Semi-arid Forests in the Western U.S.

Forests in the western U.S. are subject to increasing wildfires, drought, and land use that is fundamentally altering their utility as natural climate solutions. We used time series of remote sensing data create annual time series datasets (1985-2021) of vegetation cover and disturbance in California, finding fire-driven net declines in tree cover from 1985 to 2021 across California. In collaborator-led projects, we found that the rate of harvest did not necessarily decline following the establishment of a carbon offset project, and that fires are driving significant foregone carbon sequestration potential as a result of reduced photosynthetic capacity. The vegetation cover and disturbance datasets are publicly available!

In a new funded NASA Land Cover and Land Use Change project, we are combining drone-based imagery with time series of thermal data to improve maps of forest mortality occurring due to drought and insect attack. These maps will provide essential information on sensitivity of western U.S. forests to rapid climate change.

Selected relevant publications:

Losses of tree cover in California driven by increasing fire disturbance and climate stress. (AGU Advances, 2022)

Using remote sensing to quantify the additional climate benefits of California forest carbon offset projects. (Global Change Biology, 2022)

The magnitude and pace of photosynthetic recovery after wildfire in California ecosystems. (Proceedings of the National Academy of Sciences, 2023)

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Left: Map of average tree cover in California. Right: changes in tree cover from 1985-2021 [Wang et al., 2022]