TREE SELECTION AND CONVERSION OF A PROVENANCE TEST TO A SEED PRODUCTION STAND

Abstract

The objectives of this study were to select the best seed trees and to design, by thinning simulations, a seed tree stand in a plantation of three provenances test of Pinus greggii Engelm. var. greggi: Los Lirios and Jamé, Arteaga, Coah., and Cuauhtémoc, Saltillo, Coah., During 13 years, no significant differences were found among provenances on the evaluated, tree characteristics and the trees have reached the right size and age for converting the provenance test into a seed tree stand. Currently, the test plantation has a density of 1246 trees ha^-1. For this conversion it was necessary to select the best seed trees, which was come by means of a selection index developed using a data base of 16 tree variables. The data base was analyzed by multivariate procedures and was reduced to seven variables which explained 84.8 % of the variance. Three groups of trees were classified based on the grouping analyses. These groups of trees were used to design the seed tree stand, using a simulation of two thinning phases with the “Stand Visualization System” (SVS) program version 3.36. The first thinning phase eliminated the shortest and thinnest trees; the second phase was a geometrical thinning in order to assign more free space for the remaining seed trees. The thinning simulations allowed to reduce, the tree density to 245 trees ha^-1, so that only 35 seed trees were selected from 178 individuals, as the seed tree stand in an area of 0.1428 ha. The simulations will be adjusted based on the growth response of the residual trees after the thinning simulation.