Assessment of river geomorphology and anthropogenic interventions promoting the invasion of Salix spp. in riparian habitats of South America
摘要
River managers have commonly implemented practices to manage river fluvial dynamics to reduce flood risk, control erosion, and manage sediments. However, the potential promotion of invasive plants associated with these practices is frequently overlooked. Determining what factors, human interventions or the river morphology, relate to plant invasion could inform plans to reduce invasion along waterways. Our goal was to evaluate the association between Salix spp. and river geomorphology and anthropogenic interventions that may be promoting its establishment at a whole watershed. Using data from 213 riparian sites in the Toltén Watershed (~ 8,000 km2) in Chile, we compared the composition of woody species between sites with and without Salix spp. Then, we assessed the relationship between Salix spp. and eight river geomorphology and anthropogenic variables. We applied a backward-forward selection approach using Akaike’s information criterion to select the best model. Then, we created a predictive map of the presence of Salix spp. We found Salix spp. in 87 sites (41%), and that the average species richness was higher in sites without Salix spp. (6.53 ± 3.59 and 5.79 ± 4.08, without and with Salix spp. for 0.15 ha plots). The best model showed that channel width, gravel extraction, riprap and forest amount were the best variables explaining Salix spp. presence. Our predictive map was better predicting absences (88.4% sensitivity), with a Kappa coefficient of 48%. Our results suggest that human interventions could promote the presence of Salix spp. and that preventive and mitigation strategies during interventions should be part of management protocols.