After decades of fire suppression, California’s forests face increased fire risk from the buildup of fuels. Measurements of fuel loads suggested that stands dominated by a sugar pine (Pinus lambertiana) had significantly higher loads of fine fuels than ponderosa pine (Pinus ponderosa). Based on fire modeling, sugar pine may also show more severe fire behavior than ponderosa. Standard fuel models did not closely correspond to the custom fuel models in either fuel loads or predicted fire behavior, suggesting a need for further development of new fuel models. Climate can impact both fire behavior and species dominance, as well as overall forest health. Dendroclimatology suggested that warmer winters, cooler summers, and cooler springs in the past year were the best growing conditions, although effects varied by species. Greater precipitation and climate moisture index tended to be beneficial to all species almost year-round. Results on climate and competition indicated that climate could affect which species had a competitive advantage – e.g. conditions that were negative for pines but neutral for other species tended to produce greater growth from interspecific competitors than from dominant pines. However, conditions that were negative for both the dominant pine and the competitor showed some tendency to favor the dominant tree, while conditions that were beneficial to both tended to favor the competitor. Future climate change may have negative impacts on growth and alter competitive dynamics. Dominant trees may show greater resilience to negative conditions, and thinning treatments to reduce competition may also reduce climate stress in all trees.
Read
