Short-term effects of pine straw raking on plant species richness and composition of longleaf pine communities.

摘要

Pine straw (pine needles) is commonly used as landscaping material throughout the southeastern USA, but little is known regarding the effects of raking and removal of straw in natural longleaf pine (Pinus palustris) communities. In a 2-yr experimentat 2 sites in the Croatan National Forest, North Carolina, USA, the effects were tested of community type (scrub oak, dry savanna, and mesic savanna, all with widely scattered longleaf pine) and number of mechanized rakings (0-4 times over the 2-yr period) on species richness and floristic composition of vascular plants at spatial scales of 1 and 100 m2. The sites were selected on the basis of controlled burning history, and had no history of raking activities. Multiple rakings caused richness to decline in the scrub oak community (1 m2) and to increase in the more heavily-vegetated mesic savanna (1 and 100 m2). Changes in richness were not proportional to the number of rakings, perhaps because (1) vegetation injury was minimal, (2) regrowth was possible owing to a largely perennial flora, and (3) the first litter removal removed the greatest amount of vegetation. In the mesic savanna, the only significant decline in richness, relative to initial values, occurred immediately after the first raking. Some seasonal variations were observed in species richness and in the quantity of vegetation removed by raking. Although raking may selectively injure shrubs and wiregrass (Aristida stricta), it did not allow the introduction of non-native plants and generally had little effect on floristic composition.