地理分区视角下的蒙古国土地退化量化分析

Natural and anthropogenic disturbances accelerate land degradation (LD) in arid, semi-arid, and dry sub-humid areas, leading to reduced land quality and productivity, loss of biodiversity, degradation of ecosystem services, and a decline in the quality of life of local people. To address this issue, the United Nations Convention to Combat Desertification (UNCCD) has set a target for LD neutrality (LDN). However, quantifying and comparing the status of LD at global or regional scales remains challenging due to the lack of coherent quantitative methods and tools. In this study, we focused on Mongolia, a region with significant LD problems, to examine patterns of LD and changes from 2015 to 2020, accounting for regional differences. Trends.Earth was used, as recommended by the UNCCD. The main findings are as follows: (1) Overall, the degraded land area in Mongolia accounted for 12.11% of the total land area, predominantly located in the southwest desert and desert steppe, gradually spreading to the northeast steppe. (2) The areas showing improvement in the land productivity index and degradation were 17.62% and 11.79%, respectively, with the most severely degraded areas concentrated in the southern desert and desert steppe regions. (3) The areas of improvement and degradation in the land cover index were 1.80% and 0.16%, respectively, with degraded areas scattered across regions of steppe, high mountains, and mountain taiga. (4) The areas of improvement and degradation in the land organic carbon index were 1.54% and 0.22%, respectively, with degradation primarily observed in adjacent areas of mountain taiga, steppe, and desert steppe. (5) The improved area (2.999× 10 ⁵ km ² ) of LDN are more than the degraded area (1.895× 10 ⁵ km ² ), indicating a positive trend toward LDN in Mongolia.

自然和人为因素的干扰加速了干旱、半干旱和亚湿润干旱地区的土地退化（LD）过程，导致土地质量和生产力降低、生物多样性丧失、生态系统服务功能退化，乃至当地人民生活质量下降。为了防止土地退化，联合国防治荒漠化公约（UNCCD）提出土地退化零增长（LDN）目标。然而，由于缺少一致性评估的定量方法和工具，很难对全球或区域土地退化状态进行量化和对比研究。本研究尝试利用 UNCCD 推荐的 Trends.Earth 工具，选择土地退化问题突出的蒙古国为研究区，引入地理分区视角，研究其 2015–2020 年土地退化的格局与变化。主要结果如下：（1）总体上，2015–2020 年有 12.11%的地区新增加了土地退化，退化区域位于西南部荒漠、荒漠草原，并逐渐向东北部草原地理分区蔓延。（2）土地生产力指标恢复和退化区域分别为 17.62%和11.79%，严重退化区域位于蒙古国南部荒漠和荒漠草原地理分区。（3）土地覆盖指标恢复和退化区域分别为 1.80%和 0.16%，退化区零散地分布在草原、高山和山地针叶林地理分区。（4）土地有机碳指标恢复和退化区域分别为 1.54%和 0.22%，退化区主要位于山地针叶林、草原与荒漠草原相邻地带。（5）LDN 综合指标恢复区面积（2.999×10 ⁵ km ² ）大于退化区面积（1.895× 10 ⁵ km ² ），反映出土地退化零增长目标有向好趋势。