Biodiversity does not Correlate with Productivity in Temperate Forests at Local Scales

In grassland ecosystems, biodiversity and productivity have been found to be positively correlated. However, studies of forested ecosystems have found mixed results. Biodiversity in forests has primarily been measured through species diversity, but recent studies have shown that biodiversity is more complex than simply quantifying the number of species occupying an area. Biodiversity can also be represented by other components of diversity such as functional, phylogenetic, and structural diversity; all three of which have been shown to be more strongly correlated to productivity than species diversity alone. Here, we examined the relationship between four biodiversity components (species, functional, phylogenetic, and structural diversity) and their respective relationship with productivity at a local scale for two northeastern United States temperate forests. Biodiversity indices were calculated using site specific inventory data while productivity was calculated using measures of wood growth and foliar nitrogen estimates from remotely sensed spectral imagery. Overall, patterns were similar between sites; indices of species, functional, and phylogenetic diversity were strongly to moderately correlated with each other while indices of structural diversity were not correlated with the other three components. All four biodiversity components were found to be either negatively or weakly correlated to productivity. Therefore, at these local sites, factors other than biodiversity may be driving patterns of productivity.