and based on some characteristics they hold in common. Communities can be classified based 

 on different kinds of parameters, such as growth-form dominance, structure by strata, species 

 composition or dominance based on an abstract grouping of samples "stands." 



There are at least 20 schools of synecology (Shimwell 1971) based on different sets of 

 classfication criteria and the accompanying concepts of and terminology for vegetation 

 "organization." In the Inland Northwest and Northern Rocky Mountains, R. Daubenmire 

 originated and applied a widely-used structured hierarchical classification system. The next 

 several paragraphs will explain concepts of this classification because so many of the 

 classifications developed tliroughout the west are the intellectual lineal descendants of those 

 developed by Daubenmire (e.g. Daubenmire 1970 and Daubenniire and Daubenmire 1968). 



Daubemnire is best known for his "habitat type" concept; a habitat tj'pe (h.t.) being all those land 

 areas potentially capable of supporting similar plant communities at climax or some long-term 

 stable state. Although this "climax" state is theoretical and seldom develops because of recumng 

 disturbance, the trend toward climax can be identified in the field from an examination of stand 

 age class structure (at least for forest and woodland formations). The climax plant community is 

 the most meaningful index of the environmental factors affecting vegetation because it is the 

 relatively stable concluding stage of plant succession and in dynamic equilibrium whh 

 macroclimate. A habitat type represents a discrete segment of the environmental spectrum. 

 Thus the habitat type system has been treated as a land classification system centered around the 

 potential plant community as an integrated bioassay of environmental factors as they affect 

 species reproduction and competitive effects (Pfister and Arnol980, Steele et al. 1981) . Others 

 (Hall 1980, Mueller-Dombois 1964) specify that to function as a management-oriented site or 

 land classification system, habitat types should be more naiTOwly defined. These authors include 

 landscape features, productivity', and other management-oriented variables in defining taxonomic 

 units (habitat type or plant association). 



Habitat types are conveniently named for the potential climax community type, teirned plant 

 association (Daubemnire and Daubenmire 1968). For example, Abies lasiocarpa/Xerophyllum 

 tenax is the plant association potentially dominated in the tree layer by A. lasiocarpa (subalpine 

 fir) and having an undergro\\lh in which A'! tenax (beargrass) is diagnostic. In the classification 

 hierarchy, the series (or alliance, TNC) level is denoted by the first Latin binomial; in forest and 

 woodland types this is usually the most shade-tolerant tree adapted to the site. The species may 

 be represented by little cover, but from successional studies and knowing its ecology we can 

 project it to be an important component, the climax dominant. In the simplified ecology of 

 western forests virtual single-species dominance is often the end-point of succession. For slirub- 

 and forb-dominated types the strategy is basically the same but projecting population structure is 

 more problematical. The second part of the t>'pe name is that of another indicator species (that 

 may also be a dominant species as well), usually of a lesser lifeform; it is this second portion of 

 the name that confers a higher degree of specificity and designates the association level. 

 Indicators are chosen for their fidelity to a certain portion of the environmental spectrum and 

 usually highly constant occurrence. Occasionally a type will be identified (in keys to types) by 

 multiple and approximately equivalent indicator species, but be named for only one of the suite 

 of indicator species. The presence of a third species name may indicate a phase (and be so 

 noted), usually a minor floristic variation, difference in vegetation dominance in a third layer, or 



