Produção de frutos e distribuição espacial de angiospermas com frutos zoocóricos em uma Floresta Ombrófila Mista no Rio Grande do Sul, Brasil

Abstract

We investigated, during 14 months, patterns of fruit production of animal dispersed angiosperms in a patch of Mixed Ombrophilous Forest (MOF) in the National Park of Aparados da Serra, State of Rio Grande do Sul, south Brazil. For a total of 570 individuals sampled in a 2.56 ha area we identified 27 species of animal dispersed angiosperms (13 families). The most abundant families were: Myrtaceae (eight species), Melastomataceae, Solanaceae, and Rubiaceae (three species each). Most sampled life forms were shrubs (46.0% of all individuals 37.0% of species total), followed by treelets (31.9% and 22.2%), herbs (10.2% and 18.5%), trees (8.7% and 18.5%), and epiphytes (3.2% and 3.7%). Red (22.2%) and orange (18.5%) fruits prevailed, as well as small fruits (70% of fruit total with size of 1-10 mm × 1-10 mm), and fruits with one to ten small seeds (96% of total species with seed size of 1-10 mm × 1-10 mm). The three species that produced the greatest amount of fruits were: Myrceugenia miersiana (Gardner) D. Legrand & Kausel (Myrtaceae) (tree – 61.0% of total production of fruits), and the melastomes Leandra variabilis Cogn. (shrub – 18.1%) and Miconia cinerascens Miq. (shrub – 8.6%). These species showed an aggregated dispersion pattern (Standardized Morisita index > 0.5 for all of them). The monthly number of fruiting species was significantly correlated with monthly temperature in the same month (rs in the previous month (rs = 0,70; p < 0,01), and with rainfall = 0,67; p < 0,02). The seed production of Araucaria angustifolia (Bertol.) Kuntze occurred during the period with the lowest number of angiosperm species producing animal-dispersed fruits. This non-overlapping between events might favor the occurrence of frugivorous animals, enabling a higher resource offer during the entire year.