Plano amostral para coleta de serapilheira na floresta ombrófila mista no estado do Rio Grande do Sul

Abstract

The present work was carried out at the National Forest of São Francisco de Paula - FLONA/RS Araucaria Forest, which is of a great species diversity of Rio Grande do Sul. Litter is the material deposited on the soil in the forests and this is very important to the maintenance of soil fertility, because this is how the nutrients return to the plants in the ecosystem. The objective of this study was to estimate the accumulated litter and sampling intensity in each season in this Araucaria Forest. 15 random samples in four different size frame were used. a) Great (G) = 1m x 1m (1m2); b) medial (M) = 1m x 0,75m (0,75m2); c) Small (P) = 0,75m x 0,75m (0,56m2); d) Very Small (MP) = 0,5 x 0,5m (0,25m2), per hectare in each season (Autumm Spring Summer and Winter) totalizing 60 samples in one hectare, per season. After the litter was separated in storeys (branches, rinds, leaves, and miscellaneous) at the Laboratory of the Departmento of Fitotecnia , UFSM, and later placed in the greenhouse (75º C) until it get constant weight, and then, weighted on scale of precision (0,1g). The delineation used was completely random in each frame and season, for later commun joint analysis of the experiments. The simple random sampling admits a maximum estimated error of 10, 15, 20 and 25%. However, the intensity of sampling (n) per hectare was calculated with an estimated error probability of 5%. The interaction results (frame and season) in the joint analysis were not significant for the total and storeys. The behavior of the frames is the same in the different seasons and the response of the treatments can be used for all seasons. The variances verified in the seasons are not null, that is, heterogeneity can be found in different seasons regarding the litter accumulation. The total effect of the frames and storeys, branches, rinds and miscellaneous does not differ between themselves, presenting a significant difference only in leaves. There aren t significant differences between the frame and the total. As the most adjusted would be the Very Small frame (0,25 m²), with homogeneity of the variance in the season. It s necessary 27 samples in the winter, 25 in the spring, 33 in the autumn, and in the summer 15 sample units in order to get 15% of samples the averages.