Caracterização fitossociologica e relações hipsometricas da plantação de chafuta em michefutene no Distrito de Marracuene

Abstract

For the application of correct forest management projects, as well as the permanent use of forests, the composition and structure of the forests must be known, on the other hand, when carrying out the inventory, the use of instruments for measuring the height of the trees constitutes an exhaustive and time-consuming operation. Thus, the present work arises with the aim of evaluating the hypsometric relationships, the vertical and horizontal structure of the Michafutene forest in the Marracuene district. For this purpose, a forest inventory was carried out in the total area of ​​31.37 ha, where 31 plots of 0.125 ha were established, equivalent to a sampling intensity of 12.5%. The plots were selected systematically in the study area with the help of the map, GPS and compass. Within each sample unit, DBHs and the total heights of all trees with DBH greater than 10 cm were measured. A total of 561 trees were measured, where the average abundance of 145 Arv / ha was obtained for the horizontal structure and the total of 4542 trees, the average dominance was 4,515 m2 / ha and the total population was 141,629 m2. The diametric distribution resulted in a "J inverted" type graph that allowed to affirm that the plantation is in a stable and self-regenerating state and that there is a balance between mortality and recruitment. For the vertical structure, the dominant height of the population was 5.14 m, which allowed the definition of the forest strata and the number of trees per stratum. The upper stratum with about 134 Arv / ha and the middle stratum with 12 Arv / ha. The data collected did not allow the determination of the number of trees per unit area for the lower stratum. From the dendrometric variables measured in the study area, it was possible to adjust the 8 hypsometric models. The adjusted models were proposed by Trorey, Azevedo et al. (1999), Henricksen, Linha Recta (without author), Stofel, Curtis, Silva (1980) Azevedo et al. (1999). The model that best presented a relationship between height and tree diameter was the model proposed by Silva (1980). It obtained the best result both for the adjusted determination coefficient [R2aj (%) = 27.1295] and for the standard error of the estimate, the Furnival Index equivalent for logarithmic models [IF (%) = 20.9505 ]. When verifying the regression, through a graphical analysis of the residues, it was noted that there was no significant difference between the models tested. By the Chi-square test (χ²) it was possible to conclude that the selected equation is valid to estimate the total heights of Afzelia quanzensis trees planted in Michafutene in Marracuene district (TRADUÇÃO NOSSA)