Introduced harmful species have become one of the major threats to biodiversity and ecosystem function. Despite their impacts, management of invasive species is often ineffective or only temporally successful. However, by considering invasion from the perspective of the affected community, i.e. its impact, we can address invasion in a proactive, rather than reactive, manner. In particular, assessing how abiotic conditions and native community biotic resistance interact could provide an effectual framework for assessing resilience (i.e., resistance and recovery) to biological invasions. This would shift the focus from specific invasive species management to the management of the native community. This approach would likely improve the effectiveness of management since we cannot forecast what the next invasive agent will be, but we can predict a site’s vulnerability to invasions and then manage accordingly.
To identify the abiotic conditions and biotic factors that would determine resilience to the invasion in forest ecosystems we carried out a systematic review of the literature, i.e., a meta-analysis. We focused our search on invasions by shrub species. Observational and experimental data were included, however reviews and species distribution modeling were not.
Results/Conclusions
We reviewed 1,154 abstracts, from which we selected 25 articles for the analysis after screening for relevance. Rainforests, deciduous temperate forests, montane forests, secondary forests, and forests embedded into urban landscapes were the forest types most frequently studied. Results from this search show that although the effects were mixed, forests with closed canopies, fewer disturbances, and low nutrient availability, e.g. N and P, were more resilient to biological invasion. At the landscape level, distance from potential sources, e.g. cities, played an important role in influencing forest invasion by shrubs. These results suggest that management should focus on strategies that reduce forest canopy loss and limit the levels of nutrient input in their forests.