Oaks (Quercus spp.) have dominated eastern forests of the United States for centuries; however, current disturbance regimes discourage oak recruitment and allow shade-tolerant mesophytic species (e.g., maples, Acer spp.) to out-compete oaks. I assessed the effects of mesophication on bird communities by examining differences in breeding bird community structure, abundance, and diversity across 8 and 12 deciduous forest stands in southern Illinois during 2009 and 2010, respectively, using line transects, and by examining a 5-year monitoring data set from across the Shawnee National Forest in 2005-2009. I predicted that variation in bird community structure between maple- and oak-dominated forests can be explained by differential availability of foraging niches. Forest stands used in 2009-2010 were separated along a gradient of hard-mast tree composition, which was defined as the percentage of tree basal area in the stand contributed by oaks and hickories (Carya spp.). Linear regression and Akaike's Information Criteria were used to assess habitat-association models for 7 bird community metrics: bird species diversity, species richness, overall abundance, and abundance of aerial foragers, bark gleaners, foliage gleaners, and ground gleaners. Bird species diversity (Shannon-Wiener H') and species richness ranged from 2.97 to 3.15, and 29 to 37, respectively, over both years. Bird species diversity and species richness were best modeled by a negative relationship with % hardmast tree basal area across both years, whereas overall abundance was best modeled by a positive relationship with understory woody stem diversity. Detection rates for foraging guilds were best modeled by various metrics of habitat structure. Aerial foragers, bark gleaners, foliage gleaners, and ground gleaners responded positively to stem density, downed coarse woody debris density, basal area, and stem diversity, respectively. I used non-metric multidimensional scaling (NMDS) and analysis of similarity (ANOSIM) to examine the degree of dissimilarity among bird communities and site type. In 2010, the bird community differed overall, with communities in oak forests tending (P = 0.09-0.11) to differ those in non-oak and mixed-mesophytic sites. Analysis of a 5-year data set yielded similar results. All models tested for bird-species diversity and species richness were competing, suggesting no individual habitat factor was a strong predictor. Overall abundance and abundance of aerial foragers, bark gleaners and foliage gleaners showed negative relationships to hardmast basal area in all years combined. Ground gleaners responded positively to tree diversity. A post-hoc analysis revealed that overall bird abundance and abundance of foliage-, bark- and ground-gleaning guilds responded positively to an index of riparian areas. Resource use during the breeding season may be shifted to mesic habitats, possibly due to increased resource availability in terms of arthropods and water. Results indicated that mesophication may not have the predicted effects on forest-breeding bird communities, and that vegetation structure was more important in determining bird community structure than tree composition in small-scale forest stands during the breeding season. Resident and over-wintering bird species may be most affected by the loss of oaks due to use during time periods when mesic habitats do not supplement resources. Managers should consider maintenance of a diversity of forest types to maximize avian diversity.

No description available.

Prolific oak regeneration occurred over past centuries from anthropogenic cutting, grazing, and fire, and has declined over the past century due to decreased disturbance. Mesophication within closed-canopy forests of the eastern deciduous region has resulted. Oaks are a keystone species and provide abundant resources for forest wildlife; the ability of late-successional tree species to provide similar resources is relatively understudied. To determine the importance of oak-hickory stands for forest birds, we examined two habitat-selection hypotheses that influence avian abundance and distribution: (1) Habitat heterogeneity (i.e. differences in forest structure) and (2) Availability and distribution of food resources (i.e. index of arthropod biomass). We examined avian response across a gradient of oak-hickory to non-oak tree-species dominance. Non-oak stands were largely dominated by sugar maple, American beech, and yellow poplar (Liriodendron tulipifera). We predicted that migratory breeding-species of concern would respond positively to oak-dominated stands and associated vegetation (e.g. oaks and hickories) because they provide more heterogeneity and likely more food than non-oak stands and associated vegetation (e.g. yellow poplar, maples and beech). We hypothesized that oak and hickory species contain more arthropod biomass and diversity than late-successional species. We conducted breeding bird surveys from 30-April to 15-July 2013-2014 in the Shawnee National Forest, Illinois at 22 study sites. We characterized study sites by dominant canopy vegetation. We used a modified version of the branch-clipping technique to sample arthropods on tree species that represented a gradient of succession. We used generalized linear mixed models to examine differences in arthropod metrics. We estimated detection probabilities for PIF-concern, breeding species and modeled density as response to a priori habitat models using hierarchical distance sampling in R package unmarked. We compared best-fit habitat models for each species with a model of our derived index of food availability (i.e. mean total arthropod biomass (g/m)) for each study site. Habitat heterogeneity was higher in oak-hickory dominated sites. Aerial foragers and foliage gleaners responded predominantly to forest composition and structure, whereas ground foragers responded largely to microhabitat. Density estimates from five of seven species that included percent oak-hickory composition in top models exhibited positive responses. All species that included canopy tree diversity (n=6) in top models responded positively to increasing canopy diversity, and canopy diversity was significantly higher in oak-hickory sites than non-oak sites. Yellow poplar, oak and hickory species yielded more total arthropod biomass (g/m), Lepidopteran biomass (g/m), and guild diversity and richness than late-successional beech and maples. Heterogeneity and food biomass both influenced avian abundance of aerial foragers and foliage gleaners. Our results imply that oak-hickory stands are ecologically important for migratory forest birds of concern because heterogeneity and food resources increase as oak-hickory canopy composition increases. Oak regeneration is a challenging process to manage because oaks require frequent disturbance to achieve the high levels of light needed by this genus. Therefore, it may be beneficial to manage stands for yellow poplar dominance because this species grows rapidly. Moreover, our results suggest that yellow poplar yields comparable and higher estimates of arthropod biomass and diversity on hickories and oaks, respectively. However, foraging opportunities are likely restricted on yellow poplar because of limited structure, attributed to excurrent branching.

