Ecological Field Theory: the concept and field tests

Ecological field theory (EFT) quantifies plant spatial influences as pulsating geometric zones about individual plants. It provides the basis for a methodology to include spatial interactions between plants of different size, function and growth-form in models of plant community dynamics. The key components of EFT are: 1. the influence domain of individuals (D), 2. the field intensity within the domains (I), 3. the influence surface (ID) and 4. the intensity of interactions (II). The means to calculate these key components are outlined and several tests of the methodology as applied to a semi-arid eucalypt woodland are presented. The tests include a comparison of measured shrub growth with a computer implementation of EFT (the RESCOMP model) and spatial growth data from the eucalypt woodland to support the postulates included in EFT. Practical uses expected for the method are in agroforestry, landscape rehabilitation, simulations of disturbance effects and in determining invasibility of plant communities.Abbreviations ARGR = Actual Relative Growth Rate - EFT = Ecological Field Theory - IRM = Integrated Rate Method - PRGR = Potential Relative Growth Rate - RESCOMP= RESource COMPetition model - SMRGR = Spatially Modified Relative Growth Rate