Title: Silvicultural performance of five forest species in the central Brazilian Amazon
Estimates indicate that around 20% of the Brazilian Legal Amazon has been deforested, especially due to timber industry. This scenario makes planting of forest tree species a priority to recover all the environmental services and products of such rich ecosystem. Unfavorably, little is known regarding the silvicultural performance of forest species under the Amazonian edaphoclimatic conditions. The study aimed to assess the survival rate and growth of four native (Swietenia macrophylla, Parkia decussata, Dipteryx odorata and Jacaranda copaia) and one exotic (Acacia mangium) species in monospecific plantations (spacing of 2 x 2 m) throughout four years in former grazing land, in Itacoatiara, Amazonas state, Brazil. For each species plantation, three plots of 128 m² have been established, containing 32 trees each, all under similar relief conditions. The following measurements have been conducted: (a) diameter at breast height (1.30 m) (DBH, cm); (b) total height (Ht, m); (c) commercial cylinder volume (Vcyl, m3 ha-1); (d) survival rate (S, %); (e) crown projection area (CPA, m2). Qualitative variables have been estimated by visual inspection of: (a) stem bifurcation (B, %); (b) stem quality (LQ, R = rectilinear, T = tortuous); (c) crown quality (CQ, C = circular, I = irregular); (d) nutritional status (NS, B = good, D = deficient); and (e) phytosanitary status (PS, S = satisfactory, NS = non-satisfactory). All the species have exceeded 80% of survival rate, except Jacaranda copaia, however, it has presented the best performance results concerning stem and crown quality, phytosanitary and nutritional status, DBH and CPA. Acacia mangium has obtained the highest mean annual increment (51,87 m3 ha-1 yr-1), being 222% greater in Vcyl than the second ranked Jacaranda copaia, although it has been affected by the higher values of exchangeable aluminum in the soil, as well as Swietenia macrophylla. This species has suffered a severe attack of Hypsipylla grandella, having therefore the lowest performance. The study found that amongst the five evaluated forest species, Jacaranda copaia, followed by Dipteryx odorata and Parkia decussata, have obtained the highest silvicultural performance in most of the measured variables, being suitable for planting in areas with similar edaphoclimatic conditions.
Keywords: Brazilian Amazon, Silvicultural performance, Forest species, Edaphoclimatic conditions
(M.R. Machado 2017)