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1 January 2008 Defining and Quantifying Canopy Strata
R. Everett, D. Baumgartner, P. Ohlson, R. Schellhaas
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Number and location of canopy strata have been key forest structure variables that guide the management of wildlife habitat, timber production, and fire hazard. Forest canopy stratification algorithms Forest Vegetation Simulator (FVS), Landscape Management Systems (LMS), Vertical Tree Stratification Program (TSTRAT), and Mid Crown Line (MIDCL) reported different numbers and locations for canopy strata in artificial stands where these strata parameters were known. Number and location of strata identified by algorithms varied in unmanaged fir-pine stands as well. LMS failed to identify well-populated stratum and reported stratum in a continuum of tree heights. The TSTRAT algorithm truncated lower stratum bounds causing numerous strata to be identified regardless of foliage discontinuities. FVS failed to identify strata in the upper canopy of tall stands or when transition trees were present between strata. MIDCL results closely agreed with the tree list standard in artificial stands and the number of age cohorts in unmanaged stands. The fixed 50% crown line threshold in MIDCL reduced MIDCL stratification capability in crown ratios over 60%. Existing forest structure classifications based on canopy strata assume a close relationship between strata and age cohorts. The more accurate linkage between strata and age cohorts in MIDCL may improve classification efforts. An add-on process in MIDCL checked for discontinuities in lower crown base height and layering within individual strata; together they described canopy strata and porosity and may enhance the linkage between canopy structure and wildlife habitat.

R. Everett, D. Baumgartner, P. Ohlson, and R. Schellhaas "Defining and Quantifying Canopy Strata," Northwest Science 82(1), 48-64, (1 January 2008).
Received: 31 October 2006; Accepted: 1 November 2007; Published: 1 January 2008
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