Applying palaeoecology to conservation: a long-term perspective for informed management of a fynbos nature reserve

James MacPherson

Abstract


This investigation proposes that long-term perspectives are essential in ecological conservation/restoration. Such a perspective is particularly important for fynbos, which has been substantially altered by an unspecified level of anthropogenic disturbance. Fossil pollen and micro-charcoal deposits are used to establish a proxy record for ecosystem state that can be applied to conservation. This is carried out at a nature reserve in the Langeberg Range, Western Cape, South Africa. Modern pollen-vegetation relationships are also examined to reduce inaccuracies in the fossil record. Three distinct phases are identified for the reserve over a period extending up to ~1000 years before present (BP). Phase 1a (pre-colonial settlement) was characterised by ~85-135% fynbos cover, relative to present cover, and greater than present afromontane forest propagation. This may be a result of warm, mesic climatic conditions which occurred ~1000-600 years BP Phase 1b saw fynbos proliferate to between ~135-225% of present cover, while afromontane forest declined. This might be a result of cool, xeric conditions which occurred ~600-200 BP; conversely, the ‘intermediate disturbance hypothesis’ cannot be ruled out as a possible cause. Phase 2 appears to show colonial environmental degradation and fynbos decline (50-100% of present cover), initiating c. mid - late nineteenth century. In contrast, recent conservation efforts appear to have encouraged a return to conditions statistically analogous with those of phase 1a. Quantitative ‘thresholds of potential concern’ are defined for fynbos at 85-135% of present cover. Should fynbos cover breach these thresholds, this may indicate deviation from ‘natural’ conditions relative to present climate. However, given predicted future aridity, it is suggested that the full ‘range of natural variability’ exhibited by fynbos for the extension of the record might provide more appropriate parameters; 85-225% of present cover. Fire does not appear to be linked to fynbos proliferation/decline, but this could be a result of human perturbation.

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