A new study published in Acta Oecologica by researchers from the Poznań University of Life Sciences and the Remote Sensing Centre of the Institute of Geodesy and Cartography focuses on the transmittance of photosynthetically active radiation (PAR) through grassland canopies. Conducted between 2020 and 2023 across 22 mesic grasslands in Poland, the research addresses a key factor influencing ecosystem productivity and biodiversity, whose direct measurement is both time-consuming and challenging.
The study demonstrates a strong relationship between light transmittance and canopy height, aboveground biomass, and the Leaf Area Index (LAI) derived from Sentinel-2 data. As these parameters increase, the amount of light reaching lower vegetation layers decreases, rapidly at low values and more gradually beyond certain thresholds. This relationship can be effectively modeled using broken line regression, with its shape influenced by the proportion of forbs. The authors also show that commonly used vegetation indices such as NDVI, EVI, SIPI are not suitable for estimating this phenomenon, while the complexity of the models may limit their direct practical application.
Research article is available at the https://doi.org/10.1016/j.actao.2025.104102
