Overview

plagioclimax


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A term that is almost synonymous with biotic climax, although they are sometimes given different meanings. Generally, both refer to a stable vegetation community arising from a succession that has been deflected or arrested directly or indirectly as a result of human activities. In a deflected succession, the resulting stable community, even when composed entirely of native species, is one that would not have occurred in the absence of human intervention (e.g. most lowland heath communities of western Europe arose as a consequence of forest clearance, subsequent grazing pressure, and controlled burning). Associated changes in the physical environment may mean that even when these pressures are removed succession to the original climax community is no longer possible. In an arrested succession, the stable community is a naturally occurring successional phase and it should be possible for the natural succession to continue once the disturbing factor has been removed (e.g. the cutting of reed beds arrests the natural succession to alderwood in a hydrosere). Some authors restrict ‘plagioclimax’ to deflected successions; some use ‘plagioclimax’ where human intervention is more direct, reserving ‘biotic climax’ for more indirect effects (e.g. grazing by non-domesticated but introduced animals, such as the rabbit in Britain). ‘Biotic climax’ may also be applied to a natural, undisturbed succession in which the form of the final community is determined by a naturally occurring biological agent (e.g. grasslands in guano-enriched coastal areas).

Subjects: plant sciences and forestry — ecology and conservation.


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