Competition indices after reduced impact logging in the Brazilian Amazon

Competition for resources can affect growth and increase mortality in forest stands. The effects of this process are little known, especially in areas subjected to forest management which show distinct growth dynamics when compared to unmanaged natural areas. This study aimed to estimate, evaluate and select the best fit competition indices (CI) for individual trees in a managed forest in the eastern Amazon. The data used originated from 18 permanent plots of 1 ha each, which were monitored for 12 years after Reduced Impact Logging (RIL). For the competition analysis, 23 indices were tested. CIS were evaluated based on graphical analyses and linear correlation coefficients(r)between each index and variables, basal area growth(Delta G), probability of mortality(Pm), and post-logging period (PLP). In addition, the partial F-test was applied to verify how well the calculated CIS explain the variations observed in Delta GandP(m). The distance-independent index for BAL (Basal Area Larger) performed the best. For the distance-dependent and semi-independent indices, the best interactions with the variables tested occurred in radii of 15 and 20 m away from the object tree. The largest trees presented higher values of Delta G. While P(m)was similar among the three tree classes, larger trees had a slightly higher P(m)due to thier low density of individuals. The results obtained in this study may help to include Cis in growth and production models at the individual tree level in tropical rainforests, especially in those managed in the Brazilian Amazon.

Automated summary

Competition for resources can impact growth and mortality in forest stands, especially in managed forests like those in the eastern Amazon. This study tested and evaluated various competition indices, with the basal area larger index performing the best in explaining competition effects on individual tree growth and mortality.