Aspectos florísticos e ecológicos de fragmentos florestais urbanos em Cuiabá - Mato Grosso

Abstract

The urban forest fragments protect part of the biodiversity of their original matrix serving as a refuge for fauna and help to regulate the temperature of the region where they are located. However these environments suffer direct or indirect anthropogenic pressures. Therefore, the goal of this study was to evaluate the floristic composition and ecology of three areas with urban forest fragments in the Administrative Political Center of Cuiabá - Mato Grosso, Brazil, which are in a transition area between forested savannah and semideciduous seasonal forest phytophysiognomies. In areas 1 and 2, 50 sampling units of 400 m2, from these 25 plots were installed in each of them, while in area 3 a census was carried out with information on DAP and total height of all arboreal individuals with diameter ≥ 5 cm being collected. Their floristic compositions, phytosociology, diameter distributions and total heights were evaluated. In addition to these, the ecological classification of species was carried out through the ecological group, dispersion syndrome, extinction risk and natural occurrence. Among the 5,170 individuals sampled in the three fragments, 93, 96 and 98 species were identified in areas 1, 2 and 3, respectively. From these, four species are exotic, two of which are cultivated (Mangifera indica and Spondias purpurea) and two have invasive potential (Albizia lebbeck and a Leucaena leucocephala). Area 2 was considered the most diverse by the diversity profile and the lowest evenness was found in area 3. 19 unique species were identified in the first fragment, 23 species in the second and 27 species in the third, while 57 species are shared between the three areas, which the Protium heptaphyllum stands out with large populations in all areas. The negative exponential shape and normal distribution patterns identified for the diameter and total height distributions, respectively, are characteristic of uneven forests. The initial secondary species were the most representative, representing 48.39%, 53.12%, and 47.96% of the species present in areas 1, 2 and 3, in the same order. Zoochoric was the dispersion syndrome identified for most species in all areas with 49, 52 and 47 species, respectively. As for the risk of extinction, it was found that most species are included in the unassessed category, however the species Cedrela fissilis and Swietenia macrophylla belong to the vulnerable category. The ecological and structural characteristics of the three forest fragments indicate that they are all in an intermediate stage of ecological succession, moving towards dynamic equilibrium.