underbrush

Underbrush is the layer of vegetation that grows beneath the forest canopy and above the forest floor, typically dense and dominated by shrubs, young trees, vines, and other shade-tolerant plants. It forms a continuous but patchy cover that can impede movement and visibility in wildland areas.

Ecology: Underbrush provides important habitat and food for wildlife, helps stabilize soil, and influences moisture retention and nutrient cycling. It affects light availability for the overstory and responds to disturbance, climate, and fire. The species composition of underbrush varies by region; temperate forests may host thickets of shrubs and saplings, tropical forests feature a dense understory of small trees, ferns, and vines, and boreal zones include dwarf shrubs and regenerating saplings.

Management: In forestry and land management, underbrush is often thinned or removed to reduce wildfire risk, improve access, or promote growth of desired tree species. Practices include mechanical thinning, mowing, and prescribed burning. Controlling invasive underbrush species is also a common objective to protect native ecosystems.

Relationship to understory: The term underbrush is sometimes used interchangeably with the forest understory, though some definitions reserve underbrush for the denser, woody components, while herbaceous layers are treated as part of the understory.