Xi Dan, Yu Ze-Ping, Xiong Yong, Liu Xiao-Yu, Liu Jun
Forest Ecology Stable Isotope Center, College of Forestry, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Administration of Jiangxi Guanshan National Nature Reserve, Yichun 336000, Jiangxi, China.
Ying Yong Sheng Tai Xue Bao. 2020 Oct;31(10):3349-3356. doi: 10.13287/j.1001-9332.202010.009.
We investigated soil total organic carbon (TOC), recalcitrant organic carbon (ROC), and labile organic carbon (LOC) of evergreen broadleaved forests at different altitudes (400, 600, 800, 1000 and 1200 m) in Guanshan National Nature Reserve, Jiangxi Province, with the aim to understand their altitudinal distribution. The results showed that soil TOC, ROC and LOC contents were the highest in the surface layer and decreased with soil depth. With the increases of altitude, contents of soil TOC, ROC, readily oxidizable organic carbon (ROOC), microbial biomass carbon (MBC), and particulate organic carbon (POC, 0-20 cm depth) increased with a peak at 1000 m and then decreased, whereas soil water-soluble organic carbon (WSOC) contents and POC contents in 20-40 cm layer did not change. In 0-10 cm soil layer, the proportions of ROC to TOC at 800 and 1200 m were significantly higher than those at 400 and 1000 m, while the proportions of LOC to TOC were the highest at 400 m. The proportions of ROC and LOC to TOC in 10-40 cm layer showed a low-high-low tendency along the altitude, with peaks at 1000 and 600 m, respectively. Soil organic carbon fractions were positively correlated with soil moisture, microbial biomass nitrogen, and soluble organic nitrogen. A positive correlation was observed between LOC and ammonium concentration. Our results suggested that altitude significantly affected the distribution of soil organic fractions, with soil ROC, ROOC and MBC being more sensitive to altitudinal changes. Soil ROC and LOC at high altitude were prone to decomposition and transformation under conditions with sufficient water and nitrogen, which reduced soil carbon stability. It was essential to study the dyna-mics of soil organic carbon in high altitude forests under global warming scenarios.
我们对江西省官山国家级自然保护区不同海拔（400、600、800、1000和1200米）的常绿阔叶林土壤总有机碳（TOC）、难降解有机碳（ROC）和易降解有机碳（LOC）进行了调查，旨在了解它们的海拔分布情况。结果表明，土壤TOC、ROC和LOC含量在表层最高，并随土壤深度的增加而降低。随着海拔的升高，土壤TOC、ROC、易氧化有机碳（ROOC）、微生物生物量碳（MBC）和颗粒有机碳（POC，0 - 20厘米深度）含量先增加，在1000米处达到峰值，然后下降，而土壤水溶性有机碳（WSOC）含量以及20 - 40厘米土层中的POC含量没有变化。在0 - 10厘米土层中，800米和1200米处ROC占TOC的比例显著高于400米和1000米处，而LOC占TOC的比例在400米处最高。10 - 40厘米土层中ROC和LOC占TOC的比例沿海拔呈低 - 高 - 低趋势，分别在1000米和600米处达到峰值。土壤有机碳组分与土壤湿度、微生物生物量氮和可溶性有机氮呈正相关。LOC与铵浓度之间存在正相关关系。我们的结果表明，海拔显著影响土壤有机组分的分布，其中土壤ROC、ROOC和MBC对海拔变化更为敏感。在水分和氮素充足的条件下，高海拔地区的土壤ROC和LOC易于分解和转化，这降低了土壤碳稳定性。在全球变暖情景下，研究高海拔森林土壤有机碳动态至关重要。
