Aspectos silviculturais e ecológicos em área de restauração florestal com diferentes espaçamentos de plantio

Abstract

Planting spacing in mixed stands interferes in the competition for environment elements, in the control of unwanted species and in forest succession facilitation. Therefore among other variables, it will affect species growth, as well as vegetation nutrients cycling and consequently litter deposition. On a restoration planting, in Seropédica (RJ), were employed different spacing, 1 m x 1 m; 1.5 m x 1.5 m; 2 m x 2 m and 3 m x 2 m, and six species were studied as to its growth during six years after planting. The variables evaluated were total height (m) and diameter at ground level (DGL), in order to and canopy area, those were used to compare average growth in two periods, the third and sixth year after plantation. The species behaviors in all characteristics were different, at three and six years old, where, 1 m x 1 m spacing provided smaller values. Deciduous material was studied during two years. In 1 m x 1 m spacing was observed the largest litter deposition, and no differences between the units of the other spacing. The fraction leaves showed in all spacing greater supply (77%). Upper litter intakes and leaf fraction were observed in the dry season (March to September) in the 1 m x 1 m spacing, being the average value contributed of litter, in the range of two years, equal to 7.48 Mg.ha-1.year-1. The material contributed in the dry season, after four years of planting, showed that the amount of macronutrients (g.kg-1) N, K and Mg were little influenced by the spacing. The highest nutrient content was observed in 1 m x 1 m spacing. In General, it was found the following order as the nutrient content of litter, N > Ca > K > Mg > P. The species were assessed of macronutrient quantity in the compartments of biomass. With regard to the presence of macronutrients quantity (N; P; K; Ca; Mg) at compartments noteworthy are at leaves (2.41; 0.21; 1.29; 1.12; 0.41 g nutrient.kg sample); secondly bark; thirdly branches; fourthly root and fifth wood. It is concluded that there are differences in nutrient quantity of biomass among the six species studied, being more demanding Chorisia speciosa on nutrients, and Schinus terebinthifolius and Schizolobium parahyb less demanding. Also that the nutrient quantity followed the order leaf > bark > branch > root > wood. The macronutrient content presented the order N > K > Ca > Mg > P.