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SUMMARY:Measuring Small-scale Tropical Forest Disturbance with GEDI - Amel
 ia Holcomb
DTSTART:20231006T120500Z
DTEND:20231006T130000Z
UID:TALK204418@talks.cam.ac.uk
CONTACT:114742
DESCRIPTION:Forest disturbance\, defined as partial reduction in forest co
 ver that does not result in conversion to non-forested land\, has surpasse
 d deforestation by area in the Brazilian Amazon. In addition to causing di
 rect carbon emissions\, disturbance also diminishes ecosystem integrity by
  harming forest structure\, even when canopy cover remains. Recent advance
 s using LandSat and Sentinel-1 have improved detection of disturbances at 
 fine spatiotemporal resolution but are so far unable to quantify the chang
 es in forest structure and biomass associated with a detected disturbance.
  The Global Ecosystem Dynamics Investigation (GEDI)\, a novel spaceborne L
 iDAR system\, has captured billions of 25-meter diameter footprints measur
 ing forest height\, plant area\, and understory structure since it began c
 ollecting data in 2019. Though there is no guaranteed repeat cycle\, GEDI 
 often measures the same location several times\; some of these coincident 
 footprints happen to fall before and after a detected disturbance. In this
  work\, we develop a general-purpose open-source pipeline for identifying 
 these locations and use it to find over 7\,100 coincident footprint pairs 
 with intermediate disturbance events across the Amazon basin. We also iden
 tify a control set of over 34\,000 coincident footprint pairs from disturb
 ed areas but without intermediate disturbance events. Analysis of this con
 tinent-scale dataset demonstrates that GEDI can detect canopy and biomass 
 losses in non-stand-replacing disturbances as small as 0.09 ha. GEDI’s u
 nique three-dimensional view of forest structure allows us to identify var
 ied effects of different disturbance types\, including areas where the upp
 er canopy retains its height\, but the understory suffers substantial loss
 es. Finally\, we model the relationship between LandSat and Sentinel-1 dis
 turbance detection parameters and GEDI-measured percent biomass loss. This
  is the first step towards a pan-tropical\, spatially explicit estimate of
  carbon losses and structural changes due to forest disturbance.\n\nAmelia
  Holcomb is a second-year PhD student in Computer Science and Plant Scienc
 es. Her PhD brings together these two fields to develop novel remote sensi
 ng techniques for measuring biomass and structural changes following tropi
 cal forest disturbance and regrowth. 
LOCATION:FW 11\, William Gates Building. Zoom link: https://cl-cam-ac-uk.z
 oom.us/j/4361570789?pwd=Nkl2T3ZLaTZwRm05bzRTOUUxY3Q4QT09&from=addon 
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