Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

Caldeira, M. C., Lecomte, X., David, T. S., Pinto, J. G., Bugalho, M. N., & Werner, C. (2015). Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates. Scientific reports, 5, 15110. PDF.

Summary

Climate change is expected to bring more extreme drought events. In arid systems, these events may be particularly pronounced if high water use native or invasive species are present. However, the combined impacts of drought events and invasive species on ecosystem services and resilience is not well understood. High water use invasives can impact ecosystems though direct precipitation interception, and indirectly through water loss from transpiration, and these effects can be even more pronounced during drought times. In this study, the authors examine the impacts of an invasive native shrub Cistus ladanifer on a native Spanish Mediterranean cork oak trees (Quercus suber L.) ecosystem using a shrub removal experiment during two drought years. They found that trees in the invaded plots lost resilience in the wet year following drought. Their results suggest that invasive plants may push native plants past their critical thresholds for drought tolerance, and result in higher tree mortality during drought events. 

Take home points

• High water use species may exacerbate the impacts of drought on native species.

• Some native shrubs may exhibit invasive tendencies under climate change, particularly if they are tolerant of climate extremes

Management implications

• Synergistic impacts of invasives and climate change will be important in determining management and mitigation strategies. 

• Mechanical removal of invasive, high water use species may alleviate drought stress.

Keywords

Climate Extremes; Impact Study; Experiment; Invasive Plant; Terrestrial Habitat; Cistus ladanifer; Gum Rockrose