soil-site relationships for young white spruce plantations in north central ontario
abstract
site index of white spruce (picea glauca (moench) voss) in north
central ontario was related to features of soil and topography using both
multiple regression techniques and principal component analysis. two
different measures of site index, totsi25 (site index is total height at
total age of 25 years) , and bhsi15 (breast height site index is total
height at 15 years breast-height age) were used as dependent variables; 81
soil and topographic values were independent variables considered for
analysis. preliminary regressions computed from 54 plots indicated poor
relationships between totsi25 and soil and topographic variables.
preliminary regressions also indicated that the correlations were much
stronger using bhsi15. correlations also were much stronger when the plots
were stratified into three landform types as opposed to unstratified
regressions. three final regression equations were based on the
relationship between bhsi15 and lacustrine, morainal, and glaciofluvial
landform groups, and explained 77, 73, and 65 percent of the variation in
bhsi15, respectively. the final regression equation for the lacustrine
landform included the type of clay deposit (clay) , the depth to a root
restricting layer (drrl), and the hue of the c horizon (huec). the final
regression equation for the morainal landform included the natural
logarithm of the depth to a root restricting layer (lndrrl), and the ph of
the c horizon (phc). the final regression equation for the glaciofluvial
landform included the drainage class of the soil (drain). the ability of
the final regression equations to predict bhsi15 was tested on 14
independent test plots; these tests showed close agreement between actual
site index based on stem analysis and site index predicted from the
regression equations.
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