Distribution and abundance of Malayan trees: Significance of Family Characteristics for Conservation

Taxonmic families of plants that characterize the lowland  Malayan rain forest differ from one another nearly ten-fold in quantitative measures of distribution and abundance.  A 50-ha sample of 300,000 trees includes 814 species or fully one-fourth of the Malayan tree-flora.  The median adult population size for trees and shrubs is a linear function of area.  From the Pasoh equations, we can calculate the area needed to capture an adult population of a specific size for a particular fraction of the flora, i.e., for 90% of the Pasoh tree flora to be represented by more than 200 adults per species will require about 3,000 ha of forest.  These equations indicate how many species will have a specific population size within a forest, but not which species.  I test the alternative hypothesis that the large characteristics families of the Malayan forest either do or do not differ more than 10-fold in median abundance and species representation.  The Pasoh data reject the latter hypothesis.  The characteristic taxonomic families of the lowland forest, e.g., Dipterocarpacaeae, Sapotaceae, and Burseraceae vary in representation from 10% of regional species to 60%, the power functions of species- area curves vary nearly 10-fold, and median abundances vary from less than 1 to more than 10 individuals per ha.  These findings are confirmed in part from an analysis of the flora of Singapore which, with regard to representation, illustrates patterns identical to those at Pasoh.  The consequences for conservation are two fold: (1) general conservation strategies should not be based on studies of focal familiesl (2) different taxonomic families of trees and shrubs will require very different strategies of reserve design for their conservation.  

James V. LaFrankie
Garden's Bulletin Singapore