Ecohydrology is an emerging discipline which has become increasingly important in the context of global climate change. Invasive ecology has similarly experienced an explosion of recent studies. We examine the interface between these two current fields, comparing water use of several hundred native vs. alien species pairs from over 60 studies worldwide. Previous ecohydrology reviews have investigated landscape-scale water yield of paired-watershed systems, or compared water use of woody vs. non-woody plant forms. Our review complements these types of studies by presenting the first in-depth meta-analysis which examines water use of alien and native plants of the same life form at multiple scales: leaf level, plant level, and landscape level. We have re-analyzed all paired data to glean global trends, and to highlight how patterns vary depending on scale and field methodology.

Results/Conclusions

We found a consistent and strong pattern of greater stomatal conductance for alien species than native species, but this pattern did not translate into greater whole-plant water use rates. At the landscape scale, alien species showed higher transpiration rates per unit ground area, but total evapo-transpiration was no different between aliens and natives. The data show a need for detailed understanding of processes at a range of scales, and for inter-disciplinary research combining ecology, hydrology and invasion biology. The amount of available data decreases from the many studies at leaf level to very few studies at landscape level, indicating a critical the need for large-scale measurements of the water use of alien vs. native plants.