Abstract
We estimated ecosystem respiration (Re) and its components in a rainfed spring maize field in the Loess Plateau, China, during the growing seasons of 2012, 2013, and 2014 using measurements of eddy covariance and soil respiration (Rs). The multi-factor equation, which included photosynthetic active radiation, 5-cm soil temperature, 10-cm soil water content, and green leaf area index (GLAI), had goodness-of-fit values of between 0.81 and 0.94 for Re, autotrophic respiration (Ra), and above-ground autotrophic respiration (Raa), and goodness-of-fit values of between 0.50 and 0.67 for Rs, below-ground autotrophic respiration (Rab), and heterotrophic respiration (Rh). The highly significant linear correlations between gross primary production (GPP) and Re and its components indicate that GPP had a strong influence on Re and its components. The growing season Re was dominated by Ra (64–71%), which in turn was dominated by Raa (63–73%). Although Rs was mainly made up of Rh (56–61%), Rs resembled Rab more closely than Rh. The relationships between GLAI and Ra/Re and between GLAI and Rab/Rs were described by logarithmic equations with goodness-of-fit values of between 0.88 and 0.89 and between 0.77 and 0.84, respectively, indicating that GLAI controlled Ra/Re and Rab/Rs.
Highlights
The amount of carbon released to the atmosphere by ecosystem respiration (Re) represents the second largest carbon flux after photosynthesis, and photosynthesis generally referred to as gross primary production (GPP)[1]
photosynthetically active radiation (PAR) had a positive effect on Re (2013 and 2014), Ra (2014), Rab (2012), and Rh (2013) (Fig. 3), which implies those respirations may decrease in spring maize croplands in the Loess Plateau as dimming develops further[30]
The ratios of Raa to Ra in our study were 64%, 73%, and 63% in 2012, 2013, and 2014, respectively, indicating that Ra was dominated by Raa in the growing season and that canopy development controlled Ra in our spring maize field
Summary
The amount of carbon released to the atmosphere by ecosystem respiration (Re) represents the second largest carbon flux after photosynthesis, and photosynthesis generally referred to as gross primary production (GPP)[1]. It is necessary to identify the relationships between Re and its components to improve our understanding of the mechanisms that control Re. cropland accounts for about only 12% of the global land area[9], carbon cycling in cropland can significantly affect the global carbon balance[10]. Warming and dimming trends, accompanied by a significant decrease in the average daily rainfall intensity and an increase in the number of consecutive dry days, have been reported for the Loess Plateau[29,30]. These changes in climate may have noticeable impacts on the growth of spring maize and the local carbon budget.
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