub sprouters (Dickmann 1991). In addition, 31 Table 8. Species with. Greater than 1% Ground Coverage, Averaged by Treatment Two Year Burns % Coverage Five Year Burns % Coverage 1. Brackenfern 10.9 1. Grasses 12.7 2. Rubus 7.4 2. Brackenfern 6.8 3. Grasses 4.4 3. Rubus 6.0 4. Moss/Lichens 2.2 4. Hawkweed 2.8 5. Black cherry 1.6 5. Wild Saspirilla 2.7 6. Aster 1.5 6. Moss 2.0 7. Red pine 1.8 8. Black cherry 1.5 9. Strawberry 1.0 Ten Year Burns Control Plots 1. Grasses 16.9 1. Moss/Lichens 9.1 2. Brackenfern 14.0 2. Brackenfern 7.3 3. Rubus 9.1 3. Grasses 4.2 4. Moss/Lichens 4.3 4. Rubus 2.8 5. Red pine 1.7 5. Choke cherry 1.4 6. Hawkweed 1.5 6. Wild Sasparilla 1.4 7. Strawberry 1.5 7. Red pine 1.4 8. Bergamot 1.2 8. Hawkweed 1.3 9. Sugar maple 1.2 32 forage increases in underburned stands because burning stimulates the growth of grasses and forbs (Ffolliott et al. 1977, Lewis et al. 1982). Other benefits to wildlife include cover and increased production of fruit and seeds by grasses, herbs, and shrubs (Ahlgren. and .Ahlgren 1960, Lewis and Harshbarger 1986) . Burning under pine can also increase quantity and nutritional value of browse and forage (Dickmann 1991). Rubus, herbs, grass, and sedges increase after burning, causing an improvement in deer forage conditions. Frequency of prescribed burns is also important. Two- year burn intervals may be too soon because sprouts haven’t recovered sufficiently to produce seed (Ahlgren 1979). Indeed, the two-year burn intervals in this study (although differences were not significant) had the lowest percent ground cover. The highest percent ground covers, although again results were not significant, were found in the 5-year and 10-year treatments. This would seem to be supported by the literature as cited earlier. The control plots also had lower coverage, most likely due to greater competition and a high percentage of mosses and lichens outcompeting other species for water, nutrients, and space. In this sense, burning also affects species composition and species importance. For example, while mosses and lichens were highest in the control.plots (9%), grasses were most important in the 10-year and 5-year treatments, representing 17% and 13% of total coverage, respectively. Fox (1986) reported that sites burned twice in 12 years had significantly more plant 33 species, higher shrub density, and a greater cover than those burned only once. In addition, the understory that had experienced two fires in 12 years was significantly richer than that which was burnt only once. On post-fire lands, ashes often stimulate a lush, early herb and shrub growth. Lemon (1949) has shown that survival and increase of herbs under prescribed burning are related to life form and life history of the species concerned ( as cited by Buell and Cantlon 1953). Buell and Cantlon (1953) found that when stands were burned at 3-year intervals or oftener, cover by the shrub layer was reduced by as much as 50%. Two to five burns during a 5-year period caused a reduction in.the average height of shrubs by 30 - 40% in one study (Little and Moore 1945). Little and Moore (1945) also reported few changes following single burns; the effects largely disappeared within the ensuing five years. Two annual burns so reduced the shrub and humus layer that it no longer would carry a fire. However, a 10-year burn interval may not be frequent enough to ensure antabundant.herbaceous cover, due to the buildup of woody vegetation, producing competition and shade. Forbs could decrease in subsequent years as grass and woody vegetation cover increases. Therefore, fire can be a. dominant factor in controlling species composition and species importance of the herbaceous understory, with fire frequency playing a large role. 34 Woody Understory Density Total stems per hectare was lowest in the 2-year treatment at 210 stems/ha, and increased as time between burning increased (Figure 4). The trend was nearly exponential, with 385 stems per hectare in the 5 year- treatments, 2069 in the 10-year treatments, and reaching an average high of 4336 stems per hectare in the control plots. There were significant differences in total stems per hectare between treatments at an alpha level of 10% (Table 9). Significant differences existed when comparing the 2- and 5- year treatment against the 10-year treatment and the control. This suggests a definite relationship between frequent burn intervals (2 and 5-years), and longer burning intervals (10 years) or no burning at all. Significant differences were also found. between the 2-year treatment and the 5-year treatment, but not between the 10-year treatment and the control. Table 9 and Figure 5 further break down total stems per hectare by treatment into the various size classes; 0 - 1.9 cm, 2 - 5.9 cm, and 6 - 9.9 cm respectively (0-0.75 in., 0.75- 2.3 in., and 2.3-3.9 in.). Total number of stems per hectare was lowest in the 2-year treatment and reached a high in the control. In addition, it appears that burning affected the number of stems in each size class, with larger trees (6 - 9.9 cm) appearing mostly in the control plots. Little and Moore (1945) also reported that two or more burns within a 5-year period resulted in a net decrease of 18 - 51% in all 35 ’. e444. v" 0 00. O . ‘.‘.‘.“““.““““ wwwnewwfloawwnweooomaar 0) 0 O» )0 >O>O>O>O>O 4e4e4e VEw- . . . . we. .e.e.e.e.e. .e.ew ewewewe. 41 Li H! Fl 3 7. 11 mecca—6.3. 888.5803 M control 3 a e Y mm W e t .m u Sb 3 v. 5 m m v. 2 Figure 4. Total Stems per Hectare by Treatment 36 Table 9. Effects of Burning Interval on Density (stems/ha) of the Woody Understory in a Mature Red Pine Stand.* Diameter Size Burn Interval (years) Class (cm) 2 5 10 control All classes 209 a 385 b 2069 c 4336 c (169) (166) (767) (1646) 0 - 1.9 181 a 283 b 1944 c 2907 c (181) (193) (740) (1045) 2 - 5.9 6 a 79 b 79 b 1088 c (6) (37) (54) (522) 6 - 9.9 23 a 23 a 45 b 340 c (23) (23) (20) (142) *: Means followed by the same letter are not significantly different (p <= 0.2) using the orthogonal test. Standard errors shown in parentheses. 