Levels of Ecological Classification
Ecology is the study of the relationships between organisms and the environment. Ecologists use a number of levels of classification that reflect ecological relationships. These terms have specific meanings in ecology. As in taxonomic classification, the fundamental unit of ecological classification is the species. For example, the most common species of mammal within the bosque is the white-footed mouse, whose scientific name, which is unique to this species, is Peromyscus leucopus. A population is a group of organisms of the same species that live in the same area at the same time. Thus we can talk about a population of white-footed mice living within a particular forest. A community is an association of organisms (plants, animals, microorganisms) that live in a particular place or habitat. These organisms affect each other in various ways, such as through a food chain or web (see below). For example, coyotes may eat white-footed mice; this predator-prey relationship is part of the community dynamics.
An ecosystem includes all the living organisms, the non-living components, a source of energy and the interactions among these in a given area. One difficulty in defining an ecosystem is in choosing the area you wish to discuss. An ecosystem can be as small as a drop of water or as big as the planet, the global ecosystem. Thus the term "ecosystem" sometimes seems a bit vague, or may seem like a catchall to include a wide variety of concepts. Throughout this site, we will refer to the "riparian ecosystem." By this we mean the living organisms (bacteria, fungi, plants, animals) that are found along the river, specifically the Rio Grande, and the interactions that occur among them and with the various non-living components, such as soil, as well as processes such as the hydrology and chemical reactions in the system and the input of sunlight energy.
A landscape is an area of land containing a patchwork of ecosystems. We can take a landscape perspective to look at the Middle Rio Grande Valley, which would include several ecosystems such as the riparian forest, wetlands (marshes, wet meadows), grasslands and agricultural fields.