Root stock biomass and productivity assessments of reforested pine stands in northern Mexico

• An allometric equation was a good model for measurements of coarse root biomass.
• A basal area growth model was able to predict rootstocks and rootstock productivity.
• Independent measurements of coarse roots validated well the growth model.
• Rootstock and productivity can be evaluated with shoot values using a variation factor.

Assessments of root biomass stock and rootstock productivity are critical for understanding ecosystem function and the cycles of several biogeochemicals, including carbon and nitrogen. An allometric equation provided a good model for measurements of coarse tree root (d > 1.0 cm) biomass, and a basal area growth and yield model was able to predict rootstocks and changes in rootstock biomass productivity. Independent spatial assessments and additional temporal measurements of coarse roots validated the empirical model, which predicted a wide range of rootstock and productivity values as a function of stand age, site index and tree dimension. In agreement with field measurements, the model predicted that the root to shoot ratio approach for estimating belowground biomass and productivity must include a correction factor in case forests under study miss measurements of stand age and site index parameters.