Abiotic conditions, such as temperature and precipitation, affect the functioning of ecosystems, both directly and indirectly via impacts on plant community composition and diversity. In general, increasing biodiversity exhibits a positive and saturating relationship with ecosystem function. Leveraging information about environmental variation and multiple dimensions of biodiversity may yield better predictions of the ecosystem-level consequences of shifting patterns of biodiversity. However, few studies to date have integrated multiple dimensions of biodiversity and environmental gradients in order to better understand and predict ecosystem carbon dynamics. Here, we use variation in temperature and precipitation along an elevational gradient near the Rocky Mountain Biological Laboratory located in the West Elk range of the southern Rocky Mountains in Colorado, USA to examine (1) the relative contributions of abiotic (temperature and precipitation) and biotic factors to ecosystem carbon exchange, and (2) the relationship between multiple dimensions of biodiversity (i.e., functional, phylogenetic and taxonomic) and ecosystem carbon dynamics.
Results/Conclusions
We found that the model including an integrated climate variable, actual evapotranspiration (AET), multiple dimensions of plant diversity, and canopy leaf area (LAI) explained 47% of the variance in net ecosystem exchange (NEE), and AET was significantly and positively related to functional, phylogenetic, and taxonomic diversity, but had no direct effect on NEE. Furthermore, phylogenetic diversity was significantly, positively related to NEE. In bivariate models, we found that all three dimensions of biodiversity were positively associated with NEE, however the amount of variance explained varied among functional, phylogenetic, and taxonomic metrics, with species richness accounting for most of the variance. Our findings highlight key indirect effects of abiotic conditions on the functioning of ecosystems and the significant relationship between dimensions of diversity (e.g., phylogenetic diversity) that capture plant traits critical to ecosystem carbon dynamics, but not easily measured or included in other metrics.