Pacific Northwest Dry Douglas-fir and Madrone Forest

This ecological system is most common in the Puget Trough - Willamette Valley ecoregion of Oregon and Washington but also occurs in adjacent ecoregions. It occupies small patches associated with dry sites or larger areas in prairie landscapes. This system historically had moderate- to low-severity fires moderately frequently. Historically, these communities were either part of larger forested landscapes or occupied sheltered topographic positions in prairie-dominated landscapes. They now also occur on some sites that formerly supported prairies or tall shrublands (Corylus cornuta) with scattered trees. In the mountains, this type occurs locally on dry sites within dry to mesic (for the coastal areas) climates up to about 1220 m (4000 feet) elevation. This is a forest or woodland primarily dominated by the long-lived conifer Pseudotsuga menziesii. The broadleaf evergreen Arbutus menziesii, the short-lived conifer Pinus contorta, the broadleaf deciduous Acer macrophyllum, and the shade-tolerant conifer Abies grandis are local dominant or codominant species. These sites are too dry and warm or have been too frequently and extensively burned for anything more than small amounts of Tsuga heterophylla or Thuja plicata to be present as regeneration. Arbutus menziesii dominance is favored by high-severity fires on sites where it occurs, and Pseudotsuga menziesii can be locally eliminated by logging and hot fire or repeated high-severity fires. Calocedrus decurrens is absent. Abies grandis can be an important subcanopy or sapling tree, especially in and around the Willamette Valley and in the driest portions of the Georgia Basin (Coastal Douglas-fir Zone).

This system is limited to the foothill transition zone of the Puget Trough - Willamette Valley - Georgia Basin ecoregion.