Inputs to the model are:
          -age
          -site index
          -stand basal area and/or trees per acre

     Outputs include:
          -total stand basal area, number of trees and volume
          -total and merchantable volume by diameter class

     YPOP was developed around simultaneous growth and yield equations for predicting basal area growth and cubic-foot volume growth and yield in thinned stands of yellow-poplar. A joint loss function involving both volume and basal area was used to estimate the coefficients in the system of equations. Given estimates of basal area and cubic-foot volume from these equations, board-foot volumes can also be calculated. The thinning algorithm removes a proportion of the basal area from each diameter class and produces stand and stock tables after thinning from below that are consistent with those generated before thinning. Multiple low thinnings to a specified residual basal area can be accomplished using YPOP and projections made to future ages.

     A detailed manual documenting the modeling methodology and containing a users guide to the software is available at no charge.  The Windows application software compatible with Windows 95 and above operating systems is available for $50.

      Download a Demonstration Version 

To download a demonstration version:

1. Click YPOP to start downloading.

2. With your web browser select "save this program to disk".

3. Run the file saved in step 2 by double clicking it. The setup utility starts.

4. Run the demo program in the destination directory of step 3.

5. The demonstration version site index is set to 90 ft. 

     A detailed users manual is available with the Demo version. The executable computer code for Windows can be obtained for $50.00. To place an order or obtain additional information, contact ralph@vt.edu.

YPOP user manual

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