Large-scale rain-fed to paddy farmland conversion modified land-surface thermal properties in Cold China

Tao Pan; Chi Zhang; Wenhui Kuang; Geping Luo; Guoming Du; Zherui Yin

doi:10.1016/j.scitotenv.2020.137917

Large-scale rain-fed to paddy farmland conversion modified land-surface thermal properties in Cold China

Sci Total Environ. 2020 Jun 20:722:137917. doi: 10.1016/j.scitotenv.2020.137917. Epub 2020 Mar 13.

Authors

Tao Pan¹, Chi Zhang², Wenhui Kuang³, Geping Luo⁴, Guoming Du⁵, Zherui Yin⁶

Affiliations

¹ Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi 276000, China; State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; University of Chinese Academy of Sciences, Beijing 100049, China; Department of Geography, Ghent University, 9000 Ghent, Belgium; Sino-Belgian Joint Laboratory of Geo-information, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Sino-Belgian Joint Laboratory of Geo-information, Ghent University, 9000 Ghent, Belgium. Electronic address: tao.pan@ugent.be.
² Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi 276000, China; State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Research Center for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Urumqi 830011, China. Electronic address: zc@ms.xjb.ac.cn.
³ Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: kuangwh@igsnrr.ac.cn.
⁴ State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China; Research Center for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Urumqi 830011, China. Electronic address: luogp@ms.xjb.ac.cn.
⁵ School of Public Administration and Law, Northeast Agricultural University, Harbin 150030, China. Electronic address: nmgdgm@126.com.
⁶ Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: yinzr@igsnrr.ac.cn.

PMID: 32199392
DOI: 10.1016/j.scitotenv.2020.137917

Abstract

The recent acute evolution of cropland structure in Cold China could lead to rapid rice paddy expansion, potentially altering land-surface thermal processes and influencing climate. To address the issue, this study investigated the changes in cropland type, land-surface temperature (LST) and heat fluxes in the agricultural region of Cold China during 2000-2015 based on time-series of land-use data and MODIS LST product, using the split-window algorithms (SWA) model and the pixel component arranging and component algorithm (PCACA). The investigation revealed large-scale land transformation from rain-fed farmland to paddy field in Cold China during 2000-2015. Compared to the rain-fed farmland, lower LST was observed in paddy field throughout crop growing seasons, with the highest LST threshold found in June (7.17 ± 1.05 °C) and the lowest value found in August (1.04 ± 0.35 °C). The cooling effect of paddy-field ranged from 0.59 ± 0.06 °C, 0.77 ± 0.07 °C, and 1.08 ± 0.08 °C for the low-, medium-, and high-density paddies, respectively. Compared to other months, stronger cooling effect was found in May and June. Further analysis showed the conversion of a rain-fed farmland to paddy field reduced the sensible heat flux and soil heat flux by 52.94 W/m² and 15.26 W/m², respectively, while increased the latent heat flux and net radiation by 115.66 W/m² and 47.34 W/m², respectively. The findings from this study indicated the changes in cropland structure and management regime (e.g., irrigation) could profoundly modify land-surface thermal processes and local/regional climate, interfering the signals from global warming. Therefore, instrumental climate data that collected from areas experienced large-scale conversion between rain-fed and paddy farmland should be carefully screened and corrected to prevent land-use induced biases.

Keywords: Cold China; Land use change; Remote sensing; Surface thermal environment.