Su Jingxuan, Fan Liangxin, Yuan Zhanliang, Wang Zhen, Wang Zhijun
School of Surveying and Land Information Engineering, Henan Polytechnic University, Jiaozuo, Henan 454003, China.
School of Surveying and Land Information Engineering, Henan Polytechnic University, Jiaozuo, Henan 454003, China.
Sci Total Environ. 2024 Feb 1;910:168688. doi: 10.1016/j.scitotenv.2023.168688. Epub 2023 Nov 20.
Grassland is essential for maintaining the stability and functionality of terrestrial ecosystems. Although previous research has explored how grassland responds to drought, the drought sensitivity of grassland (DSG) across climate zones and aridity gradients remains uncertain. In this study, we conducted a comprehensive investigation spanning 1982 to 2015 in Northwest China. To assess the time-cumulative effect (TCE) and the time-lag effect (TLE) of drought on grassland, we employed Spearman rank correlation analysis, utilizing long-term datasets of the normalized difference vegetation index (NDVI) and the standardized precipitation evapotranspiration index (SPEI). This analysis allowed us to quantify the DSG in the region and further examine its variations across climate zones and aridity gradient. Our results revealed that 81.2 % and 99.7 % of the grassland in Northwest China was influenced by the TCE and TLE of drought, respectively, with 38.2 % and 60.9 % of these effects being statistically significant (p < 0.05). The mean accumulated and lagged timescales of drought on grassland were 7.89 and 9.41 months, respectively. Remarkably, the highest DSG was observed in the semi-arid zone (0.58), followed by the arid (0.54), sub-humid (0.51), and humid (0.44) zones. Furthermore, we identified significant nonlinear variation patterns of DSG along the aridity gradient, characterized by several discernible trend breaks. These findings contribute to our understanding of the impacts of drought on vegetation, particularly in ecologically fragile regions.
草原对于维持陆地生态系统的稳定性和功能至关重要。尽管先前的研究已经探讨了草原对干旱的响应，但不同气候区和干旱梯度下草原的干旱敏感性（DSG）仍不明确。在本研究中，我们对中国西北1982年至2015年进行了全面调查。为了评估干旱对草原的时间累积效应（TCE）和时间滞后效应（TLE），我们采用Spearman秩相关分析，利用归一化植被指数（NDVI）和标准化降水蒸散指数（SPEI）的长期数据集。该分析使我们能够量化该地区的DSG，并进一步研究其在不同气候区和干旱梯度上的变化。我们的结果显示，中国西北分别有81.2%和99.7%的草原受到干旱的TCE和TLE影响，其中38.2%和60.9%的影响具有统计学意义（p < 0.05）。干旱对草原的平均累积和滞后时间尺度分别为7.89个月和9.41个月。值得注意的是，半干旱区的DSG最高（0.58），其次是干旱区（0.54）、亚湿润区（0.51）和湿润区（0.44）。此外，我们还确定了DSG沿干旱梯度的显著非线性变化模式，其特征是有几个明显的趋势断点。这些发现有助于我们理解干旱对植被的影响，特别是在生态脆弱地区。