37 w I .28 6-9.9 cm 3500 3000 L 8362580.... 2-5.9 cm size class Q ’2 year burns ’5 year burns ’10 year burns E] control Figure 5. Total Stems per Hectare by Size Class and Treatment 38 reproduction. The loss of seedlings between 0.5 meters and 1.1 meters tall (1.6 and 3.5 feet) was approximately 95%, and in those over 1.1 meters in height it was about 50%. Significant differences at a 10% alpha level were found between treatments when analyzing the 0 - 1.9 cm size class. Again, the control had the largest number of stems in this size class, at an average of 2908 per hectare, followed by 1944, 283, and 181 stems per hectare in the 10-year, 5-year, and 2-year treatments, respectively. Obviously, the more frequent the burning interval, the greater number of small stems killed, and a lower number of stems per hectare. The kill of small hardwoods by fire will depend on species and diameter of trees, season of burning, heat of fire, and frequency and interval of burning (Hodgkins 1958) . The present data indicates that younger trees are more vulnerable to fire than older ones. Significant differences were found between treatments at an error level of 1% in the 2 - 5.9 cm size class (Table 9). As expected, total stems were highest in the control and lowest in the 2-year treatment" Results were similar for both the 5-year and 10-year treatments, both reporting 79 stems per hectare. Only 6 stems per hectare in this size class were found for the 2-year burns and 1088 stems per hectare in the control or no burn plots. Differences were found between frequent burns and infrequent or no burns, between one burn and no burn at all (lo-year treatment vs. the control), and also between 2-year burns and 5-year burns. Even one burn 39 significantly affected this size class, dropping the total number of stems from 1088 in the control to 79 in the 10-year treatment. Obviously, fewer stems are being recruited into this size class as a direct result of fire. Again, significant differences in total stems per hectare were found between treatments in the 6 - 9.9 cm size class (Table 9) . Total stems per hectare were highest in the control plots at 340 stems per hectare, followed by 45, 23, and 23 stems per hectare in the 10, 5, and 2-year treatments respectively. Significant differences could only be detected when comparing the 2- and 5-year treatments against the 10- year treatment and the control, and in comparing the 10-year treatment to the control. Therefore, larger size classes were more affected by frequent fires than by infrequent or no fires at all. The net effect of burning has been to reduce the total number of stems available in each size class. In addition to significant differences observed between treatments, differences between experimental blocks probably affected stocking of the woody understory. Disturbance from logging may have affected understory density of the 6 - 9.9 cm size class in Block B, accounting for its lower values. Block C, with less overstory than Block A, had the most stems in this size class for the 10-year treatment and the control. Whereas no stems were recorded in this size class for the 2- year and 5-year treatments in Blocks B and C, 68 per hectare were found in Block A. Burning affects total stems per hectare as well as total 4O stems per hectare in various size classes. Frequent burns (2 and 5-year) kill mostly young, small stems primarily in the 2.5 - 10 cm size class (1-4"); larger trees appear undamaged except for occassional basal bark injury (Niering 1970). Hodgkins (1958) reported. similar’ findings for“ hardwoods; prescribed fires top killed 62% of 2.5 centimeter trees, 52% of 5 centimeter trees (2 inch), and 38% of 7-8 centimeter trees (3 inch). In addition, Luppino (1984) reported that saplings in burned areas were at browse level, while saplings in unburned areas were forming an understory canopy that further suppressed browse level.growthu Burning in this study also limited the number of stems recruiting into the larger size classes. Prescribed burns have restricted the total number of stems to smaller size classes, making them more available to wildlife. Frequency of burns also affected stems per hectare; 2-year and 5-year burns were relatively void of an understory as compared to the 10-year burns and control. Many authors report that reproduction of hardwoods is more dense on burned vs. unburned plots. Hodgkins (1958) reported that new hardwood growth replaced original growth up to 1.8 meters in height (6 feet) after about three growing seasons; the net effect of burning on total hardwood cover was simply a reduction of its average height. 41 Species Richness - Woody Understory Significant differences between treatments were found for species richness, the total number of different woody species (Table 10). A separation of means test showed significant differences existed between all means tested. Species richness was lowest in the 2-year burns (average = 2 species) and increased to 5 species in the 5-year treatments, almost 8 in the 10-year treatments, to a high of nearly 12 species in the control plots. Fire, therefore, has a definite impact on the number of different species that may be found in a certain burning regime. Frequent burns are considerably less rich because very few species can tolerate and resprout following a fire every two years. .As time between burns increases, more species are able to grow in a given area, giving species which are not normally thought of as fire adapted (such as white ash (Fraxinus americana) or sugar maple) a chance to establish themselves. This has important ramifications for wildlife, leading to a more diverse and abundant food supply with a longer fire rotation. Species richness was further broken down into the three size classes (Table 10). Significant differences existed between treatments for the 0-1.9 cm size class at an error level of 1%. An expected pattern developed, with the largest number of species found in the control and the fewest in the 2-year treatments. Only an average of one species could be found in the 2-year treatments, followed by four, eight, and nearly 11 in the 5-year, 10-year, and control plots 42 Table 10. Effects of Burning Interval on Average Species Richness (no. of species) in the Woody Understory of a Mature Red Pine Stand.