A influência de uma espécie exótica invasora, Artocarpus heterophyllus Lam. (jaqueira), sobre uma comunidade de pequenos mamíferos e sua interferência na dinâmica de dispersão de sementes nativas

Abstract

Nowadays, it is known that damages caused by invasive exotic species are one of major causes of species extinction, most seriously affecting species that evolved on islands. The jackfruit, Artocarpus heterophyllus Lamarck (Moraceae) is originated from tropical forests of India, being the tree that produces the largest fruit. It was introduced in Brazil in the colonial period and is now invasive in several localities of the Atlantic Forest, including Ilha Grande, RJ. During three years, were sampled bimonthly in 18 grids, 10 with different densities of jackfruits trees and eight without jackfruit trees. In each grid were placed 11 traps for capture of mammals. The traps remained open for three consecutive days monthly. During this period was also checked a number of jackfruit trees in the grids and counted mature fruits of each tree. At the laboratory, the feces of all captured animals were analyzed to verify diet and amount of native seeds defecated. To verify species capable of preying and disperse jackfruit seeds, we conducted tests with jackfruit seeds tied to reels and camera traps. In this context, this study aimed to determine an influence of jackfruit tree in a community of small mammals and in seeds dispersal of native species. The results showed that A. heterophyllus influenced in an abundance of species of small mammals in Ilha Grande. In areas with high density of adult jackfruit trees, was a greater abundance of frugivorous species, such as Trinomys dimidiatus and Guerlinguetus ingrami, and decreased abundance of species as most insectivorous as Dasypus novemcintus, Oxymycterus dasytrichus and Monodelphis americana. Although jackfruit tree has not influenced in consumption items between animal and vegetable areas with and without jackfruit trees and during periods of greater and lesser fruitification, this species discouraging dispersal of native seeds. In areas with high density of jackfruit tree we found a smaller amount of native seeds being defecated by small mammals. The number of seeds defecated during the minor fruiting period of jackfruit trees was not significant, however, during the period of greater fruiting and in all periods summed were significant. In relation to frequency of feces containing native seeds, the results of simple regressions were significant for all periods and Didelphis aurita was the species that most influenced these results. The fruit of the jackfruit tree A. heterophyllus was more consumed by D. aurita, T. dimidiatus and Cuniculus paca, and D. aurita had no influence on predation and seed dispersal of jackfruit, having no record of possible predation or seed dispersal by camera traps. Rodents T. and C. dimidiatus paca were recorded by camera traps preying 20% and 16% of seeds of jackfruit and carried 65% and 44% seeds, respectively. Tests with reel showed that 86% of seeds were predated, 10% were left intact at site and only 4% were dispersed at short distances between 2 and 15 meters, it is possible that these rodents provide to spread of this exotic and invasive species into new areas.