Variação entre espécies e procedências na forma de tronco e bifurcação de pinheiros tropicais e subtropicais em Machipanda, Manica

Abstract

Given the growing projections of scarcity of forest resources from native formations, it is becoming urgent to intensify studies that assess the silvicultural potential of stands made up of exotic species, particularly with regard to their adaptation, productivity and technological quality. In this context, the present study aimed to evaluate qualitative silvicultural characteristics, focusing on stem form and degree of bifurcation, in stands of tropical and subtropical pines aged 38 years, established in the Machipanda region, in Penhalonga (Manica). The trial was conducted under a randomized complete block design, consisting of three blocks, each containing nine experimental plots. Each plot consisted of 25 trees from the useful area. The spacing adopted was 2.5 m × 2.5 m, compatible with conventional silvicultural practices for the genus. The qualitative variables evaluated included stem shape and degree of bifurcation, measured subjectively using a previously established classification scale. The results showed relatively high average values ​​for both characteristics, with an overall average of 4.39 for stem shape and 4.24 for bifurcation, indicating a predominance of individuals with straight stems and a low incidence of bifurcation. The analysis of variance (ANOVA) did not reveal statistically significant differences between the species and/or provenances evaluated, both for the stem shape variable and for the degree of bifurcation. This result suggests homogeneous phenotypic behavior among the genetic materials tested, evidencing stability of performance under the edaphoclimatic conditions of the experimental area. In general, the species and/or provenances evaluated demonstrated high adaptive capacity with regard to the qualitative characteristics analyzed, which reinforces their potential for use in commercial plantations and in forest genetic improvement programs. The estimated coefficients of variation were 10% for stem form and 8% for bifurcation, being classified as medium and low magnitude, respectively. These values ​​indicate reduced experimental variability and high precision of the data obtained, conferring robustness to the inferences made.