Wireless Sensor Networks and Drones for Measuring Forest Photosynthetic Biophysics
1. Synergistic Use of Ground Sensor Networks
and ‘Drones’ for Measuring Forest
Photosynthetic Biophysics
Cassidy Rankine, PhD Candidate
Arturo-Sanchez-Azofeifa (PI)
U of A’s Center for Earth Observation Sciences
2. Presentation Overview
• What is a wireless sensor network and why use
them for GIS and geomatics?
• Optical WSNs for forest photosynthetic monitoring
• What are lightweight UAVs (aka civilian drones)
and how can they be used for GIS?
• Combining WSNs and UAVs for remote sensing of
forest productivity (health and resilience)
7. Assessments of global change impacts have identified
phenology as a key indicator of ecosystem alteration
(IPCC 2007; Morisette et al. 2009)
Breathing Earth – IDV Solutions. From NASA satellite imagery
8. 45% of solar radiation in visible &
photosynthetic spectrum 400-700nm
Photosynthetic Active Radiation =
9. f raction of
A bsorbed
P hotosynthetically
A ctive
R adiation
10. Light Use Efficiency Model of Plant Productivity
Gross Primary Productivity = iPAR x FPAR x LUE
• iPAR = Incident Photosynthetically Active Radiation
– Depends on atmospheric conditions
• FPAR = Fraction of Photosynthetically Active Radiation Absorbed
– Depends on canopy structure (ie. Leaf Area)
• LUE (ε)= Light Use Efficiency = εmax x STair x SVPD
11. Biospheric Process Modelling requires
integration of multi-scale observations to
relate ecosystem structure to function
13. The air above dense
forests is often hard
to see through!
14. Near-Surface Remote Sensing
• Remote observations (touchless/non-
destructive) of physical features or
processes below the majority of the
atmospheric air mass, typically within
100m of the target
• Emerging approach to investigate
whole ecosystem dynamics
Examples - LTER, TERN, FLUXNET, NEON
21. Broadband PAR Sensors
• Photosynthetically Active Radiation (PAR = 400-700nm)
• Hemispherical sensors (180° FOV)
22. Synchronized PAR sensors
above and below canopy
FAPAR = 1 - t - r
t = fraction of PAR transmitted through canopy
r = fraction of PAR reflected by canopy
FAPAR
23. 3D Understory Light Contours
(canopy transmitted light in deciduous tropical forest at 1m height)
As ecosystem phenology changes, so does primary productivity
PAR_VIS light
life on earth evolved to utilize these wavelengths
not coincident we see and plants use these same wavelengths,
very useful band energetically for life
Gross primary production (GPP) is the amount of chemical energy as biomass that primary producers create in a given length of time. (GPP is sometimes confused with Gross Primary productivity, which is the rate at which photosynthesis or chemosynthesis occurs.) Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues (i.e., "growth respiration" and "maintenance respiration").[2] The remaining fixed energy (i.e., mass of photosynthate) is referred to as net primary production (NPP).
Scaling Up – ground up remote sensing
quantum flux, 8-10 photons to fix 1 CO2 molecule
how to quantify at larger scales?
We work from meso scale – canopy to pixel and image scale
Examples include photography, meteorological sensors, infrared carbon flux, scintillometers, laser trace gases, lidar systems
The marriage of satellite/airborne data with accurate ground based measurements
The sun produces light with a distribution similar to what would be expected from a 5525 K (5250 °C) blackbody, which is approximately the sun's surface temperature
Cables are expensive, time and money, significantly limits coverage distance, and can interfere with plot. Non-intrusive!
Synchromization is important
Enter the EOSL...
Transmitted par is averaged across the entire understory sensor network
FAPAR more robust to changes in spatial resolution of observation. Compared to LAI, fPAR is a flux ratio, advantage being that retrieval accuracy less dependent on canopy 3D structural knowledge – Meroni et al., 2012
----- Meeting Notes (13-04-09 10:11) -----
MODIS resolution not as good
integrated fAPAR linearly related the GPP for the period of observation
Burts of Carbon Sequestration!
Collaborations with computer sciences, electrical engineering, physics, and industry enables rapid advancement of research capabilities in earth system monitoring
Sensor cloud demo anyone? http://sensorcloud.com/