Early effects of site preparation on the native ground layer vegetation of a hydric soil in North Carolina, USA

Ecological restoration of the longleaf pine (Pinus palustris) ecosystem requires successful establishment of longleaf pine seedlings while maintaining the characteristically diverse native ground layer vegetation.  This is especially difficult on wet sites where intensive site preparation methods are often used to control competing species.  On a poorly drained North Carolina soil, we tested the effects of eight site preparation treatments on the initial response of ground layer vegetation.  We examined effects of the treatments on abundance and species richness of vegetation on 1 m² plots for the following groups:  all vegetation, all woody species, all herbaceous species, large graminoids, small graminoids, forbs, ferns, woody species, and vines.  We found that after the first growing season (2004), all treatments had significantly reduced total vegetation abundance when compared to the untreated check.  However, after two growing seasons (2005), only treatments involving herbicides reduced total vegetation abundance when compared to the check.  Treatments with herbicides also reduced total species richness in 2004.  When 2005 data were analyzed by vegetation group, abundance and species richness displayed similar patterns.  Herbicides decreased the abundance and species richness of large graminoids, woody species, and vines, but increased abundance and species richness of small graminoids and ferns.  In 2005, the treatments did not have a significant effect on the abundance (p = 0.751) or species richness (p = 0.295) of forbs.  Although we found total species richness to vary by treatment at small scales, no significant differences were detected as scale increased (range of 23.6 to 30.4 species/100 m²).