Cambios en la diversidad funcional del sotobosque y la tasa de descomposición frente a diferentes intensidades de uso silvopastoril en el noroeste de la Patagonia, Argentina

Abstract

Functional diversity loss by human land-use changes is of great importance for achieving sustainable management, as it plays a key role in ecosystem functioning through a direct influence over ecological processes. In northwest Patagonian forests, livestock production is among the main activities affecting natural ecosystems. The aim of the study was to characterize changes in functional diversity of understory vegetation in sites with different silvopastoral use intensity, and the effects that these variations may have on rate of litter decomposition in mixed forests of cypress and coihue of southwest Rio Negro Province, Argentina. Changes in plant functional traits (life cycle, life style, architecture, habitat, leaf size, leaf texture and root system) were characterized, and the decomposition rate of each site's litter was quantified. Our results showed that both functional diversity index (FD Q ) and decomposition rate were higher under high silvopastoral use intensity, but the relationship was not significant. Results also showed that certain plant functional traits (i.e., rosette architecture, prostrate habitat and fern life form) have a significant effect on litter lost weight. Under high silvopastoral use intensity, the relative proportion of species with rosette architecture and prostrate habitat increases, which led to an increase in decomposition rate. This indicates that silvopastoral activity may modify the original community composition towards species with a rapid resource acquisition, altering also nutrient cycling. In this sense, ecosystem functioning seems to be influenced by certain functional traits, rather than functional diversity itself.