School of Geographical Sciences, Shanxi Normal University, Taiyuan 030031, China.
State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
Int J Environ Res Public Health. 2023 Feb 17;20(4):3608. doi: 10.3390/ijerph20043608.
Drylands, which account for 41% of Earth's land surface and are home to more than two billion people, play an important role in the global carbon balance. This study analyzes the spatio-temporal patterns of vegetation carbon sinks and sources in the arid region of northwest China (NWC), using the net ecosystem production (NEP) through the Carnegie-Ames-Stanford approach (CASA). It quantitatively evaluates regional ecological security over a 20-year period (2000-2020) via a remote sensing ecological index (RSEI) and other ecological indexes, such as the Normalized Difference Vegetation Index (NDVI), fraction of vegetation cover (FVC), net primary productivity (NPP), and land use. The results show that the annual average carbon capacity of vegetation in NWC changed from carbon sources to carbon sinks, and the vegetation NEP increased at a rate of 1.98 gC m yr from 2000 to 2020. Spatially, the annual NEP in northern Xinjiang (NXJ), southern Xinjiang (SXJ) and Hexi Corridor (HX) increased at even faster rates of 2.11, 2.22, and 1.98 gC m yr, respectively. Obvious geographically heterogeneous distributions and changes occurred in vegetation carbon sinks and carbon sources. Some 65.78% of the vegetation areas in NWC were carbon sources during 2000-2020, which were concentrated in the plains, and SXJ, the majority carbon sink areas are located in the mountains. The vegetation NEP in the plains exhibited a positive trend (1.21 gC m yr) during 2000-2020, but this speed has slowed since 2010. The vegetation NEP in the mountain exhibited only intermittent changes (2.55 gC m yr) during 2000-2020; it exhibited a negative trend during 2000-2010, but this trend has reversed strongly since 2010. The entire ecological security of NWC was enhanced during the study period. Specifically, the RSEI increased from 0.34 to 0.49, the NDVI increased by 0.03 (17.65%), the FVC expanded by 19.56%, and the NPP increased by 27.44%. Recent positive trends in NDVI, FVC and NPP have enhanced the capacity of vegetation carbon sinks, and improved the eco-environment of NWC. The scientific outcomes of this study are of great importance for maintaining ecological stability and sustainable economic development along China's Silk Road Economic Belt.
干旱地区占地球陆地表面的 41%，居住着超过 20 亿人口，在全球碳平衡中发挥着重要作用。本研究利用卡内基-梅隆-斯坦福方法（CASA）中的净生态系统生产力（NEP），分析了中国西北部干旱地区（NWC）植被碳汇和源的时空格局。通过遥感生态指数（RSEI）和其他生态指数（如归一化植被指数（NDVI）、植被覆盖度（FVC）、净初级生产力（NPP）和土地利用），定量评估了 20 年来（2000-2020 年）的区域生态安全状况。结果表明，NWC 地区的植被年平均碳容量已由碳源转变为碳汇，2000 年至 2020 年期间，植被 NEP 以 1.98 gC m yr 的速率增加。从空间上看，北疆（NXJ）、南疆（SXJ）和河西走廊（HX）的年 NEP 分别以 2.11、2.22 和 1.98 gC m yr 的速度更快地增长。植被碳汇和碳源在地理上呈现出明显的异质性分布和变化。2000-2020 年间，NWC 约 65.78%的植被区域为碳源，主要集中在平原地区，而大部分碳汇区位于山区。2000-2020 年间，平原地区的植被 NEP 呈正增长趋势（1.21 gC m yr），但自 2010 年以来，这一速度有所放缓。山区的植被 NEP 仅呈现间歇性变化（2.55 gC m yr）；2000-2010 年期间呈负增长趋势，但自 2010 年以来，这一趋势已大幅逆转。整个 NWC 的生态安全状况在研究期间得到了改善。具体而言，RSEI 从 0.34 增加到 0.49，NDVI 增加了 0.03（17.65%），FVC 扩大了 19.56%，NPP 增加了 27.44%。最近 NDVI、FVC 和 NPP 的积极趋势增强了植被碳汇的能力，改善了 NWC 的生态环境。本研究的科学成果对维护中国丝绸之路经济带的生态稳定和可持续经济发展具有重要意义。
