Density-Size Relationships for Sitka Spruce and Douglas-Fir in Britain and Canada and Linkage to Light Capture
Event Website
http://www.nafew2009.org/
Start Date
6-23-2009 11:30 AM
End Date
6-23-2009 11:50 AM
Description
Density-size relationships have potential value in guiding thinnings and in the development of shelterwood and selection systems. Reineckes stand density index (SDI) is used by some as a measure of site occupancy and the degree to which site resources are fully captured. While a few studies indicate that SDI may be more strongly related to light capture than basal area or other stand attributes, linkages between light capture and density-size relationships need further exploration. A better understanding of how density-size relationships are influenced by environment and how changes in SDI are linked to changes in resource utilization by stands is also of ecological interest. Sitka spruce and Douglas fir from western North America have been widely planted in Great Britain. Sitka spruce comprises 49% and Douglas-fir represents 3% of the total conifer forest cover in Great Britain. During 2008 I initiated a study to: 1) Develop and evaluate density-size relationships for Sitka spruce and Douglas-fir stands in the UK (using data collected by the Forestry Commission); 2) Compare these to density-size relationships for Sitka spruce and Douglas-fir stands in British Columbia (using government and industry PSP data); and, 3) Examine relationships between understory light levels (measured using hemispherical photography) and SDI (or other stand level measurements) in Sitka spruce stands and Douglas-fir stands. Preliminary results indicate that slopes for density-size relationships are steeper than -1.6 for both species in Britain and that site quality (yield class estimated from site index) has a small but significant influence on the position of the density-size line (but not the slope). For both species, basal area performs as well as or better than SDI for estimating light capture.
Density-Size Relationships for Sitka Spruce and Douglas-Fir in Britain and Canada and Linkage to Light Capture
Density-size relationships have potential value in guiding thinnings and in the development of shelterwood and selection systems. Reineckes stand density index (SDI) is used by some as a measure of site occupancy and the degree to which site resources are fully captured. While a few studies indicate that SDI may be more strongly related to light capture than basal area or other stand attributes, linkages between light capture and density-size relationships need further exploration. A better understanding of how density-size relationships are influenced by environment and how changes in SDI are linked to changes in resource utilization by stands is also of ecological interest. Sitka spruce and Douglas fir from western North America have been widely planted in Great Britain. Sitka spruce comprises 49% and Douglas-fir represents 3% of the total conifer forest cover in Great Britain. During 2008 I initiated a study to: 1) Develop and evaluate density-size relationships for Sitka spruce and Douglas-fir stands in the UK (using data collected by the Forestry Commission); 2) Compare these to density-size relationships for Sitka spruce and Douglas-fir stands in British Columbia (using government and industry PSP data); and, 3) Examine relationships between understory light levels (measured using hemispherical photography) and SDI (or other stand level measurements) in Sitka spruce stands and Douglas-fir stands. Preliminary results indicate that slopes for density-size relationships are steeper than -1.6 for both species in Britain and that site quality (yield class estimated from site index) has a small but significant influence on the position of the density-size line (but not the slope). For both species, basal area performs as well as or better than SDI for estimating light capture.
https://digitalcommons.usu.edu/nafecology/sessions/sdi/6