Relative importance of management vs design for i

Authors: Corinna S Bazelet Michael J Samways

Publish Date: 2010/11/26

Volume: 26, Issue: 3, Pages: 341-353

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Abstract

Ecological networks ENs are used to mitigate landscapescale habitat loss and are managed and designed to conserve regional biodiversity In our study region in southern Africa ENs of isolated grassland remnants are specifically set aside and managed for conservation and are complemented by corridorlike power line servitudes which are maintained by regular mowing Using grasshoppers a sensitive and reliable bioindicator taxon we determine whether ENs effectively conserve biodiversity We used cluster analysis and variation partitioning to select the best subset of environmental variables which explained the patterns of species composition We then compared the relative importance of environmental variables grouped by the scale of their influence localscale variables affected by management practices vs landscapescale variables affected by design of ENs Management was consistently and significantly 2–5 times more influential than design in determining grasshopper assemblages within ENs and servitudes Servitudes had a higher proportion of bare ground lower proportion of tall grasses and higher abundance of grasshoppers relative to ENs Three grasshopper species were strongly associated with servitudes and exhibited traits consistent with early colonizers As management actions are primarily responsible for vegetation succession the use of ENs for conservation efforts should first focus on appropriate management strategies such as fire regime and grass height management before altering the landscape structure eg increasing connectivity or enlarging patches The conservation implications of these results are that if ENs are managed and designed for heterogeneity and to simulate multiple successional stages they may be beneficial for biodiversity conservationWe thank B Gcumisa for field assistance The Mauerberger Foundation Fund and RUBICODE provided financial support C Burchmore P Gardiner G Kruger A Madikane M Masango L Nel and D van Zyl of Mondi and SiyaQhubeka provided maps accommodation at field sites and technical assistance D Nel and M Kidd assisted with statistical analysis Ezemvelo KZN Wildlife iSimangaliso Wetland Park Mondi Business Paper and SiyaQhubeka Forestry permitted sampling on their holdings Three anonymous reviewers vastly improved the quality of the manuscript

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