Closed canopy is the characteristic of:

A closed canopy is a defining characteristic of forest ecosystems, where the crowns of dominant trees form a nearly continuous cover that blocks most sunlight from reaching the forest floor. This dense overhead coverage creates distinct microclimates and light gradients that influence understory vegetation. Grasslands have minimal canopy, tundra has low vegetation, and taiga (boreal forest) has a more open canopy structure compared to tropical or temperate forests.