Impact of the 2022 compound hot-dry extreme events on vegetation growth over the Tibetan Plateau

doi:10.12006/j.issn.1673-1719.2025.079

Abstract

Abstract:

The Tibetan Plateau (TP) experienced a record-breaking concurrence of heatwave and drought in 2022. However, the impact of this compound hot-dry extreme event on vegetation growth and its underlying mechanisms remain unclear. Based on climate data and remote-sensing derived vegetation index during 2000—2022, changes in vegetation growth in response to this event were analyzed and the potential driving mechanisms were clarified. The compound hot-dry extreme event in 2022 significantly suppressed vegetation growth over the TP, with the growing season Normalized Difference Vegetation Index (NDVI) declined by 28% compared to the previous year. About 6% of the study area experienced severe suppression, ranking the third highest during the study period. Regions with remarkable NDVI decline were primarily located in the southern and northeastern parts of TP. Further analysis indicated that the unusually high temperatures and sufficient precipitation during April-May 2022 led to earlier spring phenology and accelerated soil moisture depletion. The subsequent summer drought and elevated temperatures further intensified soil moisture deficits through land-atmosphere feedbacks. Additionally, daily maximum temperatures during July-August notably surpassed the temperature optima for plant growth for over 90% of the study area. Collectively, these compound heat and drought stresses significantly suppressed vegetation growth in 2022. This research provides critical insights into the local ecological responses to climate change.

Key words: Compound hot-dry extreme event, Tibetan Plateau (TP), Vegetation growth, Impact mechanism, Climate change

XIAO Xue, HUANG Meng-Tian, ZHOU Bai-Quan, WANG Chen-Peng, ZHAI Pan-Mao. Impact of the 2022 compound hot-dry extreme events on vegetation growth over the Tibetan Plateau[J]. Climate Change Research, 2025, 21(6): 777-788.

Figures/Tables 10

Fig. 1 Elevation and vegetation type distribution map of the Tibetan Plateau

Fig. 2 Standardized anomalies of growing-season averaged daily maximum temperature and cumulative precipitation over the Tibetan Plateau from 2000 to 2022

Fig. 3 Vegetation growth status on the Tibetan Plateau. (a) Standardized anomaly of growing-season averaged NDVI over the Tibetan Plateau from 2000 to 2022, (b) spatial distribution of standardized anomaly of growing-season averaged NDVI in 2022, (c) probability density function of detrended standardized anomaly of growing-season averaged NDVI from 2000 to 2022, (d) pixel proportion of detrended standardized anomaly of growing season average NDVI below -2.0, -2.5 and -3.0 from 2000 to 2022

Fig. 4 Principal component analysis results of NDVI standardization anomaly during the growing season in the Tibetan Plateau. (a) Time series of regional average standardized anomaly of NDVI, NDVI-PC1 reconstructed by the first principal component, and NDVI-IAV reconstructed by the 2nd to 6th principal components over the Tibetan Plateau from 2000 to 2022, (b) spatial distribution of NDVI-PC1 in 2022, (c) spatial distribution of NDVI-IAV in 2022

Fig. 5 Ecosystem GPP over the Tibetan Plateau. (a) Spatial distribution of GPP-IAV on the Tibetan Plateau in 2022 (with GPP-IAV reconstructed from the 2nd to 7th principal components of the standardized anomaly of GPP on the Tibetan Plateau from 2001 to 2022),(b) spatial distribution of standardized anomaly of GPP on the Tibetan Plateau in July-August, 2022

Fig. 6 Spatial distribution of partial correlation coefficients between detrended growing season NDVI and mean daily maximum temperature (a) and cumulative precipitation (b) on the Tibetan Plateau from 2000 to 2022

Fig. 7 The spatial distribution characteristics of vegetation change in the Tibetan Plateau caused by the compound hot-dry extreme event in 2022

Fig. 8 Changes in NDVI during the growing season in the Tibetan Plateau. (a) Interannual variability of regionally averaged NDVI, (b) spatial distribution of standardized anomaly of NDVI in July-August, 2022

Fig. 9 Monthly variations of daily maximum temperature (a), cumulative precipitation (b), and soil moisture averaged over 0-289 cm depth (c) on the Tibetan Plateau in 2022

Fig. 10 Spatial distribution of daily maximum temperature (a) and the difference between daily maximum temperature and the optimal temperature for vegetation growth (b) on the Tibetan Plateau during July-August, 2022

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