A comprehensive analysis of seasonal and interannual ecohydrological process dynamics in semi-arid dune and meadow ecosystems

Ecohydrological processes in arid and semi-arid regions play a critical role in shaping regional climate dynamics. This study focused on sand dunes and meadows, which are typical ecosystems in the Horqin Sandland, using meteorological, soil, environmental, and eddy covariance (EC) observational data for 10 years (2013–2022). An ecohydrological model (T&C model) was developed for community-scale sandy landscapes to comprehensively simulate ecohydrological processes across different time scales. The results indicated the following: (1) The T&C model effectively simulated the energy, hydrological, and biomass components, including net radiation (Rn), sensible heat flux (H), latent heat flux (LE), soil water content (SWC), gross primary productivity (GPP), and leaf area index (LAI), in sand dunes and meadows, with the R² values ranging from 0.41 to 0.93 and from 0.66 to 0.92, respectively. The model accurately captured the seasonal dynamics of ecohydrological processes using well-parameterized and portable settings. (2) Energy balance analysis revealed that the energy transport at the dune site was dominated by H from 2013 to 2016, with H/Rn and LE/Rn becoming comparable in 2017–2018 and an increasing proportion of Rn allocated to LE after 2019. At the meadow site, H dominated in the early growing season, whereas LE dominated during the mid-growing season. (3) Water balance analysis showed an average annual rainfall of 395.94 mm. At the dune site, the average annual evapotranspiration was 247.4 mm, with evapotranspiration and deep seepage accounting for over 97 % of the total water consumption. The meadow site had an average annual evapotranspiration of 620.78 mm, and the meadow belongs to groundwater-dependent ecosystems (GDEs). This study provides a theoretical framework and technical support for water resource management and prevention of desertification in desertified regions.