蒙古国植被指数时空变化特征及其对气温降水的响应

The Mongolian Plateau, a vital ecological barrier in northern China, is of great importance for studying vegetation dynamics in Mongolia against the background of climate warming. Such studies can enhance our understanding of regional vegetation responses to global warming and contribute to the establishment of a stronger ecological barrier in northern China. Here, we analyzed the spatial and temporal characteristics of the NDVI (normalized difference vegetation index) in Mongolia using 8 km resolution GIMMS NDVI3g data from 1990 to 2022, along with temperature, precipitation, and elevation data. Trend analysis and correlation methods were used to examine the relationships between the NDVI and temperature, as well as precipitation. The results showed four important aspects of these relationships. (1) The NDVI in Mongolia increased significantly from 1990 to 2022 at a rate of 0.0015 yr ^–1 （ P <0.05） . (2) Mongolia’s NDVI increased from 1990 to 2022 in 60.73% of the country. Of this total, the area with a significant increase accounted for 31.67% and was concentrated on the eastern and western edges. The area experiencing a significant decrease accounted for 15.67% and was mainly located on the southwestern edges. (3) The NDVI analysis revealed significant increasing trends in all regions except for those at elevations of 1500–2000 m. The greatest rate of increase was observed between 500 and 1000 m, and the increasing trend weakened as elevation continued to increase before gradually becoming significant again. Additionally, the NDVI increased significantly across different slopes, and the rate of increase decreased as the slope increased. (4) From 1990 to 2022, Mongolia’s NDVI was mostly negatively correlated with temperature. This occurred over 66.75% of the total land area, with 17.21% of the region exhibiting a significant negative correlation, mainly in the southwest. Conversely, the NDVI demonstrated a positive correlation with precipitation, encompassing 86.71% of the total land area. Approximately 40.44% of the region had a significant positive correlation, primarily in the southwest. In conclusion, throughout the experimental period, the vegetation state in Mongolia improved. However, due to the warming and drying climate, more attention should be paid to vegetation degradation in the south-central region.

蒙古高原是我国北方重要生态屏障，开展气候变暖背景下蒙古国植被动态变化研究，对于深入了解全球气候变暖的区域植被响应特征及筑牢我国北方生态屏障具有重要的理论与现实意义。本研究以 1990–2022 年 8 km 分辨率逐年 GIMMSNDVI3g 数据、气温和降水及高程数据为基础，采用趋势分析和相关分析方法，分析了蒙古国 NDVI（Normalized Difference Vegetation Index）时空变化特征及其与气温、降水的关系。结果表明：（1）1990–2022 年蒙古国 NDVI 呈显著增长趋势，增长速率为 0.0015 yr ^–1 （ P <0.05）。（2）空间上，1990–2022 年蒙古国 NDVI 以增加趋势为主，占国土面积的 60.73%，其中显著增加占 31.67%，集中分布在蒙古国东部及西部边缘地区；显著减少占 15.67%，集中分布在蒙古国西南部边缘地区。（3）从地形上来看，除海拔 1500–2000 m 范围 NDVI 呈不显著增加趋势外，其他区域 NDVI 均呈显著增加趋势，其中 500–1000 m 增加速率最快，并随海拔升高增加趋势先减弱后逐渐显著；不同坡度范围 NDVI 均呈显著增加趋势，并随坡度增加增速降低。（4）1990–2022年蒙古国 NDVI 与气温以负相关关系为主，占国土面积的 66.75%，其中呈显著负相关的区域占 17.21%，主要分布在蒙古国西南部地区；NDVI 与降水以正相关关系为主，占国土面积的 86.71%，其中呈显著正相关的区域占 40.44%，主要分布在蒙古国西南部地区。研究认为蒙古国植被生态质量总体改善，但气候暖干化引起的中南部区域植被生态恶化应引起重视。