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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of forest composition on trophic relationships among mast production and mammals in southern Illinois

Gillen, Carolyn Ann 01 May 2011 (has links)
Oak-dominated forest has declined in the eastern United States as shade-tolerant species (e.g., maple [Acer spp.]) replace oaks (Quercus spp.), sparking concern among ecologists regarding species that consume acorns. My goal was to describe how increasing mesophication of oak forests may affect consumers in higher trophic levels. I investigated relationships among forest composition, mast production, small-mammal density, and carnivore occurrence in 8 stands representing 4 forest types (upland oak, mixed-mesophytic, non-oak, and bottomland oak) in southern Illinois. I calculated tree-species richness, basal area, and other measures of forest composition using 3 0.04-ha plots/stand. In June-August 2009 and 2010, I live-trapped small mammals for 16,236 trap-nights with trapping webs to estimate population density of mice (Peromyscus spp.). I collected mast seeds during October-November 2009 and 2010 and calculated average dry biomass (g/m2) for each species and stand. During winter 2009-2011, I photographed carnivores using baited camera traps and combined these data with those from stands used in a concomitant large-scale carnivore survey. I regressed mast biomass, Peromyscus density, Peromyscus survival, and carnivore occurrence on measures of forest composition and hard-mast biomass. Peromyscus summer density was not related to % hard-mast basal area, nor to hard-mast biomass from the previous autumn. Survival of Peromyscus in 2010 displayed a significant positive relationship with hard-mast biomass in 2009 (F1,6 = 7.85, P = 0.04, r2 = 0.61). Logistic regressions of carnivore occurrence on Peromyscus density were not significant. Coyote (Canis latrans) occurrence at my sites and additional sites during January-April 2010 decreased with increasing % hard-mast basal area (x2 = 4.64, df = 1, P = 0.03). Bobcat (Lynx rufus) and gray fox (Urocyon cinereoargenteus) occurrence showed no relationship with % hard-mast basal area. Many other studies have demonstrated links of several species to oak forest, but the scale of this study may have been too small to detect effects of mesophication. Alternatively, small-mammal density may be influenced by invertebrate prey abundance or weather conditions. The landscape matrix of oak-hickory forest may also act to homogenize Peromyscus density across my study sites. Longer-term research could help clarify relationships among trophic levels. It is important for managers to consider techniques that may conserve oak forest.
2

Interactions between white-tailed deer and vegetation in southern Illinois

Leeson, Ryan Elizabeth 01 May 2018 (has links)
White-tailed deer (Odocoileus virginianus) have considerable impacts on woody and herbaceous vegetation. Many oak-hickory forests in the eastern U.S. are experiencing a lack of oak (Quercus) and hickory (Carya) regeneration, with deer being a likely culprit. Furthermore, few have studied deer use of different herbaceous food plot mixtures. I addressed these gaps in the literature by assessing deer impacts on forest and herbaceous vegetation in southern Illinois. I established 150 paired plots (enclosed and control) in June 2015 and measured 25 habitat variables to assess impacts of deer herbivory from August 2015 to August 2016. Oak seedlings were present more often and in higher numbers within enclosed plots (F1,299 = 6.25, P < 0.050 and F1,387 = 4.50, P < 0.050, respectively). There were no differences in the height of oak seedlings or the presence, number, or height of hickory seedlings in enclosed versus control plots (F1,53 = 0.010, P = 0.938; F1,299 = 0.850, P = 0.357; F1,267 = 1.16, P = 0.282; and F1,15 = 0.030, P = 0.855; respectively). During September-November 2015, I counted and marked fallen acorns within 50 random paired plots; the number of acorns discovered or lost did not differ between enclosed and control plots (F1,94 = 0.310, P = 0.578 and F1,8 = 0.120, P = 0.736, respectively). I suggest managers incorporate potential deer impacts when designing management plans to best encourage oak regeneration. During September-November 2015, I established 16 food plots (half tilled; each 0.05 ha in size), planted to 4 food plot types. I compared Big Tine Buck Brunch, Evolved Harvest Throw & Gro, Antler King No Sweat, and a food plot mixture that I created. I measured deer use via 2 methods: vegetation growth in exclosures versus control (i.e., unfenced) areas and camera traps. Deer used all 4 food plot mixtures (n = 292 – 2,522 pictures/plot over 9 weeks), having a negative impact on mean vegetation height outside of exclosures (F3,1148 = 6.71, P < 0.001). Analysis of camera data indicated that deer did not preferentially use any one food plot mixture over the others (F3,12 = 0.090, P > 0.050). There also was no difference in the proportion of deer pictured in the process of eating within each food plot mixture (F3,12 = 0.592, P > 0.050). I suggest any of these 4 food plot varieties could be planted by a hunter or wildlife manager in the Midwest and observe similar use by deer.
3

Ecological effects and control of woody invasive species in an eastern oak-hickory forest

Block, Jeremy A. January 2021 (has links)
No description available.

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