1 / 28

Background

Frontiers in Fuels Science: Species-Specific Crown Profiles Models from Terrestrial Laser Scanning. Background. Key Concepts: Document accuracy and validity of existing crown biomass equations (Affleck) Develop new crown biomass/fuel equations for inland northwest tree species (Affleck)

pabla
Download Presentation

Background

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Frontiers in Fuels Science: Species-Specific Crown Profiles Models from Terrestrial Laser Scanning

  2. Background • Key Concepts: • Document accuracy and validity of existing crown biomass equations (Affleck) • Develop new crown biomass/fuel equations for inland northwest tree species (Affleck) • Parameterize crown fuel density profiles over individual stems per species with TLS • Stem dimensions • Crown characteristics (e.g. shape and density) • Where We’ve Come From: • Branch Scale Biomass Using TLS

  3. Background: Working Hypotheses (TLS) • Boles • Incremental bole diameters used to generate basal area • Diameters could be used predict biomass from revised allometries • Crown profiles differ between species • A large body of previous work on crown shapes • Laser gives precise measurements and characterize crown • High replication using laser • Tests using limited sample sizes suggest between species differences are more pronounced than those within species • Biomass is distributed unequally throughout a crown: • Both vertically and horizontally • Distribution differs between species

  4. Introduction: Sampling Vicinity Map • Connection to Destructive Samples • Collect TLS data of sampled trees • Collect independent samples concurrently representing: • same species • site conditions • TLS Sampling Objective • n > 200 Trees sampled Trees & TLS sampled

  5. Introduction: TLS Instrument OptechIlris 36D HD Terrestrial Lidar System • 10 KHz sampling • Point density 1cm or less • Local characterization

  6. Introduction: TLS Sampling • Current Thinking: • Literature suggests that estimating biomass from TLS requires: Zone of Occlusion • Scanning from multiple angles • High resolution • Offsetting potential occlusion of data within tree • Project Approach: • This project seeks to optimize TLS collection by: • Limit scanning time by only sampling a hemisphere • Control errors of omission through sampling volume Zone of Interception 15m Minimum Distance

  7. Introduction: TLS Sampling • Data Resolution a Function of Range: • The instrument is parameterized to collect data at a set resolution at a determined range (focal plane) • Characterize hull of tree • Data decreases in density as it gains range Focal Plane (~4.0mm density) • Types of Occlusion: • Penetration of energy through the canopy or objects • Angle independent/dependent • Shadowing of canopy elements • Depends canopy density • Angularity (branches shadowing objects above) Origin

  8. Methods: TLS Collection and Processing • Data Process Flow • Data Collection • Largest time commitment (e.g. travel, set up, Etc.) • ~15 minutes per scan • Dependent on site conditions (e.g. adjacent tree density) • Alignment of Scans (Polyworks) • Potentially time consuming • Process Using Lab Developed Applications • Designed to begin optimizing tree processing for efficiency and repeatability • Single processing flow for applying alignment, calculating bole dimensions, and normalized canopy distance from • bole.

  9. Methods: TLS-Based Bole Measurements • Three Estimates of Bole Diameter Up The Tree: Three samples of distance from bole centroid Fitted line from selected bole points Modeled from the initial bole diameter at the bottom of the tree

  10. Methods: Distance and Tree Cleaning

  11. Methods: Building a Library of Crown Shapes Height (m) Distance (m)

  12. Analysis • Species used in preliminary work • Crown Characterization • Crown Shapes (profiles and lengths) • Biomass Distribution • Bole characterization • Integrating it all • What’s next?

  13. Analysis • Data sample for preliminary analysis • 6 Douglas firs (Pseudosugamensiesii) • 3 grand firs (Abiesgrandis) • 1 ponderosa pine (Pinus ponderosa) • 1 western larch (Larixoccidenatlis) http://www.idahoforests.org

  14. Analysis: Crown Profiles • 90th crown width percentile chosen to define outer hull • Points at each height interval

  15. Analysis: Crown Profiles • Rescaled both axes as 0-1 • Did this for 6 Douglas firs and 3 grand firs

  16. Analysis: Crown Profiles • Combined all samples per species into one “uber-tree” each

  17. Analysis: Crown Profiles • Model Fitting • curve smoothing • scale of variability • exclusion of bole/incorporation of crown base height

  18. Analysis: Crown Profiles Douglas Fir (n=6) Grand Fir (n=3) Ponderosa Pine (n=1) Western Larch (n=1)

  19. Analysis: Crown Base Height Using some impartial metric to consistently define lower bound of crown length

  20. Analysis: Crown Base Height

  21. Analysis: Crown Base Height / Crown Profiles

  22. Analysis: Crown Biomass Distribution • Hull / void • Survivability analysis • Hull delineation • Within-hull biomass distribution

  23. Analysis: Boles • Many different radius measures generated curve fitted constant dist1 dist2 dist3 average dist

  24. Analysis: Boles • Potential use in linking TLS data to allometry for biomass prediction • Problems to overcome

  25. Analysis: Integrating It All • Per Species • Apply crown base metric • Generate the “uber-tree” • Fit crown profile curve • Determine hull-void demarcation • Determine biomass allocation pattern • For New Trees • Need species, DBH, height, crown length • Use DBH to calculate biomass • Use crown profile function to build outer hull shape • Allocate biomass within defined hull

  26. Analysis: Where To Next… • Things to think about: • Occlusions (of bole, inner vegetation) • Best metric for CBH delineation • Appropriate scale of variation for crown profile curve • Defining hull/void demarcation • Distributing biomass within that hull • Next (this summer through Spring 2013) • More trees, more scanning, more data processing • Linkages to Affleck lab measures • Exploration of applications beyond fire

  27. The Laser Team: • Eric Rowell, Ph.D. Plot scale surface fuels characterization; integration of airborne and terrestrial scanning, fuel consumption. • Tara Umphries, M.S. Quantifying fuel dimensions in a grassland. • Jena Ferrarese, M.S. Measuring conifer crown dimensions and the distribution of biomass within them. • Theodore Adams, M.S. Defining/distributing fuel elements in diffuse shrubs of sagebrush and chamise.

  28. Acknowledgements: • Joint Fire Sciences Program • Inland Northwest Growth and Yield Cooperative • Affleck lab • Active Remote Sensing Lab, National Center for Landscape Fire Analysis

More Related