10.5061/DRYAD.4J0ZPC8CM
Chlus, Adam
0000-0001-6719-9956
University of Wisconsin–Madison
Townsend, Philip
University of Wisconsin–Madison
Species and foliar biochemical trait maps for Blackhawk Island, Wisconsin
May-October 2018
Dryad
dataset
2022
FOS: Earth and related environmental sciences
foliar chemistry
tree species
PLSR
random forest
USDA McIntire-Stennis*
WIS01809
USDA McIntire-Stennis*
WIS03008
NSF Macrosystems and Early NEON Science*
1638720
2022-04-06T00:00:00Z
2022-04-06T00:00:00Z
en
1176980637 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Foliar biochemical traits are important indicators of ecosystem
functioning and health that are impractical to characterize at large
spatial and temporal scales using traditional measurements. However,
comprehensive inventories of foliar traits are important for understanding
ecosystem responses to anthropogenic and natural disturbances, as inputs
into ecosystem process models, and for quantifying spatial variation in
functional diversity. Imaging spectroscopy has been demonstrated as a
valuable tool for developing maps of ecologically important foliar traits
at large scales, but its application to mapping foliar traits over the
course of the growing season has been limited. We collected
high-resolution imaging spectroscopy data over Blackhawk Island,
Wisconsin, USA at eight time points during the 2018 growing season (May –
October). Using partial least squares regression (PLSR) we developed
predictive models applicable to all dates to produce canopy-level maps of
eight traits related to ecophysiological function: chlorophyll content,
leaf mass per area and concentrations of calcium, nitrogen, phosphorus,
potassium, phenolics and lignin. The accuracy of our models varied across
traits (R2: 0.25-0.86); traits with well-defined absorption features were
retrieved with high accuracy including chlorophyll (R2: 0.86; %RMSE: 11.0)
and total phenolics (R2: 0.86; %RMSE: 11.0). We also assessed how well our
models estimated biochemistry on novel species and new dates using a
cross-validation analysis. Chlorophyll and total phenolics were well
estimated across withheld dates and species, whereas calcium was estimated
poorly on both withheld species (R2: 0.08) and dates (R2: 0.07). Our
canopy-level maps of macronutrients (N, P and K) showed general trends of
decreasing concentration over the course of the year, reflecting dilution
by carbon-rich compounds during the growing season and resorption during
senescence.