* Diameter Size Burn Interval (years) Class (cm) 2 5 10 control All classes 2 a 5.3 b 7.7 c 11.8 d (1.15) (.89) (.67) (1.6) 0 - 1.9 .67 a 3.67 b 7.67 c 10.5 d (.67) (1.2) (.67) (1.3) 2 - 5.9 .33 a 2.33 b 2.33 b 7.67 C (.33) (.89) (1.33) (.67) 6 - 9.9 1.3 a 1.0 a 2.0 b 4.67 c (1.3) (1.0) (.58) (.89) *: Means followed by the same letter are not significantly different (p <= 0.2) using the orthogonal test. Standard errors shown in parentheses. 43 respectively. This would seem to rule out 2-year burns as a treatment alternative, with fire having such a huge effect that only Block B had stems in this size class. Fire's effect on species richness can be seen.through all size classes. If only a small number of species are found in the 0-1.9 cm size class, then an even smaller number will be recruited into the next size class, 2-5.9 cm. Blocks B and C did not have ANY stems in this size class for the 2—year burns, leaving an average number of species of less than one for 2-year burns (Table 10) . Both the 5-year and 10-year treatments had an average of just over 2 different species, but the control had nearly 8. Again, differences between tested means are significant. Upon analyzing the 6 - 9.9 cm size class, a different story emerged (Table 10). Although there were significant differences between treatments, the average number of species found did not differ greatly between the 2-year, 5-year, and 10-year treatments. Significant differences existed when comparing the 2- and 5-year treatment to the 10-year treatment and the control. There are more species found in the latter two treatments, with significant differences also existing between the 10 year treatment and the control. Because the differences between the three different burning intervals are so small, fire apparently has stem killed mostly the smaller size classes but has had less of an effect on the 6 - 9.9 cm size class. In addition to treatment differences, block differences may have affected.this size class” The effects of 44 logging have probably caused the low number of species in Block B. In addition, only Block A had stems in plots burned at 2-year and 5-year intervals for this size class. It would be hard to draw further conclusions from these block differences, although overstory stocking normally has a large impact on understory composition. Woody Understory Composition Fire and fire frequencies have had an effect on species composition (Figure 6). Significant differences in black cherry density were found.between.treatments at an error level of nearly 10% (Table 11). 'Total stems per hectare were lowest in the 2-year treatment at 164 stems/hectare. Black cherry stems/hectare increased to 215 in the 5-year treatment, 595 in the 10-year treatment and.then.decreased to 306 in the control plot. Although differences between the control plot and the 10-year treatment were not significant, there does appear to be a trend. Fire has had a large impact on this species, which is particularly evident when looking at Table 12. Although total stems per hectare are greatest in the 10-year treatment and the control, black cherry stems are :most important in the 2-year and 5-year treatments where they comprise well over half of the total stems reported. Black cherry stems are second only to red maple in the 10-year burns, but are not nearly as important in the control plots. This suggests that this species responds to fire and is an 45 t eeeeeeeeeeeeeeeeeeeeeeeeeeee eee homo???»ououonouononononono».nononononeuflononouononouououon /l V...‘....‘.“‘.‘..‘V//V/¢//‘/¢/V% 0.0.0.0...0909.9.0.00.0... gX55555555555555555555555‘, O mm 600 L L 0 w m. 8802580.... 500 l- 400 m control m. m a A We 113 w m .m m u 3.0 a 8 VJ 5 @ choke cherry beech 2 years 5%.... control ‘ ‘ a P . X2 white ash B a ..... w. P , w .m m w«.~.».wwwu.w$ m w t r n .l //l m % u m b a e y 5 2 years 1500 F 8862583..“ @ black cherry birch Stems per Hectare by Treatment and Species Figure 6. 46 Table 11. Effects of Burning Intervals on Density (stems/ha) of Various Woody Understory Species in a Mature Red Pine Stand.* Burn Interval (years) Species 2 5 10 control Black cherry 164 a 215 b 595 c 306 c (164) (173) (243) (49) Red maple 0 a 23 b 612 c 1661 c (0) (15) (446) (1415) Birch 28 a 51 a 17 a 28 a (15) (29) (17) (20) White ash 6 a 28 b 85 c 340 d (6) (15) (45) (158) Beech 6 a 0 b 142 c 159 c (6) (0) (60) (99) Aspen 6 a 6 a 57 a 45 a (6) (6) (34.5) (37) Choke cherry 0 a 23 b 442 c 538 c (0) (15) (214) (253) *: Means followed by the same letter are not significantly different (p <= 0.2) using the orthogonal test. Standard errors shown in parentheses. 47 Table 12. Ranking of Species Importance, Averaged by Treatment TWO YOII Burns 1. 2. 3. 4. 