Two Decades of Changes in Forest Aboveground Biomass in the Southwestern United States from MISR on Terra

Mark James Chopping,  Montclair State University,  choppingm@mail.montclair.edu (Presenter)
Zhuosen Wang,  NASA GSFC/University of Maryland,  zhuosen.wang@nasa.gov
Michael Bull,  NASA, JPL,  michael.a.bull@jpl.nasa.gov
Crystal Schaaf,  University of Massachusetts Boston,  crystal.schaaf@umb.edu
Rocio Duchesne-Onoro,  University of Wisconsin - Whitewater,  duchesnr@uww.edu

Interannual AGB estimates from conventional nadir-viewing multispectral satellite sensor images are prone to error for biomes with highly dynamic responses to precipitation, owing to their large interannual variation in greenness. Multi-angle remote sensing provides a different axis of information, with a sensitivity to forest canopy density from varying sun-target-sensor geometry. Recently-published research has shown that 672 nm multi-angle imagery from the NASA Multi-angle Imaging Spectro-Radiometer (MISR) on the Terra satellite can be used to produce wall-to-wall forest AGB map series over long periods (doi.org/10.1016/j.rse.2022.112964). A 250 m grid interval dataset for the southwestern United States spanning 2000 - 2021 is available at the Oak Ridge National Laboratory Distributed Active Archive Center (doi.org/10.3334/ORNLDAAC/1978). For a calibration area in southern Colorado covering a range of forest densities and surface cover types (needle-leaf forest, broadleaf woodlands, grassland, irrigated crops, snow, exposed rock, desert, and water), a multiangle index showed a strong relationship with the reference dataset (NBCD 2000), with R^2 of ~0.9, and RMSE of ~20 Mg ha^-1, whereas NDVI, and red and near-infrared bidirectional reflectance factors from MISR's nadir camera show much weaker relationships: R^2= 0.32, 0.07, and 0.37, respectively, with corresponding RMSE values of 119, 120, and 120 Mg ha^-1. Preliminary calculations of the net loss of AGB in southwestern U.S. forests for 2000 – 2022 from all disturbances is estimated at 74 Tg, with maps allowing attribution to specific disturbance where historical fire, beetle, and harvest perimeters are available. The relatively small decline up to 2015 is largely owing to forest growth in northern California, resulting in +22 Tg vs -5 to -10 Tg for all other states except Nevada (+0.8 Tg). The severity of the fire seasons since, with large fires in California and elsewhere, resulted in the large net loss over the two decades to 2022.

Poster: Poster_Chopping_3-12_185_35.pdf 

Poster Location ID: 3-12

Presentation Type: Poster

Session: Poster Session 3

Session Date: Thu (May 11) 3:00-5:00 PM

CCE Program: TE