Relações solo-vegetação de fragmento florestal urbano na cidade de Cuiabá, Mato Grosso

Abstract

Urban forests are strategic tools for microclimate control and important mechanisms for biodiversity conservation. To expand the knowledge about these ecosystems, this study aimed to evaluate a remnant of native vegetation in the city of Cuiabá - MT, characterizing the adult and regenerating tree component, and its relationships with edaphic characteristics. The total area of the fragment is approximately 14 ha, which was stratified into “dry area” and “wet area”. A forest inventory was carried out by randomly distributing 25 plots of 20 x 20 m, inventorying trees with a diameter of 1.30 m from the ground (D1.30) > 5 cm. For regeneration, two subplots were installed within these plots, one measuring 5 m x 5 m for trees with D1.30 < 5 cm and height > 1 m, and another 2 x 2 m for trees with D1.30 < 5 cm and height < 1 m. In each plot, a composite sample of soil was carried out for the analysis of physical and chemical components in the laboratory. The Bootstrap richness estimator was used for the analysis of sample diversity and sufficiency. The calculation of the horizontal structure was performed, and the species were classified according to dispersion syndrome and ecological group. The Jaccard and Morisita indices were used to construct dendrograms of similarity by plot, and the indicator species index (IndVal) was calculated to obtain the characteristic species of the observed environments. Soil variables were subjected to Principal Component Analysis (PCA) to select the highly representative variables, and then a Canonical Correspondence Analysis (CCA) to verify the relationship of species with these variables. Altogether, 93 species were recorded in the adult stratum with H'= 3.45 and J'= 0.76 and 70 species in the regenerant with H'= 3.54 and J'= 0.83. The similarity dendrograms for the two evaluated indices demonstrated the clear existence of the two initially stratified environments (dry and humid areas), in both evaluated strata. The IndVal (%) indicated that the set of indicator species is different between the strata, indicating a replacement of species that are associated with the predominant ecological group (initial secondary) and the increase of zoochoric species in relation to anemochoric species in the regenerating stratum, allows to conclude that the fragment is in an intermediate stage of succession in progression. The PCA indicated that the plots located in the humid area had higher contents of Ca, Zn, Fe and pH, while the plots in the dry area did not present a clear distinction, varying in the contents of K, B and organic matter. In the CCA, a set of species that occurred exclusively in the wetland had a strong relationship with the variables analyzed. In summary, the studied fragment presents high habitat variability depending on the edaphic characteristics, which contributes to the development of distinct communities, and this reflected in a diverse ecosystem, which refers to its efficiency in the ecosystem services provided to society and should be object of conservation and research.