基于植被-土壤-微生物的退化草地恢复监测及驱动机制研究

Losses Plateau is one of the key regions of the grassland ecological projects. To understand and grasp the present situation and driving mechanisms of restoration of degraded grassland in Losses Plateau, the present situation-ecological efficiency-driving forces of restored grassland will be studied in this project with the temperate grasslands in the hilly Loess Plateau chosen as research object. The monitoring and evaluation method of restoration of degraded grassland based on “Vegetation-Soil-Microorganism” will be built by combining the remote sensing technology and ground observation data. The present situation and spatial pattern of restoration of degraded grassland will be determined by using this system. Then, the spatiotemporal dynamics of grassland net ecosystem productivity will be simulated to reveal the impacts of ecological projects on grassland carbon sequestration ability and resulting carbon sink/source effects. Finally, the relative contribution of climate and human factors to grassland restoration will be studied quantitatively and spatially based on the net primary productivity as an indicator, which will verify the dominant driving factor leading to grassland restoration in different regions. The outcomes of this research will not only provide the theoretical basis and technical support for assessing the efficiency of grassland ecological projects and the sustainable use of grassland resources comprehensively, but also will be of great significance to the adjustment of grassland ecological engineering measures in Loess Plateau during the 13th Five-Year Plan and the development of “the Silk Road Economic Belt” strategic layout.

黄土高原是草地生态工程的重点实施区，为了及时了解和掌握黄土高原退化草地恢复的现状及驱动机制，本项目以黄土丘陵区温带草地为研究对象，开展退化草地恢复现状-效应-驱动力集成研究，采用遥感技术和野外观测“天地”资料相结合的方法，综合草地植被、土壤和微生物要素指标，构建“植被-土壤-微生物”三位一体退化草地恢复监测评价方法，明确退化草地恢复的现状及空间格局；通过模型模拟，分析草地净生态系统生产力的时空动态，探究生态工程的实施对草地固碳能力的影响及产生的碳源/汇效应；以草地净初级生产力为指标，定量化、空间化的分析气候和人为因素对退化草地恢复的相对贡献，揭示不同区域草地恢复的主导驱动因素。项目研究成果不仅为全面评估黄土高原草地生态工程的生态效益及草地资源合理利用提供重要的理论依据和技术支撑，而且对“十三五”期间黄土高原草地生态工程措施调整及发展“丝绸之路经济带”的战略布局具有重要意义。

黄土高原是草地生态工程的重点实施区，为了及时了解和掌握黄土高原退化草地恢复的现状和驱动机制，本项目以黄土丘陵区温带草地为研究对象，采用遥感技术和野外观测相结合的方法，明确了退化草地恢复的现状及空间格局，探讨了生态工程的实施对草地固碳能力的影响及产生的碳源/汇效应，并定量化、空间化的分析气候因子、土地利用变化和管理措施对退化草地恢复的相对贡献。主要取得如下研究进展：1）在2000-2015年间，90%以上黄土高原的草地均呈现恢复的趋势，其中显著恢复（置信区间在99%）的区域面积占草地总面积的54%，主要分布在黄土高原的东部及中部；2）生态工程实施以来，黄土高原草地平均NEP从2000年的1.59 g C m-2·a-1增加到2015年的20.73 g C m-2·a-1，其中，在黄土高原西北部的草地与荒漠带交错区以及陕北地区，草地NEP上升趋势最为明显；3）在2000-2015年间，黄土高原草地NPP增加了11325.133 Gg C·yr-1，其中气候因子和人类活动分别贡献了78.45%和21.55%，在未发生土地利用变化地区的积极的生态管理措施是黄土高原草地NPP增加的最主要因素。项目研究成果为黄土高原草地资源合理利用及植被恢复策略调整提供重要的理论依据。