Influence of Soil Site Class on Growth and Decay of Northern White-Cedar and Two Associates in Maine

Abstract

Abstract Basal area growth of outwardly sound northern white-cedar (Thuja occidentalis L.) was compared with that of balsam fir (Abies balsamea [L.] Mill.) and red spruce (Picea rubens Sarg.) across site and light exposure class gradients on 60 sites throughout northern Maine. Once adjusted for sapwood area, northern white-cedar basal area growth was not strongly affected by site or light exposure class; growth was similar to that of red spruce but generally lower than that of balsam fir. Site index did not differ appreciably among soil drainage classes for red spruce and northern white-cedar, although small sample size limited analysis on upland site classes. Incidence of central decay was higher in northern white-cedar than balsam fir, which was higher than red spruce. Incidence of decay in outwardly sound northern white-cedar and balsam fir was highest on well-drained mineral soils, and mean proportion of basal area decayed at breast height increased in outwardly sound northern white-cedar as drainage improved from poorly drained to well-drained soils. These data suggest that northern white-cedar on lowland organic and poorly drained mineral soils in Maine have less decay, similar basal area growth, and similar site index relative to upland northern white-cedar communities.