AOBPreview published online on March 12, 2008
Annals of Botany, doi:10.1093/aob/mcn020
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Control of Pteridium aquilinum: Meta-analysis of a Multi-site Study in the UK
1 Centre for Evidence-Based Conservation, School of the Environment & Natural Resources, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
2 Applied Vegetation Dynamics Laboratory, School of Biological Sciences, University of Liverpool, PO Box 147, Liverpool, L69 7ZB, UK
3 Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK
* For correspondence. E-mail g.stewart{at}bangor.ac.uk
Received: 16 October 2007 Returned for revision: 3 January 2008 Accepted: 18 January 2008
Background and Aims: A great deal of money is spent controlling invasive weeds as part of international and national policies. It is essential that the funded treatments work across the region in which the policies operate. We argue that experiments across multiple sites are required to validate these programs as results from single sites may be misleading. Here, the control of Pteridium aquilinum (bracken) is used as a test example to address the following four questions. (1) Does the effectiveness of P. aquilinum-control treatments vary across sites? (2) Is the best treatment identified in previous research (cutting twice per year) consistent at all sites, and if not why not? (3) Is treatment performance related to P. aquilinum rhizome mass, litter cover or litter depth at the various sites? (4) Does successful P. aquilinum control influence species richness?
Methods Pteridium aquilinum: -control treatments were monitored for 10 years using six replicated experiments and analysed using meta-analysis. Meta-regressions were used to explore heterogeneity between sites.
Key Results: The effectiveness of treatments varied between sites depending on the measure used to assess P. aquilinum performance. In general, cutting twice per year was the most successful treatment but on some sites other, less expensive treatments were as good. The effectiveness of treatments at different sites was not related to rhizome mass, but the effectiveness of most applied treatments were inversely related to post-control litter. Effective treatment was also associated with high species richness.
Conclusions: It is concluded that successful development of national weed control programs requires multi-site experimental approaches. Here, meta-analyses demonstrate that variation in effectiveness between sites could be explained in part by pre-specified variables. Reliance on data from a single site for policy formulation is therefore clearly dangerous.
Key words: Bracken, Pteridium aquilinum, weed, control, herbicide, litter dynamics, species diversity, meta-analysis