INF VS SIBIFOR ON VOLUME ESTIMATION FOR FORESTS OF SAN JUAN QUIAHIJE, OAXACA, MEXICO

Abstract

Forest inventories depend on the cubication equations used to quantify the volume or biomass of trees in stands; results will vary depending on the equation type, as well as on its predictive ability. The objective of this research was to compare estimates of standing volumes when using the equations of the National Forest Inventory (NFI) vs those of the Forest Biometric System (SiBiFor) for volume estimation of the different tree components for 25 temperate climate species of San Juan Quiahije, Oaxaca, Mexico. Four hundred and fifty sites of 1000 m² were established where information was collected on 16,863 trees of the genera Pinus and Quercus following the manual recommended by the Temperate Forest Planning System (SiPlaFor). As a discriminant criterion the hypothesis test with t-Student (P ≤ 0.05) was used to determine the best cubication system, as well as 10 % of the branches to calculate the total tree volume (Ttv) of each species with the NFI. By using the average volume ha^-1 per species it was shown that there are no statistically significant differences between the two systems as the confidence intervals overlap; however, SiBiFor is more conservative in volume estimate. This encourages the use of SiBiFor allometric equations for the development of forest management programs under the sustainability approach in the study area.