This guidebook describes major biological and physical attributes of the 243-ha (600-ac) North Fork Silver Creek Research Natural Area (RNA), Josephine County, Oregon. Chosen to represent the diversity of shrub species that occur in the western Siskiyou Mountains on non-serpentine metamorphic bedrock, the RNA supports manzanita (Arctostaphylos spp.), giant chinquapin (Chrysolepis chrysophylla), deer oak (Quercus sadleriana), Sierra laurel (Leucothoe davisiae), Pacific rhododendron (Rhododendron macrophyllum), and salal (Gaultheria shallon). The site was also designated to represent examples of two forest types present on non-serpentine soils in southwestern Oregon: (1) Port Orford cedar-western hemlock (Chamaecyparis lawsoniana-Tsuga heterophylla) with Sierra laurel and western swordfern (Polystichum munitum); and (2) white fir/Cascade barberry (Abies concolor/Berberis nervosa) forest with longtube twinflower (Linnaea borealis) and sweet after death (Achlys triphylla).