5. Ten 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Black cherry Birch Aspen White ash Beech YOII Burns Red maple Black cherry Choke cherry Beech White ash Aspen Ironwood Sugar Maple White oak Red oak Birch Stems/ha 164 28 6 6 6 Stems/ha 612 595 442 142 85 57 40 34 28 17 17 Five Year Burns 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Black cherry Birch White ash Red maple Choke cherry Red pine Aspen Red oak White oak White pine Control Plots 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. Red maple Sugar maple Choke cherry White ash Black cherry White pine Beech Ironwood Red pine Amelanchier Aspen Birch Red oak Balsam fir Basswood White oak Jack pine Stems/ha 215 51 28 23 23 23 O\O\O\O\ Stems/ha 1661 675 538 340 306 232 159 156 77 65 45 28 23 17 6 6 3 48 opportunist occupying bare areas free from competition. This species has hard-coated seeds which are capable of surviving in the forest floor and springing up after fire. Significant differences in red maple density were found between treatments (Table 11), especially when plotting frequent fires (2-year and 5- year rotations) against less frequent fires or no fire at all. There does appear to be a trend; red maple follows an exponential curve, starting with a low of 0 stems per hectare in the 2-year plots and increasing to 23, 612, and 1661 stems in the 5-year, 10-year, and control plots respectively. Obviously, fire frequency has a big impact on the number of red maple stems. The 2-year interval was too frequent and, therefore, lethal to red maple stems. However, red maple was the most important species in the 10-year treatment, and the control (Figure 6, Table 12). It was also one of the ten species found in the 5-year treatments. Red maple is a moderately tolerant species, capable of dominance in.the absence of fire. IHowever, it is also capable of responding to fire, provided fire frequency is not too high. Although temporarily set back by fire, red maple comes back strong after one or two growing seasons. Red.maple is an example of a species capable of sprouting from roots or portions of the stem left unkilled by the fire. Red maple’s sprouting abilities and subsequent attractiveness as browse to wildlife has been documented extensively in the literature. For example, Fowells (1965) reported that fire-killed red 49 maple trees sprout vigorously, and the species may become a more important stand component after a fire than it was before. Red maple may also suffer when large populations of deer are present, as it is a preferred deer food (Fowells 1965). No significant differences were found in birch (Betula W) stems per hectare (Table 11) . Although birch stems were found across all treatments, they appeared to be of much greater importance in the 2-year and 5-year treatments (Table 12), especially in the smaller size classes. Birch is an example of a pioneer species with light seeds which are disseminated by wind from adjacent areas. There were also differences between blocks, with no birch reported in Block C. This may suggest that the composition of the post-fire stand will depend upon the relative supply of wind-disseminated seed for species such as birches and aspens (Populus trgmuloides and P. grandidentata), or bird-disseminated seed as for the cherries (Barnes and Spurr 1973). Significant differences in white ash density were observed between treatments at an alpha level of 5% (Table 11). Total stems per hectare rose from a low of 6 in the 2- year treatment to 28, 85, and 340 stems per hectare in the 5- year, 10-year and control plots, respectively. White ash stems are much more important in the control plots, making up a larger part of total stems per hectare than in other treatments. This is also true of the 10-year treatment as compared to the 2- year and 5-year treatments. White ash 50 stems were found in all three size classes in all treatments except the 2-year burns. Only white ash stems in the 6-9.9 cm size class were found in the 2-year treatments Thus, frequent fires kill mostly smaller stems and have altered recruitment and species composition of white ash. White ash is able to increase in importance with increasing time between fires; it is an example of a species which is killed by fire and mostly recovers by seeding. In addition to significant differences between treatments, differences between experimental blocks also existed. Blocks B and C had relatively fewer stems of white ash than did Block A. Block C had a large shrub cover, under which the moderately tolerant ash could not establish itself. Block B had experienced disturbance in the form of logging which may have eliminated the white ash understory. Beech (Fagus grangifglia) followed a similar trend as that of white ash, except that virtually no stems were found in the 2-year and 5-year treatments. Beech was adversely affected by frequent fires, and unable to:re-establish itself, although it is capable of sprouting. Given more time between fires, this tolerant species is able to revive in importance (Table 12). .A huge difference between treatments existed in sugar maple density. Sugar maple, a poor sprouter, was non-existent in the 2-year and 5-year treatments, fairly unimportant in the 10- year treatment, and very important in the control plots. There, it was second in total number of stems only to red maple. The largest number of stems per hectare in the 10-year 51 treatment existed in the 6-9.9 cm size class, once again suggesting that fire kills mostly smaller sized trees. Fire has seriously affected the composition and abundance of this species. Another species adversely affected by fire in much the same way as sugar maple was red pine. No stems of this species were reported in either the 2-year or 10-year treatments, and only a small number were found in the 5-year treatments. Red pine is not recruiting from seedlings less than 1.5 meters in height to seedlings.greater than 1.5 meters in height except in the control areas. Fire is necessary to promote a mineral seedbed for red pine germination, but is destructive to the small, thin barked trees until approximately 50 years of age. Amelanchier was only present in the control plots and was destroyed easily by fire of any sort or frequency. White (1983) also reported finding Amelanchier in unburned areas only, and that it may be adversely affected by fire. Aspen seemed to be effected by frequent