Estimation of soil carbon pools in the forests of Khyber Pakhtunkhwa Province, Pakistan

摘要

Forest soils have high carbon densities compared to other land-uses.Soil carbon sequestration is important to reduce CO 2 concentrations in the atmosphere.An eff ective climate change mitigation strategy involves limiting the emissions of greenhouse gases from soils.Khyber Pakhtunkhwa is the most forested province of Pakistan,hosting about one-third of the country’s 4.5×106 ha forest area.Soil organic carbon in the province’s forests was estimated through a fi eld-based study carried out during 2014–17 covering the whole province.Data was collected from 373 sample plots laid out in diff erent forest types using a stratifi ed cluster sampling technique.The total quantity of soil organic carbon was estimated at 59.4×106 t with an average of 52.4±5.3 t/ha.About 69%of the total soil carbon is present in temperate forests.Subtropical broad-leaved and subtropical pine forests constitute 11.4%and 8.8%of the soil carbon stock respectively.Similarly,subalpine and oak forests have respective shares of 5.1%and 5.7%in the soil carbon pool.The lowest carbon stock(0.1%)was found in dry-tropical thorn forests.The highest soil carbon density was found in subalpine forests(69.5±7.2 t/ha)followed by moist temperate forests(68.5±6.7 t/ha)and dry temperate forests(60.7±6.5 t/ha).Oak forests have carbon density of 43.4±7.1 t/ha.Subtropical pine,subtropical broad-leaved and dry tropical thorn forests have soil carbon densities of 36.3±3.7,32.8±6.2 and 31.5±3.5 t/ha,respectively.The forests of the Khyber Pakhtunkhwa province have substantial amounts of soil carbon which must be conserved for climate change mitigation and maintenance of sound forest health.