Ten-year study of vegetation dynamics in wetlands subject to human disturbance in Western Mexico

Abstract

Sustained human disturbances cause trajectory shifts in wetland plant communities and allow invasive species to colonize. Understanding long term impacts of these disturbances is necessary for better management practices and environmental restoration. In this study we evaluated species composition in a fen type wetland for 10 consecutive years subjected to intentional fires and cattle grazing. We found that fires alter spatial distribution and relative abundance of wetland species but, at least in this wetland, no species loss was recorded for the 10-year period. We did document an increment over time in the proportion of facultative hydrophytes and a decrease in the number of obligate species. Cattle browsing damaged wetland plants, but its removal allows the introduced species Festuca arundinacea to dominate areas formerly occupied by Schoenoplectus americanus . These results show the interplay of disturbances and how elimination of a single disturbance can degrade the plant community. The changing trends suggest that current species composition might not revert naturally and that active management for restoration is needed.