贺兰山不同海拔土壤团聚体碳氮磷含量及其化学计量特征变化

探究干旱半干旱区山地森林生态系统不同海拔土壤养分在团聚体中的分布规律,可为理解脆弱山地生态系统养分循环提供理论依据.本研究以贺兰山不同海拔(1380 ～2438 m)土壤为对象,分析0～20 cm土层团聚体分布及其稳定性、不同粒级团聚体有机碳、全氮、全磷储量及其化学计量特征.结果 表明:随海拔升高贺兰山主要土壤团聚体由...

Changes of the concentrations and stoichiometry of carbon,nitrogen and phosphorus in soil aggregates along different altitudes of Helan Mountains,Northwest China.

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.