Impacts of Saline-Alkali Land Improvement on Regional Climate: Process, Mechanisms, and Implications

Lingxue Yu,Shuwen Zhang,Luoman Pu,Tingxiang Liu,Guangshuai Li,Jiuchun Yang,Kun Bu,Yue Jiao

doi:10.3390/rs13173407

Abstract

Studying land use change and its associated climate effects is important to understand the role of human activities in the regulation of climate systems. By coupling remote sensing measurements with a high-resolution regional climate model, this study evaluated the land surface changes and corresponding climate impact caused by planting rice on saline-alkali land in western Jilin (China). Our results showed that paddy field expansion became the dominant land use change in western Jilin from 2015 to 2019, 25% of which was converted from saline-alkali land; this percentage is expected to increase in the near future. We found that saline-alkali land reclamation to paddy fields significantly increased the leaf area index (LAI), particularly in July and August, whereas it decreased albedo, mainly in May and June. Our simulation results showed that planting rice on saline-alkali land can help decrease the air temperature and increase the relative humidity. The temperature and humidity effects showed different magnitudes during the growing season and were most significant in July and August, followed by September and June. The nonradiative process, rather than the radiative process, played a dominant role in regulating the regional climate in this case, and the biophysical competition between evapotranspiration (ET) and albedo determined the temperature and relative humidity response differences during the growing season.

Highlights

(3228 km2 ) and paddy field expansion (1738 km2 ) dominated the land use changes, whereas from 2015 to 2019, paddy fields increased by 2031 km2 and became the main land use change characteristic in this region
Our results showed that 25% of the paddy field increase in the latter period was reclaimed from saline-alkali land, and that percentage is expected to increase in the future
We found that saline-alkali land reclamation to paddy fields significantly increased leaf area index (LAI), in July and August, whereas it decreased albedo, mainly in May and June

Summary

Introduction

Both land use changes and CO2 emissions have been documented as dominant driving factors influencing the climate system at different scales from global to regional [1,2,3,4,5].at the regional scale, some studies emphasize that climate change induced by land use change is even greater than climate change induced by greenhouse gases [6,7,8].Understanding the predominant regional land use change as well as the mechanisms by which it affects climate through altering energy, momentum, and water exchange processes is crucial to fully clarify how humans modify and regulate climate [9,10,11]. Both land use changes and CO2 emissions have been documented as dominant driving factors influencing the climate system at different scales from global to regional [1,2,3,4,5]. At the regional scale, some studies emphasize that climate change induced by land use change is even greater than climate change induced by greenhouse gases [6,7,8]. Studying land use changes and estimating their climate impact is a major requirement for the sustainable development of agriculture [12,13,14,15].

Methods

Results

Discussion

Conclusion