_Data_ECOLIND_43655_2025_

This dataset includes measurements of structural attributes (DBH, height, crown traits) and biomass components (stem, branch, foliage) from 90 destructively sampled Scots pine and Pyrenean oak trees under varying competition intensities in mixed stands in northern Spain. It supports the article submitted to Ecological Indicators on how competition influences allometric relationships and biomass allocation in early stand development.