Root biomass and carbon storage of ponderosa pine in a northwest Patagonia plantation

Abstract

Ponderosa pine is the most common tree species planted in northwest Patagonia, Argentina. Rotation periods and relative high harvest and transport costs make the eventual trade of carbon offsets an attractive option to complement wood production. Although root biomass constitutes an important component of total carbon storage in a pine plantation, the difficulties in measuring root biomass often lead to the omission of this component in estimating carbon sequestration. In this work we carried out field research on samples of roots from two differently aged stands of similar site quality to develop regression equations relating root dry weight, root volume, and carbon storage as functions of tree diameter (at breast height). Results show that root biomass and volume can be highly explained by this variable. There were not significative differences between the regression equations obtained from 10- and 20-year-old stands. Total biomass at stand level was 8.3 and 144.5 Mg ha −1 for 10- and 20-year-old plantations, respectively. Root–shoot ratios calculated for sampled trees ranged in average 0.21–0.24 and 0.23–0.25 for stands. This is in accordance with other studies on temperate conifers biomass. Some inferences about root carbon storage at stand level are discussed.