| parts | | type | Technical Summary |
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| value | Forests of the Navajo Nation are experiencing warming temperatures that exacerbate drought stress, along with increased risk of bark beetle outbreaks and high-severity fire, the last resulting from high fuel loads associated with fire exclusion. Navajo foresters are increasingly concerned about loss of forest to these stressors, along with the loss of ecosystem services. Density reduction treatments and the use of surface fire in management are proven silvicultural strategies to reduce these vulnerabilities and increase forest resilience, but translating strategic directives into tactical (actionable) plans requires a local, forest-scale analysis to inform placement and specifics of treatments. In collaboration with Navajo foresters Alexious Becenti (Navajo Forestry Department, NFD) and Jamie Yazzie, we propose to catalyze this process by collecting local data, analyzing them, and deliberating on those results to support NFD prioritization and placement of treatments. Now is the time to do this work. The Navajo forest inventory plot network has not been measured in 15 years; it will be measured in the 2019 field season, and not again for another 15 years. Specifically, we will augment this planned forest monitoring by collecting ~1,000 increment cores in the Navajo forest inventory plot network, across a representative sample of forest types, stand densities, and canopy classes, adding annual-resolution information about how year-to-year climate (e.g., drought) variation affects tree growth. The proposed funding would support this tree ring sampling, conducted by a crew of two Navajo foresters led by Jaime Yazzie. The samples would then be crossdated and measured in the Dendro Lab at Utah State University under the supervision of coPI DeRose. Variation in tree-level basal area increments will be analyzed using multiple regression models, to evaluate the many and interacting factors (e.g., tree size and canopy position, species, stand density, biophysical variables) that influence tree growth and its drought sensitivity. This will generate a refined picture of how and why drought stress varies on the landscape – for example, how drought stress affects trees in different canopy classes, or is influenced by stand density – which can then be used to inform specific silvicultural practices aimed at climate adaptation. We plan for an in-person meeting at the Navajo Forestry Department Office in Ft. Defiance in the first quarter of project year two (September, 2020) to discuss results as they emerge and deliberate on silvicultural tactics. Deliverables will include the representative tree-ring collection, a final report delivered to the NFD summarizing the treatment options expected do the most good at the fastest pace, a short fact sheet with strong visuals that can be used by the NFD in chapter house meetings to discuss forest health and management, and the dissemination of results at the 2021 Intertribal Timber Symposium and Navajo Department of Natural Resources Summit by Jaime Yazzie. Finally, the tree-ring data and multiple regression analyses produced here can, in the future, serve as the basis for the development of a tree ring-based, climate-sensitive version of the Forest Vegetation Simulator, the growth and yield model used by foresters across the U. S. to project forest dynamics into the future and make decisions about forest treatments. |
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