USDA Forest Service
 

Land and Watershed Management

 
 
   
Land and Watershed Management Program
   
Pacific Northwest Research Station
   
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United States Department of Agriculture Forest Service.

Genetic and Silvicultural Foundations for Management

Selected Studies

Potential Pitfalls in Applying Variable Density Management

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  1. New treatments require learning by both the practitioner/prescriber (forester, silviculturist, wildlife manager, riparian specialist, ecosystem manager, conservationist). Some potential problems:1.Existing policies or regulations may not be appropriate with new practices. Although policies or guidelines may be changed in the future, they can be difficult to work with in the short term. For example, reporting systems for even-aged management may not lend themselves well to uneven-aged systems. Most organizations will eventually change the reporting system to better reflect what is being accomplished on the ground but it may be frustrating in the short term.

  2. When starting a new type of treatment, practitioners have a limited information base to work with so they may be tempted to use a "cookbook" approach to the same treatment each time. It is important to recognize that most variable density prescriptions are based on guesses and should not be applied to large land areas. Adaptive management will be most successful if prescriptions are varied so we can better learn what the advantages and disadvantages are of each one.

  3. New practices usually require more information (asking questions, reading, going on tours, training), monitoring, and more record keeping. There is no easy way around this, but managers would be wise to plan for the training and learning time that will be required.

  4. Most variable treatments are inherently more expensive to apply than uniform ones (primarily because they require covering more ground to get the same amount of work done. Increases in cost can also result from being low on the "learning curve" but those cost increases should be short-term in nature.

  5. Contractors may be unfamiliar with practices so costs may be high, mistakes may be made or a contractor may underbid a job and later default on the contract. Changes in contracts from traditional practices will require more effort to ensure that the contractor or potential contractor understands what is required.

  6. WindthrowSome treatments will require new ways to specify and monitor work. This is especially important when the work will be contracted as there are more limited opportunities for changing the specifications.

  7. Increasing "gaps" in forest stands may result in greater windfall.


  8. Most growth and yield models were based on uniform stands with one or a few species and a limited number and range of treatments. Most of these models assume the treatments are applied uniformly. Thus, existing models may not be easy to use or give the correct results for treatments applied non-uniformly.

  9. Larger scale of application of some treatments may result in less uniformity for comparisons (this may make it difficult to test or easily compare alterative treatments).

  10. Bear damage

    Variation in marking trees within a unit may increase the sample size needed for a timber cruise (or different approach such as stratified sampling will be needed).

  11. Selecting individual trees for release may make them more susceptible to damage or loss; however, loss of these trees is more important as you have invested more money in them. For example, in a pre-commercial thinning operation it will cost more to release a tree to be open-grown than to select it as a future crop tree because more trees have to be cut to create the open-grown condition. However, the open-grown trees may also be more susceptible to bear damage. Other hazards such as windthrow or top breakage may also be greater to widely-spaced trees, especially shortly after treatments.

  12. Creating gaps or more open areas may encourage colonization, growth, or retention of exotic plants.
    Scots broom  

USDA Forest Service - GenSilv Team
Last Modified: Monday, 16 December 2013 at 14:18:50 CST


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