Plant spectral diversity integrates functional and phylogenetic components of biodiversity and predicts ecosystem function

Abstract

Biodiversity promotes ecosystem function as a consequence of functional differences among organisms that enable resource partitioning and facilitation. As the need for biodiversity assessments increases in the face of accelerated global change, novel approaches that are rapid, repeatable and scalable are critical, especially in ecosystems for which information about species identity and the number of species is difficult to acquire. Here, we present 'spectral diversity'-a spectroscopic index of the variability of electromagnetic radiation reflected from plants measured in the visible, near-infrared and short-wave infrared regions (400-2,400 nm). Using data collected from the Cedar Creek biodiversity experiment (Minnesota, USA), we provide evidence that the dissimilarity of species' leaf spectra increases with functional dissimilarity and evolutionary divergence time. Spectral diversity at the leaf level explains 51% of total variation in productivity-a proportion comparable to taxonomic (47%), functional (51%) or phylogenetic diversity (48%)-and performs similarly when calculated from high-resolution canopy image spectra. Spectral diversity is an emerging dimension of plant biodiversity that integrates trait variation within and across species even in the absence of taxonomic, functional, phylogenetic or abundance information, and has the potential to transform biodiversity assessment because of its scalability to remote sensing.

Partitioning plant spectral diversity into alpha and beta components

“…containing communities that are most spectrally dissimilar from the average community within the region of interest. Given that species spectral dissimilarity is linked to their functional and phylogenetic dissimilarity (Schweiger et al ), spectrally rare communities can be expected to have rare taxonomic and/or functional composition, either because they harbor uncommon species, or rare combinations of common species.…”

“…While spectral diversity does not isolate any particular facet of plant biodiversity (e.g. taxonomic, chemical, structural), it integrates all of these facets (Schweiger et al ; Appendix ). From a practical perspective, casting spectral diversity as spectral variance depends on fewer user decisions compared to other approaches (e.g.…”

Diversification, adaptation, and community assembly of the American oaks (Quercus), a model clade for integrating ecology and evolution

“…A final advantage of emphasizing ecological dominants as model clades is that their large size makes them amenable to novel methods for detecting changes in functional traits (Cavender‐Bares et al ., ; Schweiger et al ., ) that can be applied with high frequency at large spatial scales. Detecting changes at the canopy scale in an era of global change is increasingly important to manage and protect ecosystem services (Jetz et al ., ).…”

Challenges and opportunities for biogeography—What can we still learn from von Humboldt?

“…Recent advances in remote sensing technology and data storage offer unprecedented opportunities to assess change in both living and non‐living nature. For example, remote sensing has been used to assess changes in land cover (Amici, Marcantonio, La Porta, & Rocchini, ), species abundance (Paganini, Leidner, Geller, Turner, & Wegmann, ), functional traits (van Cleemput, Vanierschot, Fernández‐Castilla, Honnay, & Somers, ; Lausch et al, ) and even phylogenetic composition of plant communities (Schweiger et al, ). It is increasingly used for abiotic aspects, such as soil (Rogge et al, ) and hydrological features (Bierkens et al, ).…”