Changes in Plant Species Diversity During Early Secondary Succession in an Experimental Old-Field System

Abstract

Plant species diversity was examined during early secondary succession 1-6 yr in an experimental old field system at the Waterloo Mills Field Research Station at Devon, Pennsylvania, USA. Replicated subplots within a randomized complete block design were treated after fallowing by the addition of seeds of 0, 15 and 34 spp. to the residual seed pool. Subplots were sampled annually with 100 1/32 m2 quadrats and the data were used to calculate several indices of species diversity. Patterns of change through time in areal species richness, Shannon''s H'' and community dominance diversity curves suggest that these successional communities develop as a series of alternating high dominance-low diversity and low dominance-high diversity situations superimposed on a general trend of increased species richness through time. Evidence presented supports the concept of widespread intrinsic pattern in diversity during early secondary succession.