PARENT SESSION
Poster Session # 14: Forest Ecology.
Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Effects of regeneration harvest methods of floral diversity and soil properties.
Elliott, Katherine*,1, Knoepp, Jennifer1, 1 Coweeta Hydrologic Laboratory, Otto, NC, USA
ABSTRACT- Forest practices that alter site conditions, either as a consequence of a timber harvest or a practice intended to improve tree regeneration, may change biological diversity. We examined how regeneration harvest methods (two-aged shelterwood (2A), shelterwood (SW), and group selection (GS) cutting) affected floristic diversity, species composition, and soil characteristics of high elevation, mixed-hardwood ecosystems in the southern Appalachians. Within each treatment area and two uncut areas (UC), four 0.08 ha permanent plots were located to inventory overstory, understory and herbaceous layer species before (1994) and one year (1998)and three years after (2000)the harvest treatments. Within each plot, we collected soil samples at two depths (0-5 cm and 5-15 cm) to determine soil pH, exchangeable calcium (Ca), potassium (K), and magnesium (Mg), percent soil carbon (C) and nitrogen (N), cation exchange capacity (CEC), and bulk density. Species diversity was evaluated using species richness (S), Shannon-Wiener's index (H'), and Pielou's evenness index (E). In the overstory, H' and E were significantly reduced in the SW and 2A treatments after harvest, but no changes in diversity were detected for the GS or UC treatments. Understory density and basal area increased in the 2A and SW treatments after harvest. H' and E were higher on the 2A, SW, and GS treatments than the UC sites, but there were no significant differences among the three harvest treatments. In the herbaceous layer, differences among treatments after the harvest were found for density and percent cover in 1998 and S in 1998 and 2000. No differences were detected for H', E, or D among treatments. In 1998, H' and E were higher on all regeneration harvest treatments than before harvest (1994). By 2000, H' and E were no longer different than before the harvest. However, we did find changes in species composition following the harvest treatments. Significant differences among the treatments varied depending on soil depth and year of post-harvest measurement. For the 0-5 cm depth, soil Ca and C were higher for the 2A treatment in 1998 and CEC was lower on the SW treatment in 2000 compared to the other treatments. For the 5-15 cm depth, Ca and K were higher on the 2A than on the UC treatment. In 2000, herbaceous layer diversity was significantly related to soil K, Ca, Mg, CEC and N.
Key words: nitrogen, biodiversity,