藏北高寒草原样带土壤有机碳分布及其影响因素

沿藏北高寒草原冈底斯山-申扎-双湖样带（30°25′N至33°6′N）,在37个样点采集土壤和植物样品,分析藏北高寒草原土壤有机碳含量及其影响因素。结果表明：藏北高寒草原土壤0~15、15~30和0~30 cm有机碳含量分别为2.27、2.17和4.44 kg.m-2。土壤有机碳含量沿样带呈随着纬度的增加而减少的趋势。藏北高寒草原土壤质地总体偏粗,不同质地土壤之间有机碳含量大小关系为砂土〈壤质砂土〈粉壤土〈砂质壤土〈壤土。不同深度土壤有机碳含量与土壤颗粒含量相关性存在显著差异,0~15 cm土壤有机碳与粉粒、黏粒含量呈显著性正相关,与砂粒含量呈显著性负相关,而15~30 cm土壤有机碳含量与土壤颗粒组成相关性不显著。0~15 cm土壤有机碳含量与草地盖度、地下生物量和总生物量呈显著或极显著正相关,与优势种高度呈极显著负相关;15~30 cm土壤有机碳含量与优势种高度呈显著负相关。

Spatial distribution of soil organic carbon and influencing factors in the alpine steppe of northern Tibet

In this study,we investigated soil organic carbon（SOC）,vegetation coverage,height of dominant species and above-and below-ground biomasses at 37 sites along a 300 km transect across the alpine grassland of Northern Tibet.The aim of our study was to explore the spatial distribution of SOC and identify the key factors inducing SOC changes.The results showed SOC stored in the 0-15,15-30 and 0-30 cm depths to be 2.27,2.17 and 4.44 kg.m-2,respectively.SOC was observed to decrease as latitude increased from 30°25′N to 33°6′N in the alpine steppe of northern Tibet.The soil texture in the area of study was very coarse.For different soil texture,there is a great difference in organic carbon content.Organic carbon content in Silt loam is the highest,and in sand is the lowest.SOC content was negatively correlated with sand content and positively correlated with silt and clay at 0-15 cm depth.There was no significant correlation between SOC and particle size at 15-30 cm depth.Vegetation coverage and above-and below-ground biomasses have significantly positive effects on SOC content at 0-15 cm depth.Surprisingly,we found significantly negative correlation between SOC and the height of the dominant species