The __________ is the primary layer of the rainforest and forms a roof over the two remaining layers.

In a tropical rainforest ecosystem, the layers are stratified as follows from top to bottom: Emergent layer, Canopy layer, Understory layer, and Forest floor. The canopy layer functions as the primary layer of the forest, with its dense network of overlapping leaves and branches forming a continuous ceiling or "roof" over the understory and forest floor layers.