<P> Although Clements recognized that vegetation follows gradients rather than being tightly bound, his rhetorical comparisons of ecological communities to organisms fostered the impression that communities, including the climax, have distinct edges in space and time . Yet Robert Whittaker's research demonstrated plant species distribute themselves along nutrient and other environmental gradients . Many ecologists saw this as a major reason to stop using the climax concept . </P> <P> More recent palynological studies showed that modern species assemblages are ephemeral; vegetation in eastern North America since the last glacial maximum has consisted of several different species assemblages, many of which have no analogues in modern "climax" communities . That would mean, at least, that the climax types for those areas could not be stable to the degree Clements believed they were . </P> <P> Ultimately, even if succession tends towards a steady state, the time required to achieve this state is unrealistically long; in most cases, external disturbances and environmental change occur so frequently that the realization of a climax community is unlikely, and therefore it has come to be regarded as a less useful concept . Long - term vegetation dynamics are now more often characterized as resulting from the action of stochastic factors . </P> <P> Despite the overall abandonment of climax theory, during the 1990s use of climax concepts again became more popular among some theoretical ecologists . Many authors and nature - enthusiasts continue to use the term "climax" in a diluted form to refer to what might otherwise be called mature or old - growth communities . The term "climax" has also been adopted as description for a late successional stage for marine macroinvertebrate communities . </P>

Why would a climax community such as an oak woodland have high species diversity