The study introduces a new way to measure tree species diversity in forests. This method, called D RE , looks at both the number of different species and how evenly they are distributed. By comparing real forests to theoretical ones with equal species and abundance, researchers can better understand diversity. The new measure, D RE , outperforms traditional methods, especially in forests with uneven species distribution. It is more sensitive to changes in rare species and provides clearer results. This approach offers a more accurate and meaningful assessment of species diversity in any ecosystem.