Characterization of heat, water and CO2 fluxes in La Herrería Forest environment (Madrid, Spain)

Vegetation plays a key role in the interchange of water, energy, and carbon fluxes between the land surface and the atmosphere. This study aims to determine the relationship between these fluxes and meteorological conditions, soil moisture, and vegetation dynamics in La Herrería forest area (Madrid, Spain). Observations over two years are available (2018 and 2019) at two nearby mountainous ecosystems with contrasting surface characteristics. The first site (HER) is a grassland with scattered shrubs and trees, while the second site (PORT) exhibits a higher tree density and the soil has a higher sand content, favouring faster water drainage. Turbulent and meteorological variables were measured using eddy-covariance towers, while satellite data was used to estimate the vegetation activity from the normalized difference vegetation index (NDVI). A joint meteorological and turbulent analysis shows that the interannual variability measured at the weather stations is greater than the differences obtained when comparing both locations for the main variables. Both ecosystems show a remarkably similar response to atmospheric forcing, with strong linear correlation for different atmospheric and turbulent parameters. In contrast, vegetation dynamics differ between both sites, showing the impact of soil type on plant growth and demonstrating how precipitation and its distribution modulate vegetation growth and, therefore, CO₂ exchanges with the atmosphere. These results underline the importance of combining in situ flux measurements and remote sensing to better understand how soil and vegetation characteristics modulate land-atmosphere interactions in Mediterranean mountainous environments.