Southwest Mabou Nature Reserve protects 3.5 km of river corridor, with rich floodplain, several rare sedges and other plants. It also supports older hardwood forest of sugar maple, yellow birch, beech, and white ash.

The exposed calcareous banks of the Southwest Mabou River provide a refuge for rare plants that thrive in alkaline environments.

This nature reserve is the only protected area within the Judique Hills and Plain natural landscape.