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| A stand may loosely be defined as a contiguous group of trees sufficiently
uniform in species composition, arrangement of age classes and general
condition so as to be considered a homogeneous and distinguishable unit. For
management that includes a variety of goals and purposes, it is sometimes
necessary to use a more general term since "stand" normally refers to
a community of trees. "Vegetation unit" can be used whether we are
referring to a forest or any other vegetation such as shrub thicket, meadow or
prairie. However, because of its well established use, the term
"stand" will be used here when referring to forest vegetation. One of the most serious obstacles to intensive forest management and particularly "ecologically based" management is the practice of defining stands too broadly. If a stand is delineated chiefly by a loosely defined composition (cover type), it may encompass more than one site type, as' well as a range of advance reproduction and other regeneration opportunities and limitations. If a stand is to be used as a basic unit of manipulation, it should represent a uniform "ecological opportunity unit." This concept is illustrated in Figure 4, which shows two site types (loamy soil and sandy soil) and two forest cover types (aspen and red oak). The two cover types are each divided into four stands based on differences in understory composition (i.e., advance regeneration). |
 Figure 5. A single stand (red oak overstory with white pine regeneration) "straddles" two significantly different site types. Because ecological and silvicultural potentials differ for the two site types, the stand was split (A and B) to identify two ecological and silvicultural opportunity units. |
 Figure 6. This stand is divided into two management units on the basis of different management objectives. E.g., in stand A, oak will be harvested and white pine released to form a new crop, while in stand B, oak overstory will be retained to provide a food source for wildlife and conditions for future old growth." |
| If the aspen cover type regenerated on both site types after the same fire,
a forester unaware of site type differences could have grouped stands 1-4 into
one large stand. If site differences were recognized (e.g., by differences in
tree height and density or soil texture), but advance regeneration was ignored,
only two stands would have been recognized, one on each site type. Only when
regeneration was duly noted were four ecological opportunities recognized and
four stands delineated. A similar scenario is depicted for a red oak cover type
in Figure 4 (stands 5-8). Consideration of this many stands may be practical
only if they were large enough to make individual treatment prescriptions
economical. Thus, the actual minimum size of stands will vary with ownership.
Many tree species have wide ecological amplitudes (i.e., grow on a wide range of sites). Cover types comprised of such species are often lumped into large, single stands even if they cross significantly different site types. Under such conditions, important management opportunities may be lost. Figure 5 (page 12) illustrates such a case. There is one situation in which a stand representing a uniform ecological opportunity unit may not be considered as a basic treatment unit. If the owner chooses different management objectives for different parts of a uniform stand, then each objective defines a separate "management unit" and new stands should be delineated (Figure 6). These stands will become more different from each other as different prescriptions are applied. |
