Invariant scaling relations across tree-dominated communities.
Organizing principles are needed to link organismal, community and ecosystem attributes across spatial and temporal scales. Here we extend allometric theory-how attributes of organisms change with variation in their size-and test its predictions against worldwide data sets for forest communities by quantifying the relationships among tree size-frequency distributions, standing biomass, species number and number of individuals per unit area. As predicted, except for the highest latitudes, the number of individuals scales as the -2 power of basal stem diameter or as the -3/4 power of above-ground biomass. Also as predicted, this scaling relationship varies little with species diversity, total standing biomass, latitude and geographic sampling area. A simulation model in which individuals allocate biomass to leaf, stem and reproduction, and compete for space and light obtains features identical to those of a community. In tandem with allometric theory, our results indicate that many macroecological features of communities may emerge from a few allometric principles operating at the level of the individual.
Enquist
B J
BJ
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA. benquist@u.arizona.edu
Niklas
K J
KJ
D000465:Algorithms; D005075:Biological Evolution; D018533:Biomass; D003198:Computer Simulation; D004463:Ecology; D008954:Models, Biological; D014197:Trees / Q000502:physiology*