SG is an uncommon Discharge Slope Ecosystem map component dominated by a white spruce (Picea glauca) forest.  SG units are uncommon, found on the northern part of the peninsula at the margin of large relict glacial lakebeds, both along Kalifonsky Beach Road and northwest of the City of Kenai.

This component occurs as a woodland or moderately open stand with a diverse Barclay's willow dominated understory at the edge of a large peatland complex.  Microtopography is well-developed as hummocks.  Fire, or another stand-replacing natural disturbance event, has probably played a role in the development of these stands.

White spruce is commonly regarded as an upland plant, and is categorized as facultative upland on the Alaska Wetland Plant List (US Fish and Wildlife Service, 1996).  On the Kenai Lowlands, however, white spruce sometimes occupies wetlands, though no white spruce communities are described in the plant community classification.

SG has formed complexes with three other Discharge Slope ecosystem components. The first is with willow (SGS); the second is with alder (SAG and SGA); and the third is with black spruce (SMG and SGM).