CONICET | Buscador de Institutos y Recursos Humanos

Natural fodder and the secondary productivity derived from it are among the ecosystem provisioning services most valued by the inhabitants of the semi-arid Chaco region of Argentina. Under different land use regimes, plant communities and their associated ecosystem processes can vary considerably. These changes may be determined either by changes in the identity of the dominant species, or by changes in their relative abundances. Under the mass ratio theory (Grime, 1998) it is expected that those communities dominated by plant species of a higher quality for herbivores, as reflected by plant attributes positively related to consumption rates, would result in higher-quality fodder. Considering this, we aimed to analyze changes in the community weighted means for a number of traits related to species potential for trophic transfer to herbivores. We sampled vascular plant communities corresponding to three different land use types: Secondary Forest, Closed Shrubland and Open Shrubland). We measured the relative abundances of the ten dominant species, and analyzed five leaf traits: Specific Leaf Area (SLA), Leaf Dry Matter Content (LDMC), Leaf Toughness (LT), Leaf Nitrogen (LNC) and Phosphorus Content (LPC). Based on the relative abundances and attributes of the dominant plant species, we obtained the Community Weighted Mean (CWM) for each trait, under each land use type. Open shrublands showed a significantly lower leaf phosphorus content CWM than secondary forests and closed shrublands, higher LDMC CWM than Secondary Forests, and a lower value of SLA CWM than Closed Shrublands. We found no significant difference in leaf toughness or leaf nitrogen content CWMs. Therefore open shrublands are inferior than secondary forests or closed shrublands in terms of forage quality.