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(1 - 3 of 3)
- Title
- Satellite time-series data for vegetation phenology detection and environmental assessment in Southeast Asia
- Creator
- Suepa, Tanita
- Date
- 2013
- Collection
- Electronic Theses & Dissertations
- Description
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The relationship between temporal and spatial data is considered the major advantage of remote sensing in research related to biophysical characteristics. With temporally formatted remote sensing products, it is possible to monitor environmental changes as well as global climate change through time and space by analyzing vegetation phenology. Although a number of different methods have been developed to determine the seasonal cycle using time series of vegetation indices, these methods were...
Show moreThe relationship between temporal and spatial data is considered the major advantage of remote sensing in research related to biophysical characteristics. With temporally formatted remote sensing products, it is possible to monitor environmental changes as well as global climate change through time and space by analyzing vegetation phenology. Although a number of different methods have been developed to determine the seasonal cycle using time series of vegetation indices, these methods were not designed to explore and monitor changes and trends of vegetation phenology in Southeast Asia (SEA). SEA is adversely affected by impacts of climate change, which causes considerable environmental problems, and the increase in agricultural land conversion and intensification also adds to those problems. Consequently, exploring and monitoring phenological change and environmental impacts are necessary for a better understanding of the ecosystem dynamics and environmental change in this region. This research aimed to investigate inter-annual variability of vegetation phenology and rainfall seasonality, analyze the possible drivers of phenological changes from both climatic and anthropogenic factors, assess the environmental impacts in agricultural areas, and develop an enhanced visualization method for phenological information dissemination. In this research, spatio-temporal patterns of vegetation phenology were analyzed by using MODIS-EVI time series data over the period of 2001-2010. Rainfall seasonality was derived from TRMM daily rainfall rate. Additionally, this research assessed environmental impacts of GHG emissions by using the environmental model (DNDC) to quantify emissions from rice fields in Thailand. Furthermore, a web mapping application was developed to present the output of phenological and environmental analysis with interactive functions. The results revealed that satellite time-series data provided a great opportunity to study regional vegetation variability and internal climatic fluctuation. The EVI and phenological patterns varied spatially according to climate variations and human management. The overall regional mean EVI value in SEA from 2001 to 2010 has gradually decreased and phenological trends appeared to shift towards a later and slightly longer growing season. Regional vegetation dynamics over SEA exhibited patterns associated with major climate events such as El Niño in 2005. The rainy season tended to start early and end late and the length of rainy season was slightly longer. However, the amount of rainfall has decreased from 2001 to 2010. The relationship between phenology and rainfall varied among different ecosystems. Additionally, the local scale results indicated that rainfall is a dominant force of phenological changes in naturally vegetated areas and rainfed croplands, whereas human management is a key factor in heavily agricultural areas with irrigated systems. The results of estimating GHG emissions from rice fields in Thailand demonstrated that human management, climate variation, and physical geography had a significant influence on the change in GHG emissions. In addition, the complexity of spatio-temporal patterns in phenology and related variables were displayed on the visualization system with effective functions and an interactive interface. The information and knowledge in this research are useful for local and regional environmental management and for identifying mitigation strategies in the context of climate change and ecosystem dynamics in this region.
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- Title
- Climatology of springtime freeze events in the Great Lakes Region and their impact on sour cherry yields in historical and projected future time frames
- Creator
- Rill, Lydia
- Date
- 2016
- Collection
- Electronic Theses & Dissertations
- Description
-
"Production of sour cherries has a significant impact on the economy of the Great Lakes Region, valued at more than $74 million. In contrast to cereal crops where water is the most limiting factor, perennials in temperate regions are limited by freeze injury, especially in the spring following initial phenological development, which was highlighted in 2002 and 2012 when yields decreased considerably. This study analyzed the spatial and temporal variability of springtime freeze events in the...
