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

ABSTRACT

Since the initiation of the Grain for Green Project (GFGP) in 1999, dramatic change in vegetation status on the Loess Plateau. Spatially, geographical detector was employed to detect dominant variables influencing the spatial arrangement of normalized difference vegetation index (NDVI). Temporally, lagged or accumulated monthly precipitation, temperature and standardized precipitation evapotranspiration indices (SPEIs) sensitive to the monthly NDVI were first detected for every individual pixel, and the correlation between the NDVI and meteorological elements with time-lag effects was established a random forest model of unchanged land cover, followed by attributing impacts of climatic alterations and human interventions through residual examination across changed land cover. The findings indicate that (1) precipitation, slope, and soil dominantly influence the spatial arrangement of the NDVI. (2) Precipitation in current the month and cumulative temperatures of the previous 1–2 months steadily affect vegetation growth significantly, the optimal accumulation time interval for SPEI around 2000 are 8 months and 4 months, respectively. (3) Increases in the average NDVI within woodland and meadow vegetation on the Loess Plateau were primarily driven by climate change before 2000, accounting for 76.2%, whereas after 2000 it was dominantly driven by human activities, accounting for 64.16%.

KEYWORDS:

• NDVI
• climate change
• human activities
• geodetector
• random forest model
• loess plateau

Acknowledgments

The authors thank Haolin Huang, Shuaifeng Peng and Yi Zhang for assistance in writing the code. The authors also thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The code used in this study is available upon contacting the corresponding author.

Author contributions

Acquisition of financial support for the project leading to this publication, Z.W.; Application of statistical, mathematical, computational, or other formal techniques to analyze or synthesize study data, M.C. and Z.W.; Y.Z. helped with some data processing; Preparation, creation, and/or presentation of the published work by those from the original research group, specifically critical review, commentary, or revision, including pre- or post-publication stages, S.W., Z.W., X.L. and W.J.

Additional information

Funding

This research was funded by National Key Research and Development Program of China (2022YFC3205200), Science Foundation for Young Elite Talents of YRCC (HQK-202307), and the State Key Project of National Natural Science Foundation of China-Key projects of joint fund for regional innovation and development (U22A20620).