Quercus rugosa seedling dynamics in relation to its re-introduction in a disturbed Mexican landscape

. In order to define the regeneration niche and then promote the re-introduction of Quercus rugosa into a disturbed area we studied seed predation, germination, seedling survival and growth of this species at three different sites: the forest interior, the forest border and a disturbed site, along a disturbance gradient. Acorn removal on the ground was high at the sites, with higher removal rates from 25-seed clusters than from 5- and 1-seed clusters. More seeds were removed at the forest border than at the other two sites, although in all cases some seeds remained in the soil for periods long enough for them to germinate and produce seedlings. Seed germination and seedling establishment were more successful and similar in the forest interior and the forest border, and much less successful at the disturbed site, due to acorn desiccation. Seedling survival was strongly affected by site, with the highest survival at the forest border and the lowest survival at the disturbed site after a year. The subsequent dry season, which was particularly harsh, caused a drop in survival both at the forest border and the disturbed site. In the former, a closer analysis revealed that partially shaded microsites enhanced survival, while in the latter overall survival was very low, with approximately 5 % of the seedlings surviving, compared to 50 % final survival at the other sites. There was a positive correlation between seed size and seedling survival at the forest border. The three size variables measured (seedling height, basal diameter and crown area) did not increase noticeably during the 20-month study period at the forest interior, while growth still occurred at the forest border and the disturbed site. However, during the two dry seasons there were large drops in mean seedling height and crown area at the disturbed site, due to more frequent dieback, causing large variation in seedling size. These results show that extensive re-introduction of this species to the disturbed area will probably fail under present conditions, and that careful selection or duplication of microsites that mimic the partial shade of the forest border is a sound method for improving oak establishment at this site.