Show more"Production of sour cherries has a significant impact on the economy of the Great Lakes Region, valued at more than $74 million. In contrast to cereal crops where water is the most limiting factor, perennials in temperate regions are limited by freeze injury, especially in the spring following initial phenological development, which was highlighted in 2002 and 2012 when yields decreased considerably. This study analyzed the spatial and temporal variability of springtime freeze events in the Great Lakes Region and their impact on sour cherry production, as well as explored the use of gridded climatic datasets. Additionally, this study examined the historical trends in sour cherry yield and potential future changes by the mid-century. The Great Lakes played a major role in the spatial variability of springtime freezes, as locations inland experienced colder temperatures than near the coast. Simulated damaging freeze events over the past 50 years were most common during the later phenological stages of the crop, while the most severe damage occurred in the earlier stages. Gridded datasets were less suitable for this application than individual station observations. Over time, phenological development has tended to begin earlier, and this trend was projected to continue into the mid-century at three stations located in northwest, west central, and southwest Lower Michigan. An ensemble of climate projections indicated a large uncertainty envelope surrounding changes in simulated sour cherry yield. The projected changes varied by emissions scenario, downscaling method, and climate model."--Page ii.
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- Title
- Factors affecting mating, monitoring and phenology of grape berry moth, Paralobesia viteana, in Michigan vineyards
- Creator
- Mason, Keith Scott
- Date
- 2018
- Collection
- Electronic Theses & Dissertations
- Description
-
Paralobesia viteana (Clemens), the grape berry moth (GBM), is a major economic pest of cultivated grapes in Eastern North America. Although pheromone lures and traps are available for monitoring this pest, male moth captures in these traps are not consistent between Michigan grape-growing regions, and male captures decline as the infestation increases through the multiple generations that occur during a season. This makes it difficult to use traps to monitor this pest’s population dynamics...
Show moreParalobesia viteana (Clemens), the grape berry moth (GBM), is a major economic pest of cultivated grapes in Eastern North America. Although pheromone lures and traps are available for monitoring this pest, male moth captures in these traps are not consistent between Michigan grape-growing regions, and male captures decline as the infestation increases through the multiple generations that occur during a season. This makes it difficult to use traps to monitor this pest’s population dynamics and complicates the timing of pest management activities. Substantial regional variation exists in the magnitude of the response of male GBM to sex pheromone-baited traps in Michigan vineyards. Males are readily captured in traps in the southwest region, whereas in the northwest very few males are captured. However grape berry moth larval infestation is found in fruit in both regions. Using Y-tube choice tests and trapping trials with captive females, I determined that males from Southwest and Northwest Michigan responded similarly to the standard pheromone blend, and males did not preferentially choose females from the same population. From these results I conclude that the regional differences in male captures are not due to differential responses of males in these respective areas. I postulate that the reason fewer males are trapped in Northwest Michigan is because the P. viteana population is much smaller than in Southwest Michigan. To test whether seasonal changes in the plant canopy affect captures of male grape berry moth, I manipulated grapevine fruit density or canopy structure in multiple growing seasons, and measured male captures under these conditions. Removal of either 50 or 100% of the fruit clusters from vineyard plots did not consistently affect captures in pheromone traps. In a separate canopy manipulation experiment, I detected significant differences in male captures between unaltered and open canopies for some sample periods, and there was a trend toward numerically more male captures in unaltered than in open canopies. I conclude that fruit presence, fruit density and canopy fullness do not reduce male P. viteana captures late in the season, and thus do not explain the seasonal pattern of development and abundance of this insect.Experiments that measured the frequency, intensity and duration of mating and reproductive behaviors in colonies held under different temperature and photoperiodic conditions were used to determine that temperature is the likely driving force behind the seasonal variation in male P. viteana captures, and thus shapes the observed phenology of this pest. The frequency of male flights, mating and oviposition increased with temperature. This amplified activity helps to explain the intensification of oviposition and subsequent larval feeding damage in vineyards during the summer and early fall when conditions are warm. My data also show the proportion of male flights that occur when females are not receptive to mating is greater at lower temperatures, which helps explain why more males are trapped in the spring when temperatures are cool. Traps baited with lures that contained different quantities of P. viteana sex pheromone were used to determine that the increased amount of pheromone released by lures during hot periods can reduce male captures. My research shows that temperature is an important factor that governs the behaviors associated with mating and reproduction, and also influences the main tool for monitoring this pest, the pheromone trap. Taken as a whole, the effects of temperature on behavior and trapping strongly shape the observed phenology of this pest.
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