Present Address: US Geological Survey, Southwest Biological Science Center, Northern Arizona University, 2255 N, Gemini Drive, Flagstaff, AZ 86001, USA.
REVIEW AND SYNTHESIS
Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis
Article first published online: 18 MAY 2011
© 2011 Blackwell Publishing Ltd/CNRS and State Government of NSW
Volume 14, Issue 7, pages 709–722, July 2011
How to Cite
Eldridge, D. J., Bowker, M. A., Maestre, F. T., Roger, E., Reynolds, J. F. and Whitford, W. G. (2011), Impacts of shrub encroachment on ecosystem structure and functioning: towards a global synthesis. Ecology Letters, 14: 709–722. doi: 10.1111/j.1461-0248.2011.01630.x
- Issue published online: 16 JUN 2011
- Article first published online: 18 MAY 2011
- Editor, John Arnone Manuscript received 25 February 2011 First decision made 28 March 2011 Manuscript accepted 19 April 2011
- ecosystem processes;
Ecology Letters (2011) 14: 709–722
Encroachment of woody plants into grasslands has generated considerable interest among ecologists. Syntheses of encroachment effects on ecosystem processes have been limited in extent and confined largely to pastoral land uses or particular geographical regions. We used univariate analyses, meta-analysis and structural equation modelling to test the propositions that (1) shrub encroachment does not necessarily lead to declines in ecosystem functions and (2) shrub traits influence the functional outcome of encroachment. Analyses of 43 ecosystem attributes from 244 case studies worldwide showed that some attributes consistently increased with encroachment (e.g. soil C, N), and others declined (e.g. grass cover, pH), but most exhibited variable responses. Traits of shrubs were associated with significant, though weak, structural and functional outcomes of encroachment. Our review revealed that encroachment had mixed effects on ecosystem structure and functioning at global scales, and that shrub traits influence the functional outcome of encroachment. Thus, a simple designation of encroachment as a process leading to functionally, structurally or contextually degraded ecosystems is not supported by a critical analysis of existing literature. Our results highlight that the commonly established link between shrub encroachment and degradation is not universal.