Landscape dynamics and ecological change in the Southern Appalachians

Contacts

Monica Turner

Keywords

COWEETA LTER, historical land use, land-use change, Southern Appalachians

Research Overview

Most recently, we extended our vegetation studies to non-native invasive plants that are shade tolerant and hence have the potential to impact this densely forested region. Our field data revealed that Celastrus orbiculatus (oriental bittersweet, a woody vine native to east Asia) and Microstegium vimineum (Japanese stiltgrass, a shade-adapted C-4 grass) were the invasives that were encountered most freqeuntly. As part of his doctoral dissertation, Tom Albright found that oriental bittersweet was more likely to be found in locations closer to its introduction locus (near Asheville, NC), at lower elevations, with greater forest edge habitat and near roads (Albright 2007, Albright et al. in press). Furthermore, oriental bittersweet appears to be expanding its distribution in the Southern Appalachians. Analyses of the regional distribution of Microstegium, using data from the Carolina Vegetation Survey, revealed that that, at broad scales, areas with high human activity and low forest cover were at highest risk of M. vimineum invasion (Anderson et al., in review). At fine spatial scales, the probability of M. vimineum presence increased with increasing native species richness and followed a soil fertility gradient. Spatial parameters suggested that areas within a 3-km distance of established locations, including high fertile sites with well-established native plant communities, were at an elevated risk of invasion.

Doctoral student Tim Kuhman focused on how land-use history influences the presence and abundance of non-native invasive plants (Kuhman 2009). This work included a field study of the effects of land-use history on invasive species presence and abundance at the Bent Creek Experimental Forest, for which land-use history is well known and mapped. These data revealed a very strong positive association between land-use history and invasive species occurrence, along with intriguing differences in both overstory composition and the evergreen understory (which is drastically reduced in areas that were farmed historically). Experimental germination studies were conducted with Celastrus seeds to identify the factors that could lead to increased success of invasives in sites that were previously cultivated. To determine whether recent exurban development is facilitating the spread of non-native plants, Kuhman also sampled the presence and abundance of non-native invasive plants within 25 watersheds varying in housing development patterns.

Read more on Tim Kuhman’s studies…

Current research

CWT research has focused extensively on understanding the patterns and ecological implications of natural disturbances and land-use changes throughout the Southern Appalachian region. However, potential climate change effects have received less attention.  The steep environmental gradients that characterize the Southern Appalachians provide an outstanding opportunity for studying climate effects on vegetation and how climate and land-use change will interact. During the 2008-2014 funding cycle, we are studying key elements of this interaction, including (1) understanding the effects of projected climate and land-use changes on biodiversity, emphasizing native herbs, non-native invasive forest plants, birds, and forest diseases; and (2) understanding how changes in climate and forest communities will influence ecosystem processes, particularly carbon and nitrogen dynamics, and how these ecosystem processes may feedback to affect the future forest community.

For the southern Appalachians and Piedmont, projections of land-cover change with global warming indicate strong sensitivity to increasing aridity.  Forests are expected to expand under more moderate scenarios, where moisture stress is less severe, but decline under more extreme climate scenarios. Temperate deciduous forest communities are likely to be replaced by southeast mixed forests in most scenarios, but if moisture is sufficiently limiting, replacement by savanna/woodland may occur. Mammal and bird richness are also predicted to decline in much of the southern US.  Few (if any) studies have been considering understory species, however.  We are conducting a set of linked studies that evaluate (1) the joint effects of climate and land-use history on native forest herbs, led by PhD student Michelle Gooch, and (2) joint effects of climate and contemporary land-use patterns on avian communities and nest predation, led by MS student Heather Lumpkin.

Read more on Michelle Gooch’s studies…

Read more on Heather Lumpkin’s studies…

Selected Publications

Completed Dissertations

Albright, T. P.  2007.  Invasive plant distributions: lessons from native and exotic ranges.  PhD dissertation, University of Wisconsin, Madison, WI.

Fraterrigo, J. M.  2005.  Influence of land-use change on the long-term persistence of forest underestory herbs in the southern Appalachian highlands.  PhD dissertation, University of Wisconsin, Madison, WI.

Journal articles

Fraterrigo, J. M., M. G. Turner, S. M. Pearson, and P. Dixon.  2005.  Effects of past land use on spatial heterogeneity of soil nutrients in Southern Appalachian forests.  Ecological Monographs 75:215-230.

Fraterrigo, J. M., T. C. Balser and M. G. Turner. 2006a. Microbial community variation and its relationship with nitrogen mineralization in historically altered forests. Ecology 87:570-579.

Fraterrigo, J. M., M. G. Turner and S. M. Pearson.  2006b.  Plant allocation and growth in the herb layer of historically altered forests.  Journal of Ecology 94:548-557.

Fraterrigo, J. M., M. G. Turner and S. M. Pearson.  2006c. Interactions between past land use, life-history traits and understory spatial heterogeneity.  Landscape Ecology 21:777-790.

Hicks, N. G. and S. M. Pearson.  2003.  Salamander diversity and abundance in forests with alternative land-use histories in the southern Blue Ridge Mountains.  Forest Ecology and Management 177:117-130.

Mitchell, C. E., M. G. Turner and S. M. Pearson. 2002. Effects of historical land use and forest patch size on myrmecochores and ant communities. Ecological Applications 12:1364-1377.

Pearson, S. M., A. B. Smith, and M. G. Turner.  1998.  Forest fragmentation, land use, and cove-forest herbs in the French Broad River Basin.  Castanea 63:382-395.

Turner, M. G. 2005a. Landscape ecology: what is the state of the science?  Annual Review of Ecology, Evolution and Systematics 36:319-344.

Turner, M. G. 2005b. Landscape ecology in North America: past, present and future. Ecology 86:1967-1974.

Turner, M. G., S. Collins, A. Lugo, J. Magnuson, S. Rupp and F. Swanson.  2003a. Long-term ecological research on disturbance and ecological response. BioScience 53:46-56.

Turner, M. G., S. M. Pearson, P. Bolstad and D. N. Wear. 2003b.  Effects of land-cover change on spatial pattern of forest communities in the southern Appalachian Mountains (USA). Landscape Ecology 18:449-464.