Julia I. Chapman

Tree regeneration ecology of an old-growth central Appalachian forest: diversity, temporal dynamics, and disturbance response.

Abstract Diversity and compositional dynamics in deciduous forests of eastern North America are subject to an array of drivers, and these forests are thought to be undergoing a long-term dominance shift in which maples (Acer spp.) are replacing oaks (Quercus spp.). We examined dynamics of woody understory species in an old-growth central Appalachian forest to document baseline dynamics over a decade and describe the relationships between diversity and surrogate measures of productivity (density and cover). We also investigated the reaction of shrub- and ground-layer vegetation to a recent fire in one portion of the study site. Over a ten-year interval (2000–2010), shrub-layer densities of Acer spp. decreased significantly (P < 0.01) and Quercus spp. did not change. Ground-layer densities of Acer spp. increased significantly (P < 0.01) while mean cover decreased significantly (P < 0.01). For a few Quercus species, ground-layer densities increased significantly (P < 0.01), and mean cover of ground-layer Quercus alba increased significantly (P < 0.05). Significant unimodal relationships (P < 0.01) were exhibited between diversity/richness and density/cover in both understory strata. Plots burned by a wildfire in 2010 had significantly lower shrub-layer density and species richness (P < 0.01) compared to pre-disturbance data in 2000. In the same area, the ground-layer response to this fire disturbance was equivocal, with increased density, decreased cover, and unchanged diversity and richness. Decadal oak-maple dynamics in the woody understory of this old-growth stand did not fully support the hypothesized oak-to-maple dominance shift; changes in shrub- and ground-layer populations of Acer spp. were erratic while Quercus spp. populations appeared stable. Unimodal relationships between diversity and productivity surrogates were found in both woody understory layers and are likely driven by the range of environmental conditions found within the study site. Fire induced short-term changes in the shrub- and ground-layers and may have facilitated colonization of invasive species. Quantification of changes across all woody forest strata in areas of minimal anthropogenic disturbance (e.g., old-growth stands) is important for understanding baseline dynamics of deciduous forests in eastern North America.

Composition Shifts, Disturbance, and Canopy-Accession Strategy in an Oldgrowth Forest of Southwestern Ohio, USA

ABSTRACT: Forest composition can shift through time in response to a variety of factors including changes in climate conditions and disturbance regimes. In many forests of eastern North America, oak (Quercus) populations are decreasing while maple (Acer) populations are increasing. Altered fire regimes over the last century are thought to be the primary driver of oak-to-maple dynamics; however, other factors may be playing an important role in this dominance transition. Our study sought to determine the community structure and disturbance history of an old-growth forest remnant in an area of western Ohio where fires were historically infrequent. To determine community structure, abundance of woody species was measured within 32 plots at four canopy strata. Dendrochronology was used to determine the disturbance history of the site and canopy accession patterns of canopy trees. We found that oaks and hickories (Carya) were important contributors to the forest canopy, but were less numerous than maples in sub-canopy layers. There was vastly higher biomass of standing dead material from oaks than from other genera. We propose that a cohort of oak and hickory dominance was initiated by a change in historical disturbance regime, and that in recent decades the stand is responding to a suite of multiple interacting ecosystem drivers, which have favored maple regeneration. In the coming decades, this forest, along with others in the region, will be faced with a new suite of interacting drivers including exotic insects, invasive plants, and climate change.

Changing flora of an old-growth mesophytic forest: previously undetected taxa and first appearance of non-native invasive species.

Abstract An important concern of natural areas management is preserving rare taxa in the face of increasingly pervasive plant invasions. This is one study in an ongoing long-term botanical analysis of Big Everidge Hollow, a watershed containing old-growth forest within the Lilley Cornett Woods Appalachian Research Station on the Cumberland Plateau of eastern Kentucky. We report 23 new records from the site representing an array of life histories. Many of these species are scarce and difficult to identify; however, we also detected several non-native invasive species moving into the study site, which had previously been completely free of these species. The appearance of exotic species may have been facilitated by a recent wildfire that occurred in one portion of the watershed. This site remains one of the best examples of old-growth mixed mesophytic forest, and in our view, this nascent invasion poses a significant threat to the sites biological integrity.

Thirty Years of Compositional Change in an Old-Growth Temperate Forest: The Role of Topographic Gradients in Oak-Maple Dynamics.

