GAINSVILLE, Florida — When policymakers make tough calls on which areas to prioritize for conservation, biodiversity is often their top consideration. Environments with more diversity support a greater number of species and provide more ecosystem services, making them the obvious choice. …There are several ways to measure diversity, and each reveals a slightly different, and sometimes conflicting, view of how life interacts in a forest or other ecosystem. In a new study… three measures of biodiversity are related to productivity, or the amount of growth, in forests across the eastern United States. …The team found that a greater number of tree species, called species richness, consistently resulted in a more productive forest. …The researchers assumed that other measures of diversity would also show a strong, positive relationship with productivity. Instead, they found that the measure of relatedness (phylogenetic diversity) and of various structural and chemical differences (functional diversity) were both negatively correlated with productivity.