Carbon density and sequestration in the temperate forests of northern Patagonia, Argentina

Abstract

Introduction: Forests are a crucial part of the global carbon cycle and theirproper management is of high relevance for mitigating climate change. Thereis an urgent need to compile for each region reference data on the carbon(C) stock density and C sequestration rate of its principal forest types tosupport evidence-based conservation and management decisions in terms ofclimate change mitigation and adaptation. In the Andean Mountains of northernPatagonia, extensive areas of temperate forest have developed after massiveanthropogenic fires since the beginning of the last century.Methods: We used a plot design along belt transects to determine referencevalues of carbon storage and annual C sequestration in total live (above- andbelowground biomass) and deadwood mass, as well as in the soil organiclayer and mineral soil (to 20 cm depth) in different forest types dominated byNothofagus spp. and Austrocedrus chilensis.Results: Average total carbon stock densities and C sequestration rates rangefrom a minimum of 187 Mg.ha1 and 0.7 Mg.ha1.year1 in pure and mixed N.antarctica shrublands through pure and mixed A. chilensis forests taller than7 m and pure N. pumilio forests to a maximum in pure N. dombeyi forestswith 339 Mg.ha1 and 2.2 Mg.ha1.year1, respectively. Deadwood C representsbetween 20 and 33% of total wood mass C and is related to the amount oflive biomass, especially for the coarse woody debris component. The topsoilcontains between 33 and 57% of the total estimated ecosystem carbon in thetall forests and more than 65% in the shrublands, equaling C stocks of around100–130 Mg.ha1 in the different forest types.Conclusion: We conclude that the northern Patagonian temperate forestsactually store fairly high carbon stocks, which must be interpreted in relationto their natural post-fire development and relatively low management intensity.However, the current high stand densities of these forests may well affect their future carbon storage capacity in a warming climate, and they represent agrowing threat of high-intensity fires with the risk of a further extension ofburned areas in the future.