[Effects of topographies and land uses on soil organic carbon in subsurface in hilly region of Loess Plateau].
It is important to accurately assess soil carbon sequestration potential and the global carbon cycle to study effects of topographies and land uses on soil profile organic carbon in subsurface. In Yangou watershed of hilly region of Loess Plateau, based on three topographies (tableland, slopeland, gullyland) and seven land uses (farmland, orchard, secondary grassland, manmade and secondary shrubland and manmade and secondary woodland), 53 soil profiles (0-100 cm) in six soil depths up to 898 samples were collected to investigate effects of topographies and land uses on contents and spatial distribution of soil organic carbon in subsurface. Topographies, land uses, depths and interaction of them significantly (p < 0.01) affected spatial distribution of soil organic carbon in subsurface in Yangou watershed. SOC had different spatial distribution in topographies between subsurface (10-100 cm) and surface (0-10 cm). In 0-10 cm soil layer, the content of soil organic carbon of slopeland (10.7 g x kg(-1)) was the highest, followed by gullyland (8.9 g x kg(-1)), the content of SOC of tableland (4.4 g x kg(-1)) was the lowest. But the contents of SOC every layer in 10-100 cm expressed as gullyland > slopeland > tableland trends, the average contents of SOC were 5.6 g x kg(-1), 4.5 g x kg(-1) and 3.2 g x kg(-1). Land uses significantly (p < 0.05) affected spatial distribution of SOC in subsurface in Yangou watershed. Compared with farmland, the content of SOC of orchard in 0-40 cm decreased by 21%, yet increased by 13% in 80-100 cm. The content of SOC of manmade shrubland (2.6 g x kg(-1)) was 19% lower than that of farmland, while SOC content of manmade woodland (3.4 g x kg(-1)) was 6% higher than that of farmland. The content of SOC of secondary shrubland was higher than that of any other land uses in 20-100 cm, but it is significantly (p < 0.05) different form other land uses in 40-100 cm, the average contents was 5.3 g x kg(-1), which was 66% higher than that of farmland. The content of SOC of secondary woodland was higher than that of any other land uses in 0-20 cm, but it was less differences form other land uses in 40-100 cm. The storage of SOC of gullyland (5.04 kg x m(-2)) in subsurface (20-100 cm) was the highest, accounted for 71.4% in 1 m profile, the relative storage of SOC of slopeland and tableland accounted for 63.6% and 72.3% respectively. The storages of SOC of secondary shrubland in subsurface (20-100 cm) were the highest, it was 6.01 kg x m(-2) accounted for 64.7% in 1 m profile, while the relative storage of secondary woodland was the lowest, only accounted for 49.7%. The storages of SOC of farmland and orchard both accounted for more than 70% of 1 m profile.
Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resource, Yangling 712100, China. sunwy0715@126.com
Wen-Yi
WY
Sun
Sheng-Li
SL
Guo
Xiao-Gang
XG
Zhou
D000383:Agriculture / Q000379:methods; D000531:Altitude; D002244:Carbon / Q000032:analysis*; D057486:Carbon Cycle; D002681:China; D009930:Organic Chemicals / Q000032:analysis*; D006109:Poaceae / Q000254:growth & development*; D012987:Soil / Q000032:analysis*; D014197:Trees / Q000254:growth & development*
D009930:Organic Chemicals; D012987:Soil; D002244:Carbon