Canadian Forest Service Publications

Forest understory plants as predictors of lodgepole pine and white spruce site quality in west-central Alberta. 1991. Strong, W.L.; Pluth, D.J.; La Roi, G.H.; Corns, I.G.W. Canadian Journal of Forest Research 21(11): 1675-1683.

Year: 1991

Issued by: Northern Forestry Centre

Catalog ID: 11348

Language: English

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The feasibility was explored of using cover estimates of a few understory species with high indicator value, rather than total species lists, to evaluate site quality for lodgepole pine (Pinuscontorta Loudon var. latifolia Engelm.) and white spruce (Piceaglauca (Moench) Voss). Analysis of 112 vascular and 7 nonvascular understory plant species from 211 lodgepole pine and white spruce dominated forests revealed that 39 and 30 of these species had significantly different percent cover among site-index classes for stem-analyzed pine and spruce, respectively. Individual species cover values were then used in simple and multiple linear regression equations to predict the site index (at 70 years) for pine and spruce in 60–90 year and 91–160 year stand age subsets. Equations for pine based on understory species cover explained 38% of the variance in site index in younger stands and 59% in older stands; comparable maxima for spruce were 42% in younger stands and 50% in older stands. These percentages may be too low for stand-alone predictions of site index. Several possible sources of error may cause the low explained variance, including crude field estimates and seasonal variations of cover. Many of these potential sources of error could be minimized, allowing better prediction of forest site quality.