Comportamento da mortalidade natural em bracatingais nativos em diferentes densidades iniciais e classes de sítio

Abstract

This research had as objective to analyse the effects of initial density and site on the natural mortality in native bracatinga stands (Mimosa scabrella Benth.) located in the Curitiba metropolitan region. The utilized data for this research came from a trial in a random blocks design, with 4 treatments and 5 repetitions instaled on 4 different farmers, covering 3 different site classe s. The experimental plots with an area of 325 m2 (13 x 25 m) were set when the stands had one year of age. The counting of the remaining number of trees was done yearly until 7.6 years of age in every one of the 20 permanent plots. The results showed that as higher the initial density, higher was the mortality rate until the age of 5 years. From this age, the treatments with lower initial density tended to present higher mortality rate. This indicates that independently from the initial number of trees, there is a trend of convergency to a same number of survival trees as the bracatinga stands become older. Results also indicated that the site had litle influency on natural mortality rate in native stands of this species.