贺兰山西坡草地土壤碳特征及潜在退化损失分析

Distribution of soil carbon and its losing risk with potential degradation on the grasslands along western slope of Helan mountain,China

本研究分析了干旱区贺兰山西坡山前草地土壤碳的分布特征及其与气候、植被和土壤因子的关系,并探讨了潜在退化状态下土壤碳的变化特点。结果表明,随着海拔的增加,土壤有机碳含量和密度逐渐增加,表现为山地草原>荒漠草原>草原化荒漠;而土壤无机碳、全碳含量和密度随海拔增加先逐渐增加随后有所降低。偏相关及逐步回归分析表明,土壤有机碳含量与全氮显著相关,而影响土壤无机碳含量的因素因土层不同而有所差异,土壤无机碳与土壤容重显著相关,且受年降水量和年均温因子的共同影响。土壤碳密度受土壤碳含量的影响大于土壤容重。另外,当各高海拔草地群落潜在退化为低海拔草地群落时,土壤有机碳含量及密度变化较大,呈减少趋势,无机碳和全碳表现不一致,但当草地类型发生改变时,两指标减少幅度较大。上述结果表明,草地退化对土壤有机碳和无机碳影响显著,且土壤无机碳受土壤母质的影响也强烈。

In order to study the distribution and changes of soil organic carbon （SOC） and inorganic carbon （SIC） and total carbon with grassland potential degradation following altitudes along Helan Mountain,meanwhile explore their relationships with environment factors of climate, vegetation and soil, we collected soilsamples and plant samples in three grassland types at different altitudes along Helan mountain in Alxa , InnerMongolia, China. The different soil indexs which mainly included soil pH , Soil organic carbon, total carbon, soil total nitrogen （TN ） , total phosphorus, available nitrogen and soil bulk density were measured. The rela-tionships between soil carbon with environment factors of climate, vegetation and soil were analyzed by inte-grated partial correlation analysis. The results showed, as the altitude increasing, soil organic carbon content and density increase and were expressed as grassland types： steppe〉desert steppe〉steppe desert. However, soil inorganic carbon and total carbon content and density increase gradually with altitude increasing, but itslightly decreased at the grassland at altitude of 2 100 m. Integrated partial correlation analysis showed TN was significantly correlated with soil organic carbon. While, the factors affecting soil inorganic carbon varied great-ly. Soil bulk density was significant correlated with soil inorganic carbon and annual rainfall and annual average temperature were the main factors too. Because soil carbon density was influenced greater by soil tent than soil bulk density, similar to soil carbon content, soil carbon density in steppe was significantly greater than soil carbon density in steppe desert. Additionally？ if the grassland at the higher altitude changes to the suation as the lower altitude, soil organic carbon content and density decreased？ but soil organic and total carbon content and density decreased only when the grassland types changed. The whole research revealed that the degradation of the grassland influenced both soil organic and inorganic carbon content and density, and the soil development influenced the soil organic carbon characteristics too.