PETER D. MOORE
Department of Biosphere Sciences
Fungal epidemics in natural plant communities are influenced by a wide range of climatic and other factors, but not, apparently, by high density of the host species or by human disturbance. The outcome of periodic fungal attacks is diversification of the plant community, but diversity itself does not offer in return any protection against further epidemics. Attacks on juvenile plants can cause considerable modification to the subsequent composition of a community, and the impact of exotic diseases is often much more severe than that of endemic ones.
J. Kranz, "Fungal diseases in multispecies plant communities," New Phytologist, 116, 383-405, November 1990. (Justus-Liebig-Universitat, Giessen, Germany)
One might expect intense cattle grazing in the tropical savannas to result in a decrease in shrub density, but in fact the reverse is the case. Intense grazing reduces the grass cover, and this may...