Perry, David A. 1995. Forests, competition and succession. In: Encyclopedia of Environmental Biology, Volume 2. New York: Academic Press, Inc.: 135-153.
Competition, the struggle for limited resources,and succession, the sequence of change in dominantorganisms following colonization, have long beenkey concepts employed by ecologists to understandand organize the patterns of nature. Although com-petition and succession are distinct processes, theyare closely related for at least two reasons. First,successional trajectories are largely driven by inter-actions among organisms, including (but not re-stricted to) competition. Second, both are inti-mately related to the degree of equilibrium ordisequilibrium in ecosystems and landscapes. Ecol-ogists once believed that succession led inexorablyto a stable equilibrium within a given communityof organisms, the composition of which was deter-mined in large part by who won the struggle forlimited resources. Although that view has not beentotally discarded, most ecologists now recognizethat change is the rule rather than the exception innature, with few if any ecological communitiesachieving a long-lasting equilibrium in speciescomposition. Disturbances at many spatial andtemporal scales create "shifting mosaics" of com-munities in different stages of succession, resultingin diverse niches that allow more species to coexist
Portions excerpted from D. A. Perry (1995). "Forest Ecosys-tems.- Copyright Johns Hopkins University Press, with per-mission.
than would be possible if all were competing forthe same set of resources.
This article first discusses competition: why itoccurs, why it does not occur, and how it shapesthe structure of communities. It then turns to thepatterns and mechanisms of succession, many ofwhich turn on the nature of both competitive andcooperative interactions among species.