Clonal integration benefits invasive alien plants under water variability in a native community.
Aims: Many invasive alien plant species are clonal and can greatly propagate and spread through clonal integration (sharing resources between connected ramets) in heterogeneous and variable environments. Here, we tested whether water variability influences clonal integration of invasive alien plant species and consequently facilitates their growth and dominance in a native community. Method: We selected four typical invasive clonal plant species in China. Connected (with clonal integration) and disconnected (without clonal integration) clonal fragments were established either under constant watering or variable watering condition in an experimental native plant community consisting of three naturally co-occurring grassland species. Proximal part of the container received high nutrient and distal part received low nutrient. Important Findings: Clonal integration significantly increased biomass, aboveground mass and belowground mass of invasive alien plants in the proximal ramets, the distal ramets and the whole clone and decreased the growth of native community. Interestingly, clonal integration significantly increased the growth of invasive plants in variable watering. The positive effect of clonal integration was stronger in variable watering than in constant watering. Invasive plants with clonal integration had high biomass proportion (>0.6) in the whole community. Our results suggest that invasive clonal plants benefit more from clonal integration in variable water environments when established in a native community, and to some extent, clonal integration potentially contribute greatly to the invasiveness of alien clonal plants when they enter a new community with resource variability.