New technologies in forestry monitoring

  • Terrestrial LiDAR
    • Ground-based approach generating “a high number of points … able to describe with high accuracy the understory of the forest (Henry et. al. 2015)
    • “Potential to estimate in a standardized and automatic way tree diameters, tree height, tree volume, and thus tree biomass” (Henry et. al. 2015)
    • Suggests potential for tech deployment by independent stewards on the ground. This means that a measurement system will be available for forest measurement crowdsourcing in areas which are difficult to assess from above or are heavily utilized.  Ground-based LiDAR can be utilized by hikers, bikers, campers, or travelers that wish to help the US Forest Service obtain ongoing metrics as they pursue their own outdoor activities.
    • terrestrial-lidar
  • Airborne LiDAR
    • Airborne LiDAR is useful for assessing larger areas by creating a manageable view of the canopy concerned with canopy height and density of trees. This approach is more broad than ground based Li-DAR.  Airborne LiDAR is limited by point density, that is, as the trees become thinner, the data becomes less-accurate.
    • Drone deployment will be a game changer for Airborne LiDAR as it is cheaper, more environmentally friendly, and does not require a conventional pilot to be effective. The introduction of unmanned LiDAR systems marks a new stage in forest metrics efficacy.
    • arial-lidar
  • Spaceborne LiDAR
    • Spaceborne LiDAR has the potential to monitor and influence global natural resource management. Geoscience Laser Altimeter System (GLAS) is a spaceborne LiDAR instrument deployed to measure ice-sheet elevations and changes therein over time.  Secondarily, “forest canopy metrics can be generated form the GLAS waveforms (Lefsky et al. 2005; Simard et al. 2011; Xing et al. 2010), and these metrics can, in turn be used to generate estimates of aboveground biomass or carbon (Baccini et al. 2008; Boudreau et al. 2008; Saatchi et al. 2011)”
    • ICESat2 is another spaceborne LiDAR instrument “having a smaller footprint than the previous one … this new instrument will have a blue-green wavelength system that is optimized for ice sheets, not for forest, and will thus only be able to map canopy heights in forests with cover that does not exceed ~70% (Goetz and Dubayah 2011).
    • spaceborne-lidar
  • Radio detection and ranging technology
    • “The ability of a Synthetic Aperture Radar (SAR) is used to improve the resolution beyond the limitation of physical antenna aperture.  Basically, the ability of a SAR system to detect structures of different sizes depends on its frequency.”
    • C-Band, being of short wavelength, is very good at quickly saturating the forest and is therefore more useful in denser biomass areas.
    • L-Band is a longer wavelength which has been used to measure biomass in much thinner areas such as the Savannah.
    • radar
  • Stereoscopy and photogrammetry
    • Three-dimensional imaging
    • Much cheaper alternative to laser scanning data when “modeling key forest attributes, such as tree or forest canopy height” (Straub et al. 2013).
    • Can be effective in measuring difficult-to-measure variables “such as course and fine woody debris and has been shown to be useful to assess forest biomass even in tropical areas (Ottmar et al. 2001; Alvarado-Celestino et al. 2008)”.
    • high-def-imaging
  • Very high-resolution optical imagery
    • Limited by the effects of pollution and angular photography.
    • Able to convey a much more comprehensive image with respect to color and detail in comparison with only airborne LiDAR technology
    • Can be combined with airborne LiDAR for a very comprehensive approach
    • Can be attached to drones to cut down on costs and man hours  stereography