Wang Haijun, Peng Peihao, Kong Xiangdong, Zhang Tingbin, Yi Guihua
College of Earth Science, Chengdu University of Technology, Chengdu, Sichuan, China.
Engineering and Technical College of Chengdu University of Technology, Leshan, Sichuan, China.
PeerJ. 2019 Dec 13;7:e8223. doi: 10.7717/peerj.8223. eCollection 2019.
This study focuses on the vegetation dynamic caused by global environmental change in the eastern margin of the Qinghai-Tibet Plateau (EMQTP). The Qinghai-Tibet Plateau (QTP) is one of the most sensitive areas responding to global environmental change, particularly global climate change, and has been recognized as a hotspot for coupled studies on changes in global terrestrial ecosystems and global climates. An important component of terrestrial ecosystems, vegetation dynamic has become a key issue in global environmental change, and numerous case studies have been conducted on vegetation dynamic trends using multi-source data and multi-scale methods across different study periods. The EMQTP is regarded as a transitional area located between the QTP and the Sichuan basin, and has special geographical and climatic conditions. Although this area is ecologically fragile and sensitive to climate change, few studies about vegetation dynamics have been carried out in this area. Thus, in this study, we used long-term series datasets of GIMMS 3g NDVI and VGT/PROBA-V NDVI to analyze the vegetation dynamics and phenological changes from 1982 to 2018. Validation was performed based on Landsat NDVI and Vegetation Index & Phenology (VIP) data. The results reveal that the year 1998 was a vital turning point in the start of growing season (SGS) in vegetation ecosystems. Before this turning point, the SGS had an average slope of 9.2 days/decade, and after, the average slope was 3.9 days/decade. The length of growing season (LGS) was slightly prolonged between 1982 to 2015. Additionally, the largest national alpine wetland grassland experienced significant vegetation degradation; in autumn, the degraded area accounted for 63.4%. Vegetation degradation had also appeared in the arid valleys of the Yalong River and the Jinsha River. Through validation analysis, we found that the main causes of vegetation degradation are the natural degradation of wetland grassland and human activities, specifically agricultural development and residential area expansion.
本研究聚焦于青藏高原东缘（EMQTP）全球环境变化所引发的植被动态。青藏高原（QTP）是对全球环境变化，尤其是全球气候变化最为敏感的地区之一，并且已被视作全球陆地生态系统变化与全球气候耦合研究的热点地区。植被动态作为陆地生态系统的一个重要组成部分，已成为全球环境变化中的一个关键问题，并且在不同研究时期，已经运用多源数据和多尺度方法针对植被动态趋势开展了大量案例研究。EMQTP被视为位于QTP与四川盆地之间的过渡区域，具有特殊的地理和气候条件。尽管该地区生态脆弱且对气候变化敏感，但针对该地区植被动态的研究却很少。因此，在本研究中，我们使用了GIMMS 3g NDVI和VGT/PROBA-V NDVI的长期序列数据集，来分析1982年至2018年期间的植被动态和物候变化。基于陆地卫星NDVI和植被指数与物候（VIP）数据进行了验证。结果显示，1998年是植被生态系统生长季开始（SGS）的一个关键转折点。在这个转折点之前，SGS的平均斜率为9.2天/十年，之后平均斜率为3.9天/十年。1982年至2015年期间生长季长度（LGS）略有延长。此外，全国最大的高寒湿地草原经历了显著的植被退化；秋季，退化面积占63.4%。雅砻江和金沙江的干旱河谷也出现了植被退化。通过验证分析，我们发现植被退化的主要原因是湿地草原的自然退化和人类活动，特别是农业发展和居民区扩张。
