Long-term (17-year) dynamics of herbaceous plant communities after shelterwood regeneration harvests in southern Appalachian cove- and upland hardwood forests

The southern Appalachians are a “hotspot” of plant diversity. Herbaceous communities are especially rich in mesic cove hardwood forests, compared to drier upland hardwood forests. We evaluated changes in forest structure and herbaceous plant communities over 17 years in mature cove- (CHM) and upland hardwood (UHM) forests, and young 2-age cove- (CHSW) and upland hardwood (UHSW) stands created by shelterwood-with-reserves regeneration harvests (SW). Structure of mature forests was relatively static. In contrast, reduced canopy cover after harvests initiated rapid increases in small tree stem density and blackberry ( Rubus) cover, followed by dense shade as young trees gained height. We identified 201 herbaceous species including 156 forbs. Species richness was about double in CHM and CHSW than in UHM and UHSW; composition changed little over time within treatments, even as forest structure changed in SW. Among the 79 herbaceous species analyzed, relative abundance of 26 showed a response; most were more abundant in CHM, CHSW, or both compared to UHM, UHSW, or both. Our results indicated that shelterwood harvests had a neutral or positive effect on herbaceous plant richness, diversity, and abundance of most species, and suggested that environmental gradients associated with forest type influenced herbaceous communities much more than SW alone.