Global patterns of rainfall partitioning by invasive woody plants

Aim: Invasive species have the potential to alter hydrological processes by changing the local water balance. However, general patterns of how rainfall is partitioned into interception, throughfall and stemflow for invasive species worldwide have been seldom explored. We (a) describe the percentage of interception, throughfall and stemflow for the invasive woody plant species; (b) analyse the influence of morphological attributes (i.e., life-form, bark roughness, leaf type, leaf phenology and leaf area index) of invasive species on rainfall partitioning; and (c)  compare the rainfall partitioning fluxes for co-occurring invasive and native species, testing whether these fluxes variation depends on water availability of the study location.

Location: Global.

Time period: Present.

Major taxa studied: Plants.

Methods: We compiled data of 100 studies that assessed rainfall partitioning by invasive species (N=67) and registered their morphological attributes. By means of a meta-analysis we compared the rainfall partitioning by native and invasive species (N=47 comparisons) and assessed how their fluxes were affected by water availability.

Results: Interception, throughfall and stemflow ranged from 1.6 - 59.5%, 39.1 - 92.7% and 0.1 - 31.6% of total rainfall, respectively. The bark roughness and leaf type were the most important attributes driving rainfall partitioning fluxes. While rough-barked species constrain rainfall inputs by promoting higher losses due to interception, smooth-barked species with broadleaves enhance the amount of rainwater reaching the soil by maximizing stemflow. For pair-wise comparisons, invasive species have higher stemflow values than native species for both drylands and humid areas, and higher throughfall in drylands, but less in humid areas.

Main conclusions: Our findings suggest that specific morphological attributes of invasive species determine higher localized water inputs, which may represent an ecohydrological advantage, particularly in water-limited ecosystems. These insights also suggest that the ecological role of stemflow, throughfall and interception should be considered in future plant invasions research.