呼伦贝尔草原辉河湿地不同淹水状态的土壤碳氮磷特征比较

碳(C)、氮(N)、磷(P)生态化学计量比是生态系统过程及其功能的重要特征。为了比较不同淹水状态下草原区河岸湿地土壤生态化学计量特征差异,探讨用土壤生态化学计量特征来表征草原河岸湿地的退化状态,以呼伦贝尔草原辉河河岸湿地为研究对象,分别选择完全退化和未退化河岸湿地,从中选取常年淹水区域(W)、年际干湿交替区域(WD)以及河岸带边缘多年未曾淹没的干燥区域(D)为观测样地,对比研究退化与未退化草原河岸湿地土壤C、N、P化学计量比在不同淹水状态下的表征。结果表明:(1)随着淹水状态的改变,不论是退化河岸湿地还是未退化河岸湿地,不同淹水状态下的土壤C/N、C/P、N/P均差异显著(P0.05);(2)退化河岸湿地的C/N、C/P和N/P的平均值分别为9.05、273.08和28.25,与未退化河岸湿地相比(7.85、95.48、11.41)值显著升高;(3)相关性分析结果显示,土壤总磷与有机碳、全氮显著正相关,与C/N、C/P、N/P负相关,这可能是限制退化河岸湿地土壤养分元素循环的主要因素。研究结果表明:呼伦贝尔草原辉河河岸湿地不同淹水状态的土壤碳、氮、磷特征差异明显(P0.05),尤其是土壤C/P和N/P。与未退化河岸湿地相比,退化河岸湿地的C/N、C/P、N/P均明显高于未退化河岸湿地(P0.05),因此可以将土壤碳、氮、磷化学计量比特征作为草原区河岸湿地退化的评价指标。

Comparison of soil carbon, nitrogen, and phosphorus characteristics of Hulun Buir grassland under different flooding conditions in the Hui River wetland

The ecological stoichiometric ratio of carbon, nitrogen, and phosphorus is an important feature of ecosystem processes and functions. In this study, we examined soil stoichiometric characteristics of degraded and undegraded riparian in the Hui River wetland under different flooding conditions, and explored whether soil stoichiometric characteristic can be used to evaluate degeneration of grasslands wetland riparian. Within the riparian area, perennial wetted areas, areas of interannual wet-drying cycles, and dried areas along riparian margins that have not been submerged for many years were selected to study their soil stoichiometric characteristics. The results showed that (1) in both degraded and undegraded grasslands wetland riparian, there were significant differences in soil C/N, C/P, and N/P across the three areas (P < 0.05), (2) in degraded grassland wetland riparian, the average values of C/N, C/P, and N/P were 9.05, 273.08, and 28.25, respectively, which were higher than undegraded grassland wetland riparian (7.85, 95.48, and 11.41, respectively), (3) correlation analysis showed that soil total phosphorus were positively correlated with soil organic carbon and total nitrogen, but negatively correlated with C/N, C/P, and N/P. Soil total phosphorus may be the main factor limiting nutrient cycling in degraded grassland wetland riparian. These results indicate that soil carbon, nitrogen, and phosphorus characteristics, particularly soil C/P and N/P were significantly different among areas of the Hui River wetland under different flooding status in Hulun Buir grassland. Compared with undegraded grassland wetland riparian, degraded grassland wetland riparian showed a significant increase in the values of soil C/N, C/P and N/P. Therefore, the stoichiometric characteristics of soil carbon, nitrogen, and phosphorus can be used as evaluation indices for grassland wetland riparian.