Plant biodiversity is essential to the functions and services ecosystems provide to humanity. Functionally diverse plant communities are generally more productive, more stable over time, and more resistant to invasion and disease. In this era of accelerated global change, monitoring plant biodiversity consistently over large areas is becoming increasingly important. Spectrometers measure the interaction between electromagnetic radiation and matter continuously across a range of wavelengths, and can be operated at different scales, including contact measurements and remote sensing approaches at the proximal, airborne, and spaceborne level. Differences in chemistry, anatomy, and morphology influence the reflectance properties of plants from the visible, to the near-infrared, and short-wave infrared regions of the electromagnetic spectrum. Spectroscopic measurements thus capture functional characteristics of individual plants and plant communities. Here we use leaf level spectra and spectra of plants acquired with proximal remote sensing (400-2500 nm) at the Cedar Creek Long-Term Ecological Research site in Minnesota to address the following questions: 1) Is the spectral dissimilarity among plant species associated with their functional dissimilarity and evolutionary divergence time? 2) If so, can plant spectra be used as a novel means to calculate biodiversity indices to predict ecosystem function?
Results/Conclusions
We found an overall pattern of increasing spectral dissimilarity with functional dissimilarity and evolutionary divergence time for pairwise distances between species included in our study. Spectral diversity calculated from leaf level and remotely sensed plant spectra predicted aboveground productivity, a measure of ecosystem function, as well as taxonomic, functional, and phylogenetic diversity. In addition, more productive plant communities filled the total spectral niche space more completely than less productive communities while maintaining low levels of spectral niche overlap among species. These results highlight the linkages between spectral diversity, resource partitioning and species coexistence. Spectral diversity provides a useful alternative to other plant biodiversity metrics because it integrates functional variation within and across species even in the absence of taxonomic, functional, phylogenetic, or abundance information and has the potential to transform biodiversity assessment given its scalability to remote sensing.