(see, for example, Kuchler 1964). These approximations 

 should be developed for local, State, or regional areas by 

 vegetation classification specialists most familiar with the 

 local vegetation. They also should be formally described 

 as approximations for current use and recognized as a 

 framework for future development. 



Successional Communities 



in Relation to Potential Natural Vegetation 



A knowledge of existing vegetation, its distribution, 

 and status helps land managers make management deci- 

 sions on use of vegetation resources. Inventory identifies 

 and determines the distribution of existing vegetation on 

 the landscape. Existing vegetation may be natural, cul- 

 tural, or agricultural plant communities. Natural vegeta- 

 tion consists of indigenous species and introduced species 

 that have naturalized to an area to the extent that they 

 may be considered a part of the natural vegetation. Cul- 

 tural vegetation includes communities of introduced 

 plants where management objectives may be for perpetu- 

 ation of introduced stands or nonindigenous species 

 using extensive rather than agronomic practices. Range- 

 land seedings with introduced species or areas of afores- 

 tation are examples of cultural vegetation. Agricultural 

 vegetation includes plant communities established and 

 managed under agronomic principles such as fertilization 

 and irrigation, and used primarily for production of 

 food, fiber, or feed crops. 



Successful plant communities are classified by iden- 

 tifying secondary successional (serai) stages of potential 

 natural vegetation. Ecologists and other vegetation spe- 

 cialists link successional plant communities to potential 

 natural vegetation by making generalized inferences from 

 surrounding natural vegetation, using soils information 

 correlated with potential natural vegetation and making 

 inferences for similar soils, referring to maps such as 

 those presented by Kuchler (1964), or referring to histor- 

 ical records. 



Ground examination and remote sensing are used to 

 classify and inventory existing natural plant communities 

 and interpret their link as successional communities to 

 potential natural vegetation. Shiflet (1973) has adequately 

 discussed how existing plant communities are interpreted 

 and related to climax communities or potential natural 

 vegetation using soils and related information. Generally, 

 the process includes searching the landscape to find, mea- 

 sure, and classify the highest serai stage of natural vegeta- 

 tion and describing its setting in relation to soils, topogra- 

 phy, and climate. Using inventory procedures, the existing 

 plant community is measured together with its associated 

 soils, topography, and general climate. The soils, topog- 



raphy, and climate of the existing plant community are 

 then compared to similar features of previously defined 

 potential natural vegetation, and the linkage is estab- 

 lished based on similarities of abiotic features. 



Remote sensing, including satellite imagery and 

 aerial photography, records the existing vegetation. The 

 more detailed the level of classification to be identified 

 through remote sensing, the greater the resolution and 

 scale of remote sensing data that will be required. For 

 example, associations or serai stages of associations would 

 not be positively identified directly by any current remote 

 sensor data for two reasons: photographic remote sensors 

 do not "see" entirely through layered vegetation to "re- 

 cord" the layers of vegetation required for association 

 classification and identification; and the identification of 

 individual plant species required to classify associations is 

 generally not possible through remote sensing. Satellite 

 imagery would be most successful in classifying the class 

 levels of the vegetation hierarchy. Low-, medium-, and 

 high-altitude aerial photography would provide informa- 

 tion for classification at the series through subclass levels 

 respectively, provided land surface modifiers such as 

 slope and aspect, and film image characteristics such as 

 color, texture, and tone are used as photointerpretation 

 aids. The expectations and limitations of remote sensing 

 for vegetation classification and other land-surface fea- 

 tures have been extensively discussed by Aldrich (1979). 

 Anderson and others (1976) presented a land-use and 

 land-cover classification system for application with 

 remote sensor data. 



Although knowledge of successional communities is 

 needed, it, in itself, does not always reflect inherent site 

 potential. Existing natural vegetation occurs as infinite 

 secondary successional stages, which are related to time 

 elapsed since such disturbance as timber harvesting, live- 

 stock grazing, or unnatural wildlife population concen- 

 trations. Secondary successional stages of vegetation are 

 abundantly represented in most areas of the United States. 

 Plant communities representing late successional stages 

 or potential natural communities are less common and in 

 some areas rare. These areas can and should be located 

 (Braun 1964, Mueggler and Stewart 1980, Steel and others 

 1981) to define the inherent biological potential of the 

 land and develop the relationships between successional 

 communities and potential natural vegetation. 



Only the potential natural vegetation or a high serai 

 stage of vegetation reliably reveals the natural biological 

 potential of an area. Therefore, classifications based on 

 potential natural vegetation are powerful, integrated 

 expressions of the inherent natural biological capability 



9 



