Composição florístico-estrutural na avaliação de florestas ripárias urbanas

Abstract

Riparian forests are ecosystems that are crucial for the protection of water resources and the maintenance of biodiversity, although they are often degraded by unplanned urban growth. Given this, the objective of the study was to evaluate the floristic composition and horizontal structure of tree communities subjected to varying degrees of anthropogenic influence in small (S - Ipameri) and medium-sized (M - Caldas Novas) cities, comparing them with protected areas (P) located in rural areas. Data collection was conducted in 59 plots of 400 m² (20x20 m) distributed across urban streams and legal reserves. Phytosociological parameters such as density, basal area, aboveground biomass, and carbon stock were estimated. Diversity was measured using the Shannon and Simpson indices, and richness using the Chao 1 estimator. To compare the areas (P, M, and S), the Kruskal-Wallis test with Dunn’s post-hoc test was used. Floristic and structural similarity was assessed using the Jaccard and Morisita-Horn indices, supplemented by multivariate analyses, PERMANOVA, PCoA, and Indicator Species Analysis (IndVal). A total of 199 species were sampled. Protected forests (P) exhibited significantly higher values for all structural parameters: average species richness of 19 species per plot, density of 1,138.3 individuals/ha, and carbon stock of 36.8 t/ha. In contrast, the urban areas M and S showed reduced richness values and were similar to each other, with carbon stocks of 15.5 t/ha and 17.1 t/ha, respectively. The floristic composition revealed that the ETEPs maintain native species typical of riparian forests, such as Tapirira guianensis and Licania apetala, whereas urban areas are dominated by exotic species, including Leucaena leucocephala and Mangifera indica. Multivariate floristic and structural analyses showed greater similarity among forests in the urban zone, and PERMANOVA indicated no significant differences among these plots. Only four species (three of them exotic) were identified as indicators of riparian forests in the urban zone. The results demonstrate that urbanization promotes biotic homogenization, and the studied urban fragments can be characterized as novel ecosystems, marked by new species combinations and structurally simpler communities with lower levels of species richness and biomass.