Stand growth model for Nothofagus antarctica primary forests

H IVANCICH; G MARTÍNEZ PASTUR; JM CELLINI; MV LENCINAS; P PERI

BARILOCHE

Congreso; VI SOUTHERN CONNECTION CONGRESS; 2010

The estimation of growth is crucial in the forest planning, for this reason the objective was develop a stand model in pure forests of Nothofagus antarctica of complete density in a site quality and ages gradients. The sample was obtained in an age gradient (20 to 220 years) and site quality (IS50= 2.5 to 10.8 m). In each plot, data of forest structure and samples for tree-ring measurement were taken in all trees (n= 1480), in order to estimate growths using biometric models previously developed. To fit the model the growth values of each plot during the last twenty years were calculated, using the ratio of total volume increment/basal area as variable to be estimated. The developed model brings this relationship in function to the site quality and stand age. The statistics (r²= 0.804, mean error= 0.0002, absolute mean error = 0.028), residual analysis and biological behavior were satisfactory. Values obtained through this model multiplied with the stand basal area offers the volumetric growth per hectare per year. The obtained values varied between: 15-40 years between 0.31-0.16 m³.m-².ha-1.year (site I) and 0.08-0.05 m³.m-².ha-1.year (site V); and 160-200 years between 0.07-0.06 m³.m-².ha-1.year (site I) and 0.025-0.022 m³.m-².ha-1.year (site V). The obtained stand growths varied between 1.3-8.3 m³.ha-1.year. This simple model allowed obtaining precise growth values at stand level from of easy mensuration and estimation variables.