Efeitos de fragmentação florestal na guilda de borboletas frugivoras do Planalto Atlantico Paulista

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Fragmentation effects on frugivorous butterflies (Nymphalidae) and the ecological indicator status of the members of this guild were evaluated comparing continuous forest sites (Morro Grande State Reserve, Cotia, SP) and nearby fragments. In 36,000 trap-hours of sampling, 70 species of six Nymphalidae subfamilies were captured, summing 1,810 individuals (661 of 54 species in the reserve and 1,149 of 64 species in the fragments, with 48 species in common). Unlike most butterfly population studies, the sex ratio observed for most of the species was not male-biased. Recapture rate was moderate (less then 30%) in both landscapes. Different temporal distribution patterns were found for the most abundant families, possibly related to three main factors: voltinism, larval resource availability, and predator/parasitoid abundance. The null hypothesis of distributional homogeneity between the two landscapes was accepted in 21 of the 35 species with eight or more individuals recorded; four were more abundant in the reserve and 10 in the fragments. In the species that had significant differences in distribution, all Brassolinae were more abundant in the reserve, and all Biblidinae and Charaxinae in the fragments. The species-abundance distributions fitted both logseries and lognormal models for the total fauna of reserve and fragments and for each sampling unit independent1y except for reserve ? D, that did not fit the logseries model. Species accumulation curves did not reach asymptotes in any sampling unit, suggesting that communities were not totally sampled. Faunistic similarity between landscapes was high, both quantitative (90%) and qualitatively (81 %). Despite this high similarity, c1uster analysis separated reserve and fragment sampling units into different c1usters, indicating forest fragmentation effects on the community composition of frugivorous butterflies. In this study, Satyrinae did not respond to forest fragmentation, being equally distributed in both landscapes. This subfamily also did not show correlation with any environmental variable, even those that could indirect1y indicate some kind of disturbance. Larger butterflies like Brassolinae may be more sensitive to environment variation due to the fragmentation process, directly indicating effects on the landscape and indirect1y the effects on vegetation variables. The subfamilies Biblidinae, Charaxinae and their components were c1early favored by forest fragmentation, correlating with variables that responded positively to fragmentation, and showing preferential occurrence in the fragmented landscape. Frugivorous butterfly species richness was positively correlated with tree species richness, a variable that did not differ between landscapes, suggesting that this butterfly guild may act as a biodiversity indicator. Thus, fragmentation effects are present in the study area, and these effects are reflected in different ways at different scales (sampling unit versus landscape, specie versus subfamily, and populations versus guilds). These results can guide future works in both population biology and community ecology, and may be adopted as guidelines for a protocol on frugivorous butterfly inventory in the Atlantic Forests, to measure the conservation condition of forest habitats

ASSUNTO(S)

mata atlantica borboleta diversidade indicadores (biologia)

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