Skip to page content
USDA Forest Service
  
Treesearch

Research & Development Treesearch

 
Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Northern
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern
Help
 

GeoTreesearch


Science.gov - We Participate


USA.gov  Government Made Easy


Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.
20090-6090

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

(1.3 MB)

Title: Validation of SILVAH for tolerant hardwoods in Ontario

Author: Bankowski, Jacek; Dey, Daniel C.; Jim, Rice; Boysen, Eric; Miller, Roj

Date: 1995

Source: Forest Research Information Paper. Issue 128. 1995. pp. 1-28

Publication Series: Journal/Magazine Article (JRNL)

Description: SILVAH, a stand growth simulator commonly used in the northeastern United States, has been evaluated by comparing predicted and actual growth of tolerant hardwoods in southern Ontario. The data came from 139 stands, unmanaged or managed (thinned), even-aged or uneven-aged. The data were used to test the accuracy of diameter distribution, basal area, mean quadratic DBH, number of trees per hectare, and stand volume predictions for periods from 5 to 20 years. The accuracy of short-term basal area projections, expressed by modelling efficiency, ranged from 62% to 94%. The reliability of stand density projections was especially low (modelling efficiency from 15% to 88%). Despite underpredicting the number of trees in small DBH classes, SILVAH provided reliable predictions of DBH distribution, especially for unevenaged, unmanaged stands. Basal area of stands was underestimated by 2% to 6% on the average for 5-year projections (except for low productivity sites). During the same projection period, the error of predicted individual stand basal area ranged from -22% to 25%. Prediction bias increased with longer projection periods. The trend of underestimating stand density and overestimating mean quadratic DBH resulted from low predicted numbers of small DBH trees. Consequently, the basal area of pole and small sawlog timber classes was underestimated (on the average 1% to 28% in 5 years). A few factors contributed to the poor performance of the model: 1) lack of ingrowth data or lack of an automatic ingrowth submodel; 2) incompatibility of model requirements and data sets related to the range of tree sizes in the input list; and 3) inability of the model to account for differences in site productivity.

Keywords: growth model, tolerant hardwood, thinning, timber class, basal area, stand density, stand volume

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • This publication may be available in hard copy. Check the Northern Research Station web site to request a printed copy of this publication.
  • Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact Sharon Hobrla, shobrla@fs.fed.us if you notice any errors which make this publication unusable.

XML: View XML

Citation:


Bankowski, Jacek; Dey, Daniel C.; Jim, Rice; Boysen, Eric; Miller, Roj 1995. Validation of SILVAH for tolerant hardwoods in Ontario. Forest Research Information Paper. Issue 128. 1995. pp. 1-28

 


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.