Altitudinal genetic variation in plant growth of Pinus pseudostrobus Lindl. in field testing

To determine whether there is a pattern of altitudinal genetic variation for growth, survival, and frost resistance among Pinus pseudostrobus Lindl. populations, seeds of eight populations along an altitudinal transect (2100 to 2800 in) were collected within the Nuevo San Juan Parangaricutiro forests in Michoacan, Mexico. Provenances were evaluated on two field sites at contrasting altitudes (2200 and 2800 in). Although there were significant differences among provenances for height growth and crown diameter, a clear altitudinal pattern of genetic differentiation was not detected among these populations. Significant differences (p <= 0.05) among test sites were found for 15-month-old height growth, basal diameter, crown diameter, and bud phenology at two ages (16 and 27 months), frost damage, and survival. Average growth was significantly larger at the low elevation site (Los Amoles, 2200 in) than at the high elevation site (Cerro de Pario, 2800 in) by the end of the study- There was no significant evidence (p <= 0.05) of genotype-environment interaction.