Soil carbon stocks of Jordan and projected changes upon improved management of croplands.

摘要

Inventories of carbon stocks and projected changes at national scale are needed in the context of the Framework Convention on Climate Change (UNFCCC), but uncertainties in the necessary soil data remain large. Soil organic carbon (SOC) and inorganic carbon (SIC) reserves in Jordan were estimated using a revised 1:500 000 soil and terrain database, providing baseline data. The 95% confidence limits for the median, total stock of carbon to 1 m depth were estimated at 1877-1896 Tg C (Tg=1012 g or million tonnes). About 7% thereof is organic, reflecting the predominantly arid conditions in the Kingdom. Many cultivated areas have been degraded by inappropriate management and overgrazing. An empirical approach that considers spatial data on climate, soil conditions and land cover was used to estimate the ecologically and technically feasible gains in SOC in Jordan's croplands over 25 years of sustained, adapted management. The projected gains for the reference scenario were estimated at 25-124 Gg C (Gg=109 g or thousand tonnes). This would correspond to an estimated annual mitigation potential of 0.5% of Jordan's CO2-C emissions from fossil fuels and land use change for 1990, the baseline year for Kyoto Protocol reporting. This exploratory study suggests that follow-up studies that use dynamic C-models should focus on scenarios for the conservation and rehabilitation of Jordan's degraded rangelands..