Michael A. Jenkins

Vegetation Communities of Great Smoky Mountains National Park

Abstract Great Smoky Mountains National Park (GSMNP) contains one of the most diverse assemblages of vegetation communities in North America. Over 70 unique community associations comprised of over 1300 native plant species have been identified in the Park. This wide array of communities provides habitat for unknown multitudes of other taxa whose abundance, distribution, and ecological importance remain largely unknown. The All Taxa Biodiversity Inventory (ATBI) underway in the Park is the first comprehensive attempt to better understand the vast array of species present in the Park. This paper discusses the composition, structure, distribution, and extent of vegetation communities in GSMNP. Detailed assessments of the vegetation, site, and soil characteristics of the 19 ATBI plots are also included.

The response of herbaceous-layer vegetation to anthropogenic disturbance in intermittent stream bottomland forests of southern Indiana, USA

Between 1993 and 1995 we sampled herbaceous layer vegetation on 84 plots in Platanus/Asarum Wet-Mesic Bottomland forests to determine how these forests have responded to human disturbance. Four different disturbance types were sampled (abandoned agricultural are as, clearcuts, group-selection openings, and single-tree selection openings), and uncut 80–100 year-old reference stands were sampled for comparison. Detrended Correspondence Analysis (DCA), distance analyses (chord distance and normalized Euclidean distance) and similarity analysis (Bray-Curtis similarity coefficient) suggest that agricultural use has shifted herbaceous-layer vegetation composition away from that typical of the reference forests, but that clearcutting, group-selection harvest, and single-tree selection harvest have not greatly shifted herbaceous composition. This shift in vegetation on abandoned agricultural land resulted from a loss of indicator species, such as Cardamine concatenata (Michx.) Sw., Stellaria pubera Michx., and Laportea canadensis (L.) Weddell and an influx of disturbance, exotic, and nonforest species (e.g., Lycopodium complanatum L., Lonicera japonica Thunb. and Senecio aureus L.). However, only two species found in reference stands, Erigenia bulbosa (Michx.) Nutt. and Sphenopholis obtusata (Michx.) Scribn., were missing from clearcuts, group-selection openings, and single-tree selection openings. The species richness values of abandoned agriculture, clearcut, and group-selection plots were generally greater than those of single-tree selection and reference plots. Abandoned agricultural areas had much greater total species richness because of the influx of dry-site, exotic, disturbance, and non-forest species.