干旱区三工河流域土壤有机碳储量及空间分布特征

精确估算干旱区流域生态系统土壤有机碳库是进行干旱区土壤碳循环研究的重要前提。论文利用改进的土壤类型法--基于网格的土壤类型法，以干旱区典型的三工河流域为例，精确估算流域土壤碳储量，分析土壤碳密度的空间分布特征，为干旱区土壤碳循环研究提供数据支撑。研究结果显示，三工河流域0~20cm土壤有机碳储量为14.35Tg，平均土壤有机碳密度为6.70kgC/m²，其中山地灰褐土土壤有机碳密度最大，这主要是受中山带较低的气温和丰富的森林凋落物的影响；流域土壤有机碳密度表现出了明显的垂直地带性和水平地带性特征，即碳密度从山地区、丘陵区、绿洲区到荒漠区呈逐渐减小的趋势，且随海拔高度的降低碳密度逐渐减小。

Soil Organic Carbon Storage and Its Spatial Distribution Characteristic in the Sangong River Watershed of Arid Region

Carbon cycle research of terrestrial ecosystems plays a pivotal role in global change. Accurate estimation of soil organic carbon storage in the watershed scale ecosystems of arid region is one of the important premise to study the carbon sink and source effect. In the past 50 years, the large-scale exploitation has resulted in the spatio-temporal distribution change of water and land resource in the northwest arid region of China. All the human activities have resulted in the change of SOC storage in the arid region. In this study, the Sangong River watershed was taken as a study case. We have estimated the soil carbon storage in oasis area using the improved soil type method and in mountain area, hilly area and desert area using the soil type method, and analyzed the spatial distribution characteristic of soil organic carbon density in order to offer a data supporting for soil carbon cycle study of arid region. The results showed that the total soil organic carbon storage in 0 -20cm depth was 1431. 5 × 10~4 t (14. 3 Tg) , mean soil organic carbon density was 6. 70 kgC/m~2, and soil organic carbon content was 34. 26 g/kg in the whole Sangong River watershed, while it is only 170. 4 × 10~4t C in the oasis area based on improved soil type method ( grid method) estimation. At all soil types, the mountain grey cinnamon forest soil has maximum carbon storage (548. 6 × 10~4t C) due to the impact of lower temperature and forest litter on soil humus accumulation process in the mid-mountain zone of Tianshan Mountains. The distribution of soil organic carbon density showed significant characteristic of vertical zonality and horizontal zonality, this is that carbon density tends to decrease from mountain area, hilly area, oasis area to desert area, and change with altitude from high to low. In the whole watershed, mean soil carbon density of mountain area was 25. 92 kgC/m~2, being more than the watershed mean carbon density (6. 70 kgC/m~2) , while in the hilly area, oasis area and desert area, it was less than the watershed mean carbon density, being consistent with the thermal and vegetation distribution in the northwest arid region of China.