在退耕还林草的背景下，本研究明晰了植被变化对气候和人类活动的响应机制。
文章概述>>
文章题目
Determining the impacts of climate change and human activities on vegetation change on the Chinese Loess Plateau considering human-induced vegetation type change and time-lag effects of climate on vegetation growth
文章摘要
自1999年退耕还林工程启动以来，黄土高原植被状况发生了巨大变化。在空间上，利用地理探测器确定影响归一化差异植被指数（NDVI）空间分异的主导因子。
本研究首先利用NDVI月尺度数据与降水量、温度和标准化降水蒸散发指数（SPEI）月尺度数据逐像元分析植被对气象因子的时滞效应，然后在土地覆盖类型不变的区域构建NDVI与具有时滞效应的气象因子之间的随机森林回归模型，应用到土地覆盖类型发生变化的区域，基于残差归因气候变化和人类活动对黄土高原植被动态的影响。
研究结果表明：（1）降水、坡度和土壤类型是影响黄土高原NDVI空间分异的主导因素。（2）当月降水量和前1-2个月的累积温度对植被生长有显著影响，2000年前后SPEI的最佳累积时间分别为8个月和4个月。（3）2000年前，黄土高原林地和草地植被平均NDVI的增加主要由气候变化驱动，占76.2%，2000年后，主要由人类活动驱动，占64.16%。
关键词
NDVI
climate change
human activities
Geodetector
random forest model
Loess Plateau
引用格式
Miaomiao Cheng, Zhihui Wang, Shidong Wang, Xinjie Liu, Wenzhe Jiao & Yi Zhang (2024) Determining the impacts of climate change and human activities on vegetation change on the Chinese Loess Plateau considering human-induced vegetation type change and time-lag effects of climate on vegetation growth, International Journal of Digital Earth, 17:1, 2336075.
文章链接
https://doi.org/10.1080/17538947.2024.2336075
重点学术成果>>
图3. Evaluations of NDVI patterns on the Loess Plateau from 1982 to 2020. (A) Chronological progression of NDVI. The figures represent the rates of NDVI alteration, * denotes noteworthy alterations at the significance threshold of P < 0.05, and ** denotes noteworthy alterations at the significance threshold of P < 0.01. (B) Probability density distribution of the NDVI tendencies throughout the two intervals. The bars illustrate the ratios of heightened (gray) and diminished (black) reactions. (C) Average monthly NDVI variations between the two durations. The shaded region in (A) and the error bars in (C) signify ±1 SD.
图4. (a) Linear slope of the annual NDVI, (b) significance threshold of the annual NDVI, and (c) NDVI trend in the unchanged and variable areas from 1982 to 1999 on the Loess Plateau. (d) Linear slope of the annual NDVI, (e) significance threshold of the annual NDVI, and (f) NDVI trend in unchanged and variable areas from 2000 to 2020 on the Loess Plateau. SUT, significant upwards trend; NUT, non-significant upwards trend; SDT, significant downwards trend; and NDT, non-significant downwards trend.
图5. (a) Changes in the explanatory powers (q-values) during the two periods. (b, c) The explanatory powers (q-values) after interactions during the two periods. X1–X12 represent precipitation, temperature, aspect, slope, elevation, clay content, sand content, silt content, soil type, terrain index, population density, and nighttime light data, respectively.
图6. Spatial distributions of the lag and accumulation durations of meteorological elements influencing the NDVI on the Loess Plateau.
图9. Contributions of climate change (CC) and human activities (HA) to the NDVI of the forest and grassland vegetation from 1982 to 2020 on the Loess Plateau. The regions studied in (a) and (c) are unchanged forest, unchanged shrubland unchanged grassland, unchanged bare land, farmland transformed into forest and grassland, grassland transformed into forest and shrubland, and bare land transformed into forest and grassland, and the regions studied in (b) and (d) are farmland transformed into forest and grassland, grassland transformed into forest and shrubland, and bare land transformed into forest and grassland areas.
图10. (a) Proportion of the unchanged and variable areas in the two periods; contributions of (b) meteorological elements and (c) human endeavors to NDVI in unchanged and variable areas on the Loess Plateau from 1982 to 2020. In the box plots, the two boxes of the same color represent the two periods.
编辑：耿雅琦
审校：李 敏
终审：刘 珍
