Influência de microbacias hidrográficas na estrutura, diversidade e composição florística de uma floresta ombrófila densa na Serra da Mantiqueira

Abstract

The National Water Resources Policy proposes the hydrographic basin as the strategic geomorphological unit for landscape management. The State Park of Serra do Papagaio (SPSP), have hydrographic microbasins (MB) of various sizes and orders of magnitude covered by Ombrophylous Dense Upper Mountain Forest (ODUMF). The objectives of this study were to inventory, analyze and compare the floristic composition and tree community structure in five MBs in ODUMF of SPSP. Five permanent plots of 20 x 20 m per MB were allocated and the trees with a diameter of 1.30 m of soil ≥ 5 cm, the slope of the land and the opening of the canopy were measured. The area and order of drainage were obtained in the Google Earth Pro program and contours (1: 25.000). Environmental and structural variables were tested by the Shapiro-Wilk test and the differences between MBs by ANOVA and Tukey's test. Diversity and equability were verified using the indices of Shannon-Weaver (H ') and Pielou (J') respectively. The H 'values of the MBs were compared by Hutcheson's t-test. The species richness by MB was verified by rarefaction, ordering the differences and similarities of Bray-Curtis and Jaccard by nonmetric multidimensional scaling (NMDS) and similarity analysis (ANOSIM). There were 31 families, 54 genera and 79 species, represented by 2.172 individuals. The richest families were Myrtaceae (11), Melastomataceae (8), Lauraceae (8), Asteraceae (6), Rubiaceae (4). The H 'value of the sample was 3,69 nats. ha-1 and the equability J '= 0.84, while in MB the H' ranged from 2.88 nats.ha-1 (MB1) to 3,53 nats.ha-1 (MB4). The Hutcheson's t-test indicated that MB1 has the lowest diversity of all, MB3 is less diverse than MB2, MB4 and MB5, which are the same with each other. The rarefaction showed that MB1 and MB3 have lower species richness, MB4 and MB2 are the same and MB5 is the richest. The NMDS generated three floristic groups (G): G1 (MB1), G2 (MB3) and G3 (MB2, 4 and 5). ANOSIM confirms these results (Jaccard (R = 0.4651, P = 0.001), Bray-Curtis (R = 0.4538, P = 0.001). The ANOVA showed differences (p <0.05) between basal areas, mean diameters and MB abundances. The Tukey test indicated that the basal area of MB2 is greater than that of MB 4, the abundance of MB1 was lower than that of MB3 and MB4. The results indicate that the area is in advanced secondary successional stage, with diversity and structure similar to the other areas studied in Mantiqueira considered mature forests. The differences between MBs corroborate with the national water resources policy, since MB serves as a strategic physiographic unit for studies of land use and occupation. It is concluded that there is a difference between the structure, composition and diversity of the MB of ODUMF of SPSP. This is important for the conservation and propagation of species of this ecosystem in the Serra da Mantiqueira. Plant communities should be investigated by taking MB as their strategic unit.