Dual Roles of Water Availability in Forest Vigor: A Multiperspective Analysis in China

Hui Luo; Tao Zhou; Xia Liu; Peijun Shi; Rui Mao; Xiang Zhao; Peipei Xu; Peixin Yu; Jiajia Liu

doi:10.3390/rs13010091

Remote Sensing (Dec 2020)

Dual Roles of Water Availability in Forest Vigor: A Multiperspective Analysis in China

Hui Luo,
Tao Zhou,
Xia Liu,
Peijun Shi,
Rui Mao,
Xiang Zhao,
Peipei Xu,
Peixin Yu,
Jiajia Liu

Affiliations

Hui Luo: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Tao Zhou: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Xia Liu: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Peijun Shi: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Rui Mao: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Xiang Zhao: State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of Sciences, Beijing Normal University, Beijing 100875, China
Peipei Xu: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Peixin Yu: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
Jiajia Liu: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China

DOI: https://doi.org/10.3390/rs13010091
Journal volume & issue: Vol. 13, no. 1
p. 91

Abstract

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Water availability is one of the most important resources for forest growth. However, due to its complex spatio-temporal relationship with other climatic factors (e.g., temperature and solar radiation), it paradoxically shows both positive and negative correlations (i.e., dual roles) with forest vigor for unknown reasons. In this study, a multiperspective analysis that combined the deficit of the Normalized Difference Vegetation Index (dNDVI) and multitimescale Standardized Precipitation Evapotranspiration Index (SPEI) was conducted for the forests in China, from which their correlation strengths and directions (positive or negative) were linked with spatio-temporal patterns of environmental temperature (T) and water balance (WB) (i.e., precipitation minus potential evapotranspiration). In this way, the reasons for the inconsistent roles of water were revealed. The results showed that the roles of water availability greatly depended on T, WB, and seasonality (i.e., growing or pregrowing season) for both planted and natural forests. Specifically, a negative role of water availability mainly occurred in regions of T below its specific threshold (i.e., T ≤ Tthreshold) during the pregrowing season. In contrast, a positive role was mainly observed in warm environments (T > Tthreshold) during the pregrowing season and in dry environments where WB was below its specific threshold (i.e., WB ≤ WBthreshold) during the growing season. The values of Tthreshold and WBthreshold were related to the vegetation type, with Tthreshold ranging from 1.3 to 4.7 °C and WBthreshold ranging from 129.1 to 238.8 mm/month, respectively. Our study revealed that the values of Tthreshold and WBthreshold for a specific forest were stable, and did not change with the SPEI time-scales. Our results reveal the dual roles of water availability in forest vigor and highlight the importance of environmental climate and seasonality, which jointly affect the roles of water availability in forest vigor. These should be considered when monitoring and/or predicting the impacts of drought on forests in the future.

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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