Letters to Nature

Nature 401, 907-911 (28 October 1999) | doi:10.1038/44819; Received 9 June 1999; Accepted 12 August 1999

Allometric scaling of production and life-history variation in vascular plants

Brian J. Enquist1,2, Geoffrey B. West2,3, Eric L. Charnov4 and James H. Brown4,2

  1. National Center for Ecological Analysis and Synthesis, 735 State Street, Suite 300, Santa Barbara, California 93101-5504, USA
  2. Department of Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
  3. The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501, USA
  4. Theoretical Division, T-8, MS B285, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

Correspondence to: Brian J. Enquist1,2 Correspondence and requests for materials should be addressed to B.J.E. (e-mail: Email: enquist@nceas.ucsb.edu).

A prominent feature of comparative life histories is the well documented negative correlation between growth rate and life span1, 2. Patterns of resource allocation during growth and reproduction reflect life-history differences between species1, 2. This is particularly striking in tropical forests, where tree species can differ greatly in their rates of growth and ages of maturity but still attain similar canopy sizes3, 4. Here we provide a theoretical framework for relating life-history variables to rates of production, dM/dt, where M is above-ground mass and t is time. As metabolic rate limits production as an individual grows, dM/dt proportional to M3/4. Incorporating interspecific variation in resource allocation to wood density, we derive a universal growth law that quantitatively fits data for a large sample of tropical tree species with diverse life histories. Combined with evolutionary life-history theory1, the growth law also predicts several qualitative features of tree demography and reproduction. This framework also provides a general quantitative answer to why relative growth rate (1/M)(dM/df) decreases with increasing plant size (proportional toM-1/4) and how it varies with differing allocation strategies5, 6, 7, 8.