Distribución de luz en canopias forestales en sistema silvopastoril

In silvopastoral systems (SPS), tree canopy architecture regulates the vertical distribution of radiation, affecting the productivity of the herbaceous layer, the growth of the forest component, and the microclimatic conditions in the system. This work evaluated the vertical distribution of photosynthetically active radiation (PAR) and the canopy interception efficiency of two Eucalyptus species (E. grandis and E. dunnii) under a silvopastoral system at the Bernardo Rosengurtt experimental station in Cerro Largo, Uruguay. Two types of spatial arrangements (single and triple row) and two types of genetic material (seeds and clones) were compared, evaluating light transmission using PAR measurements at different vertical strata of the canopy during the summer and winter of 2024. The results showed significant differences between species and arrangements in light interception. E. grandis presented greater volumes and heights, but a lower proportion of live canopy, which implied greater variability in transmittance. During the summer, trees grown from seed showed clear differences between species: E. dunnii had lower light extinction coefficients than E. grandis in both single and triple arrangements, indicating greater light penetration through the canopy. However, during the winter, this relationship: was partially reversed: E. dunnii showed grater attenuation in the single treatment, but less in the triple treatment. In clonal material, differences between species were minimal, and k values were practically equivalent. A seasonal effect on light attenuation was also observed, with higher extinction coefficient values ​​in winter. These results provided insight into how canopy architecture and spatial arrangement influence light availability in silvopastoral systems, providing key information for optimizing forest and forage productivity in multiple land-use schemes. This study highlights the importance of proper species selection to optimize production in these types of systems.