Stability and diversity at three trophic levels in terrestrial successional ecosystems.

An ecosystem perturbation experiment in which inorganic fertilizer was added to two successional old fields of different ages indicated that stability, expressed as resistance to modification by enrichment, increased during succession only at the primary trophic level. The perturbation was propagated throughout the arthropod herbivores and carnivores. Both herbivores and carnivores were less stable in the older field. In contrast to current ecological theory, greater diversity at a trophic level was accompanied by lower stability at the next higher level.