Phase II of NAFD Project
Woody Encroachment
FIGURE: Three phases of juniper encroachment in the Great Basin.
According to the 1st State of the Carbon Cycle Report, woody encroachment is associated with the second largest terrestrial sink of carbon, but is also the second most uncertain sink term. North American forests are a major contributor to woody encroachment, yet the rates and extent of forest encroachment remain uncertain. Our proposed research is well positioned to improve estimates of this highly uncertain, but important forest carbon process, in a consistent, repeatable manner across all forest types currently undergoing encroachment in the conterminous US.
We have a variety of field datasets for use in our analyses. The most important of these will be where we have actual observations of juniper cover change at two points in time over the period of the Landsat record. These will include datasets from FIA, Rick Miller, and airphoto interpretation.
The remote sensing approach to be used in this analysis include both the LandTrendr algorithm and the TimeSync calibration/validation tool. Using TimeSync, we can evaluate spectral trends of specific locations of areas known to be, or suspected of, increasing in juniper cover to determine if spectral trends for these locations are consistent with juniper cover increase. This can serve to both calibrate and validate maps derived from the dense LTSS. For eastern Oregon alone there are ~10 contiguous Landsat scenes over which we will evaluate run LandTrendr and collect validation data to characterize both juniper increase and its consequences in terms of biomass change.