Determinants of the abundance of invasive annual weeds: community structure and non-equilibrium dynamics

Freckleton, R. P., Watkinson, A. R., Dowling, P. M. and Leys, A. R. (2000) Determinants of the abundance of invasive annual weeds: community structure and non-equilibrium dynamics. Proceedings of the Royal Society B: Biological Sciences, 267 (1448). pp. 1153-1161. ISSN 0962-8452

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The dynamics of an annual pasture community are described from a five–year experimental and monitoring study. The community was dominated by two grasses (Lolium rigidum and Vulpia bromoides) and a legume (Trifolium subterraneum). Fits of population dynamic models to per capita rates of population change indicate that interactions between the grasses were generally strong, while interactions between the grasses and legumes were weaker. Most, but not all, of the net effects of competition on population growth could be attributed to interactions occurring during plant growth. Phase–plane analysis indicated that, for a constant environment, a joint equilibrium of the two grasses is unstable since interspecific competition between Lolium and Vulpia is stronger than intraspecific competition. Consequently, the community will tend to a mixture of only one or other of the grass species and T. subterraneum, depending on the founding composition of the pasture. Analysis of data taken from a year in which a drought occurred (1993–1994) demonstrated profound effects on all three species. Modelling of the long–term impacts of the effects of repeated droughts showed that disturbance of this form overrides the founder effect observed under constant conditions. Consequently, Vulpia is ultimately able to invade any mixture of the other species in environments where stochastic disturbances occur.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
Faculty of Science > Research Groups > Collaborative Centre for Sustainable Use of the Seas
Depositing User: Rachel Snow
Date Deposited: 07 Apr 2011 10:32
Last Modified: 25 May 2023 13:32
DOI: 10.1098/rspb.2000.1122

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