Chen Zhixuan, Xu Xia, Wen Yongli, Cheng Man, Wang Xiao
Institute of Loess Plateau, Shanxi University, Taiyuan 030006, China.
School of Environmental and Resource Sciences, Shanxi University, Taiyuan 030006, China.
Plants (Basel). 2024 Aug 20;13(16):2320. doi: 10.3390/plants13162320.
The ecological stoichiometric characteristics of soil elements have greatly enhanced our understanding of the circulation of soil nutrients. However, there is limited knowledge regarding the alteration of carbon, nitrogen, and phosphorus stoichiometric ratios in deep soil after afforestation. To examine the variations in stoichiometric ratios of soil elements with different vegetation types, restoration times, and soil depths, we collected soil samples from grassland, shrubland, and forestland at different stand ages (10a, 25a, and 40a) in Xining City, which is located on the Loess Plateau. Our results showed that, at 25a, the carbon-to-nitrogen (C:N) and carbon-to-phosphorus (C:P) ratios were significantly higher in the grassland soil than under other vegetation types, whereas the nitrogen-to-phosphorus (N:P) ratio had no significant difference among the three vegetation types. At 40a, the ratios of soil C:N, C:P, and N:P in the shrubland were the highest. With the increasing of the restoration time, the ratios of soil C:N, C:P, and N:P in grassland with 25a became higher than for 40a or 10a. The ratios in the shrubland were highest at 40a, followed by 25a and then 10a, while the ratios in the forestland showed no significant difference. At 40a, the soil C:N, C:P, and N:P ratios of shrubland were highest at the soil depth of 40-100 cm. The soil C:N, C:P, and N:P ratios showed positive correlations with soil ammonium nitrogen and nitrate nitrogen, and the soil N:P ratios showed a negative correlation with soil available phosphorus. Plant diversity significantly influenced the soil stoichiometric ratio of the upper soil layer. In the upper soil layer (0-40 cm), species richness showed a positive correlation with soil C:N, C:P, and N:P ratios, and the Margalef index exhibited a positive correlation with soil C:N and C:P ratios. The results of this study indicate that the stoichiometric ratio and nutrient availability of shrubland were the highest over time. Therefore, these findings can be served as a valuable reference for local revegetation and ecological restoration.
土壤元素的生态化学计量特征极大地增进了我们对土壤养分循环的理解。然而，关于造林后深层土壤中碳、氮和磷化学计量比的变化，我们所知有限。为了研究不同植被类型、恢复时间和土壤深度下土壤元素化学计量比的变化，我们在位于黄土高原的西宁市，采集了不同林龄（10年、25年和40年）的草地、灌木林和林地的土壤样本。我们的结果表明，在25年时，草地土壤中的碳氮比（C:N）和碳磷比（C:P）显著高于其他植被类型下的土壤，而氮磷比（N:P）在三种植被类型之间没有显著差异。在40年时，灌木林的土壤C:N、C:P和N:P比最高。随着恢复时间的增加，25年草地的土壤C:N、C:P和N:P比高于40年或10年的草地。灌木林的这些比值在40年时最高，其次是25年，然后是10年，而林地的这些比值没有显著差异。在40年时，灌木林在40 - 100厘米土壤深度处的土壤C:N、C:P和N:P比最高。土壤C:N、C:P和N:P比与土壤铵态氮和硝态氮呈正相关，土壤N:P比与土壤有效磷呈负相关。植物多样性显著影响上层土壤的土壤化学计量比。在上层土壤（0 - 40厘米）中，物种丰富度与土壤C:N、C:P和N:P比呈正相关，Margalef指数与土壤C:N和C:P比呈正相关。本研究结果表明，随着时间推移，灌木林的化学计量比和养分有效性最高。因此，这些发现可为当地植被恢复和生态修复提供有价值的参考。
