Large, easily recognized terrestrial community units are known as biomes. In a given biome the life form of the climax vegetation is uniform, and is the key to recognition. Thus, the dominant chmax vegetation in the grassland biome is grass. Although the species of dominant grasses will vary in different geographical regions where the grassland biome occurs. Other types of vegetation will be included in the biome, as for example, ‘’weedy’’ seral stages in succession, forest subclimaxes related to local soil and ater condition crops, and other vegetation introduced by man.

    The distribution of six major biomes in relation to temperature and rainfall. If you will check the mean annual temperature and rainfall of your locality you can determine from which biomes you live in, even if you are now sitting in the middle of a city with no climax vegetation anywhere around. Several other biomes, such as chaparral, tropical savanna, thorn shrub, and tropical monsoon forests are related to seasonal distribution of rainfall rather than annual means.

   For the past 6 year most nations of the world have taken part in what is known as the ‘’international biological program’’ involving govermental grant support for interdisciplinary team research and systems modelling of major biomes. Both the ‘’modelling up’’ and the ‘’modelling down’’ approaches, as mentioned, are bing tested in fefforts to develop realistic working model that will help man better inderstand his impact on the matiral biome matrisx in which his civilization is embedded. For a brief rebiw of the inited states program and some of its accomplishments, see hammond (1974). Other natons have, in general, taken a less holistic approach with varying emphasis on such aspects as natural area inventory, impact of grazing animals, secondary production, detailed descriptive analysis of vegetation, environmental health, and preservation of genetic stocks of endangered wild and domestic organisms.