The prediction of understory vegetation by environmental factors for the purpose of site classification in forestry: an example from northern Ontario using residual ordination analysis

Abstract

Problems arise in the use of understory vegetation as an indicator of site condition in that impermanent factors such as microclimate, succession, and chance may play significant roles in determining local composition. Residual ordination analysis is a method which facilitates quantification of the sources of variation in understory vegetation over a landscape. Here it is applied to survey data, representing 250 stands upon which the forest ecosystem classification programme for the Clay Belt portion of northeastern Ontario is based, to test the premise that vegetation types will differentiate soil conditions for forestry purposes. Ordination of the data by detrended correspondence analysis yielded a bivariate scatterplot which, through visual appraisal, seemed readily interpretable in terms of site-related nutrient and moisture gradients. Formal exploration, using canonical redundancy analysis, yielded the following predictive model: understory vegetation (detrended correspondence analysis axes 1 and 2) = soils (67%) + canopy (8%) + succession (1%) + error (24%). Extraction of residual ordinations confirmed this general model and demonstrated that although canopy and successional influences are minor in the data, they are significant. Because the nonsite-related, predictable components account for only 9% of the variation at most, the premise of the existing forest ecosystem classification system is judged to be sound insofar as the data upon which it is based adequately describe the range of commercial stand conditions normally encountered. The results are discussed in relation to vegetation survey design and the performance of residual ordination analysis on a large data set is assessed.

Changes in the understory of Canadian southern boreal forest after fire

“…Because many understory species can regenerate by sprouting after a fire and persist during succession by clonal growth, opportunities for invasion and establishment in the past may have played an important role in determining the present community (Carleton, Jones & Pierpoint 1985). If no other disturbances occur, there will be a net decrease in species diversity and abundance.…”

Woody vegetation responses to fire versus clear-cutting logging: A comparative survey in the central Canadian boreal forest

“…Two hundred and fifty stands of postfire stand data from the Forest Ecosystem Classification (FEC) survey of site region 3E (Clay Belt) in northeastern Ontario, Canada, were used (Jones et al, 1983;Carleton, Jones & Pierpoint, 1985). Methods for the collection of plot data are detailed in Jones et al (1983).…”

Assessing site productivity in tropical moist forests: a review

“…and West et al (1988) reported that both soil moisture and fertility affected species occurrence. Carleton et al (1985) examined the influence of temporal factors such as stand density and succession on understorey vegetation in northern Canada, and found that these have minimal influence on vegetation. They found that the understorey vegetation was most influenced by soil, and concluded that the understorey vegetation should provide a reliable indicator of site quality.…”