Frutificação, produção e predação de sementes de Carapa guianensis Aubl. (Meliaceae) na Amazônia oriental brasileira.

Abstract

This study was carried out in a production forest located at the municipality of Breu Branco, south east of Para State, Brazil. The objective was to better understand fructification and predation patterns of Carapa guianensis in order to recommend silvicultural practices for sustainable management of the species. In a 100 ha, the reproductive phenology of 563 trees with dbh  10 cm was monitored during 6 months. Fruit production was assessed using collectors below the crown of 50 trees and with periodical record every two weeks. Seed removal by terrestrial animals was also assessed below 10 trees. Among the 563 trees monitored, only 34.5 % bear fruits, suggesting therefore a very low fruit production. The proportion of trees with fruits increased significantly with dbh and 65% of the trees bearing fruits were 20-40 cm dbh. The smallest tree with fruits recorded was 11.7 cm in dbh. Dominant and co-dominant trees showed the highest percentages of fructification suggesting that crown position is an important factor. No significant difference in regards of the presence or absence of lianas was shown. The total fruit production was estimated to 18,118 seeds (93 seeds/tree), trees with dbh  40 cm being the most productive. The main predators observed in the crown were Araras which were responsible for 50% of the damaged seeds counted in the collectors. The insects and particularly the larva of the genus Hypsipyla sp were also important seed predators. In all, only 20% of the seeds escape from predation. On the soil, about 98% of the seeds dispatched along transects were removed by rodents, 50 % after 4 days. In regards to silviculture, considering that the most productive trees were more than 40 cm dbh, we suggest the liberation of individual belonging to the 20-30 cm dbh classes. Liana cutting is not apparently necessary.