Sulinski et al. (2026) Model for estimating solar radiation transmission through horizontal layers in complex tree stands

Identification

• Journal: The Science of The Total Environment
• Year: 2026
• Date: 2026-01-01
• Authors: J Sulinski, Przemysław Sypka, Rafał Starzak
• DOI: 10.1016/j.scitotenv.2025.181320

Research Groups

• University of Agriculture in Krakow, Faculty of Forestry, Department of Ecological Engineering and Forest Hydrology, Krakow, Poland
• AGH University of Krakow, Faculty of Computer Science, Electronics and Telecommunications, Institute of Electronics, Krakow, Poland

Short Summary

This study developed and validated a novel model for estimating solar radiation transmission through horizontal layers in complex tree stands, demonstrating high precision (97.9%) and an average error of 12% using field measurements from diverse stands.

Objective

• To develop and verify a model for estimating solar radiation transmission through arbitrarily chosen horizontal layers within complex tree stands.

Study Configuration

• Spatial Scale: 26 diverse tree stands located in the Western Carpathians (temperate climate zone), varying in age, species composition, and vertical structure. Solar insolation was measured at four vertical levels within each stand, defining six horizontal layers (156 layers total).
• Temporal Scale: Not explicitly stated for data collection duration, but implies a period sufficient for solar insolation measurements.

Methodology and Data

• Models used: A newly developed empirical model for solar radiation transmission. Its parameters are primarily determined by volumetric biomass density, layer thickness, foliage biomass, and the height of the top surface of the investigated layer above ground level relative to tree stand height.
• Data sources: Field measurements of solar insolation recorded in the 26 tree stands.

Main Results

• The developed model's parameters are largely influenced by volumetric biomass density, layer thickness, foliage biomass, and the relative height of the layer's top surface.
• Volumetric biomass density, calculated as the ratio of above-ground biomass to the total stand volume, is independent of tree species.
• The model explains 97.9% of the variation in solar transmittance with an average error of 12%.
• The model allows for arbitrary selection of horizontal layers, with the caveat that the entire crown zone (from treetops to crown base) must be treated as a single, indivisible layer due to measurement limitations during model evaluation.

Contributions

• The model utilizes parameters largely free from species-specific features, making it broadly applicable.
• Model parameters are derived from data commonly available in standard forest inventory plans, enhancing practical utility.
• The model can be effectively used to estimate the effects of various silvicultural practices in complex forest stands.
• High precision (97.9%) and low average error (12%) were achieved through verification with field measurements in highly diverse stands.
• Facilitates direct comparison of vertical solar transmittance profiles across different stand types.

Funding

• Not explicitly stated in the provided text.

Citation

@article{Sulinski2026Model,
  author = {Sulinski, J and Sypka, Przemysław and Starzak, Rafał},
  title = {Model for estimating solar radiation transmission through horizontal layers in complex tree stands},
  journal = {The Science of The Total Environment},
  year = {2026},
  doi = {10.1016/j.scitotenv.2025.181320},
  url = {https://doi.org/10.1016/j.scitotenv.2025.181320}
}