Cumulative and Lagged Effects: Seasonal Characteristics of Drought Effects on East Asian Grasslands

Weiwei Huang; Mark Henderson; Binhui Liu; Yuanhang Su; Wanying Zhou; Rong Ma; Mingyang Chen; Zhi Zhang

doi:10.3390/rs16183478

Remote Sensing (Sep 2024)

Cumulative and Lagged Effects: Seasonal Characteristics of Drought Effects on East Asian Grasslands

Weiwei Huang,
Mark Henderson,
Binhui Liu,
Yuanhang Su,
Wanying Zhou,
Rong Ma,
Mingyang Chen,
Zhi Zhang

Affiliations

Weiwei Huang: College of Forestry, The Northeast Forestry University, Harbin 150040, China
Mark Henderson: Mills College, Northeastern University, Oakland, CA 94613, USA
Binhui Liu: College of Forestry, The Northeast Forestry University, Harbin 150040, China
Yuanhang Su: Soil and Water Conservation Monitoring Center of Songliao Basin, Songliao Water Resources Commission, Changchun 130021, China
Wanying Zhou: College of Forestry, The Northeast Forestry University, Harbin 150040, China
Rong Ma: College of Forestry, The Northeast Forestry University, Harbin 150040, China
Mingyang Chen: College of Forestry, The Northeast Forestry University, Harbin 150040, China
Zhi Zhang: College of Forestry, The Northeast Forestry University, Harbin 150040, China

DOI: https://doi.org/10.3390/rs16183478
Journal volume & issue: Vol. 16, no. 18
p. 3478

Abstract

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With the acceleration of global warming, droughts are expected to both intensify and become more frequent. More so than forests, the productivity of grasslands is largely controlled by soil moisture and is highly susceptible to drought. Drought can impact grasslands though the effects may lag and accumulate over time. Because prior research has mainly focused on the annual or growing season scale, it remains unclear whether there are seasonal differences in the cumulative and lagged effects (CALEs) of drought. This study uses Normalized Difference Vegetation Index (NDVI) and Standardized Precipitation Evapotranspiration Index (SPEI) data to explore the seasonal characteristics of the CALEs of drought on grassland growth in East Asia from 2001 to 2020. The main results include the following: (1) More than 40% of grasslands are significantly affected by the CALEs of drought for all three seasons (spring, summer, and autumn). (2) Grasslands are more sensitive to the CALEs of drought in summer. The spatial variability of the cumulative time scale is the greatest in spring, whereas the spatial variability of the lagged time scale is the greatest in summer. The lag time scale gradually shortens as moisture decreases in summer and autumn but shows an inverted U-shape in spring. As drought conditions intensify, the cumulative time scale gradually increases in spring and autumn, while gradually decreasing in summer. (3) The dominant drought effects vary among different seasons: the lagged effect (LE) predominates in spring and autumn, whereas in summer it is the cumulative effect (CE) that dominates. The LE exceeds the CE in 54.89% of the study area during the growing season. We emphasize that annual- or growing season-scale studies of drought CE and LE may obscure seasonal response characteristics. Given the seasonal nature of droughts and the seasonally varying sensitivities of grassland growth to these droughts, the impacts on vegetation fluctuate significantly across different seasons. The results help us more accurately predict grassland ecosystem changes under the background of global warming and the increasing probability of severe drought, providing important reference values for future grassland ecological protection and planning.

Published in Remote Sensing

ISSN: 2072-4292 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science
Website: http://www.mdpi.com/journal/remotesensing/

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