The ecosystem primarily found at lower elevations of the Rockies is a Deciduous forest.

At these elevations, the Rockies are characterized by forests with a mix of broadleaf trees like aspen, oak, and maple, which thrive in the warmer, milder conditions of lower altitudes. Common species include aspen, oak, and maple, which create vibrant seasonal landscapes, especially in the fall when the leaves change color. This ecosystem hosts a diverse range of wildlife, including deer, foxes, and many bird species, all adapted to the forest environment. Deciduous forests play an important role in the Rockies by supporting biodiversity, enhancing soil fertility through leaf decomposition, and providing essential habitats for numerous plants and animals.