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WOODLOT for Windows 2.1 - Reference Manual | ||
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Appendix 5 - Managed or Natural Stands (Source: Description for TFL/TSA Data Package - A. N., Research Branch) The following information will help planners identify managed vs. unmanaged stands (polygons), for the application of appropriate yield models (curves). The distinction is important because managed stands tend to be more productive. A decision tree is provided to help make the distinction between managed and unmanaged stands and suggest yield models for various stand types. Even-aged Stands
Managed stands, defined for this exercise, are even-aged and have benefited from activities that encourage stands to reach their growth potential. They have known establishment conditions including species, density, and distribution of stems. Managed stands can be of planted or natural origin but have not experienced repression or overstory competition. Most clearcut stands regenerated after 1986 which have achieved "free growing" status, as specified in the regional free growing guide books, can be classified as managed. For stands regenerated before 1987, silviculture records, management plans, and local knowledge are needed to determine if stands are managed. Young spaced and fertilized stands can generally be considered managed if establishment conditions can be approximated. Partially harvested even-aged stands, such as commercially thinned stands, are managed if they were unsuppressed or unrepressed during establishment, establishment conditions can be approximated, and removals are documented. Unmanaged Stands Unmanaged stands have not had the benefits of management and their establishment conditions are unknown. Although some stands may achieve their potential, others may have inadequate stocking, experience overstory competition, or repression.
All uneven-aged stands are considered unmanaged for this exercise, as the concept of establishment conditions holds little meaning, and a large number of stems could be suppressed by an overstory. Uneven-aged stands generally contribute to non-timber objectives where maximizing growth is not the primary concern. Uneven-aged stands have historically been handled as natural. Forest growth and yield models have been developed for many different purposes. It is important to choose the proper model and understand it's assumptions and limitations. Models can be sophisticated computer models or simple yield tables derived from appropriate data. The above distinction between managed and unmanaged stands should help in choosing an appropriate yield model for use in TFL or TSA planning. All yield curves used in TFL/TSA plans must be submitted for approval to Timber Supply Branch, Ministry of Forests. Yield curves, rather than models, are approved as they are specific to the stand or analysis unit. Models can produce a wide array of yield curves depending on input parameters. 
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