As all vegetation, the structure of a forest is determined by natural factors such as regional climate and patterns that describe attributes including density, composition, condition, and cover. Forest function depends on structure to provide for ecological processes that define environmental quality. In urban areas, canopy cover determines air and water quality, heat island reduction, water mitigation, biodiversity, among others, and is the driver for all benefits derived from the urban forest. Native species are a crucial part of creating a functioning urban forest structure.