祁连山森林草原带坡面尺度土壤有机碳分布

Distribution of Soil Organic Carbon at Hillslope Scale in Forest-steppe Zone of Qilian Mountains

以祁连山森林草原带3个山头为研究对象,在坡面尺度上分析了坡向和坡位对不同深度（0~10、10~20、20~40、40~60cm）土壤有机碳浓度和密度的影响。结果表明：坡肩、背坡及坡脚各层有机碳浓度变化趋势为北坡〉西坡〉西南坡〉南坡,不同沟谷土壤有机碳浓度差异不显著。有机碳浓度的坡位分布因坡向而异,在南坡、西南坡及西坡,沟谷各层有机碳浓度均显著高于其他坡位（P〈0.05）,坡脚高于坡肩与背坡;在北坡,坡肩、背坡及坡脚有机碳浓度无显著差异,沟谷20~40、40~60cm土层有机碳浓度显著低于坡肩（P〈0.05）。不同层次土壤有机碳密度的变化特征与有机碳浓度相似,0~60cm有机碳密度最大值出现在北坡（33.64±0.91kg·m-2）及沟谷（34.30±2.55kg·m-2）,约为南坡的3.20倍,西南坡的2.87倍、西坡的1.90倍。

This study examined the effect of slope aspects and positions on SOC concentration and density of different soil depths（0-10,10-20,10-20,20-40,40-60 cm）in forest-steppe zone of Qilian Mountains.Results showed that SOC concentration of whole soil profile increased continuously from south,southwest,west to north-facing slopes at shoulderslope,backslope and footslope positions,while no significant differences were found among valleys.The distribution pattern of SOC concentration among slope positions varied with slope aspects.On south,southwest,and west-facing slopes,SOC concentration at valleys was significantly higher than other slope positions（P〈0.05）,and footslope position tended to be higher than shoulderslope and backslope positions.On north-facing slope,there was no significant difference among shoulderslope,backslope and footslope positions,and SOC concentration at 20-40 cm and40-60 cm depths of valley was significantly lower than shoulderslope position（P〈0.05）.The distribution pattern of SOC density was similar to concentration.SOC density at 0-60 cm depth was maximal on north-facing slope（33.64±0.91 kg·m-2）and valley（34.30±2.55 kg·m-2）,and was significantly larger than south,southwest and west-facing slopes by factors of 3.20,2.87 and 1.90,respectively.