NIKLAS, KARL J.1* and BRIAN J. ENQUIST2. 1Department of Plant Biology, Cornell University, Ithaca, NY 14853; 2Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721. - An axiomatic tree biomass allocation pattern: derivation and verification.
A quantitative framework describing how biomass allocation varies
across plant species, communities, and ecosystems is lacking despite
its fundamental importance to basic plant biology, global change
studies, and evolutionary and ecological theory. Here we derive a
model for biomass allocation using an allometric and engineering
approach. This model predicts that foliage biomass will scale as the
3/4–power of stem (and root) biomass and as the 2–power of trunk
diameter. These scaling relationships are predicted to be invariant
with respect to species phyletic affiliation as well as community
latitude or elevation (which may be used as crude surrogate measures
of community diversity). A world-wide compendium for tree biomass is
used to test these predictions in terms of empirically determined
scaling exponents. The data in this compendium are shown to comply
with the predictions of our model in every critical respect. The
implications of our axiomatic tree biomass allocation pattern are
discussed in the broader context of ecological and evolutionary
theory.
Key words: allometric theory, biomass allocation, biomechanical theory, ecology, trees