These three sample attributes describe environmental systems have influences on living organisms.


In the Environment Ontology (ENVO), the biome [ENVO_00000428] classes are subclasses of environmental system.The env_biome represents environmental systems to which resident ecological communities have evolved adaptations.Thus, a env_biome may be thought of as a community-centric ecosystem, whose extent is defined by the presence of the communities adapted to it.This requires that a env_biome possesses a degree of spatial and temporal stability that has allowed at least some of its constituent communities to adapt.Classes such as tundra biome [ENVO_01000180] and coniferous forest biome [ENVO_01000196] are included in ENVO.Currently, the biome branch of the ontology makes no commitment to a specific spatial or temporal scale.


The biome described above are useful in ecological settings; however, environments are often described by referencing a single entity that has a strong causal influence on its surrounding space.For example, a coral reef environment is determined by the presence and influence of a coral reef [ENVO_00000150].Similarly, the human gut environment is determined by the human gut.Removal of either the coral reef or the human gut would cause the associated environmental system to collapse.Environmental systems of this kind make no specific reference to ecological communities or populations (as do biomes),but to some central, supporting ‘feature’.Entities that act in this way as the causal ‘hubs’ or supports of a given environmental system are referenced by classes in ENVO’s top-level environmental feature [ENVO_00002297] hierarchy.For example, the environmental feature seamount [ENVO_00000264] would support a seamount environment, i.e. an environmental system which is supported by, and whose properties are determined by, the presence of a seamount.


In contrast to the classes above, which identify countable entities, the subclasses of the top-level environmental material [ENVO_00010483] class refer to masses, volumes, or other portions of some medium included in an environmental system. A portion of environmental material is understood to be more complex and variable in composition than a simple collection of material entities (e.g. a collection of silicate particles). For example, the environmental material soil [ENVO_00001998] typically contains aggregates of fine rock particles, sand grains, clay particles, silt particles, communities of animals, plants, fungi and microbes, small parts of organisms, organic matter, water inclusions, and airspaces.