fires (Table 11) . However, the differences between treatments were insignificant. While adversely affected by frequent fires, aspen responded to fires of longer rotation. Aspen is a pioneer species, which readily occupies bare land. In addition, it suckers profusely and is known to increase after fire (Fowells 1965). However, differences between experimental blocks may have masked the expected response in this case. iBlock.B, recently logged, contained no aspen stems 52 at all and Block C only had aspen stems in the 10-year and control plots. Differences between treatments in choke cherry (Eggggg Virginiana) density were significant at the 5% error level (Table 11). Stems per hectare went from a low of 0 in the 2-year treatments to 23, 442, and 538 in the 5-year, 10- year, and control plots, respectively. Frequent fires, especially at 2—year intervals, have diminished the abundance of this species. Choke cherry responded.to fire at longer burn intervals, increasing in importance from the 5-year to the 10- year treatment. It is one of the few species which is fairly important in the burning treatments and in the control plots. It represents a large percentage of total stems per hectare of the control plots (Table 12). It comes in after fire as seen by its representation in the smaller size classes. Choke cherry is an example of a species which reproduces vegetatively and sexually. It is also known to be well adapted to disturbance by fire. It is thought to be moderately resistant to fire mortality, and although easily top killed, plants resprout vigorously following most burning (as cited by FEIS). Species have adaptations to different fire frequencies. In general, the distribution of plants on burned and unburned land is dependent on. the type of :reproduction, whether vegetative or by seed, the extent to which vegetative parts are heat tolerant, and the extent to which the species are able to compete.in the opening created.by fire (Ahlgren 1964). 53 Ahlgren (1964) found that vegetatively reproduced species were more frequently dominant components of burned lands. The dominant species of more frequently burned associations recover by sprouting or resist fire. Dominants of less frequently burned areas that are killed by fire can also recover by seeding. Fire kills most or all of the plant above the soil surface; succeeding vegetation tends to be made up of light- seeded species that can move in from outside the burned areas, species with perennial root systems capable of sending up new sprouts, and species with dormant seeds buried in the forest floor that are stimulated by heat (Barnes and Spurr 1973) . Species sprout quickly after losing their above ground parts to fire, recovering their pre-burn dominance levels in 2-3 years (Abrahamson 1984) . Plants that survive fire and regenerate vegetatively have a root system ready to utilize nutrient flushes from fire (Trabaud 1987). New shoots grow fast with an established root system to nourish them. Individual species responses vary considerably, but the majority of woody species, such as aspen, red oak (Qu_e_r_gy_s_ Ma) , and red maple, are sprouters rather than seeders. Other species exhibit a sit-and-wait strategy and can be released by fire when dead litter and grasses are consumed. Others, such as black cherry, will utilize a buried seed strategy. Vegetative reproduction is an important recovery mechanism when fires are too frequent to permit seed production. Repeated fires not only kill back the woody 54 understory, but they also cause shifts in its composition. Sprouting varies by species with, for example, red maple intermediate and sugar maple low in this sense (Dickmann 1991). Stem kill of certain smaller trees and shrubs is limited.to the more fire sensitive tree species (Niering et al 1970). Fire frequency has a large impact on species composition and abundance, with fewer species present in more frequently burned areas“ Trabaud (1987) found that in.plots burned every other year, the amount of seed buried in the soil progressively decreased, resulting in fewer individuals present. Where fires occur too frequently, species disappear. Fox (1986) found that of species present only on single-fire (12-year fire rotation) plots, all were obligate seedling regenerators, while the larger number of species found only on twice burned plots were mostly vegetative regenerators. The results have implications for vegetation managers; areas burned too frequently may lose obligate seedling regenerators, while an area remaining unburnt for too long may lose some vegetative regenerating species, as well as short- lived obligate seedling regenerators (Fox 1986). The inference is that some species require longer than 6 years to establish an adequate seed reserve either on the plant or in the soil seed bank. Fox (1986) found that fires every 6 years were too frequent, while fires. every' 12 years 'were :not frequent enough. The data indicates that the frequency of prescribed 55 burning has a marked effect on the lower vegetation layers. However, there is not a uniform reduction in all species. A shift in the relative importance of species can be found with increased burning frequency, also leading to shifts in species dominance. A good summary was provided by Hodgkins (1958) of prescribed burning effects in loblolly pine stands: 1. Thin-barked species are more susceptible to fire killing and damage than are thick-barked species. 2. Late spring or early summer fires have the greatest weakening effect on understory hardwoods. 3. Hotter fires top-kill the larger hardwoods. 4. Any reduction of hardwoods with a single fire is usually temporary, and the net result after a few years is often an increased coverage of hardwoods. The burning influence appeared to last about 3 years. 5. After 6 years, the amount of hardwood cover in the 0.3 - 1.2 meter (1 - 4 feet) height class was greater on the burn than on the control. 