Aboveground and belowground carbon sequestration in a silvopastoral system of Nothofagus antarctica forests in Southern Patagonia, Argentina.

PERI, P.L.; MARTÍNEZ PASTUR G.; GARGAGLIONE V.; LENCINAS M.V.

Buenos Aires

Congreso; Proceedings XIII World Forestry Congress, FAO; 2009

Deciduous Nothofagus antarctica (Forster f.) Oersted tree is a native species with a wide ecological distribution in the southern areas of Argentina and Chile (from 36° 30´ to 56°00´ S) and has been usually used as silvopastoral systems (trees growing with natural pastures in the same unit of land to feed cattle). These forests are considered efficient carbon (C) sink ecosystems. However, there are few estimates of C storage for these forests under a silvopastoral use. The aim of this work was to quantify the aboveground and belowground C sequestration for different components of trees (leaves, small branches, whiteness, duramen, rot, bark and roots) and pasture (green and dead leaves, pseudostem and coarse and fine roots), and the C storage in litter floor and different horizons of mineral soil (from 0 to 0.6 m depth) in a N. antarctica silvopastoral system grown in Southern Patagonia (51º 39´ S; 72º 01´ W). For this, samples of trees, pasture and soil were taken from three different stands in plots of 150 m2 randomly selected (mean dominant trees height of 7.8 m, stocking of 180 trees ha-1 and mean age of 195 years old). The C concentration was higher in the tree component of rot (55.3%) and lower in the dead leaves component of pasture (40.5%). The C concentration decreased from 46.9% in floor litter to 2.5% at 0.6 m mineral soil depth. At the silvopastoral stand level, the total C stored was 252 t C ha-1 distributed 86.7% in soil, 11.9% in trees and 1.4% in pasture. Belowground biomass represented an important C storage pool in the ecosystem with mean values of 8.9 and 2.6 t C ha-1 for trees and pasture roots components, respectively. Total C accumulation in trees (30.1 t C ha-1) followed the order duramen > coarse roots > whiteness > bark > small branches > rot > leaves > fine roots. C storage in litter floor was 7.4 t C ha-1, and in the mineral soil ranged from 13.6 t C ha-1 (horizon 0-0.03 m depth) to  98.6 t C ha-1 (horizon 0.30-0.60 m depth). This study improved the understanding about the potential of C sequestration of N. antarctica forests under silvopatoral management and highlights the importance of these forests as efficient carbon sink ecosystems.