An ecological community is an assemblage of co-existing, interacting species, considered together with the physical environment and associated ecological processes, that usually recurs on the landscape.
Natural communities are those which have experienced only minimal human alteration or have recovered from human-caused disturbance under mostly natural regimes of species interaction and disturbance.
(Excerpted from Virginia DCR’s Introduction to Natural Communities of Virginia Classification of Ecological Groups and Community Types)
No portion of Virginia’s landscape, however, has altogether escaped modern human impacts – direct or indirect – and only a few small, isolated habitats support communities essentially unchanged from their condition before European settlement. Most of the communities here, while somewhat modified in composition or structure, are in mid- to late-successional stages of recovery from some form of human disturbance, such as agricultural conversion or logging.
Classifications of natural communities can be based on numerous variables that account for the complexity we see in nature (e.g., vegetation, fauna, landforms, hydrologic regime, geography), used singly or in combination.
Plant species are faithful indicators of site conditions, and plant species collectively (i.e. vegetation) reflect the biological and ecological patterns across landscapes. Thus, plants are commonly used as surrogates to characterize and define ecological communities.
Learn more by exploring this great resource: The Natural Communities of Virginia Classification of Ecological Groups and Community Types