Functional indicators to explain the anthropic effects on community plant composition changes: The case of a temperate forest in Mexico

Abstract

Abstract In plant communities, changes in composition driven by the dominance of weed species have been used as ecological indicators to predict the anthropic impacts on these species. Nevertheless, anthropic disturbances do not act directly on species composition, but their effects depend on the species' functional responses. Hence, anthropic effects follow a logical sequence, in which disturbances act at different levels. In order to understand the sequence of the changes in the community there is a need to develop functional and compositional integrated indicators. In order to integrate them we suggest a method based on inference by abduction, to reduce the complexity in predicting the anthropic effects on species functional responses. With this method we develop functional indicators of responses to anthropic disturbances and the effect on composition changes. The method involves building structural equation models (SEMs), through which we evaluate the anthropic and environmental effects on the functional response of species and composition changes in an integral way. From these causal paths, we select the best-fitting model with plausible functional indicators to explain the anthropic effects, according to Akaike’s information criterion (AIC). This research develops a methodological proposal to build up functional indicators with foliar attributes associated to resource acquisition and use strategies of herb and shrub species in the temperate Abies religiosa forest in the Magdalena river basin in Mexico City. The built indicators demonstrate for the first time and in a simultaneous way, that characteristic species (original component) and native weeds (component established under perturbation conditions) have different responses to anthropic perturbations as well as different contributions to community composition changes. This result represents a methodological contribution in the evaluation of anthropic impacts and the use of native weed species as functional indicators.