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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.
- 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]
- Subjects :
- LEAF area index
RANDOM forest algorithms
FARMS
CORN
ECOSYSTEMS
ARID regions
Subjects
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