Environmental Drivers of Succession in Jack Pine Stands of Boreal Ontario: An Application of Survival Analysis

Author： Longpre Trevor W. Morris Dave M.

Publisher： Society of American Foresters

ISSN： 0742-6348

Source： Northern Journal of Applied Forestry, Vol.29, Iss.2, 2012-06, pp. : 81-92

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Abstract

In this study, we present a quantitative approach to examining species compositional changes in jack pine (Pinus banksiana Lamb.)-dominated forests that combines photo chronosequencing and survival analysis. Study sites (178) were selected from Ontario's Growth and Yield Permanent Sample Plot network and supplemented with archived aerial photographs that captured stand conditions at four additional points in time. Environmental attributes specific to geographic location, topography, soil characteristics, and climate were also used in the analysis. The nonparametric Kaplan-Meier method was used to derive cumulative survival functions, and Cox regression analysis was used to determine the significant environmental factors that resulted in downward shifts in jack pine persistence over time. Only 26% of the stands included in this study were observed to have a pure jack pine canopy during some stage of stand development, with black spruce (Picea mariana [Mill.] B.S.P.) being the most common associate. Although shifts in species composition occurred in the majority of stands, much of the observed succession was a reflection of differential growth rates and responses to suppression between contemporaneously established populations. Based on the Cox regression model, sites with sloped terrain, sites that had deep sandy soils, and sites that received high precipitation during the growing season all retained high abundances of jack pine over time.