Allometric Analysis of Plant Growth in Woodland Communities

Several allometrically-based equations were derived to describe the changes and the similarities in the structure and shape of semiarid woody plants that occur with growth. The derivations utilized general hypotheses based on the assumption that one of the principal purposes of a plant’s structure is the efficient support and distribution of its leaves. Results from analyses of plant branching systems were used to derive allometric relationships between selected variables of plant size and shape. A close correspondence often occurred between the parameters resulting from the derivations and those that resulted from empirical analyses of field data. The variability of some relationships was found to be linked to increasing tree dominance, and/or increasing tree size. Changes potentially linked to differing site quality were also observed for some relationships. Other relationships remained relatively uniform over a range of successional stages and also potentially uniform over a range of site quality. The analyses revealed important crown structure and foliage distribution similarities, as well as differences, between the plant species studied. In general, large plants were often less variable, relative to their size, than small plants. Each species also has a relatively consistent leaf distribution within its crown. A number of implications and applications of the results to plant sampling and vegetation analyses were discussed. This includes discussions of the need for, and possible means of obtaining, adequate methods of determining site quality for woody plant communities in non-timber producing regions. Overall, the analyzed allometric relationships resulted in a generalized working model of plant growth and development, particularly for the changes in size, shape and biomass that occur with growth.