CORVALLIS, Ore. – A satellite imagery analysis shows that the 2021 “heat dome” scorched almost 5% of the forested area in western Oregon and western Washington, turning foliage in canopies from a healthy green to red or orange, sometimes within a matter of hours. Damage to foliage leads to a range of problems for trees including reduced photosynthesis and increased vulnerability to pests and disease, scientists at Oregon State University say. …The forest analysis showed that sun exposure, microclimate and aspect – the direction a slope faces – were factors that made some areas more sensitive to the heat dome. Other factors were tree species, stand age, the timing and pattern of budburst – when dormant buds open and begin to grow – and the presence of foliar pathogens such as the fungus that causes Swiss needle cast in Douglas-fir trees.