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Variations in seasonal and inter-annual carbon fluxes in a semi-arid sandy maize cropland ecosystem in China's Horqin Sandy Land.

Authors :
Niu, Yayi
Li, Yuqiang
Wang, Mingming
Wang, Xuyang
Chen, Yun
Duan, Yulong
Source :
Environmental Science & Pollution Research; Dec2021, Vol. 28 Issue 46, p5295-5312, 18p
Publication Year :
2021

Abstract

Sandy cropland ecosystems are major terrestrial ecosystems in semi-arid regions of northern China's Horqin Sandy Land, where they play an important role in the regional carbon balance. Continuous observation of the CO<subscript>2</subscript> flux was conducted from 2014 to 2018 using the eddy covariance technique in a sandy maize cropland ecosystem in the Horqin Sandy Land. We analyzed carbon fluxes (the net ecosystem exchange (NEE) of CO<subscript>2</subscript>, ecosystem respiration (R<subscript>eco</subscript>), and the gross primary productivity (GPP) and their responses to environmental factors at different temporal scales using Random Forest models and correlation analysis. We found that the sandy cropland was a carbon sink, with an annual mean NEE of –124.4 g C m<superscript>−2</superscript> yr<superscript>−1</superscript>. However, after accounting for carbon exports and imports, the cropland became a net carbon source, with net biome production ranging from –501.1 to –266.7 g C m<superscript>−2</superscript> yr<superscript>−1</superscript>. At a daily scale, the Random Forest algorithm revealed that photosynthetic photon flux density, soil temperature, and soil moisture were the main drivers for variation of GPP, R<subscript>eco</subscript>, and NEE at different integration periods. At a monthly scale, GPP and R<subscript>eco</subscript> increased with increasing leaf area index (LAI), so the maize ecosystem's carbon sequestration capacity increased with increasing LAI. At an annual scale, water availability (precipitation and irrigation) played a dominant role in explaining inter-annual variability of GPP and R<subscript>eco</subscript>. Affected by climate (e.g., precipitation) and field management (e.g., cultivation, irrigation), carbon fluxes differed greatly between years in the maize system. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09441344
Volume :
28
Issue :
46
Database :
Complementary Index
Journal :
Environmental Science & Pollution Research
Publication Type :
Academic Journal
Accession number :
156190664
Full Text :
https://doi.org/10.1007/s11356-021-15751-z