Seasonal variation and environmental regulation mechanisms of energy fluxes and energy allocation in dune and meadow ecosystems

Abstract

Surface energy exchange at the canopy-atmosphere interface exerts a substantial influence on microclimate, hydrological cycles, and geochemical processes. This study analyzes eddy covariance data from two observation stations in the Horqin Sandy Land for a period of 10 years (2013–2022) to investigate the temporal patterns and environmental regulatory mechanisms of energy fluxes and their allocation in the dune (A4) and meadow (C4) ecosystems. The findings reveal that net radiation (Rn), latent heat flux (LE), sensible heat flux (H), and ground heat flux (G) in different ecosystems exhibit a unimodal distribution. Both Rn and LE reach their maximum during the mid-vigorous growth phase, whereas G peaks at the onset of the growth period. At the A4 site, H peaks in the early vigorous growth phase, while at the C4 site, H peaks in the late vigorous growth phase. From the dune to the meadow ecosystem, the peak values of LE and Rn increase, and the dominant period of LE extends. Consequently, LE becomes the main component of energy fluxes within the meadow ecosystem. Climate and vegetation factors jointly regulate the temporal variation of energy fluxes and their allocation. From the dune to the meadow ecosystem, the influence of canopy conductance (gc) becomes more pronounced. This study highlights the importance of vegetation, particularly the significance of physiological control in determining the seasonal patterns of energy fluxes and allocation in water-limited arid and semi-arid ecosystems. Moreover, the observed sensitivity of energy allocation to vegetation changes suggests that, under future climate scenarios, attention should be given to the response of ecosystem energy transfer to greening trends in arid and semi-arid regions.