Community Ecology

Within the field of ecology, a community is a group of organisms coexisting within a defined area. Community ecology is the study of the interactions that occur among populations of that live within a specific region. It is also concerned with the distribution andabundance of the various populations within the area. For example, a community ecologist might consider the ways in which the white pine and the white pine weevil in an old-growth forest in Maine affect one another’s survival and reproduction.

Most communities are quite complex, containing many coexisting plant, animal, bacterial, fungal, and protozoal (single-celled) populations. Community ecology seeks to understand how species interact by studying many different kinds of relationships between these populations. Animal-animal interactions, animal-plant interactions, and plant-plant interactions are examples of community relationships considered. A plant-plant interaction might include the ways in which weeds affect growth of tomatoes in a garden, or how a tall tree blocks sunlight from smaller plants in a Costa Rican rain forest. An important type of animal-animal interaction is competition, such as that between two populations of finches for seeds for food on an island in the Galapogos. Another animal-animal interaction is predations, for example understanding how snakes prey on mice in a meadow in western Texas. Plant-animal interactions include herbivory (animals eating plants) or in rare cases plant carnivory (plants eating animals; an example is a Venus fly trap plant ingesting insects). Symbioses are another type of interaction that may involve plants, animals, fungi or bacteria. These relationships involve the beneficial and parasitic coexistence of any of these organisms, such as the symbiosis between photosynthetic algae, called zooxanthellae, in the dermis of stony corals.

Along with studying relationships among populations, community ecology is concerned with understanding the ecological niche of different populations, species diversity, and the biogeography of species. Community ecology is concerned with all of these concepts as ameans to understanding what types of forces may result in changes to or may increase the stability of biological communities.

Terry Watkins