Annals of Botany Lecture
Niklas, Karl J. .
Plant Allometry: Is There a Global Theory?.
Research on the effects of plant biodiversity on ecosystem function and structure has intensified with the realization that global biodiversity is declining. Yet, some of our most fundamental questions concerning species richness and community structure remain unanswered, e.g., we have no generally accepted explanation for why biodiversity varies as a function of latitude or elevation, nor have we reached consensus regarding the effects of disturbance or climatic variation on species richness, community productivity, or standing biomass. Past studies revealed divergent relationships for different taxonomic groups or geographic areas resulting in a field of enquiry less subject to prediction than to observation. In contrast, recent advances in allometric theory have provided detailed and testable predictions about community structure. Aspects of this theory will be explored empirically and analytically using large worldwide data sets for forested communities and for local climatological and soil conditions. It will be shown that much of the variance in plant biodiversity is explained statistically by local variations in abiotic variables, which is consistent with theory. Thus, across communities between 20º S and 20º N latitude and elevations below 500 m, multiple regression analysis shows that more than 82% of the variance observed for tree species diversity is explained by differences in average monthly precipitation, average annual temperature, the number of months precipitation exceeds estimated potential ground evaporation, average monthly temperature during the growing season, and soil type. For communities between 10º S and 10º N, these variables explain more than 90% of the variance in species number. Yet, as predicted, total community standing biomass and estimates of annual productivity are, on average, indifferent to species number. The implications of these and other allometric trends to ecology and evolutionary biology will be discussed.
1 - Cornell University, Department of Plant Biology, Tower Road, Ithaca, New York, 14853-5908, USA
Presentation Type: Special
Location: Wasatch (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 11:00 AM