Evaluation of biomass, carbon storage capability, tree-ring and cork-ring growth of Quercus suber: a review

Abstract

ABSTRACT Background Cork oak (Quercus suber) forests and woodlands cover an area of ca. 2.1 M ha in the Mediterranean Basin. Cork oak stands are important for biodiversity conservation, and ecosystem services (carbon storage and the provision of cork, timber, and firewood). Their sustainable management is essential for their continued multifunctional existence and for providing ecosystem services. Aims The aims of this study were to estimate the biomass production of the species and quantify its potential carbon storage capacity in the Mediterranean Basin and to make management recommendations. Methods We used a literature survey of allometric equations and cork annual total tree-ring growth data and applied them to determine the productivity of the species. Estimate biomass by using regression models and dendrometric characteristics is very important for cork oak in the Mediterranean region. Results The studies reported a wide-ranging above-ground biomass for cork oak: 42 Mg ha−1 for Italy, 64–120 Mg ha−1 for Morocco, 41–50 Mg ha−1 for Portugal, 29–328 Mg ha−1 for Spain, and 80–312 Mg ha−1 for Tunisia. The radial wood increment ranged from 0.78 to 8.01 mm yr−1. The annual increment of cork-ring growth was between 0.8 mm yr−1 (northern Algeria) and 5.25 mm yr−1 (Spain), with most values being between 2 and 4.4 mm yr−1. In dry years, major reductions (10−15%) in the growth of Quercus suber were observed. Conclusion Most studies showed stand-specific growth responses to climate variables, with the radial growth of cork oak being greater in relatively mesic and cool conditions.