In the greater Central Hardwood Region, advance regeneration of oak (Quercus spp.) and hickory (Carya spp.) has been in decline for several decades. Facilitated in part by an abrupt change in disturbance regime, coupled with an increase in herbivore density, the existing mid-successional, mast-producing species are being outcompeted by late-successional, mesophytic species. Oak-hickory forests provide keystone resources for a diverse forest wildlife community, and a decline in its dominance will likely impact habitat use and occupancy patterns in the mammal community, but to what extent is unclear. During May-August 2015-2016, I deployed 150 remotely-triggered camera traps in Trail of Tears State Forest (TTSF), Union County, Illinois to investigate single-season, site occupancy patterns and detection probabilities as a function of forest composition and structure for 3 mammals (eastern gray squirrel [Sciurus carolinensis], raccoon [Procyon lotor], and white-tailed deer [Odocoileus virginianus]). I collected microhabitat data at each camera-site and utilized a GIS application to estimate spatial relationships among anthropogenic features and camera-sites. I recorded 404 photographs of 11 endothermic species during 3927 days of survey effort, with white-tailed deer, raccoons, and eastern gray squirrels as the most detected species, respectively. Detection probability of eastern gray squirrels was best explained by the global detection model, indicating no covariate measured explained the variation in detection rates. Raccoon detection probability was best described by a negative relationship with the average temperature recorded during survey period. The best-fitting detection model for white-tailed deer indicated detection probabilities declined throughout the sampling period and across seasons. Eastern gray squirrel site occupancy models received little support, however, ecological land type phase was the most supported model. The best fitting habitat model described a negative relationship between eastern gray squirrel site occupancy probability and coarse woody debris volume. For raccoons, no model with habitat covariates was better fitting than the null model. Raccoon occupancy probability increased with maximum DBH at a site, ground cover, and beech-maple importance values, but decreased with oak-hickory importance values. White-tailed deer occupancy was most positively influenced by ground cover and oak-hickory importance values, but decreased with distance to forest edge, number of understory stems, and beech-maple importance values. My research provides empirical evidence to predictions made regarding the impact of a decline in oak dominance across the Central Hardwood region on a portion of the region’s mammal community. Shifts to late-successional conditions in the Central Hardwood region will likely continue and magnify if forest management approaches continue to minimize the frequency and occurrence of large, anthropogenic disturbances to the forest overstory. A mosaic of forest conditions will be needed to best support a diverse and complete mammal community across the region.

Early land survey records can be used to reconstruct the historical distribution and abundance of tree species prior to the large-scale impact of industrialized societies. Comparing these records to current vegetation patterns enables an examination of the shifts that have occurred in plant communities since the arrival of European settlers in North America. I used presettlement (1859-1874) land survey records from southeastern Vancouver Island and Saltspring Island, British Columbia, Canada to reconstruct the relative abundance and density of tree species in these areas. I then collected equivalent vegetation data from the same points in the modern landscape, which enabled me to compare the two points in time and identify the changes in large-scale vegetation patterns that have occurred since European settlement. My results show a significant increase in the relative abundance of maple (Acer macrophyllum) and cedar (Thuja plicata), and a corresponding decrease in Douglas-fir (Pseudotsuga menzeisii). Furthermore, there has been a considerable increase in tree density in undeveloped areas. The 1859 records indicate that at least one third of the land surveyed was made up of prairies or open “plains,” while a combination of open woods and forests made up the remaining two thirds. Based on comparable density measures from 2007, prairies and plains now represent less than 5% of the undeveloped landscape, while forests comprise nearly 90%. These changes are likely due to a combination of factors that have been influenced by European settlement, most notably logging and fire suppression. The suppression of fire has led to an infilling of trees into previously open areas and has led to the rapid decline of the open prairie and savanna habitat types once common in this area. The results of this study can inform conservation efforts throughout the study area, particularly those involving the restoration of prairie or savanna habitats.

Early land survey records can be used to reconstruct the historical distribution and abundance of tree species prior to the large-scale impact of industrialized societies. Comparing these records to current vegetation patterns enables an examination of the shifts that have occurred in plant communities since the arrival of European settlers in North America. I used presettlement (1859-1874) land survey records from southeastern Vancouver Island and Saltspring Island, British Columbia, Canada to reconstruct the relative abundance and density of tree species in these areas. I then collected equivalent vegetation data from the same points in the modern landscape, which enabled me to compare the two points in time and identify the changes in large-scale vegetation patterns that have occurred since European settlement. My results show a significant increase in the relative abundance of maple (Acer macrophyllum) and cedar (Thuja plicata), and a corresponding decrease in Douglas-fir (Pseudotsuga menzeisii). Furthermore, there has been a considerable increase in tree density in undeveloped areas. The 1859 records indicate that at least one third of the land surveyed was made up of prairies or open “plains,” while a combination of open woods and forests made up the remaining two thirds. Based on comparable density measures from 2007, prairies and plains now represent less than 5% of the undeveloped landscape, while forests comprise nearly 90%. These changes are likely due to a combination of factors that have been influenced by European settlement, most notably logging and fire suppression. The suppression of fire has led to an infilling of trees into previously open areas and has led to the rapid decline of the open prairie and savanna habitat types once common in this area. The results of this study can inform conservation efforts throughout the study area, particularly those involving the restoration of prairie or savanna habitats.

