Measurement type Spatial scale Temporal Scale Purpose Methods Example Citations
Laboratory or leaf-level << 1 m Snapshot Variation in leaf-level optical properties; spectral response to stress (e.g., drydown); development of leaf-scale functional trait models Collection of leaf and canopy spectra in controlled, manipulation environments and in situ; leaf spectroscopy; collection of leaf endmember spectra (Hunt & Rock, 1989; Serbin et al., 2019; Stasinski et al., 2021)
Field spectroscopy
<1 m - 10 m Canopy
Snapshot
Variation in spectral profiles by species at different scales; developing scaling approaches
Near-surface, non-contact measurement of plant canopy reflectance
(Davidson et al., 2016; Karl Fred Huemmrich et al., 2013)
Tower or automated tram
100s of m Canopy - Landscape
Continuous (hourly) over seasons
Diurnal and seasonal variation; variation between species; developing scaling approaches
Repeated manual or automated measurement of plant canopy reflectance
(Hilker et al., 2011; Pierrat et al., 2021)
UAS
0.2 - 1 m Landscape
Snapshots
Fine-scale spatial information at landscape to watershed scales; scaling; seasonal variation
Collection of surface reflectance and other composition and structural information from unoccupied platforms
(Thomson et al., 2021; Yang et al., 2021)
Piloted aircraft
0.5 - 5 m Landscape - regional
Snapshots every few years
Regional mapping and intermediate scale of observation
Imaging spectroscopy
(Maguire et al., 2021; Singh et al., 2015)
Spacecraft
10m - 8 km Regional - continental
Repeating daily - weekly
Regional to continental-scale mapping, monitoring of coarse spatial resolution phenological change
Imaging spectroscopy, change detection and time series analysis
(Puletti et al., 2016; J. A. Wang et al., 2020)