Are abandoned grasslands within forest plantations effective for the conservation of grassland birds?

Abstract

The decline and fragmentation of grasslands in recent years have stimulated efforts to preserve this ecosystem. However, even legally protected remnant grasslands are threatened by changes in the structure and composition of vegetation, which compromise their ecological functions. Shrub encroachment in grasslands is a global concern because it can reduce the occurrence of grassland birds. We evaluated the effectiveness of abandoned grassland areas under legal protection for the conservation of grassland avifauna, because the exclusion of disturbances, such as grazing and fire, favor the advancement of woody vegetation over grasslands. Birds were sampled during two periods in abandoned grasslands within farms of eucalyptus plantations. Significant differences in bird species composition were found between the two sampling periods as was a significant increase in species richness associated with shrubs and forests. There was no significant reduction in the number of grassland bird species between periods. Nineteen of the recorded species were recorded only in the second sampling period, of which only two are associated with grasslands. The results indicate that changes in vegetation mainly affect grassland specialist species and can lead to their local extinction in the long term. Furthermore, the studied grassland areas have, thus far, been effective for the conservation of birds. However, the results also demonstrate that the implementation of activities to manage woody vegetation can be a promising alternative for improving these areas for grassland birds over the medium and long term because shrub encroachment in these areas is evident.

Keywords

• avifauna
• brazilian pampa grasslands
• conservation
• shrub encroachment
• vegetation structure