National Forests in Florida Final Report
A Combined Physiognomic/Floristic System
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- FIGURE 1. VEGETATION CLASSIFICATION SYSTEM.
A Combined Physiognomic/Floristic SystemThe hierarchy of the classification system employs physiognomic criteria at the highest levels and floristic criteria at the lower levels. The formation concept, with units modified from UNESCO (1973), guides the definition of the physiognomic units, and the association and alliance concepts define the floristic units (see Figure 1 and Table 1). This system allows the broad-scale geographic application of physiognomic characteristics to be tied to local, site-specific, floristically-defined units. In combination, these hierarchical levels can satisfy a broad range of objectives for use in a single classification system. FIGURE 1. VEGETATION CLASSIFICATION SYSTEM. SYSTEM
FORMATION CLASS FORMATION SUBCLASS FORMATION GROUP SUBGROUP
physiognomic levels FORMATION floristic levels ALLIANCE PLANT ASSOCIATION TABLE 1. HIERARCHICAL VEGETATION CLASSIFICATION SYSTEM FOR TERRESTRIAL ECOLOGICAL COMMUNITIES. (Examples)
The combined physiognomic/floristic system developed by TNC/NatureServe allows identification of units from both a "top-down" (divisive) and "bottom-up" (agglomerative) approach. The top-down approach allows the use of physiognomic distinctions to help map vegetation, to stratify sampling, and to delimit vegetation units where floristic information is lacking. A bottom-up approach employs plot sampling and floristic analysis as the primary means for defining associations. Where physiognomy is variable, the bottom-up approach can also be used to help determine the important physiognomic distinctions. The relationships between physiognomy and floristics are not always simple; when they do not correspond, precedent may be given to the floristic relationships over the physiognomic structure. The basic unit of inventory, the plant association or community element, is more or less uniform in structure, composition, and habitat. The uniformity of the plant community makes the comparison and identification of protection priorities more objective than would be possible at more heterogeneous scales. The plant association is a suitable unit for conservation planning because it encompasses all the layers of vegetation in a stand, reflects ecological and human-caused processes including management activities, and is a repeating unit in different landscapes. From a site-based perspective, there may be many different community types at a given location. In fact, it is relatively rare that a site contains only a single community type. However, community elements tend to combine in predictable ways to create repeatable landscape mosaics. Thus the particular mosaic of community elements present at a site and their distribution across the landscape provide information that is fundamental to any type of ecological land management. The rationale for coupling physiognomic and floristic systems has been developed over the years (e.g., Rubel 1930, Whittaker 1962, Ellenberg 1963, Webb et al. 1970, Westhoff 1967, Beard 1973, Werger and Spangers 1982). These studies have found a good fit between floristic and physiognomic classifications of the same vegetation. In the United States, Driscoll et al. (1984) recommended the development of a joint system using the physiognomic units of UNESCO (1973) and the floristic units of habitat types, of which an example has recently been provided by Dick-Peddie (1993) in New Mexico. Vankat (1990) developed a physiognomic-dominance type classification for forest types in North America. Strong et al. (1990) in Canada also proposed a combined physiognomic-floristic approach. In addition, Specht et al. (1974) used the joint approach to develop a conservation evaluation for Australian plant communities. Directory: library library -> Strategic Plan South Sudan Country Office Context library -> The World Order of Bahá’u’lláh Selected Letters library -> Ieee/iee electronic Library (iel) library -> [0] B. Hardware [2] library -> [1] B. Hardware [1] library -> Florida public service commission library -> 1 1 before the florida public service commission 2 docket no. 070650-ei 3 In the Matter of: 4 petition to determine need for turkey point nuclear units 6 and 7 electrical 5 power plant, by florida power & light company library -> Archived Online Exhibit Download 3.16 Mb. Share with your friends:
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