Ecological communities are structured in response to spatial and temporal variation of numerous factors, including edaphic conditions, biotic interactions, climatic patterns and disturbance regimes. Widespread anthropogenic factors such as timber harvesting can create long-lasting impacts, obscuring the relationship between community structure and environmental conditions. Minimally impacted systems such as old-growth forests can serve as a useful ecological baseline for predicting long-term compositional shifts. We utilized decadal tree species sampling data (1979–2010) divided into three strata (understory, midstory, overstory) to examine temporal changes in relative abundances and spatial distributions of dominant taxa, as well as overall shifts in community composition, in a relatively pristine Appalachian old-growth forest in eastern Kentucky, USA. Quercus and Carya species persisted mainly as mature canopy trees with decreasing juvenile recruitment, especially in mesic areas. In contrast, Acer, Fagus, and other mesophytic species were abundant and spatially widespread in subcanopy layers suggesting these species are more likely to recruit in gap-scale canopy openings. In the overstory, mesophytic species were spatially restricted to lower and mid-slope mesic habitats. Temporal changes in community composition were most evident in the understory and tended to be greater in mesic areas, a trend seemingly driven by recruitment failure among xerophytic species. In subcanopy vegetation we discovered a loss of distinction through time among the ecological community designations established following the 1979 survey (Chestnut oak, Mixed mesophytic, and Beech). The overstory was more stable through time, suggesting a storage effect where long-lived trees have maintained a particular community composition through time in areas where regeneration opportunities are minimal under current environmental conditions. Overall, sitewide canopy succession is occurring slowly in the absence of major disturbance, and topography-driven environmental variation appears to have an important local-scale filtering effect on communities.

Edge Effects, Invasion, and the Spatial Pattern of Herb-Layer Biodiversity in an Old-Growth Deciduous Forest Fragment

ABSTRACT: Habitat loss and fragmentation are major threats to global biodiversity, altering both habitat structure and availability. Small preserves nested within landscapes dominated by human commerce can serve as long-term storehouses of biodiversity, yet they are vulnerable to threats such as exotic plant invasion and disturbance. The Drew Woods State Nature Preserve (DWSNP) in Darke County, Ohio, provided an opportunity to understand the capacity of a small old-growth preserve for maintaining regional floristic biodiversity and assessing ecological threats. A series of six approximately biweekly herbaceous layer samplings were conducted across 32 1-m2 circular plots within DWSNP, and percent vegetative cover was estimated for each herbaceous species identified. The vascular flora of this 6-ha site was inventoried and used for a Floristic Quality Assessment. Spatial patterns were visualized using ArcGIS software, and linear regression analyses and non-metric multidimensional scaling were used to test for relationships between measures of diversity and cover and environmental variables. A total of 176 species were identified across 124 genera and 67 families, and the majority of species were native (89.2%). Characteristic native herb species included Jeffersonia diphylla (twinleaf), Trillium sessile (toad trillium), Allium tricoccum (wild leek), and Erythronium americanum (trout lily), all of which are indicative of high-quality forest. A north—south gradient of species richness was found across all samplings, with the southernmost plots tending to be most species-rich (P < 0.01, r2 ≤ 0.42). This pattern appeared to be linked with gradients of light and temperature that are likely driven by edge effects. Old-growth forests are known for their resiliency, a trait that was evident in the high-quality flora of DWSNP; however, they are not immune to invasion by exotic species. We discovered a significant, nascent, invasion of Alliaria petiolata (garlic mustard), which has the potential to negatively impact the biological integrity of the site if left unchecked. Small forest fragments in agricultural landscapes can act as important reservoirs of biodiversity, but effective preservation and management of these sites requires an understanding of the threats to their ecological integrity as well as environmental drivers of diversity.

REPRODUCTION POTENTIAL AND NATURAL CANKER INFECTION ON BACKCROSSED CHESTNUT TREES 1

American chestnut (Castanea dentata Marsh. Borkh.) is a once- dominant hardwood species with the potential to be a valuable restoration tree for use on surface mined lands in the Appalachian region. Coupling soil ripping and plowing and disking with plantings of American and backcrossed chestnuts has resulted in high seedling survival on a reclaimed surface mine site in southeast Ohio. The objective of this study was to evaluate flowering, chestnut bur production (seed), and natural cankers caused by chestnut blight fungus (Cryphonectria parasitica) on three chestnut breeding lines, in three soil tillage treatments after seven field seasons. Pure American (Castanea dentata), and two types of C. dentata × C. mollissima hybrids (BC2F1 and BC3F1) were documented. Reproduction potential was measured via flower production in June. Canker incidence was recorded as necrotic bark lesions with the presence of orange spore bearing structures. When reproduction potential was compared among seed types, there were no differences; all chestnuts trees were flowering and producing chestnut burs after 7 seasons. Soil treatment had no impact on flowering incidence; however, hybrid breeding lines had a mild effect. Canker incidence and presence of flowers were not related statistically. When natural canker incidence was compared, pure American chestnut exhibited the most infection (P < 0.0001). There were also notable treatment effects, plots that applied the deep ripping had greater disease incidence on pure American chestnuts (P < 0.0001). Long-term survival and stand stability will depend on chestnuts tolerance to the blight at an age of fruiting and flowering. Results after seven years suggest that hybrids were exhibiting a decrease in blight incidence and were flowering and producing burs. Employing deep ripping methods to backcrossed American chestnut plantings provide a viable method for hardwood seedling establishment in soils impacted by surface mining.