Transcript 11/13/2003: John Rademacher. Edge ecology and study objectives

Remote Sensing and
Ecophysiology
Remote Quantification of
Photosynthesis
Measurement and Modeling:
Portions of Literature Review
• Measurement
– Remote sensing
– Direct Measurements
• Leaf level estimations of Chl, N, Pn, etc.
• Ecosystem flux measurements
• Modeling
– CASA
– CENTURY
– PnET… etc.
Measurement and Modeling
(cont.)
Egg
Data
Induction
Chicken
Model
Deduction
Francis Bacon
• Now although it be true, and I know it well, that there is
an intercourse between causes and effects, so as both
these knowledges, speculative and operative, have a
great connection between themselves; yet because all
true and fruitful natural philosophy hath a double
scale or ladder, ascendent and descendent, ascending
from experiments to the invention of causes, and
descending from causes to the invention of new
experiments; therefore I judge it most requisite that
these two parts be severally considered and handled.
--From Of the Proficience and Advancement of Learning
The Etymology of “Scale”
Scale > Scala, ae (from scandere)
LL. Stairway, allegorically stairway to
heaven
Transformation of measurements from the
selective to the synoptic
Scale, cont.
• Rastetter et al (2003)
– Using mechanistic models to scale
measurements through space and time
Scaling Ecological Estimates
Ollinger, Aber & Fedderer (1998)
What is Needed for Modeling
(e.g. what RS inputs)
Popularity of Nutrient Ecological
Models
300
250
Model Name
• Nitrogen-based
Modeling
• Photon-UseEfficiency
• Et cetera
200
150
100
50
ELM
GAS-FLUX
NCAR_CCM
Number of Citations
3
YN
EN
EE
D
PG
VM
G
EM
AM
BL
E
G
YB
RI
D
AS
S
H
M
T
D
C
D
N
BI
O
TR
CENTURY
Pn
E
BIOME-BGC
CA
S
BIOME3
A
0
What can we detect?
Stress
• Terrestrial plants are
regularly stressed
• Can detect
responses to stress– Conversion of
carotenoids for heat
dissipation
– Dissipation of extra
light through
fluorescence
QuickTime™ and a
GIF decompressor
are needed to see this picture.
Estimate Foliar N with
Hyperspectral Techniques
Gong et al (2002)
Importance of Photosynthetic
Pigments (and more!)
• Chlorophyll estimation (also useful, as is
often correlated with total foliar N)
• Carotenoid Estimation
• Fluorescence-based photosynthesis
estimation
– related to direct measurement of canopy
productivity
– Useful for PUE models (Freedman et al (2002)
Estimation of Chl and
Carotenoids
Blackburn (1998)
Estimation of Chl and
Carotenoids
Blackburn (1998)
Estimation of Chl and
Carotenoids
Blackburn (1998)
Licor 6400 Fluorometer
Addition
Problems with estimating
Fluorescence Outside the Chamber
• Multiple Components to apparent
reflectance signal:
– Reflectance/ Fluorescence
– Loss via transmittance
– Loss via absorbance
Problems with estimating
Fluorescence Outside the Chamber
Leaf
Incoming Solar Radiation
Leaf Reflectance Component
Chlorophyll Fluorescence
Component
Problems with estimating
Fluorescence Outside the Chamber
• Additional Problems
– Leaves heterogeneous
– Canopies Complicated
3D Model of Canopy
Fluorescence
Camenen et al (1996)
Modeling of Leaf Reflectance
and Fluorescence
• Zarco-Tejada et al (2000)
• Dawson et al (1998)
• PROSPECT (combined with SAIL),
Haboudane et al (2003)
Modeling Fluorescence
Zarco-Tejada et al (2000)
Leaf Level Radiative Transfer:
LIBERTY
Dawson et al (1998)
SAIL and PROSPECT
Parameters
Haboudane et al (2002)
Impact of Leaf Absorbance on
Measurements
Peterson et al (2001)
Net Pn vs. Red/ Far Red
Ratios
Freedman et al (2002)
Comparison of Fluorescence Ratios,
Photosynthesis and Stomatal Conductance
Flexas et al (2002)
Double Peak
Zarco-Tejada et al (2001)
Final Comments
• Fluorescence viable technique for
canopy level estimation of Pn
• Useful for estimation of Pn in realtime
(model validation and tuning)
• Useful toward PUE modeling
• Nutrient Concentration Estimations
possible (useful for PnET and other N
driven models
Further Directions
• Linkages between RS and models need
to be explicitly sought for scaling
between selective and synoptic
estimations (deeper lit. on models)
• “Direct” measurement components-eddy-covariance biophysics and
relevance to modeling process
Heterogeneity of Pn within
Leaves
Lichtenthaler & Babani (2000)