Researchers demonstrate that the simplest way to measure diversity in eastern U.S. forests is also the best way to assess its health and productivity, creating a straightforward roadmap for conservation efforts. Credit: Adolphe Millot, Larousse du XXème siècle 1932
Key points:
- Species diversity is both simple and the best way to measure the productivity of a forest.
- Other measures, such as phylogenetic diversity and functional diversity, were negatively correlated with forest productivity.
- Species diversity is a reliable biodiversity measurement that helps scientists and policymakers make conservation and restoration decisions.
During their efforts to prioritize areas for conservation, scientists and policymakers consider biodiversity. However, there are many ways to measure biodiversity and each way can provide a different and sometimes conflicting view of diversity.
A new study, published in the Proceedings of the National Academy of Sciences, uses 20 years of data to clarify which measure of diversity is best to determine productivity of a forest.
Researchers compared how three different biodiversity measures are related to productivity—the amount of growth—in forests across the eastern United States. They analyzed nearly two million tree measurements from 23,145 non-plantation forest plots and found that a greater number of tree species consistently resulted in a more productive forest.
The team also assessed diversity via a measure of relatedness called phylogenetic diversity and a measure of structural and chemical differences known as functional diversity. Unexpectedly, both phylogenetic diversity and functional diversity were negatively correlated with productivity.
A better understanding of diversity is critical for scientists and policymakers to manage forests as the relationship between diversity and productivity impacts the mitigation of carbon emissions.
This study shows that the number of species in a forest is the best proxy for forest health and productivity. Scientists can examine species richness to guide restoration of degraded ecosystems and focus their efforts on planting more species.
“It’s reassuring for other investigators and policymakers to know that species richness is reliable,” explained co-author Douglas Soltis, professor with the Florida Museum of Natural History. “This is especially important when making conservation decisions with short notice and limited data.”