6. Species, such as red maple, may receive a temporary setback as the result of fires, but will again show greater stimulation after one or two growing seasons. CONCLUSIONS AND RECOMMENDATIONS The specific objectives addressed in this study were 1) the quantification of the herbaceous and woody understory composition in once thinned red pine stands, 2) the assessment of the effects of spring' prescribed fires on overstory conditions and understory composition and development, and 3) the assessment of the effects of repeated prescribed burns at 2, 5, and 10-year intervals on understory composition and development as compared to no burning at all. The feasibility of burning will depend on various factors, including weather conditions, public opinion, and experienced personnel. Conclusions and recommendations regarding wildlife and recreation were based upon.personal observations, as specific effects on these values were not quantified. Results of this study affirmed several of the hypotheses stated in the introduction of this report. Thinning red pine stands on good soils stimulated the development of a diverse and extensive woody and herbaceous understory. This was evident in the control plots, in which a rich and extensive understory developed. in. response: to the opening of the overstory canopy. Few adverse effects were observed on the pine overstory, but the effects of burning on the herbaceous and woody understory varied with fire frequencies. Repeated burns at short intervals, as in the 2-year and 5-year treatments, did not significantly affect herbaceous cover or specieszrichness, but.did.affect.species composition. 56 57 Frequent fires did significantly affect the extent and diversity of the woody understory, which was virtually eliminated. Most species were eliminated because they had insufficient time in which to recover and respond to the fire before another burn was set. Those species which did respond exhibited different survival characteristics, including sprouting and buried seed strategies. Burning at long intervals, as in the 10-year treatments, also had no effect on herbaceous cover or species richness. Only species composition was altered in this stratum. A longer fire rotation temporarily set back the development of the woody understory, immediately following the burn. However, with increased growing time between fires, a vigorous and extensive understory developed which could be used by wildlife. Burning at longer intervals resulted in an increasingly rich and abundant food supply as compared to the frequent burning intervals. Species composition was altered, with sprouters most prominent. In addition, stems reached a greater size and, thus, become better parents for sprouting. Given a longer time between.burns, more species had sufficient time to re—establish themselves. Prescribed burning, at longer intervals, can be used to benefit wildlife by stimulating herbaceous and woody species useful in wildlife management. The 10-year treatments in this study provided a diverse and extensive understory which could be utilized by wildlife. Accessibility for humans and wildlife, in my opinion, were also better on the 10-year plots 58 as compared to the controls. Burning at longer intervals, between five and 10 years, was most appropriate for meeting timber, wildlife, and recreation objectives in this study. The Lake States are rich with red pine plantations. Management of the many hectares of mature red pine which already exist could include wildlife, recreation, and timber objectives, depending on what the values of society dictate. These data indicate that heavy thinning, combined with burning, controls the density and composition of the understory resulting in improved access and an abundant food supply for wildlife. In addition, large diameter trees were produced in an aesthetically' pleasing stand. Fire can continue to be used as a management tool when its effects are known to be beneficial. With successful results in experimental areas and elsewhere, this practice can become operational in the Lake State forests, too. APPENDIX APPENDIX Completed ANOVA's for Entire Study Table 13. Total Percent Cover of Herbaceous Vegetation by Burning Interval and Block. Burning Interval 2 years 5 years 10 years control Block I"??? """" I???” 69.5 " _ 34.0 "' Block B 35.0 19.7 29.2 24.0 Block C 51.3 60.4 69.0 47.8 Average};§"§;;"'"'"ZSTZ"""“"EZB """""" 3' 5'3"" Std. error 8.7 12.0 13.4 6.8 ANOVA of arcsin transformed data Source d.f. S.S. M.S. F. Total 11 1252.49 Block 2 641.76 320.88 Tmt. 3 290.55 96.85 1.82-NS Error 6 320.18 53.36 I 2 U) ll Not Significant 59 60 Table 14. Species Richness of Herbaceous Vegetation by Burning Interval and Block Burning Interval 2 years 5 years 10 years control Block A 16 26 22 26 Block B 24 12 19 15 Block C 23 19 28 25 Average 21 19 23 22 Standard Err. 2.52 4.04 2.65 3.51 ANOVA Source d.f. S.S. M.S. F. Total 11 278.25 Block 2 87.50 43.75 Tmt. 3 26.25 8.75 .32-NS Error 6 164.50 27.42 61 Table 15. Total Percent Ground Cover of Mosses and Lichens by Burning Interval and Block Burning Interval 10 years control 2 years 5 years Block A 1.4 3.6 Block B 3.0 0.3 Block C 2.3 2.2 Average(%) 2.2 2.0 Std. error .46 .96 Source d.f. 8.8. Total 11 253.61 Block 2 .62 Tmt. 3 178.80 Error 6 74.19 * = significant at 5% SEPARATION OF MEANS TEST 1. 2,5 vs. 10,control 3.2 Significant at .02 2. 10 vs. control t= 2.01 Significant at .10 3. 2 vs. 5 t= .39 Not Significant 62 Table 16. Total Percent Ground Cover of Grasses by Burning Interval and Block Burning Interval 2 years 5 years 10 years control Block A 0.8 6.5 34.3 4.3 Block B 2.9 7.7 5.4 1.4 Block C 9.4 23.8 10.9 5.6 Average(%) 4.4 12.7 16.9 3.8 Std. error 2.6 5.6 8.9 1.2 4 ANOVA of arcsin transformed data Source d.f. S.S. M.S. F. Total 11 852.9 Block 2 146.9 73.44 Tmt. 3 346.99 115.66 1.93-NS Error 6 359 59.83 63 Table 17. Total Percent Ground Cover of Black Cherry by Burning Interval and Block Burning Interval 2 years 5 years 10 years Block A """STS""""ZS’""""BTE"" Block B 1.8 1.1 0.1 Block C 0.83 1.4 0.17 Aver...