Publication Date:
2013-10-24
Description:
Biotic homogenisation due to replacement of native biodiversity by widespread generalist species has been demonstrated in a number of ecosystems and taxonomic groups world-wide, causing growing conservation concern. Human disturbance is a key driver of biotic homogenisation, suggesting potential conservation challenges in semi-natural ecosystems, where anthropogenic disturbances such as grazing and burning are necessary for maintaining ecological dynamics and functioning. We test whether prescribed burning results in biotic homogenisation in the coastal heathlands of north-western Europe, a semi-natural landscape where extensive grazing and burning has constituted the traditional land-use practice over the past 6000 years. We compare the beta-diversity before and after fire at three ecological scales: within local vegetation patches, between wet and dry heathland patches within landscapes, and along a 470 km bioclimatic gradient. Within local patches we found no evidence of homogenisation after fire; species richness increased, and the species that entered the burnt Calluna -stands were not widespread specialists but native grasses and herbs characteristic of the heathland system. At the landscapes scale, we saw a weak homogenisation as wet and dry heathland patches become more compositionally similar after fire. This was because of a decrease in habitat-specific species unique to either wet or dry habitats and post-fire colonisation by a set of heathland specialists that established in both habitat types. Along the bioclimatic gradient, species that increased after fire generally had more specific environmental requirements and narrower geographic distributions than the pre-fire flora, resulting in a biotic ‘heterogenisation’ after fire. Our study demonstrates that human disturbance does not necessarily cause biotic homogenisation, but that continuation of traditional land-use practices can instead be crucial for the maintenance of the diversity and ecological function of a semi-natural ecosystem. The species that established after prescribed burning were heathland specialists with relatively narrow geographical ranges. This article is protected by copyright. All rights reserved.
Print ISSN:
1354-1013
Electronic ISSN:
1365-2486
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
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