Natural communities are assemblages of species that occur together in space and time. These groups of plants and animals are found in recurring patterns that can be classified and described by their dominant physical and biological features: Red Maple swamp and Pitch Pine/Scrub Oak communities are two examples. Natural communities are not discrete units with neat boundaries; there is overlap among and between communities in their composition, structure, and physical characteristics. Large animals often make use of multiple communities.
Natural communities may be restricted or widespread in their distribution across the state. Conservation priority should be given to types of natural communities that have limited distribution in the state, and, of course, those with restricted global distribution (together considered to be Priority Types of Natural Communities or "Priority Natural Communities"). Conservation priority is also given to Massachusetts' best examples of more common types (these occurrences are called "Exemplary Natural Communities").
The Massachusetts Natural Heritage & Endangered Species Program actively inventories and tracks the distribution and status of NHESP Priority natural communities and exemplary occurrences of more common types across the state. In 2011 and 2012, we updated our 2000 draft classification of natural communities , with several newly described types of natural communities and modification of some of the original type descriptions and community names. The refined classification allows better understanding, mapping, and tracking of the biodiversity of the state as represented by natural communities.