Floristic composition and dispersal syndrome: How can environmental factors affect the Cracidae refuge in a secondary Atlantic Forest fragment?

Abstract

The Atlantic Forest is a threatened biodiversity hotspot. Anthropogenic and environmental factors affect this biodiversity, including floristics and, consequently, the seed dispersal syndrome. The objective was to evaluate the influence of environmental factors on floristic composition, seed dispersal syndrome and potential for wild fauna refuge, especially birds of the Cracidae family, in a Private Reserve of Natural Heritage (RPPN) in the Atlantic Forest. The study was carried out in a forest fragment of 631 ha in the RPPN Fazenda Macedônia in Ipaba, Minas Gerais, Brazil. Twenty-three plots (10 × 50 m) were inventoried at three sampling levels with the plots being selectively distributed, considering the different geoenvironments. Environmental factors were divided into edaphic (soil chemical and physical) and landscape (altitude, slope, terrain exposure and edge distance) variables. Species composition and plot groupings by smallest dissimilarity were calculated. The dispersal syndrome and the type of zoochoric dispersal were determined for tree species. The species dispersed by birds had records of occurrence in the verified cracid diet. Two hundred and forty-nine species from 138 genera and 46 tree families were recorded. The dissimilarity between plots ranged from 0.4 to 1.0 forming four groups. Floristic composition was influenced by soil variables (soil pH, available potassium and magnesium, exchangeable aluminum, effective and potential CEC, remaining phosphorus, organic matter and silt) and landscape (altitude). The zoochoric dispersal syndrome was the most frequent, with ornithochory (68.09%) being the most important within this group. In the RRPN, 35 species of tree were recorded in the cracids diet. Tree species composition of varied with edaphic variables and with altitude. The wide distribution of species recorded in cracid diets reaffirms the fragment's potential for the establishment and conservation of these birds, highlighting the importance of creating and protecting private conservation areas, such as the RPPN Fazenda Macedônia.