04 July 2006

Data's in on importance of diversity

Nature has published (Vol. 441:629-32) an empirical study linking diversity to ecological stability.

Tilman et al show that ecosystem stability, - the ratio of mean above ground biomass to temporal standard deviation, is positively correlated with the number of separate perennial grassland species growing at Cedar Creek Natural History Area, Minnesota, USA.

Skeptics won't have much wiggle-room with the findings of this 12-year field study. The methods section describes an experimental labour of love involving 30 replicates per experimental condition and a design that painstakingly manipulated biodiversity by carefully weeding 168 9m x 9m plots so that there was either 1, 2, 4, 8 or 16 grasses, legumes and woody species in each plot.

Be glad that scientists have now had sufficient time to silence dubious arguments that modern industrial agriculture is sustainable. But have we enough time left to save the rainforests and myriad other sensitive ecosystems harboring the secrets of a stable biosphere?