These grass-dominated landscapes are found throughout the state, but especially in the Willamette Valley and parts of the Umpqua and Rogue Valleys. They are adapted to frequent lowintensity fires in which the ground layer is burned, but tree canopies if present are generally unaffected. In addition to ignitions from lightning, indigenous people intentionally and regularly burned these landscapes for a host of reasons including to increase their productivity, optimize wildlife habitat, protect perennial streamflow, and minimize wildfire risk along travel routes and around communities. Prescribed fire on a short (3-5 year) return interval can be an effective way to restore and maintain these ecosystems today. Explore more about how fire can be used as a tool in managing fire-adapted oak habitats in Oregon.

These include Ponderosa pine dominated forests east of the Cascades, and the mixed conifer forests and oak woodlands of Southern Oregon from the Rogue Valley south. These forests are adapted to frequent, low or mixed-severity fires, and stemming from both indigenous burning and lightning ignitions. Dry forests have greatly suffered from the history of 20th century fire suppression, and can be said to have a fire deficit with excess fuel having accumulated over millions of acres. These forests need a period of careful site preparation and manual thinning before prescribed fire can be re-introduced safely.

The classic NW temperate conifer forests with sword fern/salal/Oregon grape understories, and a coniferous canopy dominated by Douglas-fir, western hemlock, or Sitka spruce, occur in the Coast range about as far south as Port Orford, and on the west slope of the Cascade mountains as far south as the Umpqua Valley. Until very recently, fire history in this forest type was thought to be limited to infrequent, stand-replacing or mixed-severity fires on a very long return interval of 150-500 years, resulting in large patches of different aged stands over the landscape.Historically they were driven by lightning ignitions coupled with hot dry east winds in late summer or fall.The Tillamook Burn of 1933, the Gorge Fire of 2017, and the Riverside/Beachie Creek/Lionshead fires of 2020 all fit into this pattern of burns being intensified by winds from the east. Recent fire scar research from OSU has shown that these forests have also been shaped by episodes of more frequent moderate and low severity fires, with great variability over time and space, leading to the conclusion that fire in west-side forests is a complex and dynamic factor that cannot be easily classified as a ‘regime’. Learn about the case for limiting fire in this ecotype in Fire, Carbon, and Climate Change in Wet-Side Forests | Cascade PBS

Dry, shrub dominated plant communities tend to be fire adapted, but on a longer return interval than grass-dominated communities.  When fires happen too frequently, those shrub species that spread by seed will be killed before they are old enough to reproduce.

Sagebrush steppe is common east of the Cascade Mountains. Fire in sagebrush is a complex topic, with some sagebrush ecosystems needing more fire than they are presently getting, and some sagebrush ecosystems needing less. As a rule though, many sagebrush ecosystems need to be protected from fire, especially with the advent of invasive annual grasses such as cheatgrass. Fire in sage brush is typically ‘stand replacing’, meaning that all of the dominant vegetation is killed by the fire, and as sagebrush grows fairly slowly it can take up to 40 years for the shrubs to grow back and be old enough to set seed. Learn more about fire management strategies for Sagebrush Ecosystems in Oregon| Oregon Conservation Strategy

Another shrub-dominated plant community is the dry chaparral of Southern Oregon. Fire plays an important part in this ecosystem, but if fire comes too often the shrubs cannot persist. There is concern that in some cases the presence of Oregon white oak is incorrectly used as an indication that an area should be maintained or restored to oak savannah, with a more frequent fire interval, when in fact an ecologically valuable chaparral plant community is present. Learn more about indigenous use of fire in chapparal plant communities here: An Ethnobiological Approach to Reconstructing Indigenous Fire Regimes | Journal of Ethnobiology

Adapted to a low severity or mixed severity regime with a 35-200 year return interval. Some of these forests would experience infrequent, stand-replacing fires from lightning ignitions. Lodgepole pine is particularly adapted to stand-replacing fires. They burn easily, and naturally grow close together. All the adult trees are killed at once, but the fire-adapted seeds resprout quickly and grow back as a thick, single-age stand.  Certain alpine areas such as huckleberry fields are intentionally burned by native Americans to support the health of the plants and prevent encroachment by trees.