Ecosystem respiration and its components in a rainfed spring maize cropland in the Loess Plateau, China.

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.