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Plant invasions, restoration, and economics perspectives from South African fynbos

  • Restoration is gaining importance in the management of plant invasions. As the success of restoration projects is frequently determined by factors other than ecological ones, we explored the ecological and financial feasibility of active restoration on three different invaded sites in South Africa's Cape Floristic Region. The aim of our study was to identify cost-effective ways of restoring functional native ecosystems following invasion by alien plants. Over three years we evaluated different restoration approaches using field trials and experimental manipulations (i.e. mechanical clearing, burning, different soil restoration techniques and sowing of native species) to reduce elevated soil nutrient levels and to re-establish native fynbos communities. Furthermore we investigated the possibility of introducing native fynbos species that can be used for sustainable harvesting to create an incentive for restoration on private land. Diversity and evenness of native plant species increased significantly after restoration at all threeRestoration is gaining importance in the management of plant invasions. As the success of restoration projects is frequently determined by factors other than ecological ones, we explored the ecological and financial feasibility of active restoration on three different invaded sites in South Africa's Cape Floristic Region. The aim of our study was to identify cost-effective ways of restoring functional native ecosystems following invasion by alien plants. Over three years we evaluated different restoration approaches using field trials and experimental manipulations (i.e. mechanical clearing, burning, different soil restoration techniques and sowing of native species) to reduce elevated soil nutrient levels and to re-establish native fynbos communities. Furthermore we investigated the possibility of introducing native fynbos species that can be used for sustainable harvesting to create an incentive for restoration on private land. Diversity and evenness of native plant species increased significantly after restoration at all three sites, whereas cover of alien plants decreased significantly, confirming that active restoration was successful. However, sowing of native fynbos species had no significant effect on native cover, species richness, diversity or evenness in the Acacia thicket and Kikuyu field, implying that the ecosystem was sufficiently resilient to allow autogenic recovery following clearing and burning of the invasive species. Soil restoration treatments resulted in an increase of available nitrogen in the Acacia thicket, but had no significant effects in the Eucalyptus plantation. However, despite elevated available soil nitrogen levels, native species germinated irrespective whether sown or unsown (i.e. regeneration from the soil seed bank). Without active introduction of native species, native grasses, forbs and other shrubs would have dominated, and proteoids and ericoids (the major fynbos growth forms) would have been under-represented. The financial analysis shows that income from flower harvesting following active restoration consistently outweighs income following passive restoration, but that the associated increase in income does not always justify the higher costs. We conclude that active restoration can be effective and financially feasible when compared to passive restoration, depending on the density of invasion. Active restoration of densely invaded sites may therefore only be justifiable if the target area is in a region of high conservation priority.show moreshow less

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Metadaten
Author:Mirijam Gärtner, Henning Nottebrock, Helanya Fourie, Sean D. J. Privett, David M. Richardson
DOI:https://doi.org/10.1016/j.ppees.2012.05.001
ISSN:1433-8319 (print)
Parent Title (English):Perspectives in plant ecology, evolution and systematics
Publisher:Elsevier
Place of publication:Jena
Document Type:Article
Language:English
Year of first Publication:2012
Year of Completion:2012
Release Date:2017/03/26
Tag:Biological invasions; Cost-benefit analysis; Degradation; Exotic species; Flower harvesting; Rehabilitation
Volume:14
Issue:5
Pagenumber:13
First Page:341
Last Page:353
Funder:Flower Valley Conservation Trust; Agulhas Biodiversity Initiative; DST-NRF Centre of Excellence for Invasion Biology; National Research Foundation; Hans Sigrist Foundation; German Research Foundation DFG [SCHU 2259/3-1]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie
Peer Review:Referiert