Material and Energy Exchange Dynamics in Paddy Fields Across Growth Stages in Liaohe Delta, Northeast China

This study examines the material and energy exchange of rice paddies during different growth stages in the Liaohe Delta, Northeast China, during an unusually warm year (2019). Utilizing eddy covariance data, we focused on four key growth stages: transplanting, jointing, heading, and maturation. The net ecosystem exchange (NEE) peaked during transplanting, shifting from carbon emission to absorption by the heading stage. Sensible heat flux (H) was highest during jointing, while latent heat flux (LE) showed a distinct peak during transplanting, highlighting the dominance of transpiration and evaporation. Photo synthetically active radiation (PAR) and net radiation (NR) were identified as pivotal environmental drivers. Temperature and soil moisture significantly influenced these fluxes, with optimal temperatures enhancing CO2 uptake and higher soil moisture promoting transpiration. The findings contribute to an understanding of the rice paddy ecosystem’s role in carbon cycling and energy balance amidst environmental variations and contribute to informed agricultural practices in the Liaohe River Delta.