摘要
通过建立长周期旱涝急转指数(LDFAI),应用Theil-Sen斜率估算、Mann-Kendall检验和Pearson相关分析等方法,揭示1982—2022年黄河中上游地区旱涝急转事件和归一化植被指数(NDVI)的时空变化特征,并探讨旱涝急转事件对植被覆盖的影响。结果表明:①黄河中上游平均2~3 a发生一次旱涝急转事件,其中黄土高原和青藏高原东部地区发生频次较高,2003年以后旱涝急转强度明显减弱。②黄河中上游植被年均NDVI以0.0132/10a的速率增长,尤其在2003年后增速达到显著水平(P<0.05),黄土高原、汾渭平原的植被覆盖度持续升高,黄河源区和鄂尔多斯高原等地植被退化与改善的区域交织共存。③旱涝急转事件对黄河中上游不同类型植被造成不同程度的影响。干旱半干旱地区的旱转涝事件能快速缓解草本植物的干旱压力从而促进生长,尽管草本植物具备一定的长期耐旱性,涝转旱事件造成的水分急剧恶化仍会显著削弱其生长潜力;黄土高原及阴山山脉地区的森林和灌丛,在涝转旱事件发生时生长受到强烈限制;汾渭平原等人工干预较强的区域,栽培植被受旱涝急转事件的影响程度相对较弱,主要得益于人类活动和高质量保护工程的积极影响。
Global climate change has led to frequent occurrence of compound extreme events.Clarifying the temporal and spatial characteristics and their effects on vegetation in ecologically fragile areas of compound events such as dry-wet abrupt alternations can provide scientific basis for safeguarding regional ecological security.By establishing the Long-cycle Drought-Flood Abrupt Alternation Index(LDFAI)and applying the Theil-Sen slope estimation,Mann-Kendall test and Pearson correlation analysis,we reveal the temporal and spatial change characteristics of dry-wet abrupt alternations and NDVI in the upper and middle reaches of the Yellow River from 1982 to 2022,and explore the impacts of these events on vegetation cover.The results indicate that:1)An dry-wet abrupt alternations occurred in the upper and middle reaches of the Yellow River every 2-3 years on average,and the frequency was higher in the Loess Plateau and the eastern Qinghai-Tibet Plateau.The intensity of these events decreased significantly after 2003.2)The annual average NDVI of vegetation in the upper and middle reaches of the Yellow River increased at a rate of 0.0132/10a,especially with a significant growth rate after 2003(P<0.05).The vegetation coverage in the Loess Plateau and Fenwei Plain continued to increase,and the vegetation degradation and improvement coexist in the Yellow River source area and the Ordos Plateau.3)The dry-wet abrupt alternations had different effects on different types of vegetation in the upper and middle reaches of the Yellow River.In arid and semi-arid regions,drought-to-flood events can rapidly alleviate drought stress on herbaceous plants,thereby promoting their growth.Although herbaceous plants possess certain long-term drought tolerance,the sharp deterioration in water availability caused by flood-to-drought events still significantly compromises their growth potential.Forests and shrublands in areas such as the Loess Plateau and the Yin Mountains exhibit strongly constrained growth during flood-todrought events.In regions with greater anthropogenic intervention,such as the Fenwei Plain,cultivated vegetation exhibits a relatively weaker degree of impact from Dry-Wet Abrupt Alternation events.This resilience is primarily attributable to the beneficial effects of human activities and high-quality conservation projects.
作者
朱子青
李铮
殷杰
郭浩
潘涛
贺山峰
Zhu Ziqing;Li Zheng;Yin Jie;Guo Hao;Pan Tao;He Shanfeng(School of Geography and Tourism,Qufu Normal University,Rizhao 276800,Shandong,China;School of Geographical Sciences,East China Normal University,Shanghai 200241,China;College of Tourism,Hunan Normal University,Changsha 410081,Hunan,China)
出处
《地理科学》
北大核心
2025年第12期2751-2763,共13页
Geographical Science
基金
山东省泰山学者青年专家计划(tsqn202103065)
国家自然科学基金项目(42371084)资助。
关键词
旱涝急转事件
NDVI
长周期旱涝急转指数
黄河中上游
dry-wet abrupt alternation event
NDVI
LDFAI
the upper and middle reaches of the Yellow River
