The number of communities in this group presently totals 482. The number of rare communities varies among regions, reflecting unevenness in the quantity and quality of community information among the regions, along with varying levels of classification development and subtle differences in procedures for conservation ranking. To some extent, the regional variation also reflects the actual differences in ecological and biological diversity, the results of landscape fragmentation, and land-cover conversion. While rarity of ecological communities is critical information for biodiversity conservation and management, appropriate protection and management activities should be determined for each individual rare community. Communities assigned a rank of G1 or G2 are very rare and occur generally within a restricted range of environmental conditions.
Some communities are naturally rare because of their association with an uncommon habitat.
The environmental characteristics that support this biological association have similarly restricted the use of this habitat for agricultural production and most other types of land conversion, although some communities have been degraded by salt-extraction operations. Though this community is unlikely to disappear because of human-induced disturbance, individual communities should be protected from degradation due to incompatible land use. It has also suffered from the large-scale alteration of historical fire regimes. Rare communities such as this are quite threatened and require immediate protection and management. The list of nationally rare communities will help ensure their recognition and set priorities for their protection, an important step for conservation.