Ecology

Ecosystems

Defining an Ecosystem

An ecosystem is a biotic community together with its physical environment, considered as an integrated unit. Implied within this definition is the concept of a structural and functional whole unified through life processes. An ecosystem may be characterized as a viable unit of community and interactive habitat. Ecosystems are hierarchical and can be viewed as nested sets of open systems in which physical, chemical, and biological processes form interactive subsystems. Some ecosystems are microscopic and the largest comprises the biosphere. Ecosystem restoration can be directed at different-sized ecosystems within the nested set, and many encompass multiple states, more localized watersheds, or a smaller complex of aquatic habitat.

Put another way, each organism (including humans) is affected by and interacts with its environment. That environment is formed from a combination of interactive non-living and living elements. The non-living elements include: energy, water, air, substrate, and chemical constituents such as nutrients. The living elements include plants, vertebrate animals, invertebrates, and microorganisms. When we consider both forms of elements and their interactions as a single entity, we have an ecosystem at some level of organization.¹