Amount of downed woody debris and its prediction using stand characteristics in boreal and mixedwood forests of Ontario, Canada

Abstract

We analyzed data on downed woody debris (DWD) from 435 permanent sample plots in boreal and mixedwood forests of Ontario seeking empirical relationships to predict DWD quantity from stand attributes. In each permanent sample plot, data were collected along three transects, including diameter, tree species, and degree of decomposition of DWD pieces with diameter greater than or equal to 7.5 cm at the point of intersection with the transect. Amounts of DWD in sample plots ranged from 0.7 to 402.7 m3·ha–1 and from 0.1 to 103.4 t·ha–1. Mean DWD values were 65.4 m3·ha–1 and 15.9 t·ha–1 in softwood- and 61.9 m3·ha–1 and 16.5 t·ha–1 in hardwood-dominated plots. Our analysis revealed no relationship between DWD and stand age, site index, or stocking for plots dominated by black spruce ( Picea mariana (Mill.) BSP), eastern white pine ( Pinus strobus L.), sugar maple ( Acer saccharum Marsh.), and red oak ( Quercus rubra L.) and weak relationships for plots dominated by jack pine ( Pinus banksiana Lamb.), red pine ( Pinus resinosa Ait.), trembling aspen ( Populus tremuloides Michx.), and white birch ( Betula papyrifera Marsh.). We submit that DWD in Ontario’s forests should be treated as a constant factor until the relationship between the amount of DWD and present stand condition is better understood and discuss considerations for future studies on DWD.