Abstract

NAVAR, José. Plasticity of biomass component allocation patterns in semiarid tamaulipan thornscrub and dry temperate pine species of northeastern Mexico. Polibotánica [online]. 2011, n.31, pp.121-141. ISSN 1405-2768.

The question of how plant communities respond to variation in the availability of resources in the environment was answered by testing the hypotheses of true adjustments and ontogenetic drift in biomass allocation patterns. The slopes of allometric equations that estimate biomass components as a function of diameter at breast height, D, root profiles and the ratio of belowground to aboveground biomass, BGB:AGB, vs. basal diameter, Db, supported these hypotheses in Mexico's northeast Tamaulipan thornscrub and dry temperate pine forests. Covariance analysis showed that plant communities allocate biomass components differently; Tamaulipan thornscrub species have larger root biomass allocation per unit Db than dry temperate pine forests in early stages of development. Tamaulipan thornscrub roots are more numerous, smaller and thinner, and differences in taper were noted for both lateral and tap root systems. This report concludes that environmental factors (more abundant soil nutrients, but less water availability in Tamaulipan thornscrub communities) play an important role in explaining higher BGB: ABG ratios, but differences can be eventually obscured by the developmental stage of these plant communities.

Keywords : bole; branch and foliage; coarse roots; root: shoot ratio; root tapering.

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