ADAPTABILITY OF Pinus pinceana POPULATIONS IN TWO SOILS

Abstract

Strong environmental and human-derived pressures are driving Pinus pinceana towards extinction, and very little ecologic and genetic information is available about this species, particularly on population variation in seedling growth and biomass distribution as adaptive mechanisms to environmental conditions. In this study, biomass distribution and root growth rate were determined for 10 natural populations of P. pinceana brought from the northern and southern region of Sierra Madre Oriental in México, and grown in rizotrons with soil from two regions. Seedling growth and biomass allocation to roots were significantly (P < 0.05) affected by soil conditions. Seedlings from the southern region accumulated more biomass than those from the northern region, but no differences (P = 0.05) were found among populations in biomass allocation to roots. A broad phenotypic plasticity of this species in root growth was found in the two soils, possibly as an evolutionary mechanism to take advantage of the sporadic favorable environmental conditions in its natural habitat.