A neighbourhood-based competition model for plant individuals is studied to
evaluate how a hierarchical structure related to size may emerge in plant
communities. It is shown by numerical simulations and linear stability anal
ysis that many stable states exist in the hierarchical structure when both
the total number of individuals and the degree of asymmetry of competition
are high. When the hierarchical structures are self-organized by the dynami
c instability of the homogeneous state due to non-linearity of competition,
it is proved that these states are always locally stable. The relevance of
the results to size structures in real plant communities (boreal forests v
s tropical and temperate forests) is discussed. This is suggested to be the
mechanism responsible for the coexistence of species in plant communities.
(C) 1999 Society for Mathematical Biology.