Successional patterns in bitterbrush habitat types in north-central Washington

Abstract

Twenty-five plant communities were classified within 3 bitterbrush (Purshia tridentata) habitat types along the Columbia River in north-central Washington. Topography, indicator species, and soils data were used to assign stands to habitat type. Ordination across 3 habitat types reflected a moisture gradient: bitterbrush/Idaho fescue (Festuca idahoensis) communities occupied the moist end, bitterbrush/needle-and-thread (Stipa comata) communities the xeric end, and bitterbrush/bluebunch wheatgrass (Agropyron spicatum) an intermediate position. Solar radiation index and elevation accounted for 76% of the variation in the major axis. Ordinations of communities within habitat types described the sere. High-seral communities were not present on the study area. Mid-seral communities had greater perennial grass cover and lower bitterbrush density than low-seral communities.