Thursday, 17 November 2011

A meta-analysis of the impacts of alien plants

Our latest review is of a meta-analysis that examines a wide range of studies from across the globe (including invasive animals, as well as plants) to try and identify some general impacts invasive species have on species, communities and ecosystems.

Vilà, M., Espinar, J. L., Hejda, M., Hulme, P. E., Jarošík, V., Maron, J. L., Pergl, J., Schaffner, U., Sun, Y. and Pyšek, P. (2011), Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems. Ecology Letters, 14: 702–708. doi: 10.1111/j.1461-0248.2011.01628.x

Our Review: Parry H, Lonsdale M: 2011.

This comprehensive meta-analysis of over 500 articles illuminates some key future research directions for the ecology of alien plant introductions. The authors draw some conclusions on the general relative impacts of alien plants on ecosystems. These impacts range from species, through community, up to ecosystem-level, including changes in nutrient levels and cycling.

Over the last ten years, since Parker et al. published a review that sought to understand the general impacts of invaders on ecosystems [1], there has been an explosion of literature on this subject. This article provides a well executed and timely summary of a wide range of studies, drawing some conclusions on the relative general ecosystem impacts of both non-native plants and animals. These conclusions primarily indicate important directions for future research in plant invasions. This includes a need to: (a) investigate further 'island' effects and the importance of scale in measuring impact; (b) consider sampling effects when exploring relationships between the impacts of alien species on native plant diversity and production; and (c) explore more thoroughly the direct and indirect ecosystem impacts of alien species.

Despite equal effort in surveying the literature on animal species and communities, one shortcoming is that this study doesn’t conclude similar future directions for animal research. Some interesting perspectives on the bias in the literature are also gained by such a study. Here, we see that there is a bias in plant research towards trees and shrubs, as well as to certain regions such as Australia. We cannot draw on a long history of research in this area as the studies are nearly all from the last ten years.

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