Lake Alva-Birch Hemlock features a mature northern mesic forest on the rolling topography south of Lake Alva. The old-growth forest is composed of hemlock, yellow birch, and sugar maple with basswood, red oak, and white pine. Very large, old trees are present including scattered super-canopy white pine. In minimally disturbed areas the hemlock comprises 50% of the canopy with trees averaging between 9-15 inches in diameter and the largest trees up to 25 inches. Although hemlock reproduction is minimal here, there are lush beds of hemlock saplings in the stand adjacent to the wetland southeast of the lake. The groundlayer includes Canada mayflower, shining club-moss, American starflower, bunchberry, three-leaved goldthread, winterberry, trailing arbutus, twinflower, and twisted stalk. On more level terrain further south and east is a second-growth hardwood forest of medium-sized sugar maple, red oak, and paper birch. A few small stands of medium to large hemlock occur within this hardwood matrix. The undeveloped 24-acre Lake Alva is a seepage lake with low fertility and a sand/gravel bottom. Surrounding the lake is a conifer swamp dominated by black spruce and tamarack with white cedar, balsam fir, and white spruce. Understory species include blueberry, leather-leaf, pond sedge, creeping snowberry, Labrador tea, bog rosemary, cinnamon fern, pitcher plant, and American starflower. Lake Alva-Birch Hemlock is owned by the DNR and was designated a State Natural Area in 2007.