中国北方自然生态系统土壤有机碳含量及其影响因素

Soil organic carbon concentrations and the influencing factors in natural ecosystems of northern China

土壤有机碳是陆地生态系统碳库中最活跃的组分,其较小幅度的变动,可导致大气中CO_2浓度的剧烈变化,从而影响全球气候变化。本研究以中国北方荒漠、草地、灌丛和森林生态系统为研究对象,结合气候、土壤和植被群落特征等因素,探究区域尺度下表层土壤有机碳含量及影响因素。结果表明:研究区内各生态系统间土壤有机碳含量差异显著,其中森林土壤有机碳含量最高,其次为灌丛和草地,荒漠土壤有机碳含量最低;土壤有机碳含量与年平均温度、土壤pH和砂粒含量呈显著负相关,与年平均降水量、黏粒含量、粉粒含量、NDVI指数和植物物种丰富度呈显著正相关,与植物物种多样性呈正相关趋势但未达到显著水平;在区域尺度下,土壤有机碳含量主要受到气候因子、土壤因子和植被因子共同作用的影响。

Soil organic carbon(SOC)is the most active component in terrestrial carbon pool.Small variations in global SOC stock could result in significant impacts on the atmospheric CO2 concentration and contribute to global climate change.In this study,we collected 528 soil samples at 77 sites from different natural ecosystems(desert,grassland,shrubland,and forest)in northern China.We compared the differences of SOC concentrations in different ecosystems and analyzed the influencing factors on SOC concentrations.The results showed that SOC concentration was the highest in forests,with an order:forest>shrubland>grassland>desert.The SOC concentrations were significantly positively correlated with mean annual precipitation,clay content,silt content,NDVI,and plant species richness,but negatively correlated with mean annual temperature,soil pH,and sand content.We found a positive but insignificant correlation between SOC concentrations and plant species alpha diversity.The variations of SOC concentrations were mainly driven by soil,climate,and vegetation factors at regional scale.