Forest Canopy Research: A Physical and Scientific Frontier Studies of warblers showcase how ecologists approach studies of one or a few species. Other ecologists have been concerned with the ecology of entire forests, lakes, or grasslands, which they treat as ecosystems. An ecosystem includes all the organisms that live in an area and the physical environment with which those organisms interact. Many ecosystem studies have focused on nutrients, the raw materials that an organism must acquire from the environ- ment to live.