Effect of herbivores and pathogens on the survival and growth of seedlingsin a fragment of the Chiloe rainforest, Chile

The physical conditions of the environment, the attack of pathogen microorg anisms, defoliating invertebrates and herbivores may affect the growth and survival of woody plant seedlings. Seedling growth, survival, proportion of damaged individuals by herbivores and pathogens, and the effect of these d amages on seedling growth and survival were evaluated in this work. Seedlin g mortality was greater during summer. Two thirds of all seedlings presente d some type of aggression when monitoring phase was over (11 months). Seedl ings with cotyledons presented greater proportion of healthy individuals. S eedlings without cotyledons presented greater proportion of damaged individ uals. The proportion of damaged individuals differed among species. Isolate d seedlings of Amomyrtus luma presented greater proportion of damaged indiv iduals. Isolated seedlings of Podocarpus nubigena presented same proportion of damaged and healthy individuals. Seedlings of Amomyrtus luma grouped wi th conspecifics presented greater proportion of healthy individuals than is olated seedlings of the same species. Seedlings of Podocarpus nubigena grou ped were all damaged. On the other hand, mean shoot growth during the monit oring phase approached 12 mm in 11 months. It was not affected by sanitary state of the seedling. 62% of the seedling survived 11 months. 72% of the s eedlings of Podocarpus nubigena survived the end of the monitoring phase, w hile 55% of the seedling of Amomyrtus luma survived. However, there are not significant differences in the seedling survival among species, between se edlings with and without cotyledons, and between healthy and damaged seedli ngs, to exception of the seedlings of Amomyrtus luma when they were not dis tinguished by age. In this last case survived a greater proportion of damag ed seedlings of Amomyrtus luma. Results in the context of known defense the ories in plants were discussed.