(41"'17?""""ITE"""'”"32"" Std. error .41 .26 .12 ANOVA of arcsin transformed data Source d.f. S.S. M.S. Total 11 61.69 Block 2 4.44 2.22 Tmt. 3 44.64 14.88 Error 6 12.61 2.10 * = significant at 5% SEPARATION OF MEANS TEST 1. 2,5 vs. 10,control t= 4.52 Significant at .01 2. 10 vs. control t= .9 Not significant 3. 2 vs. 5 t= .12 Not Significant control mu—w-' 64 Table 18. Total Percent Ground Cover of Rubus Spp. by Burning Interval and Block Burning Interval control 2 years Block A 1.3 Block B 13.1 Block C 7.8 Average(%) 7.4 Std. error 3.4 5 years 10 years 5.5 19.4 3.3 3.6 9.2 5.5 6 9.5 1.7 5.0 SOS. M.S. 355.88 .34 .17 83.50 27.8 272.00 45.0 I 2 U) ll not significant 65 Table 19. Total Percent.Ground.Cover of Brackenfern.by Burning Interval and Block Burning Interval 2 years 5 years 10 years control Block A '"'1'32""""‘ISTS""""'IT§""""mITS """" Block B 0 0 4.2 0 Block C 19.2 7.5 36.7 13.8 Average(a.i"'133""""ETE""""IZTI"""m"; """"" Std. error 5.7 3.8 11.3 4.4 ANOVA of arcsin transformed values Source d.f. S.S. M.S. F. Total 11 1562.43 Block 2 993.53 496.77 Tmt. 3 142.81 47.60 .67-NS Error 6 426.09 71.02 -NS = not significant 66 Table 20. Total Percent Ground Cover of Red Pine by Burning Interval and Block Burning Interval 2 years 5 years 10 years control Block A 0.1 0.6 0.9 1.0 Block B 1.6 4.4 3.4 3.2 Block C 0 0.3 0.75 0.6 Average(%) .6 1.8 1.7 1.6 Std. error .5 1.3 .86 .8 ANOVA of arcsin transformed data Source d.f. S.S. M.S. F. Total 11 146.75 Block 2 110.02 55.01 Tmt. 3 32.32 10.77 14.55* Error 6 4.41 .74 * = significant at 1% SEPARATION OF MEANS TEST 1. 2,5 vs. 10,control t=4.28 Significant at .01 2. 10 vs. control t= .20 Not significant 3. 2 vs. 5 t=5 Significant at .01 67 Table 21. Total Stems per Hectare by Burning Interval and Block. Burn Interval 2 years 5 years 10 years control Block A ’"’"EE""""'2§3"""'§I§3'" ""2225 """" Block B 544 714 578 1343 Block C 0 187 2500 7022 Average “"35"”"“;;;"‘““;;;; """" Z352 """"" Std. error 169 165.5 767 1646.5 ANOVA of transformed data Source d.f. S.S. M.S. F. Total 11 62.15 Block 2 3.44 1.72 Tmt. 3 37.00 12.33 3.41* Error 6 21.71 3.62 * Significant at 10% SEPARATION OF MEANS 1. 2 year, 5 year vs. 10 year, control treatments t = 2.83 Significant at .05 2. 10 year vs. control treatment t = .49 Not significant 3. 2 year vs. 5 year treatment t = 1.42 Significant at .20 68 Table 22. Total Stems per Hectare by Burning Interval and Block, 0 - 1.9 cm Burning Interval 2 years 5 years 10 years control Block A ""3""""‘SZ"""""SSEI"""'"SZEETE"" Block B 544 663 544 884 Block C 0 153 2227 4370 Average "'IEI"""";§§ """""" I §Z4""""'3339T3"" Std. error 181 193 740 1044.7 ANOVA of transformed data Source d.f. S.S. M.S. F. Total 11 94.97 Block 2 5.20 2.6 Tmt. 3 61.02 20.34 4.25* Error 6 28.75 4.79 *significant at 10% SEPARATION OF MEANS 1. 2 year, 5 year vs. 10 year, control treatments t = 3.16 Significant at .02 2. 10 year vs. control treatment t = .24 Not significant 3 2 year vs. 5 year treatment t = 1.64 Significant at .20 69 Table 23. Total Stems per Hectare by Burning Interval and Block, 2 - 5.9 cm. Burn Interval 2 years 5 years 10 years control Black A '“""1;"“““‘;;;““““";;"““';'a'; """ Block B 0 51 17 391 Block C o 34 187 2108.6 Average "”33 """"" §§"""""§3“""§3§£ """ Std. error 5.7 37 54 521.5 Source d.f. S.S. M.S. F. Total 11 61.61 Block 2 3.70 1.85 Tmt. 3 50.51 16.84 13.7* Error 6 7.40 1.23 *significant at 1% SEPARATION OF MEANS 1. 2 year, 5 year vs. 10 year, control treatments t = 16.51 Significant at .01 2. 10 year vs. control treatment t = 3.15 Significant at .02 3. 2 year vs. 5 year treatment t = 3.56 Significant at .02 70 Table 24. Total Stems per Hectare by Burning Interval and Block, 6 - 9.9 cm Burning Interval 2 years 5 years 10 years control Block A ""23"""""23"""""§Z""""""ZS§ """ Block B 0 0 17 68 Block C 0 0 85 544 Average "23""""""3§'= ’ 45 340 Std. error 23 23 20 142 ANOVA of transformed data Source d.f. S.S. M.S. F. Total 11 62.92 Block 2 15.43 7.72 Tmt. 3 35.32 11.77 5.8** Error 6 12.17 2.03 **Significant at 5% SEPARATION OF MEANS TEST 1. 2 year, 5 year vs. 10 year, control treatments t = 3.84 Significant at .01 2. 10 year vs. control treatment t = 1.62 Significant at .20 3. 2 year vs. 5 year treatment t = 0 Not significant 71 Table 25. Species Richness in the Woody Understory by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Block A 4 5 9 15 Block B 2 7 7 10 Block C O 4 7 10.5 Average 2 5.3 7.7 11.8 Std. error 1.2 .90 .70 1.6 ANOVA Source d.f SS MS F Total 11 184.25 Block 2 16.8 8.4 Treatment 3 153.75 51.25 22.48** Error 6 13.7 2.28 **Significant at 1% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 6.97 Significant at .01 2. 10 year vs. control treatment t = 3.38 Significant at .02 3. 2 year vs. 5 year treatment t = 2.7 Significant at .05 72 Table 26. Species Richness in the Woody Understory by Burning Interval and Block, 0-1.9cm Burning Interval 2 year 5 year 10 year Control Block A 0 2 9 13 Block B 2 6 7 9 Block C 0 3 7 9.5 Average .7 3.7 7.7 10.5 Std. error .7 1.2 .7 1.3 ANOVA Source d.f SS MS F Total 11 192.56 Block 2 3.37 1.69 Treatment 3 169.06 56.35 16.77 * Error 6 20.13 3.36 **Significant at 1% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 6.54 Significant at .01 2. 10 year vs. control treatment t = 1.89 Significant at .20 3. 2 year vs. 5 year treatment t = 2.0 Significant at .10 73 Table 27. Species Richness in the Woody Understory by Burning Interval and Block, 2-5.9 cm Burning Interval 2 year 5 year 10 year Control Block A 1 4 1 9 Block B 0 1 1 7 Block C o 2 5 7 Average .33 2.33 2.33 7.67 Std. error .33 .89 1.33 .67 ANOVA Source d.f SS MS F Total 11 107.7 Block 2 5.2 2.6 Treatment 3 89.03 29.68 13.19 * Error 6 13.47 2.25 *Significant at 1% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 4.23 Significant at .01 2. 