  Diversity patterns of tree species in a tropical forest community are
approached by a simple lattice model and investigated by Monte Carlo
simulations using a backtracking method. Our spatially explicit neutral model
is based on a simple statistical physics process, namely the diffusion of
seeds. The model has three parameters: the speciation rate, the size of the
meta-community in which the studied tree-community is embedded, and the average
surviving time of the seeds. By extensive computer simulations we aim the
reproduction of relevant statistical measures derived from the experimental
data of the Barro Colorado Island tree census in year 1995. The first two
parameters of the model are fixed to known values, characteristic of the
studied community, thus obtaining a model with only one freely adjustable
parameter. As a result of this, the average number of species in the considered
territory, the relative species abundance distribution, the species-area
relationship and the spatial auto-correlation function of the individuals in
abundant species are simultaneously fitted with only one parameter which is the
average surviving time of the seeds.
