Watersheds make good study areas because they have relatively defined areas with known sources of inputs and outputs. These studies allow ecologists to examine mass balance , which is the large-scale movement of materials. Hydrologic features such as precipitation, surface runoff, and groundwater flow can be examined to determine the flux of materials into and out of the system and the cycling of nutrients within the ecosystem. These factors can be integrated to obtain a more holistic view of the ecosystem. Another advantage of watershed studies is that outputs from one ecosystem are inputs into another ecosystem, so that the influences of ecosystems on each other can be studied.
Watershed studies continue to provide ecologists with a wealth of information about ecosystems.
A relatively recent addition to the discipline of ecology is the subdiscipline of landscape ecology . M.G. Turner has been a primary advocate of landscape ecology. In this subdiscipline, ecologists consider the interactions of ecosystems within large landscapes. These interactions are dependent upon the sizes and relative positions of the ecosystems within the landscape. Literally, the direction an ecosystem faces will greatly influence the processes that occur within.