The impact of land use change on soil organic carbon and labile organic carbon stocks in the Longzhong re-gion of Loess Plateau

Abstract

Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL), artificial grassland (AG), artificial woodland (AW), abandoned arable land (AAL) and desert steppe (DS) in the Longzhong region of the Loess Plateau in Northwest China. The results showed that conversions from DS to AL, AL to AG and AL to AAL led to an increase in SOC content, while the conversion from DS to AW led to a decline. The differences in SOC content were significant between DS and AW at the 20-40 cm depth and between AL and AG at the 0-10 cm depth. The SOC stock in DS at the 0-100 cm depth was 39.4 t/hm 2 , increased by 28.48% after cultivation and decreased by 19.12% after conversion to AW. The SOC stocks increased by 2.11% from AL to AG and 5.10% from AL to AAL. The LOC stocks changed by a larger magnitude than the SOC stocks, which suggests that it is a more sensitive index of carbon dynamics under a short-term LUC. The LOC stocks increased at 0-20 cm and 0-100 cm depths from DS to AW, which is opposite to that observed for SOC. The proportion of LOC to SOC ranged from 0.14 to 0.20 at the 0-20 cm depth for all the five land use types, indicating low SOC dynamics. The allocation proportion of LOC increased for four types of LUC conversion, and the change in magnitude was largest for DS to AW (40.91%). The afforestation, abandonment and forage planting on arable land led to sequestration of SOC; the carbon was lost initially after afforestation. However, the carbon sink effect after abandonment may not be sustainable in the study area.

Carbon storage and soil property changes following afforestation in mountain ecosystems of the Western Rhodopes, Bulgaria

“…Similarly, Li et al (2004) reported that conversion of natural forests to continuous cultivation and grazing decreased both the concentration and stock of SOC. Zhang et al (2012) found that SOC stock increased when arable cropland was abandoned. In our case, the lowest SOC stock was found under abandonment (RdA2).…”

Spatial heterogeneity of soil organic carbon in a karst region under different land use patterns

“…Emissions from land use and land cover change are believed to be the second most significant source of human‐induced greenhouse gas emissions into the atmosphere (1.6 Pg C/a) after fossil fuel combustion (7.2 Pg C/a) (IPCC (Intergovernmental Panel on Climate Change) , Zhang et al. , Wang et al. ).…”

Ecosystem Carbon Stock Loss after Land Use Change in Subtropical Forests in China

“…Briefly, 0.1-0.5 g air dried soil samples passed through a 0.15 mm sieve were digested in 5 mL of 0.8 mol¨L´1 K 2 Cr 2 O 7 and 5 mL concentrated H 2 SO 4 (1.84 g¨mL´1) for 5 min at 170-180˝C. Secondly, the digested solution samples were titrated with standardized 0.2 mol¨L´1 FeSO 4 solution mixed with 15 mL concentrated H 2 SO 4 per litre to prevent oxidization [32,33]. After the analysis, the soil organic C stock (Mg¨ha´1) for each layer was calculated using the following formula [34]:…”