Early land survey records can be used to reconstruct the historical distribution and abundance of tree species prior to the large-scale impact of industrialized societies. Comparing these records to current vegetation patterns enables an examination of the shifts that have occurred in plant communities since the arrival of European settlers in North America. I used presettlement (1859-1874) land survey records from southeastern Vancouver Island and Saltspring Island, British Columbia, Canada to reconstruct the relative abundance and density of tree species in these areas. I then collected equivalent vegetation data from the same points in the modern landscape, which enabled me to compare the two points in time and identify the changes in large-scale vegetation patterns that have occurred since European settlement. My results show a significant increase in the relative abundance of maple (Acer macrophyllum) and cedar (Thuja plicata), and a corresponding decrease in Douglas-fir (Pseudotsuga menzeisii). Furthermore, there has been a considerable increase in tree density in undeveloped areas. The 1859 records indicate that at least one third of the land surveyed was made up of prairies or open “plains,” while a combination of open woods and forests made up the remaining two thirds. Based on comparable density measures from 2007, prairies and plains now represent less than 5% of the undeveloped landscape, while forests comprise nearly 90%. These changes are likely due to a combination of factors that have been influenced by European settlement, most notably logging and fire suppression. The suppression of fire has led to an infilling of trees into previously open areas and has led to the rapid decline of the open prairie and savanna habitat types once common in this area. The results of this study can inform conservation efforts throughout the study area, particularly those involving the restoration of prairie or savanna habitats. / Science, Faculty of / Botany, Department of / Graduate

Many regional and local factors can influence the distribution of native and exotic species in ecological communities. I examined the regional- and local-scale determinants of native and exotic vascular plant species richness and composition in a highly fragmented oak savanna ecosystem on southeastern Vancouver Island. In sharp contrast to most reported results, I found a negative relationship between native and exotic richness at the regional scale, and no relationship at the local scale. Two extrinsic factors, surrounding road density and climate, best explained the regional-scale relationship by each affecting natives and exotics in opposite ways. Road density and climate were also the dominant predictors of native and exotic composition at the regional scale. Patterns in the patch occupancy of individual species confirmed the importance of these factors but I found that low surrounding road densities and cool, wet conditions predicted the presence of many natives and the absence of many exotics. Environmental factors explained variation in richness and composition at the local scale, but these factors were different for natives and exotics. My results suggest that natives and exotics respond to roads and climate in fundamentally different ways. Roads increase both exotic propagule pressure and disturbance, which may facilitate exotic invasion. In contrast, disturbance from roads may increase the likelihood of local extinction for particular natives. Differing climatic preferences within the native and exotic species pools may also partially explain the observed patterns. There was no evidence that native diversity directly affects exotic diversity (or vice versa). Surprisingly, I found that connectivity was not an important predictor of richness or composition despite the high degree of habitat fragmentation in this ecosystem.

Many regional and local factors can influence the distribution of native and exotic species in ecological communities. I examined the regional- and local-scale determinants of native and exotic vascular plant species richness and composition in a highly fragmented oak savanna ecosystem on southeastern Vancouver Island. In sharp contrast to most reported results, I found a negative relationship between native and exotic richness at the regional scale, and no relationship at the local scale. Two extrinsic factors, surrounding road density and climate, best explained the regional-scale relationship by each affecting natives and exotics in opposite ways. Road density and climate were also the dominant predictors of native and exotic composition at the regional scale. Patterns in the patch occupancy of individual species confirmed the importance of these factors but I found that low surrounding road densities and cool, wet conditions predicted the presence of many natives and the absence of many exotics. Environmental factors explained variation in richness and composition at the local scale, but these factors were different for natives and exotics. My results suggest that natives and exotics respond to roads and climate in fundamentally different ways. Roads increase both exotic propagule pressure and disturbance, which may facilitate exotic invasion. In contrast, disturbance from roads may increase the likelihood of local extinction for particular natives. Differing climatic preferences within the native and exotic species pools may also partially explain the observed patterns. There was no evidence that native diversity directly affects exotic diversity (or vice versa). Surprisingly, I found that connectivity was not an important predictor of richness or composition despite the high degree of habitat fragmentation in this ecosystem.

Many regional and local factors can influence the distribution of native and exotic species in ecological communities. I examined the regional- and local-scale determinants of native and exotic vascular plant species richness and composition in a highly fragmented oak savanna ecosystem on southeastern Vancouver Island. In sharp contrast to most reported results, I found a negative relationship between native and exotic richness at the regional scale, and no relationship at the local scale. Two extrinsic factors, surrounding road density and climate, best explained the regional-scale relationship by each affecting natives and exotics in opposite ways. Road density and climate were also the dominant predictors of native and exotic composition at the regional scale. Patterns in the patch occupancy of individual species confirmed the importance of these factors but I found that low surrounding road densities and cool, wet conditions predicted the presence of many natives and the absence of many exotics. Environmental factors explained variation in richness and composition at the local scale, but these factors were different for natives and exotics. My results suggest that natives and exotics respond to roads and climate in fundamentally different ways. Roads increase both exotic propagule pressure and disturbance, which may facilitate exotic invasion. In contrast, disturbance from roads may increase the likelihood of local extinction for particular natives. Differing climatic preferences within the native and exotic species pools may also partially explain the observed patterns. There was no evidence that native diversity directly affects exotic diversity (or vice versa). Surprisingly, I found that connectivity was not an important predictor of richness or composition despite the high degree of habitat fragmentation in this ecosystem. / Science, Faculty of / Botany, Department of / Graduate