Coarse woody debris in the old-growth forests of British Columbia

Abstract

This paper synthesizes data extracted from the literature and data collected in various studies by the author on the quantity, characteristics, and functional importance of coarse woody debris (CWD) in the old-growth forests of British Columbia (B.C.). There is little agreement in the literature about the minimum diameter of CWD or the number of decay classes recognized. In western North America, five decay classes are commonly used, but recent studies suggest fewer decay classes are preferable. Comparisons among decay classes and biogeoclimatic zones and subzones in B.C. reveal that quantities and volumes are greatest (up to approximately 60 kg/m 2 and approximately 1800 m 3 /ha, respectively), and CWD persists the longest (sometimes in excess of 1000 years) in the Coastal Western Hemlock (CWH) biogeoclimatic zone. The quantity and ground cover of CWD increase with forest productivity. Persistence of CWD has varied from less than 100 to over 800 years in two coastal (CWH and Mountain Hemlock (MH)) and three interior (Interior Douglas-fir (IDF), Interior Cedar-Hemlock (ICH), and Engelmann Spruce -Subalpine Fir (ESSF)) biogeoclimatic zones. Trends in CWD quantity with forest age in managed coastal B.C. forests suggest a U-shaped curve, with greater quantities occurring in recent cutovers than in old-growth forests, and lowest quantities occurring in middle-aged forests. This may be the normal trend in CWD with forest age, with departures from this trend resulting from disturbance-or environment-specific factors. Relatively large amounts of data exist on the characteristics of CWD in the CWH, IDF, ICH, ESSF, and Boreal White and Black Spruce (BWBS) biogeoclimatic zones, but such data for the Coastal Douglas-fir, Sub-Boreal Pine-Spruce, Sub-Boreal Spruce (SBS), and Spruce-Willow-Birch biogeoclimatic zones appear relatively sparse. There have been few studies of the functional role of CWD in B.C. forests, but those studies that have been completed indicate that CWD is an important habitat component for some plant and animal species. A total of 169 plant species, including >95% of all lichens and liverworts, were found to grow on CWD in old-growth forests in the CWH, MH, IDF, ICH, and ESSF biogeoclimatic zones. One third of these species were restricted to CWD. Studies in several biogeoclimatic zones have found that CWD provided preferred habitat for and was associated with higher populations of some small animal species, such as shrews, some voles, and some salamanders, in old-growth forests, but the effects varied with species and biogeoclimatic zone. The nutrient cycling role of CWD is not yet well known, but it currently appears to be relatively insignificant in B.C. old-growth forests. Although it has been considered that CWD could increase mineral soil acidification and eluviation, no Environ. Rev. 11: S135-S157 (2003) 1000 ans) dans la zone biogéoclimatique côtière de la pruche de l'Ouest (CWH). L'abondance des DLG et la superficie de sol qu'ils couvrent augmentent avec la productivité de la forêt. ...

Coarse woody debris carbon stocks in natural spruce forests of Babia hora

“…This reduction follows the pattern of decreasing dimensions of trees with increasing elevation (Merganič et al 2003). At upper elevations, climate characteristics are less favourable, which negatively affects forest productivity, and hence also the amount of CWD accumulated in the forest (Feller 2003). The highest deadwood volume as well as the highest carbon storage was found in the stage of breakdown and the first elevation category (Fig.…”

“…From the two catego-ries, coarse woody debris (CWD) is regarded as a more significant component due to its dimensions and substantial time during which it persists in the ecosystem. Hence, CWD acts as a long-term carbon sink until the decomposition process is completed, which can sometimes take up to 1,000 years (Feller 2003) depending on wood characteristics (tree species, dimensions), climate characteristics (temperature and moisture, Woodall, Liknes 2008) and the position on the ground (contact with the ground, Radtke et al 2004).…”

Preliminary study on the assessment of deadwood volume by the French national forest inventory

“…This study focuses on forest aboveground deadwood with floor coarse woody debris, referred to as CWD, snags for dead standing trees, and broken trees and stumps. There is little agreement in the literature for minimum diameters for CWD (Feller, 2003). A distinction is commonly made between CWD and fine woody debris (FWD).…”

Carbon stocks of western redcedar and western hemlock stands in Canada's inland temperate rainforests.

“…Accumulations of CWD in old-growth forests of Oregon, Washington, and BC are among the highest in the world , contributing to important DOM C reservoirs. In this study, mean CWD C stocks (39 Mg C ha" 1 ) in old-growth stands were considerably lower than those found in very wet maritime and very wet hyper maritime subzones of the CWH biogeoclimatic zone in BC (100 to 200 Mg C ha" 1 ) but similar to those of the very dry maritime subzone (15 to 55 Mg C ha" 1 , assuming wood C% is 50) (Keenan et al 1993;Feller 2003). Volumes reported across BC's coastal rainforests also support the evidence that drier CWH subzones are similar to wetter ICH subzones (Stevenson et al 2010).…”

“…Past studies have reported large reservoirs of mineral soil C in old-growth forests of the Pacific Northwestern USA Harmon et al 2004;Sun et al 2004;Bisbing et al 2010) and coastal and interior western redcedar and hemlock forests (Trofymow and Blackwell 1998;Trofymow et al 2008;Stevenson et al 2010) (Jull et al 2002;Feller 2003;Stevenson et al 2010). A global meta-analysis found that mineral soil C increased with stand age in boreal and temperate forests with the oldest stands showing the greatest soil C (Pregitzer and Euskirchen 2004).…”