TITLE:
Carbon Budget Dynamics over a Rain-Fed Maize Agricultural Ecosystem in Northeast China and Its Regulation
AUTHORS:
Rongping Li, Guangsheng Zhou, Li Zhou, Yang Yang
KEYWORDS:
Rain-Fed Maize, Carbon Budget, Dynamics, Regulation Mechanism, Northeast China
JOURNAL NAME:
Open Journal of Ecology,
Vol.7 No.6,
June
23,
2017
ABSTRACT: Based on the eddy-covariance observation data over rain-fed maize agricultural ecosystem during 2005-2011, the dynamics of net ecosystem CO2 exchange (NEE) and its control mechanism were analyzed in the present study. We found that the average carbon budget of non-growing season, growing season and annual were 153.16 - 202.03 g C/m2, −689.36 - −488.17 g C/m2, and −316.96 - −487.33 g C/m2, respectively. Maize carbon content of grain yield was −226.6 - −339.94 g C/m2, accounting for 55.4% of carbon budget in the growing season. From sowing to seven-leaf stage, the carbon budget of this ecosystem was characterized by carbon release, with the rate of 0.028 ± 0.0056 mg CO2 m−2⋅s−1. From seven-leaf to mature stage, the carbon budget was characterized by carbon absorption, with the rate of −0.256 ± 0.0693 mg CO2 m−2⋅s−1. The key meteorological factors affecting annual carbon budget included daily average temperature (R = −0.81, P = 0.03) and saturated vapor pressure deficit (R = −0.64, P = 0.12). At the same photosynthetically active radiation (PAR) level, CO2 assimilation rate was linearly correlated with leaf area index (P < 0.05), and the slopes increased with PAR, indicating the increase in net ecosystem CO2 exchange in growing season was unlikely to be resulted from the extension of growing season. On the contrary, the carbon sink of rain-fed maize ecosystem in growing season might be decreased by extending the growing season ahead of the sowing date.