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Uneven Age Timber Management Planning Questions/Analytical Problems:

Uneven Age Timber Management Planning Questions/Analytical Problems: 1) What is the "best" amount of residual growing stock (after major harvest or thinning)?. 2) What is the "best" stand structure?. The two questions are interrelated and interdependent!. Manipulation of Stand Structure.

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Uneven Age Timber Management Planning Questions/Analytical Problems:

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  1. Uneven Age Timber Management Planning Questions/Analytical Problems: 1) What is the "best" amount of residual growing stock (after major harvest or thinning)? 2) What is the "best" stand structure? The two questions are interrelated and interdependent!

  2. Manipulation of Stand Structure Current condition Desired/Target Condition????

  3. Basic Problem:What should be the residual stand structure given the desired growing stock? • This is a "stocking control" problem -- • controlling/manipulating the number of trees to be left; and the desired growing stock. • The stocking control problem can be solved if we know: • Smallest diameter class • Maximum diameter size (class) These two sets the allocation of trees by class size • Desired Basal Area – Amount of Residual Growing Stock

  4. 2) What is the "best" stand structure? (Target/Desired Condition) Stand Structure: distribution of the number of trees by diameter sizes. ?? WHAT IS THE "TARGET or DESIRED" CONDITION OF THE RESIDUAL FOREST?? * growing stock * structure DESIRED STRUCTURE: Balanced Distn.

  5. What is a balanced distribution? • · inverse J shape (following natural uneven age stand dynamics) • · negative exponential distribution. • follows a constant "q".

  6. Defining a Desired Balanced Dist. Given a desired RGS, q, what is the optimal stand structure? Questions: 1) What is the smallest diameter size? 2) What is the largest diameter size? THEREFORE: Given RGS, q, dsmallest, Dlargest defines a desired, balanced structure.

  7. Graphical Description of the Stand Structure Problem:

  8. General Formula: Nk-1 = q Nk (1)

  9. Nmax = B / Dmax bi * q(Dmax-Di)/w (2) i = Dmin Where: B = desired density (RGS) bi = basal area of diameter class i Di = midpoint of diameter class I w = diameter class width

  10. NOTE: Formula (1) and formula (2) will define a balanced distribution. THAT IS: If Formula (1) is used to calculate the optimal number of trees for all diameter size, except the largest, and Formula (2) is used to calculate the optimal number of trees in the largest diameter size, Nmax THEN: The resulting structure satisfies the stocking constraint: max B =  biNi

  11. Ni = ke-aDi Ni = no. of trees Di = diameter class i e = natural logarithm k = no. of trees at smallest diameter class a = parameter

  12. Key points that determine (affect) optimal stand structure • · objective(s) • · growth potential • · site quality • · length of cutting cycle

  13. How to optimize the management of uneven forests? Non-formal procedures: -- simple “rules of thumb” -- experiential knowledge -- trial and error Formal/Analytical methods -- enable simultaneous consideration of key decision points

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