Due largely to fire exclusion and land use changes, upland oak ecosystems in the central and eastern U.S. are shifting dominance from fire-tolerant oaks (Quercus spp.) to shade-tolerant, fire-sensitive species (mesophytes). This shift has been hypothesized to occur via a positive feedback loop termed mesophication, where mesophytes create shaded understory that limits oak growth and wetter fuels and soils, decreasing forest flammability. To determine how canopy water partitioning varies between oaks and mesophytes, I measured stemflow, throughfall, and surface soil moisture monthly over a 14-month period for overstory and midstory trees of oaks (Q. alba, Q. falcata) and hypothesized mesophytes (Carya tomentosa, Acer rubrum, Ulmus alata) in northern Mississippi. Overstory oaks partitioned 5.1% of rainwater into stemflow, while mesophytic species partitioned 7.2%, leading to 3.5% wetter soils under mesophytes. The hydrology of mesophyte canopies may reduce forest flammability and promote conditions favorable for mesophyte regeneration, ultimately compromising long-term oak regeneration.

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No description available.

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.

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Illinois has no official parameters for old-growth oak-hickory (Quercus-Carya) forests despite oak-hickory being the historically dominant ecosystem in the forested parts of Illinois (Fralish, 1997; Thompson & Dessecker, 1997). The purpose of this study was to better understand the characteristics of old-growth oak-hickory stands, as well as make management recommendations for preserving the integrity of old-growth forests and shifting second-growth stands to old-growth status. Stand structure analysis was conducted in June and July of 2022 on an old-growth oak-hickory stand (Otey-Grisley Nature Preserve) and nearby second-growth oak-hickory stand (Grisley Woods Land and Water Reserve) near Pittsburg, Illinois using dendrochronology, various stand composition analyses, and floristic assessments to compare the two forests across multiple nodes of inquiry from their canopies to their ground layers. White oak (Quercus alba L.) was of higher importance in the more open old-growth canopy than the closed second-growth canopy which had more shagbark hickory (Carya ovata L.). The old-growth stand had higher floristic quality (mean Coefficient of Conservatism and adjusted Floristic Quality Index) and lower frequency of invasive species than the second-growth stand. The dominant white oak appear to have suppressed the hickories (Carya) for over a century on both sites. However, in the sapling and seedling layer, it appears the oaks and hickories are failing to recruit into the canopy on either site. The average age of the old-growth canopy is 67 years greater than that of the second-growth canopy, the majority of which seeded in after a heavy cut in the early 1940s. The second-growth site rapidly gained early successional species after the logging. The second-growth site could come to resemble the open oak dominated character of the old-growth site. However, this will require management with fire, thinning, and invasive species treatments. The old-growth, where sassafras (Sassafras albidum L.) is crowding the understory, will also require invasive species management, prescribed fire, and thinning if it is to remain the open oak-hickory woodland it is today.

Vegetation changes in Czech lowland forests over the past decades Martin Kopecký ABSTRACT To explore decadal changes in plant species diversity and composition of typical lowland forests in the Czech Republic, I compared vegetation on plots sampled decades ago with vegetation on the same plots sampled recently. First I evaluated the robustness of the approach used in my thesis. In Chapter 1, we provided the first direct test of the effect of uncertainty in original plot location on results from vegetation resurvey. We found that temporal trends in vegetation diversity and composition were comparable between exactly relocated permanent and only approximately relocated semi-permanent plots. Therefore, we conclude that the resurvey of semi-permanent plots is robust to the uncertainty in original plot location. Then, we showed that vegetation in lowland oak forest shifted from species-rich communities of thermophilous forest toward species poorer communities of mesic forest (Chapter 2). The species typical for thermophilous oak forests and nationally endangered species suffered the most significant decline. We identified as the main driver behind these changes shift from traditional coppicing toward high forest management after WWII. Further, we explored the processes behind temporal shifts in species diversity...