草地退化与植被-土壤氮储量和土壤N2O通量的关系研究-以内蒙古典型草原为例

In natural grassland ecosystems, nitrogen is one of the major limiting factors of vegetation growth. The degraded grassland of typical steppe area in xilingol league of Inner Mongolia is taken as the research object in the project, and taken the measured data, remote sensing data and the meteorological data as data sources, through the field observation and DNDC model simulation, to study comparatively the difference of soil nitrogen storage of grassland vegetation and soil, and the characteristics of the soil N2O flux, to investigate the influence of grassland degradation on nitrogen storage of soil and vegetation and on soil N2O flux, to reveal the mechanism of vegetation, soil nitrogen storage change and soil N2O flux change. This research will provide a scientific basis for further evaluation of grassland ecosystem services and for rational management of grassland, provide theoretical basis for predicting the impact of grassland degradation on the greenhouse gas emissions.

在天然草原生态系统，氮是植被生长的主要限制因子之一。本项目以内蒙古锡林郭勒盟典型草原区的退化草地为研究对象，以地面实测数据、遥感数据、气象数据等为数据源，通过野外观测和DNDC模型模拟，对比研究不同程度退化草地植被、土壤氮储量和土壤N2O通量的特征，探讨草地退化对植被、土壤氮储量和土壤N2O通量的影响，揭示植被、土壤氮储量和土壤N2O通量变化的机理。为进一步评估草原生态系统服务、合理管理草地提供科学依据，为预测草地退化对温室气体排放的影响提供理论基础。

以内蒙古锡林郭勒典型草原区的退化草地为研究对象，在样地尺度上定量分析了不同程度退化草地植物和土壤特征的变化，观测了退化草地氮储量和N2O通量的变化，并利用DNDC模型对土壤氮储量、N2O通量进行了模拟，综合实验测定与模型模拟的结果分析了影响土壤氮储量和N2O通量的敏感因素；区域尺度上，利用遥感监测手段对研究区草地的退化情况进行识别与分级，通过路线考察与采样，对区域尺度不同退化程度的草地氮储量进行计算，利用DNDC模型结合遥感技术对研究区的植被与土壤氮储量及变化进行了探索，对模拟结果的精度、敏感参数、不确定性和影响因素进行了分析。综合不同尺度的实验结果，厘定出了一套内蒙古典型草原区DNDC模型的参数，揭示了植被、土壤氮储量和土壤N2O通量变化的机理。