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The effect of the spatial scale of recruitment on tree diversity in Afromontane forest fragments

Lawes, Michael, Joubert, Rebecca, Griffiths, Megan E., Boudreau, Stephane and Chapman, Colin A. (2007). The effect of the spatial scale of recruitment on tree diversity in Afromontane forest fragments. Biological Conservation,139(3-Apr):447-456.

Document type: Journal Article
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IRMA ID 81421842xPUB57
Title The effect of the spatial scale of recruitment on tree diversity in Afromontane forest fragments
Author Lawes, Michael
Joubert, Rebecca
Griffiths, Megan E.
Boudreau, Stephane
Chapman, Colin A.
Journal Name Biological Conservation
Publication Date 2007
Volume Number 139
Issue Number 3-Apr
ISSN 0006-3207   (check CDU catalogue open catalogue search in new window)
Start Page 447
End Page 456
Total Pages 10
Publisher Elsevier
Field of Research 0602 - Ecology
0502 - Environmental Science and Management
HERDC Category C1 - Journal Article (DEST)
Abstract In fragmented landscapes, tree recruitment is critical for forest persistence. We examined the effects of disturbance and environmental factors, isolation distance, and forest area on the spatial scale (grain) of regeneration of tree species in Afromontane forest fragments in South Africa. A species' grain is defined by whether it typically regenerates within its own canopy shadow (fine-grained) or over a larger spatial scale (coarse-grained). Species richness did not differ between small and large forest fragments but there were proportionately more coarse-grained species and fewer fine-grained species in small than in large fragments. While coarse-grained species richness increased with decreasing disturbance and increasing fragment isolation, fine-grained species richness increased with increasing fragment area. Fine-grained species are vulnerable to area-dependent fragmentation pressures. Although they regenerate in their canopy shadow, fine-grained species do not dominate disturbed fragments as expected. While able to survive in small fragments, fine-grained species are potentially dispersal limited and are not good colonisers and depend for their persistence on establishment in large forests. Conversely, because coarse-grained species have effective dispersal mechanisms they can colonise small fragments and are important for the maintenance of tree diversity in fragmented Afromontane forests. Thus, consideration of species grain of regeneration is necessary in conserving Afromontane tree diversity. Fine-grained species are conserved by protecting large forests while coarse-grained species are effectively conserved by maintaining small forest fragments often assumed to be ecologically unviable.
Keywords fragmentation ecology
tree community
tropical rainforest
janzen-connell model
south africa
habitat fragmentation
seedling recruitment
species composition
size distributions
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Created: Mon, 08 Sep 2008, 16:16:22 CST