Intra-annual taxonomic and phenological drivers of spectral variance in grasslands

Thornley, Rachael; Gerard, France F.; White, Kevin; Verhoef, Anne. 2022 Intra-annual taxonomic and phenological drivers of spectral variance in grasslands. Remote Sensing of Environment, 271, 112908. 18, pp. https://doi.org/10.1016/j.rse.2022.112908

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Abstract/Summary

According to the Spectral Variation Hypothesis (SVH), spectral variance has the potential to predict taxonomic composition in grasslands over time. However, in previous studies the relationship has been found to be unstable. We hypothesise that the diversity of phenological stages is also a driver of spectral variance and could act to confound the species signal. To test this concept, intra-annual repeat spectral and botanical sampling was performed at the quadrat scale at two grassland sites, one displaying high species diversity and the other low species diversity. Six botanical metrics were used, three taxonomy based and three phenology based. Using uni-temporal linear permutation models, we found that the SVH only held at the high diversity site and only for certain metrics and at particular time points. We also tested the seasonal influence of phenological stage dominance, alongside the taxonomic and phenological diversity metrics on spectral variance using linear mixed models. A term of percentage mature leaves, alongside an interaction term of percentage mature leaves and species diversity, explained 15-25% of the model variances, depending on the spectral region used. These results indicate that the dominant canopy phenology stage is a confounding variable when examining the spectral variance-species diversity relationship. We emphasise the challenges that exist in tracking species or phenology-based metrics in grasslands using spectral variance but encourage further research that contextualises spectral variance data within seasonal plant development alongside other canopy structural and leaf traits.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.rse.2022.112908
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	0034-4257
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	phenology, spectral variance, species diversity, multi-temporal, grasslands, vegetation
NORA Subject Terms:	Ecology and Environment
Date made live:	23 Mar 2022 11:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/532304

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