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Plant Ecol (2012) 213:19751989 DOI 10.1007/s11258-012-0154-x
Allelopathy: a tool for weed management in forest restoration
Justin A. Cummings Ingrid M. Parker
Gregory S. Gilbert
Received: 25 April 2012 / Accepted: 29 November 2012 / Published online: 9 December 2012 Springer Science+Business Media Dordrecht 2012
Abstract Forest restoration uses active management to re-establish natural forest habitat after disturbance. However, competition from early successional species, often aggressively invasive exotic plant species, can inhibit tree establishment and forest regeneration. Ideally, restoration ecologists can plant native tree species that not only establish and grow rapidly, but also suppress exotic competitors. Allelopathy may be a key mechanism by which some native trees could reduce the abundance and impact of exotic species. Allelopathy is a recognized tool for weed management in agriculture and agroforestry, but few studies have considered how allelopathic interactions may aid restoration. Here we introduce the Homeland Security hypothesis, which posits that some nave exotic species may be particularly sensitive to allelochemicals produced by native species, providing a tool to reduce the growth and impacts of invasive exotic species on reforestation. This article explores how
exploiting allelopathy in native species could improve restoration success and the re-establishment of natural successional dynamics. We review the evidence for allelopathy in agroforestry systems, and consider its relevance for reforestation. We then illustrate the potential for this approach with a case study of tropical forest restoration in Panama. C4 grasses heavily invade deforested areas in the Panama Canal watershed, especially Saccharum spontaneum L. We measured the effect of leaf litter from 17 potential restoration tree species on the growth of invasive C4 grasses. We found that leaf litter from legume trees had a greater inhibitory effect on performance of S. spontaneum than did litter from non-legume trees. However, allelopathic effects varied greatly among species within tree functional groups. Further evaluation of intra- and inter-specic interactions will help to improve our selection of restoration species.
Keywords Saccharum spontaneum Legumes
Novel weapons hypothesis Homeland security
hypothesis Allelopathy Forest restoration
Introduction
Anthropogenic disturbance of natural ecosystems is one of the biggest threats to biodiversity (Vitousek et al. 1994, 1997; Zhang and Fu 2009), and impacts are often exacerbated when disturbance facilitates invasion by exotic species (Mack et al. 2000).
J. A. Cummings (&) I. M....