10 year vs. control treatment t = 4.35 Significant at .01 3. 2 year vs. 5 year treatment t = 1.63 Significant at .20 74 Table 28. Species Richness in the Woody Understory by Burning Interval and Block, 6-9.9cm Burning Interval 2 year 5 year 10 year Control Block A 4 3 2 6 Block B 0 0 1 3 Block C 0 0 3 5 Average 1.3 1 2 4.7 Std. error 1.3 1 .6 .9 ANOVA Source d.f SS MS F Total 11 48.25 Block 2 15.5 7.75 Treatment 3 24.92 8.31 6.34* Error 6 7.83 1.31 *significant at 5% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 3.28 Significant at .02 2. 10 year vs. control treatment t = 2.85 Significant at .05 3. 2 year vs. 5 year treatment t = .36 Not Significant 75 Table 29. Total Stems per Hectare of Black Cherry by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Black A ""3"""m32 """" ZZS'mméEl' " Block B 493 561 272 391 Block C 0 51 1071 306 Average "'12; """"" 213""""333""'"§32"" Std. error 164 173 243 49 ANOVA of transformed data Source d.f SS MS F Total 11 61.96 Block 2 11.56 5.78 Treatment 3 30.78 10.26 3.14 * Error 6 19.62 3.27 **Significant at almost 10% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 2.52 Significant at .05 2. 10 year vs. control treatment t = .36 Not Significant 3. 2 year vs. 5 year treatment t = 1.72 Significant at .20 76 Table 30. Total Stems per Hectare of Red Maple by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Alger A "'3"""""§I"""IZ§2T§"""15"" Block B 0 17 68 340 Block C 0 0 272 4489.5 Average ""3"”""’;§""""'EIS""'"IEEI"' Std. error 0 15 446 1415 ANOVA of transformed data Source d.f SS MS F Total 11 100.56 Block 2 1.50 .75 Treatment 3 81.14 27.05 9.04 * Error 6 17.92 2.99 **Significant at 5% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 4093 Significant at .01 2. 10 year vs. control treatment t = .51 Not Significant 3. 2 year vs. 5 year treatment t = 1.61 Significant at .20 77 Table 31. Total Stems per Hectare of.Birch.by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Alger A '""3Z"'"'"ZSE""""§I’""""17" Block B 51 51 0 68 Block C 0 o 0 0 Average ----28----------5I--------I7----------28--- Std. error 15 29 17 20 ANOVA of transformed data Source d.f SS MS F Total 11 45.66 Block 2 31.75 15.88 Treatment 3 3.96 1.32 .80 NS Error 6 9.95 1.66 NS = Not Significant 78 Table 32. Total Stems per Hectare of White Ash by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Block A ""I;""""'§I“"""Z§B'"""EZE Block B 0 34 17 119 Block C 0 0 68 255 Average '""5"""'"SE""""§E""""318 """ Std. error 5.7 15 45 158 ANOVA of transformed data Source d.f SS MS F Total 11 55.07 Block 2 10.78 5.39 Treatment 3 36.07 12.02 8.77* Error 6 8.22 1.37 *significant at 5% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 4.61 Significant at .01 2. 10 year vs. control treatment t = 1.59 Significant at .20 3. 2 year vs. 5 year treatment t = 1061 Significant at .20 79 Table 33. Total Stems per Hectare of Beech by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Block A '"’1'?""""3’""""ZZE""""§§?" Block B 0 0 51 51 Block C 0 0 255 68 Average '"1'77"m""3"""'"IZE""""IE3"" Std. error 5.7 0 60 99 ANOVA of transformed data Source d.f SS MS F Total 11 64.44 Block 2 4.15 2.08 Treatment 3 55.42 18.47 22.50 * Error 6 4.87 .82 * Significant at 1% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 8.12 Significant at .01 2. 10 year vs. control treatment t = .10 Not Significant 3. 2 year vs. 5 year treatment t = 2.56 Significant at .05 80 Table 34. Total Stems per Hectare of Aspen by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control araer A "'17""""I§""""'EI""""IIE'" Block B 0 0 0 0 Block C 0 0 119 17 Average "'3T;"'""";T§"""";§ """"" 4'3"" Std. error 5.7 5.7 34.5 37 Source d.f 88 MS F Total 11 45.48 Block 2 26.38 13.19 Treatment 3 9.62 3.21 2.03 NS Error 6 9.48 1.58 NS = Not Significant 81 Table 35. Total Stems per Hectare of Choke Cherry by Burning Interval and Block Burning Interval 2 year 5 year 10 year Control Block A ""3"”""""3"""'23§"""'22§"" Block B 0 17 17 51 Block C 0 51 612 901 Average ----0-----------23-------442-------538 ----- Std. error 0 15 214 253 ANOVA of transformed data Source d.f SS MS F Total 11 87.52 Block 2 6.95 3.48 Treatment 3 65.63 21.88 8.78 * Error 6 14.94 2.49 * Significant at 5% SEPARATION OF MEANS 1. 2 year,5 year vs. 10 year, control treatments t = 4.81 Significant at .01 2. 10 year vs. control treatment t = .36 Not Significant 3. 2 year vs. 5 year treatment t = 1.77 Significant at .20 LI ST OF REFERENCES List of References Abrahamson, W.G. 1984. Species responses to fire on the Florida Lake Wales Ridge. Amer. J. Bot. 71(1): 35-43. Ahlgren, C.E. 1979. Emergent seedlings on.soil from.burned.and unburned red pine forest. Minnesota Forestry Research Notes No. 273. Ahlgren, C.E. 1976. Regeneration of red pine and white pine following wildfire and logging in northeastern Minnesota. J. Forestry. pp. 135-140. Ahlgren, C.E. 1964. Vegetational development following burning in the northern coniferous forest of Minnesota. Proceedings Soc. Amer. Foresters National Convention. Ahlgren, I.F. and C.E. Ahlgren. 1960. Ecological effects of forest fires. Bot. Rev. 26:483-533. Alban, D.H. 1977. Influences on soil properties of prescribed burning under mature red pine. USDA Forest Service North Central Forest Experiment Station Research Paper NC-139. 8p. Barnes, B. and S. Spurr. 1973. Forest Ecology. Ronald Press Co. NY. pp.237,349. Benzie, J. 1977. Red pine in the north central states. USDA Forest Service North Central Forest Experiment Station. General Technical Report NC-33. Berry, A.B. 1984. Volume and biomass yield tables for unthinned red pine plantations at the Petawawa National Forestry Institute. Can. For. Serv. Rep. PI-X-32. 27p. 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