Dispersal moderates recovery of aquatic plant species richness following drought disturbance
Natural disturbances play an important role in altering and maintaining patterns of species richness. However, the frequency and intensity of these disturbances is expected to increase with climate change, likely increasing species loss across ecosystems. Disturbances can have a stochastic or deterministic effect on ecological communities, which result in different changes in species composition and species richness at local and regional scales. I examined the effect of a natural drought disturbance on species richness in aquatic plant communities, and I used a null modeling approach to analyze the relative stochastic or deterministic effect of drought on aquatic plant species richness. I also investigated whether varying amounts or timing of dispersal influences the recovery of aquatic plant communities following the natural drought disturbance.
I found that local species richness decreased in response to drought, and there was a loss of some species from the entire experiment. Species composition was also affected by drought, with aquatic plant communities becoming more similar to one another after the drought. The overall effect of drought on plant species in this experiment was highly selective as regional species richness was lower than expected by chance, implying that species were lost as a result of deterministic processes. Increasing species dispersal after the drought disturbance promoted the recovery of species richness. Local species richness in all dispersal treatments recovered to their pre drought conditions, suggesting that even low amounts of species dispersal can facilitate the recovery of species richness in aquatic plant communities.