Tribal Forests and Climate Change Site visits to reservations in all regions indicated that the effects of climate change are already evident. In repeated cases, growing seasons are shifting, winter and/or summer temperatures are increasing, fire seasons are longer, precipitation patterns are changing, and tree species are moving higher, or farther north, potentially leaving reservations. Adaptation strategies can be threefold: (1) protect resources from climate change by promoting tree/ stand resistance and resilience, (2) promote stand recovery to a prior state or condition after disturbance, or (3) actively facilitate, or accommodate, forest change towards an anticipated future, such as assisted tree migration. High tree stocking and fuel loading occurs throughout Indian Country, which presents an ever-increasing forest health risk by increasing tree stress during periods of drought and/ or fire intensity and severity during wildfire events. Reducing tree density through thinning redistributes available resources among remaining trees, thereby increasing their resistance to drought as well as increasing diameter growth, particularly important for fire-adapted species. The ability of cambium tissue to survive fire is a function of bark thickness, and bark thickness is a function of tree diameter. The thicker the bark, the more resistant a tree is to surface fire. Similarly, reducing surface fuel loading decreases the probability of tree death during fire through reducing scorch height, potential for vertical spread into canopies,
A prescribed under-burn in a ponderosa pine stand on the Warm Springs Reservation in Oregon. PHOTO CREDIT: VINCENT CORRAO
and residence time at the base of trees. Backlogs in thinning and hazardous fuel reduction treatments directly reduce current forest health as well as future health of Indian forests. Projections of climate change impacts suggest longer and drier summer periods are likely. Increasing acres in the “High to Very High” Wildfire Hazard Potential classes suggest wildfires will have higher resistance to control, potentially burning larger areas as happened in 2012, 2018, and 2020 (Figure B-6). Such wildfires create exceptional seedling demands that quickly exceed normal nursery capacity, delaying forest regeneration projects and making seedling establishment more difficult through delayed planting and higher vegetation competition when weeds and shrubs occupy deforested sites. Although herbicide applications and other treatments can hold back this competition, speculative seed and seedling purchases may
be a useful tool among tribes regionally, and in collaboration with their neighbors. Maintaining a supply of surplus seed and seedlings may be cost effective considering the costs of maintaining plantable sites, physical planting costs, and potential for planting failures. Experiences by several western tribes suggest that pines at the lower elevations and western larch at the higher elevations have been most successful in weathering climate change and wildfire. True fir and other species are less successful and, particularly under high stand density conditions. Species that can be grown under uneven- or multi-aged stand conditions may also have an advantage under changing climatic conditions, with tree density and fuel maintenance remaining crucial to sustainable forest management. as the “heat dome” of 2021 demonstrated, may be less successful in the long run,
Task Findings and Recommendations 93
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