MEEKER, RALPH B.1* and KATHERINE C. LARSON2. 1University of Central Arkansas, Department of Biology, Conway, AR 72035; 2University of Central Arkansas, Department of Biology, Conway, AR 72035. - Fragmentation in a Southern Oak-Hickory Forest: Impacts on Species Richness and Invasibility.
Habitat fragmentation results in the isolation of habitats from one
another, increases the ratio of edge area to interior area, and
reduces the total area of habitat. Smaller habitats often exhibit more
dramatic microclimatic characteristics (higher light levels, higher
soil temperatures, and lower soil moisture), are more susceptible to
invasion from both non-indigenous and indigenous invasive plant
species, and exhibit lower species richness than larger habitats.
Smaller fragments are also more likely to display "edge"
effects. I measured the impact of fragment size (<5 ha, >5 ha and
<10ha, and >20 ha) and distance from the edge of the fragment (0, 5m,
20m, and 50m) on (1) tree densities for eastern red cedar,
Juniperus virginiana, and hardwood species collectively, (2)
tree/shrub species richness, and (3) frequency of the invasive vine
Lonicera japonica. The fragments were anthropogenically
created, and all edges were cut more than 30 years ago. The fragments
were formed from a southern oak-hickory forest at Ft. Chaffee, an Army
National Guard base in northwestern Arkansas. The invasive,
non-indigenous L. japonica and the invasive indigenous J.
virginiana are more abundant along edges. Preliminary analysis
indicates these species are also more abundant in smaller fragments
and that species richness is greater in large fragments.
Key words: fragmentation, invasive species