CONICET | Buscador de Institutos y Recursos Humanos

Exotic species can have a strong influence on ecosystem processes, especially when exotic invaders differfrom natives in key morpho-functional features. We explored whether exotic species, especially thoseforming monospecific patches in Chaco montane woodlands, differ from natives in leaf attributes anddecomposability. We then evaluated how exotic monospecific patches in that region alter litterdecomposability, by weighting leaf trait values and decomposability by species abundance in the communities.In general, native and exotic species from Córdoba Chaco montane woodlands did not differ inleaf attributes (specific leaf area, leaf toughness, and leaf water content), or decomposability. Because ofsimilar trait values and decomposability, we expected to find no differences in litter decomposabilitybetween plots dominated by exotic species and those of Native woodland. However, individual speciesdecomposability weighted by species abundance in the communities showed that litter from exoticmonospecific plots had slower decomposition than native ones. This pattern was confirmed by thehigher decomposability and higher quality of the naturally mixed litter collected from native plots,compared to those collected from exotic plots. Despite the general similarities between most native andexotic species inhabiting Chaco montane woodlands, the overwhelming dominance of some exotic invadersin monospecific stands (and the consequent weight of their attributes on the litter each woodlandproduces) might be driving differences in decomposition patterns between woodland types. Our resultsindicate that when estimating the impact of exotic species on ecosystem processes, we should includetheir relative abundance in the community, as well as the relevance of the traits influencing thoseprocesses. Otherwise, we may draw erroneous conclusions.