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

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. A recuperação de áreas florestais é importante para conservação e manutenção de ambientes desflorestados pela expansão agrícola. Uma alternativa de baixo custo para a restauração florestal é a utilização de poleiros secos artificiais para o recrutamento de sementes. O objetivo deste trabalho foi avaliar o efeito dos poleiros secos artificiais sobre a chuva de sementes de espécies arbóreas em uma pastagem abandonada junto a um fragmento de Floresta Estacional na sub-bacia do rio Ijuí (28°35’25”S, 54°08’09”W), em Jóia, Rio Grande do Sul, Brasil. A chuva de sementes sob os poleiros secos foi comparada com a observada sob a floresta remanescente. As aves potencialmente dispersoras foram identificadas. Foram utilizados coletores dispostos sob o remanescente florestal, sob os poleiros secos, e aleatoriamente na área de estudo como controle. As sementes foram coletadas mensalmente entre novembro de 2007 e maio de 2008. Foram coletadas 9.395 sementes distribuídas em 16 famílias na soma dos três tratamentos. Asteraceae e Poac8relativamente baixa de dispersão. As aves mais freqüentes nos poleiros pertencem à família Thraupinae e à subfamília Turdinae