基于全球土地退化零增长监测体系构建的中国沙化土地监测体系及效果评估

土地荒漠化是非常重要的生态环境问题，而科学评价荒漠化治理和零增长目标是否实现的必要前提是具有完善统一的评价体系。为此，联合国防治荒漠化公约（UNCCD）提出了土地退化零增长（LDN）的概念和监测指标。防治土地退化是中国的重要生态目标，中国已开展了多次全国土地荒漠化和沙化监测工作。但是，如何将这些监测结果用于土地退化的评估实践，尚未见报道。因此，本研究针对中国四大沙地，利用3期全国荒漠化和沙化监测数据，与基于UNCCD框架体系下的土地退化零增长（LDN）指标进行对比分析，并基于土地沙化程度变化趋势提出了中国沙化土地退化指标体系（CSLDN）。结果表明：UNCCD所提出的LDN监测指标与中国的荒漠化监测数据总体精度为0.51，中国沙化土地监测指标与LDN指标具有宏观一致性。此外，经本地优化后的CSLDN指标克服了低植被盖度区域LDN对土地退化和恢复的评价不准确的问题，更准确刻画了精细尺度空间内的土地动态变化状况，对土地退化防治意义重大。

Monitoring and evaluation of sandy lands in China and its improvement based on monitoring system of global Land Degradation Neutrality

Land desertification is a very important ecological and environmental problem， and the necessary prerequisite for desertification control and zero-growth goals is to have a complete and unified evaluation system. Therefore， the United Nations Convention to Combat Desertification （UNCCD） proposed the concept and monitoring indicators of Land Degradation Neutrality （LDN）. The prevention and control of soil degradation is also one of the important ecological goals to be achieved in China. China has carried out several national desertification and sandification survey. However， how to use the survey results in the assessment practice of land degradation has not been reported yet. Therefore， aiming at the typical areas of four major sandy land in China， this study makes a comparative analysis of LDN indicators based on the framework system of UNCCD by using three phases of national desertification and sandification survey data， and proposes a desertification land degradation indicator system CLSDN that is more suitable for this region based on the change trend of land desertification degree. The results show that the overall accuracy of the LDN monitoring indicators proposed by UNCCD and the desertification monitoring data in China is 0.51， and China's desertification land monitoring indicators and LDN indicators have macro consistency. In addition， the locally optimized CSLDN index overcomes the problem of inaccurate evaluation of land degradation and restoration by LDN in low vegetation coverage areas， and more accurately depicts the dynamic changes of land in fine-scale space， which is of great significance to the prevention and control of land degradation.