Ecological Indicators (Oct 2021)
The use of phytosociology to evaluate the efficiency of headwater preservation areas in the Andreas Stream Hydrographic Basin, RS, Brazil
Abstract
Research conducted on an area of the deciduous seasonal forest at 20 sampling sites (headwaters and riparian areas), belonging to Project “Water Guardian” in the Andreas Stream Hydrographic Basin, RS, Brazil, and established the Payment for Environmental Services (PES). The research aimed at determing the floristic groups that characterize the study area, quantifying the species phytosociological parameters and their relationship with the studied areas. At each sampling site, we allocated a 10 × 10 m permanent sampling units (plots) and counting individuals until the species/plots curve stabilization. All forest individuals with a circumference ≥ 15 cm at 1.40 m above the ground level were inventoried. Statistical differences established using the nonparametric Kruskall-Wallis statistical test, followed by the Mann-Whitney paired comparisons test for multiple comparisons (α = 5%). Aiming at grouping the species according to their Importance Value Index (IVI) similarities, we applied the cluster analysis based on Ward's method. The results indicated 170 significative plots, which sampled 3,774 individuals distributed in 101 species, including 84 genera and 36 families. Three ecological groups detected, being group 1 (G-1) characterized by presenting the highest mean (±standard deviation) value of IVI equal to 4.5 ± 1.9%, and showing significant differences when compared to the other groups (p < 0.05), highlighting Nectandra megapotamica (Spreng.) Mez as the most important species (IVI = 7.5 ± 3.8%). Thus, the plant species belonging to G-1 are directly associated with dispersing agent, which corresponds exclusively to animals, being the main food sources for the vast majority of avifauna and mastofauna in the region, contributing to its rapid dispersal, apart of being plants of fast growth, characterizing the forest physiognomy of the study region. Chemical, physical and microbiological monitoring of water quality prior to the implementation of PES, compared with recent studies carried out in these headwaters, demonstrated the efficiency of PES for improving water quality, considering that the headwaters in the Andreas Basin showed increasing water quality levels up to 73%, characterized as ”waters of good quality“. These results highlight PES as an important environment public policy tool for sustainable development.
