Dry artificial perches and the seed rain in a subtropical riparian forest

Abstract

The recovering of forest areas is important for the conservation and maintenance of environments deforested by the agriculture expansion. A low cost alternative of forest restoration is the use of dry artificial perches to increase and qualify the seed rain. The present work aimed at evaluating the effect of the dry artificial perches on the seed rain in an abandoned pasture next to a Seasonal Subtropical Forest remnant in the Ijuí river sub-basin (28°35’25”S, 54°08’09”W), Jóia, Rio Grande do Sul State, Brazil. The seed rain under the dry perches was compared to the seed rain under the forest remnant. The identification of the potentially disperser birds was also carried out. The seed traps were disposed under the forest remnant, under the dry perches and at random in the open area as a control, and the seeds were collected monthly between November 2007 and May 2008. It has been collected 9,395 seeds, distributed in 16 Families. Asteraceae and Poaceae summed 5,990 seeds. The tree species reached the amount of 2,177 (22.6%) pertaining to 15 species. Such value represents 0.76 seeds·m-2·day-1 to the tree species. Under the forest remnant, the seed rain intensity of all tree species and of the zoochoric tree species were 2.59 and 0.40 seeds·m-2·day-1, respectively. In the seed traps under the perches the seed rain intensity was 0.29 seeds·m-2·day-1, and more than 99% of them were of zoochoric tree species. The only one anemochoric species observed in the seed traps of the pasture was Helietta apiculata Bentham, which presented only two seeds in the traps of pasture, indicating a low efficiency of dispersion. The birds observed in the perches pertaining to Thraupinae and Turdinae.