 The study examined the relationship between biodiversity and ecosystem functioning in forests across the United States. It was found that mixed mycorrhizal strategies, which involve multiple types of symbiotic fungi, are beneficial for increasing productivity in forests with low levels of biodiversity. At higher levels of biodiversity, however, other factors such as resource partitioning become important for maintaining ecosystem functioning. This article was authored by Shan Luo, Richard P. Phillips, Insou Joe, and others.