祁连山中部土壤颗粒组分有机质碳含量及其与海拔和植被的关系

The soil particulate organic carbon in different elevation and its relationship with vegetation in Qilian Mountain

调查分析了祁连山中段不同海拔土壤颗粒有机碳及其与植被的关系。结果显示,土壤颗粒组分比例在0~15cm和15~35cm土层随海拔升高而呈现下降趋势(P>0.2);土壤颗粒有机碳比例在0~15cm土层随海拔升高也呈现下降趋势(P≤0.001)。土壤颗粒组分比例0~15cm土层在阴坡3000m^3500m、15~35cm土层在阴坡3200m和3500m及半阴坡2200和2800m处较高;土壤颗粒有机碳比例0~15cm土层在阴坡3000m和3200m、半阴坡2200m和2800m,以及15~35cm土层在阴坡3200m和3500m、阳坡3300m和3500m处较高(P<0.05)。土壤颗粒有机碳和颗粒组分碳含量随海拔升高变化不显著(P<0.9)。土壤颗粒有机碳含量0~15cm土层在阴坡3000m^3500m、15~35cm土层在阴坡3000m^3500m及阳坡3300m处较高;土壤颗粒组分碳含量0~15cm土层在阴坡3000m^3400m和阳坡3300m,以及15~35cm土层在阴坡3200m和3400m及阳坡3300m处较高。土壤颗粒组分比例0~15cm土层在森林和灌丛草甸中较高;15~35cm土层在森林、灌丛草甸和干旱草原中较高(P<0.05)。土壤颗粒有机碳比例0~15cm土层在荒漠草原和干旱草原,以及15~30cm土层在森林和灌丛草甸中较高(P<0.05)。土壤颗粒组分碳含量0~15cm和15~35cm土层在森林和灌丛草甸中较高(P<0.05)。土壤颗粒有机碳含量0~15cm和15~35cm土层在森林中最高(P<0.05)。土壤颗粒组分碳含量和颗粒有机碳含量与土壤有机碳含量有显著的正相关性(P<0.001),土壤颗粒有机碳含量与颗粒组分碳含量也有显著的正相关性(P<0.001),土壤颗粒组分比例与有机碳含量相关性不显著(P=0.15),土壤颗粒有机碳含量与颗粒组分比例有显著正相关性(P<0.005)。结果说明祁连山中部北坡土壤有机碳稳定性受植被和海拔共同影响,荒漠草原和干旱草原表层土壤有机碳稳定性较低,森林和灌丛草甸土壤中非保护性碳含量较高。

The soil particulate organic matter-carbon （POC） is the unprotected pool of soil organic carbon （SOC） and it would indicate the stabilization of SOC. The Qilian mountain located the northern border of Qinghai-Tibet plateau with different vegetation and soil type, the SOC under these vegetations would be changed with change in climate or human being activities, and the SOC with different stabilization would be changed differently by the disturbance. To know the different stabilization of SOC under different altitude and vegetation of this mountain for understanding the impacts of climate change on the alpine ecosystem carbon sink, the POC in different elevation and its relationship with vegetation in Qi Lian Mountain was investigated. The results showed that the ratio of soil particulate fraction decreased with increasing elevation in 0-15 cm and 15-35 cm soil depth（P〉0.2）, and the ratio of POC in 0-15 cm soil depth decreased with increasing elevation（P≤ 0.001）, while it increased with increasing elevation in 15-30 cm soil depth（P〉0.5）. Soil particulate fraction in 0-15 cm soil depth under 3 000 m-3 500 m of shady slope or which in 15-35 cm soil depth under 3 200 m or 3 500 m of shady slope or 2 200 m-2 800 m was the highest among different altitudes（P〈0.05）, and the ratio of POC in 0-15 cm soil depth under 3 000 m and 3 200 m of shady slope or 2 200 m and 2 800 m, or that in 15-35 cm soil depth under 3 200 m and 3 500 m of shady slope or 3 300 m and 3 500 m of sunny slope was also the highest under different altitudes（P〈0.05）. The POC and the carbon content of soil particulate fraction both did not significantly increase with increasing altitudes （P〈0.9）. The difference of the carbon content of soil particulate fraction between 0-15 cm and 15-35 cm soil depth under different altitudes except 2 200m -2 800 m or 3 000 m of shady slope or 3 600 m of sunny slope was not significant （P〈0.05）. The content of POC in 0-15 cm under 3 000 m-3 500 m of shady slope or that in 15-35 cm under 3 000 m-3 500 m of shady slope or 3300m of sunny slope, and the carbon content of particulate fraction in 0-15cm soil depth under 3 000-3 400 m of shady slope and 3 300 m of sunny slope or that in 15-35 cm under 3 200 m and 3 400 m of shady slope and 3 300 m of sunny slope were the highest among different altitudes（P〈0.05）. The ratio of soil particulate fraction in 0-15 cm soil depth under forest and shrub alpine meadows were the highest and the difference of this ratio between under forest and shrub meadows or desert steppe and arid steppe was not significant （P〈0.05）, and that in 15-35 cm soil depth under forest and shrub meadows or arid steppe was the highest among different vegetations （P〈0.05）. The ratio of POC in 0-15 cm soil depth under desert steppe and arid steppe or that in 15-35 cm soil depth under forest and shrub meadows was also the highest among different vegetations （P〈0.05）. The carbon content of soil particulate fraction in 0-15 cm and 15-35 cm soil depth under forest and shrub meadows was the highest, and that under desert steppe was the lowest among different vegetations （P〈0.05）. The POC content in 0-15 cm and 15-35 cm soil depth under forest was the highest among different vegetations （P〈0.05）, while that between under alpine meadows and arid steppe or desert steppe was not significant （P〈0.05）. The carbon content of particulate fraction and POC content were significantly positively related to SOC content（P〈0.001）, and POC content was also significantly positively related to carbon content of particulate fraction （P〈0.001）,while soil particulate fraction ratio was not significantly positively related to SOC content（P≤ 0.15）. Additionally, the POC content was also significantly positively related to ratio of soil particulate fraction （P〈0.005）. The results showed that the altitude and vegetation together influenced the stabilization of SOC and the stabilization of SOC under arid steppe or desert steppe was lower than that under alpine meadows, while the content of unprotected SOC was higher under forest and shrub meadows than that under other vegetations.