TREE SPECIES DIRECT SOWING FOR FOREST RESTORATION

Abstract

The direct sowing to tropical forest restoration can be viable when the ecological and silvicultural aspects of species are known. This work evaluated the effect of breaking seed dormancy and a physical protector on the initial growth of riparian tree species. The experiment was carried out in a randomized blocks design, in a factorial (2x2), with four blocks and four plots for each treatment. The treatment to break seed dormancy used were: immersion in sulphuric acid for 20 minutes and washing in water for 1 hour plus soaking for 24 hours for Trema micrantha; immersion in boiling water (100oC) with following soaking until refreshing for 24 hours to Senna multijuga and Senna macranthera and pre-soaking in water for 2 hours for Solanum granuloso-leprosum. The physical protector used was a transparent plastic cup (500mL). The breaking seed dormancy used was efficient in laboratory, except for S. macranthera. In field conditions, it was efficient only for S. multijuga and S. macranthera. The physical protector did not presented any benefit for the studied tree species regarding seedlings emergence and survival, but it provided significant differences in height and base diameter for S. multijuga and in height for S. macranthera after three months. After 24 months, T. micrantha presented the highest values for height and basal diameter. S. macranthera presented the height relative growth and T. micrantha the highest basal diameter. The studied species can be recommended for ecological forest restoration, using direct sowing.