Wu Meng-Yao, Chen Lin, Pang Dan-Bo, Liu Bo, Liu Li-Zhen, Qiu Kai-Yang, Li Xue-Bin
Ministry of Education Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China, Ningxia University, Yinchuan 750021, China.
Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan 750021, China.
Ying Yong Sheng Tai Xue Bao. 2021 Apr;32(4):1241-1249. doi: 10.13287/j.1001-9332.202104.029.
Exploring the distribution patterns of soil nutrients in aggregates of forests along different altitudes in arid and semi-arid areas can provide a theoretical basis for understanding nutrient cycling in vulnerable mountain ecosystems. In this study, we analyzed the distribution and stability of aggregates in the 0-20 cm soil layer along different altitudes (1380-2438 m) of Helan Mountains and measured the storage and stoichiometric characteristics of organic carbon, total nitrogen, and total phosphorus in soil aggregates. Results showed that the main soil aggregates of Helan Mountains changed from micro-aggregates (0.25-0.053 mm) to macro-aggregates (>0.25 mm) with increa-sing elevation. The mean weight diameter (MWD) and geometric mean diameter (GMD) of soil aggregates in high altitude (2139-2248 m) were significantly higher than those in low altitude (1380-1650 m). The content and storage of organic carbon and total nitrogen in soil aggregates of different size fractions were positively correlated with altitude, while the content of total phosphorus fluctuated with the increase in elevation and distributed uniformly in aggregates. Macro-aggregates and micro-aggregates had more contribution to soil nutrient storage than the silt and clay fractions, indicating that the proportion of aggregates with different size fractions was the key factor affecting soil nutrient storage and that macro-aggregates and micro-aggregates were the main carriers of soil nutrients. Moreover, the C:N ratio in aggregates of different size fractions did not change across different altitudes, whereas the C:P and N:P ratio were higher at mid and high elevations than those at low elevations. Our results indicated that the mid and high elevations of Helan Mountains had higher nutrient storage in the surface soil layer, and that higher content of macro-aggregates and micro-aggregates would help to retain organic carbon and nutrients in the soil. Soil nitrogen limitation was strong at low altitude in our study, suggesting that the appropriate amount of nitrogen addition in low altitudes could improve total nitrogen status during forest cultivation.
探究干旱和半干旱地区不同海拔森林团聚体中土壤养分的分布模式，可为理解脆弱山地生态系统中的养分循环提供理论依据。在本研究中，我们分析了贺兰山不同海拔（1380 - 2438米）0 - 20厘米土层中团聚体的分布和稳定性，并测量了土壤团聚体中有机碳、全氮和全磷的储量及化学计量特征。结果表明，随着海拔升高，贺兰山主要土壤团聚体由微团聚体（0.25 - 0.053毫米）变为大团聚体（>0.25毫米）。高海拔（2139 - 2248米）土壤团聚体的平均重量直径（MWD）和几何平均直径（GMD）显著高于低海拔（1380 - 1650米）。不同粒径级分土壤团聚体中有机碳和全氮的含量及储量与海拔呈正相关，而全磷含量随海拔升高波动且在团聚体中分布均匀。大团聚体和微团聚体对土壤养分储存的贡献大于粉粒和黏粒部分，表明不同粒径级分团聚体的比例是影响土壤养分储存的关键因素，且大团聚体和微团聚体是土壤养分的主要载体。此外，不同粒径级分团聚体中的C:N比在不同海拔间无变化，而C:P和N:P比在中高海拔高于低海拔。我们的结果表明，贺兰山的中高海拔表层土壤层养分储存较高，且较高含量的大团聚体和微团聚体有助于土壤中有机碳和养分的保留。在我们的研究中，低海拔土壤氮素限制较强，这表明在低海拔地区适当添加氮素可改善森林培育过程中的全氮状况。
