Productivity and carbon storage in silvopastoral systems with Pinus ponderosa and Trifolium spp., plantations and pasture on an Andisol in Patagonia, Chile

摘要

No information is available about carbon (C) sequestration potentials in ecosystems on Andisols of the Chilean Patagonia. This study was undertaken to measure the size of C stocks in three predominant ecosystems: Pinus ponderosa-based silvopastoral systems (SPS), pine plantations (PPP) and natural pasture (PST), and examine how clover affect tree growth and stocks of soil C. The C contents of trees and pasture were determined by destructive sampling and dry combustion. Soil samples were taken at 0-5, 5-20, 20-40 cm depths in order to determine soil C and N. For PPP and SPS total aboveground tree C was 38.4 and 53.1 kg tree-1 and belowground was 21.3 and 23.4 kg tree-1, respectively. Annual diameter increment at breast height was 1 and 2 cm in PPP and SPS, respectively, and was significantly higher in SPS. Trees in SPS, due to lower density and the presence of leguminous pasture, demonstrated enhanced growth and C sequestration. Soil organic C (SOC) stocks at 0-40 cm depth were 193.76, 177.10 and 149.25 Mg ha-1 in SPS, PST and PPP, respectively. The conversion of PPP to SPS and PST to PPP resulted in an increase of 44.51 Mg ha-1 and a decrease of 27.85 Mg ha-1 in SOC, respectively. Favorable microclimatic conditions in relation to air temperature and soil moisture were observed in SPS as well as a synergy between trees and pasture.