秦岭太白山北坡土壤有机碳储量的海拔梯度格局

土壤碳库是陆地生态系统的重要碳库,山区大约占全球25%的陆地表面积,因此研究山区土壤有机碳储量的变化特征及其影响因素对丰富陆地生态系统土壤碳循环理论具有重要的意义。在秦岭太白山北坡上,海拔高度每隔50 m设置一个采样点,研究土壤有机碳储量的海拔梯度变化特征及其影响因素。海拔梯度对太白山北坡的SOCD影响显著,且不同土层厚度的SOCD均呈现出随着海拔梯度的增加而增加的趋势,增加幅度高达10%—88%。不同气候带上的SOCD差异显著,呈现出亚寒带(3.63 kg/m~2)大于寒温带(3.40 kg/m~2)大于温带(3.39 kg/m~2)大于暖温带(3.30 kg/m~2)的趋势。SOCD也因植被带发生显著差异,最小值出现在低山扰动带仅为2.15 kg/m~2,而最大值出现在高山草甸带高达3.63 kg/m~2,平均2.94 kg/m~2。SOCD随着土层厚度的增加呈现出减少的趋势,减少幅度为14%—70%。在太白山北坡上,随着海拔梯度的增加,土层深度从低山区的78 cm减少到中山区的33 cm和高山区的10 cm,相应的总SOCD从低山区的35.45 kg/m~2减少到中山区的28.84 kg/m~2和高山区的12.29 kg/m~2,但是对应单位土层深度上的SOCD却从低山区的0.51 kg/m~2增加到中山区的0.87 kg/m~2和高山区的1.23 kg/m~2。因此,在秦岭太白山北坡上,除了海拔梯度、气候带、植被带、土层厚度等因素以外,土层深度对土壤有机碳储量的影响不容忽视,这对准确预测该区域的土壤碳储量具有重要的理论和实际意义。

The elevational patterns of soil organic carbon storage on the northern slope of Taibai Mountain of Qinling

Soil carbon pool is an important carbon pool of terrestrial ecosystems. The mountainous areas account for about 25% of the world''s surface area. Study on variations of the soil organic carbon storage in mountainous areas and their influencing factors is of great significance for enriching the soil carbon cycle theory of terrestrial ecosystems. On the northern slope of the Taibai Mountain in the Qinling, the sampling sites were set at every 50 meters above sea level to explore characteristics of the soil organic carbon storage along an altitude gradient. The results showed that altitude gradient had a significant impact on the soil organic carbon density (SOCD). The SOCD of different soil thicknesses increased by 10%-88% with the increasing altitude gradient. The climate zone also presented a significant impact on the SOCD. The order was subfrigid zone (3.63 kg/m²) > cold temperate zone (3.40 kg/m²) > temperate zone (3.39 kg/m²) > warm temperate zone (3.30 kg/m²). The SOCD showed significantly variation along different vegetation zones, with an average value of 2.94 kg/m². The minimum value of 2.15 kg/m² occurred in the low mountain disturbance zone, while the maximum value of 3.6 kg/m² appeared in the alpine meadow zone. The SOCD showed a decreasing trend with the increase of soil thickness, with a reduction range of 14%-70%. On the northern slope of Taibai Mountain, the soil depth was 78 cm in the low mountainous area, whereas it was 33 cm and 10 cm in the middle and high mountainous area, respectively. Total SOCD was 35.45 kg/m², 28.84 kg/m², and 12.29 kg/m² in the low, middle, and high mountainous area, respectively. As opposed, the SOCD at the depth of the unit soil in the low, middle, and high mountainous area was 0.51 kg/m², 0.87 kg/m², and 1.23 kg/m², respectively. The results indicated that, in addition to the elevation gradient, climatic zone, vegetation zone, and soil thickness, the influence of soil depth on soil organic carbon storage cannot be ignored for accurate prediction of soil carbon storage in this area.