Ecosystem multifunctionality is positively affected by remotely-sensed biodiversity at global eddy covariance sites

Biodiversity affects ecosystem functioning by regulating the biogeochemical exchange of carbon, water, energy, and nutrients within and between ecosystems. While this has been proven experimentally, ecosystem-level investigations of the effects of biodiversity on measured biogeochemical processes are understudied.

We leveraged fine-scale remote sensing data from Sentinel-2 to estimate plant diversity at 148 flux network sites across the globe. At these sites, measured eddy covariance fluxes of carbon, water, and energy can be used to compute ecosystem functions and metrics of multifunctionality, i.e. the simultaneous provision of multiple ecosystem functions. We estimated remotely-sensed biodiversity through the entropy-based metric known as Rao Q. To assess the effect of biodiversity on the biogeochemical functioning of ecosystems, we then related Rao Q to the derived ecosystem functions and ecosystem multifunctionality metrics.

Rao Q computed from near-infrared reflectance of vegetation (NIRv) was a major predictor of single ecosystem functions and multifunctionality metrics, highlighting the mostly positive effects of biodiversity on the functioning of ecosystems. Rao Q was generally more important than meteorology and comparable to vegetation structural components in predicting ecosystem functions and multifunctionality. In addition, Rao Q was more important than traditional biodiversity indices of taxonomic diversity measured at a subset of sites in North America where systematic plant species surveys were available. This reinforces the idea that structural and functional diversity, rather than species diversity per se, are key aspects in the worldwide functioning of natural ecosystems.

We provide strong evidence for significant positive effects of a biodiversity-proxy derived from satellite remote sensing measurements on single ecosystem functions and ecosystem multifunctionality. The positive biodiversity effects are robust to the inclusion of most major meteorological and structural parameters that might drive ecosystem functioning or confound the biodiversity-ecosystem functioning relationship. Considering recent and future advances in remote sensing of both diversity and ecosystem functions, our study paves the way to continuous spatiotemporal assessments of the biodiversity-ecosystem functioning relationship at the landscape, regional, and global scales.