Quantifying and modelling feedbacks between forest structure, light, microclimate and carbon cycling in temperate forests

Studying the feedback between forest structure and the environment, particularly below canopies, is crucial for sustainable forest management, biodiversity conservation, and climate mitigation. Advanced vegetation models play a key role in unraveling the complex interaction between forest composition and environmental conditions, as these allow to understand the dynamics of ecosystems by simulating the interactions between plant species and their environment. An essential aspect necessitating refinement in these models is understanding how radiation interacts with intricate structures like forest canopies. In this study, we employ advanced terrestrial laser scanning techniques, distributed fiber-optic, and microclimate sensors to investigate the relationships between light, microclimate, carbon cycling, and forest structure in temperate forests. In a temperate forest in Belgium, we implemented a sensor setup since March 2023. It comprises a Distributed Temperature Sensing (DTS) fiber, Temperature and Moisture Sensor (TMS) microclimate loggers, SurveyTag microclimate loggers, Photosynthetic Active Radiation (PAR) sensors, and pyranometer (direct/diffuse) light sensors along a 135 m long transect from forest edge to core. Monthly 3D terrestrial laser scanning (TLS) of the transect allowed us to quantify forest structure with high spatiotemporal resolution. Preliminary results reveal distinct microclimate gradients along the transect and seasonal changes in forest structure in 3D space, including budding and changes in canopy volume. These findings will be used to calibrate and improve existing radiative transfer models (RTMs) to be further implemented in vegetation models. Integrating observations and model parameters in a common framework will provide breakthrough insights into the feedbacks between light, forest structure, microclimate, and their impact on the carbon cycle in temperate forests.