摘要：Shrubs usually have a beneficial effect on herb species richness. In this study, the importance of shrubs/small trees on herb species richness and abundance in the Prepuna biogeographical region was evaluated at the patch (individual patches and all individual patches considered together, i.e., patch types), community (landscape) and regional levels. At individual patch level, a tendency towards more herb species in association with shrub undercanopies was found, although only in two of the four localities studied the differences were statistically significant. At patch type level, more species were found associated to the below shrub microhabitats in all four localities. The analyses conducted with rarefaction runs confirmed a greater species number beneath shrubs and showed the positive effect of the shrubs on species richness at community scale, although showing variations in magnitude in the different localities. The patterns found were consistent across the latitudinal gradient studied, indicating that, at least in certain years, the positive influence of shrubs on herbs is not only a local phenomenon. Moreover, as shrubs harbor different herb communities depending on locality, their positive effect seems to increase at regional scales. This study is the first reporting the beneficial role of shrubs on herb richness in the subtropical Andes.
