1620 The Pilgrims sight Cape Cod

Biological Conservation Volume 116, Issue 2, April 2004, Pages 181–189 Pitch pine (Pinus rigida Mill.) invasion of Cape Cod pond shores alters abiotic environment and inhibits indigenous herbaceous species Stephen I Craine, , Colin M Orians doi:10.1016/S0006-3207(03)00188-5 Get rights and content Abstract Invasion by pitch pine (Pinus rigida Mill.) on coastal plain pond shores may have direct impacts on the herbaceous community, or may merely indicate changes in hydroperiod, which are the actual cause of community change. We compared abiotic conditions and community composition of sites that had been invaded by P. rigida and those that had not on two Cape Cod ponds. Soil under living pines had lower pH and water content, reduced net nitrification, and increased rates of ammonification. Dense stands of pine saplings reduced PAR penetrance by 94% and excluded virtually all herbaceous species. To determine if pines alone can change community composition, we imposed artificial shade and added pine needle litter to experimental plots. In the course of one growing season, both litter and shade significantly reduced the frequency of herbs in the herbaceous zone of the pond shore. Litter had the greater effect (significant for six of seven taxa), while shade reduced the frequencies of three taxa significantly. Keywords Coastal plain pond shores; Disturbance regime; Mechanisms of competition; Native invasives; Pinus rigida Corresponding author Copyright © 2003 Elsevier Ltd. All rights reserved.