Species interactions and plant diversity during secondary succession

Interactions among species, such as competition, have been posedas mechanisms that determine the rate and direction of the changeof species composition after disturbance—succession (e.g., Connelland Slatyer 1977). Thus, as forests recover from disturbance, inter-actions among colonizing and/or surviving species may directly orindirectly influence levels of plant species diversity. Althoughchanges in diversity with time are well documented for early suc-cessional (seral) Douglas-fir forests of the Pacific Northwest (e.g.,Schoonmaker and McKee 1988; Halpern 1989), the biological pro-cesses regulating these changes are poorly understood.