Avaliação da altura de aferição de diâmetro na mensuração arbórea de cerrado lato sensu

Abstract

The woody vegetation of the Cerrado with savanna physiognomy exhibits a structure distinct from that of forest formations. Therefore, the methodology for collecting biometric data must be adapted to this structural type, ensuring that the data obtained accurately represent field conditions. Among the methodological criteria for collecting data on woody vegetation, the inclusion limit (IL) and the point of measurement (POM) stand out, as they directly influence the number of trees measured per unit area and, consequently, affect the structural and ecological parameters of the study area. Currently, the most used POM in forest inventories in Brazil is diameter at breast height (DBH = 1.3 m). Several studies conducted in Brazilian savanna formations within the Cerrado biome have been based on this POM, which was originally defined for forest environments. This results in underestimated values relative to field conditions due to the morphological characteristics of these formations, including shorter stature, branching below 1.3 m, and stem tortuosity. Given this scenario, measuring diameter at base height (DAB = 0.3 m) has been adopted by some research groups, solving the problem of underestimating variables but creating others, namely poorer ergonomics and an increased risk of accidents involving venomous animals. Consequently, the comparability among studies has been compromised because different POMs have been adopted. Standardizing the IL and the POM according to the structural and ecological characteristics of woody vegetation is necessary to ensure that results obtained from different studies are comparable. Such standardization is essential to support decision-making by administrative agencies responsible for evaluating environmental licensing projects, carbon credits, forest conservation, and forest restoration. To investigate this issue, the present study provides a comparative analysis of the results for density, basal area, timber volume, carbon, species richness, and diversity obtained from measurements taken at DAB, DBH, and a third measurement point referred to here as diameter at knee height (DKH = 0.5 m) in three phytophysiognomies: campo cerrado, cerrado sensu stricto, and cerradão. Mathematical models are subsequently presented to enable the use of the proposed POM in the existing equations for these phytophysiognomies that estimate volume, biomass, and carbon.