Nutrient Movement Through Western Hemlock-Western Redcedar Ecosystems in Southwestern British Columbia

Ecology ◽  
1977 ◽  
Vol 58 (6) ◽  
pp. 1269-1283 ◽  
Author(s):  
M. C. Feller
Keyword(s):  
British Columbia ◽  
Western Hemlock ◽  
Western Redcedar

scholarly journals Western redcedar population dynamics in old-growth forests: Contrasting ecological paradigms using tree rings

2003 ◽  
Vol 79 (3) ◽  
pp. 517-530 ◽  
Author(s):  
Lori D Daniels
Keyword(s):  
British Columbia ◽  
Population Dynamics ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Silver Fir ◽  
Old Growth ◽  
Western Redcedar ◽  
Old Growth Forests ◽  
Gap Phase ◽  
Coastal British Columbia

In coastal British Columbia, late-successional forests dominated by western redcedar (Thuja plicata Donn ex D. Don) are structurally complex, with deep multi-layered canopies, large trees that are > 250 years old, and abundant coarse woody debris (CWD). These forests are presumed to be "old-growth" forests in which fine-scale gaps are the dominant disturbance regime, accounting for their structural diversity. In this study, I have used tree-ring analyses to investigate western redcedar regeneration dynamics in these old-growth forests. Western redcedar dominates canopies of many stands, but is rare in the understorey although it tolerates shade. The traditional interpretation is that western redcedar depends on catastrophic disturbance to regenerate and that it is replaced through succession by western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes), which are abundant in the understorey. Dominant trees are perceived to represent an even-aged, post-disturbance cohort and the lack of regeneration indicates a population decline in the absence of catastrophic disturbances. In this paper, I investigate four assumptions underlying this interpretation: (1) Tree size indicates age. (2) Populations establish as even-aged, post-disturbance cohorts. (3) Abundant CWD represents recent mortality. (4) Regeneration is insufficient to maintain canopy dominance. Using tree-ring evidence, I show that population dynamics of western redcedar are a combination of gap-phase establishment and a continuous mode of recruitment from the sub-canopy to the canopy. Specifically, size is a poor surrogate for tree age. Age distributions from 15 sites revealed uneven-aged populations, rather than single post-disturbance cohorts. Both logs and snags of western redcedar may persist more than 270 years; they do not represent recent mortality that is disproportionate to the number of live western redcedar in canopy. The regeneration niches of western redcedar and western hemlock overlap. For both species, gap-phase disturbances result in substrate suitable for successful seedling establishment. Preliminary results from dendroecological analysis of radial growth rates of trees in the subcanopy and canopy strata suggest that western hemlock and Pacific silver fir depend on gaps to recruit to the upper canopy, but recruitment of western redcedar may be independent of canopy gaps. I propose that differences in mode of recruitment to the canopy may explain the differences in population structures between western redcedar, western hemlock, and Pacific silver fir in the old-growth forest. These results provide an ecological precedent for use of a range of silvicultural systems, including clearcuts through single-tree harvesting and protection forests, when managing western redcedar in coastal British Columbia. Key words: Coastal British Columbia, disturbance regimes, regeneration dynamics, Thuja plicata, variable retention silviculture

Overturning resistance of western redcedar and western hemlock in mixed-species stands in coastal British Columbia

2007 ◽  
Vol 37 (5) ◽  
pp. 931-939 ◽  
Author(s):  
Kenneth E. Byrne ◽  
Stephen J. Mitchell
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Specific Information ◽  
Mixed Species ◽  
Stem Form ◽  
Western Redcedar ◽  
Applied Forces ◽  
Coastal British Columbia

Specific information about the applied forces that cause trees to fail is required to validate mechanistic models of windthrow in different forest types. Static tree-pulling tests were conducted to examine the overturning resistance of western redcedar ( Thuja plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla (Raf.) Sarg.) in a mixed species second-growth stand in coastal British Columbia. Although widely used, tree-pulling techniques are not standardized. Data from three inclinometers were used to estimate stem deflection, which was found to increase with tree slenderness. Differing methods of fitting stem curvature had a small effect on estimates of self-loading at failure. The distance of the pivot point from the centre of the stem base increased with tree diameter. Accounting for the correct self-loading at failure produced a small difference in the overall turning moment regressions but did not improve the fit of these regressions. However, this difference increased with tree size and warrants consideration in future tree-pulling tests with large or plate-rooted trees. The stem mass – overturning resistance relationship had the best fit and was not significantly different for these species in spite of their differences in wood density and stem form.

Root structure of western hemlock and western redcedar in single- and mixed-species stands

2002 ◽  
Vol 32 (6) ◽  
pp. 997-1004 ◽  
Author(s):  
X L Wang ◽  
K Klinka ◽  
H Y.H Chen ◽  
L de Montigny
Keyword(s):  
British Columbia ◽  
Forest Floor ◽  
Soil Depth ◽  
Root Density ◽  
Western Hemlock ◽  
Root Structure ◽  
Mixed Species ◽  
Coarse Roots ◽  
Western Redcedar ◽  
Size Classes

Root structure of western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn. ex D. Don) was studied in single- and mixed-species stands of hemlock and western redcedar in Capilano River watershed, University of British Columbia Malcolm Knapp Research Forest, and Mission, southern coastal British Columbia. We sampled roots using a tree-to-tree trench excavation method. In each stand, roots were collected from three randomly located trenches using a 20 × 20 × 10 cm template along (i) a soil depth gradient: forest floor (FF), 0- to 10-cm (MS1), and 10- to 20-cm mineral soil layers (MS2) and (ii) a lateral soil gradient (tree-to-tree trenches). Hemlock–redcedar mixtures had the greatest root density, followed by pure hemlock and redcedar stands. In both pure hemlock stands and hemlock-redcedar mixtures, root density of all size classes (fine, medium, and coarse roots) decreased with increasing soil depth, whereas that of pure redcedar stands peaked at the MS1 layer. Density of roots along the lateral gradient varied among stand types and root size classes. Density of coarse roots was higher towards tree stems, while that of fine and medium roots was more evenly distributed. In the forest floor of the hemlock–redcedar mixtures, root density of all sizes except that of redcedar coarse roots was not related to the distance to stems, but fine root density of hemlock was greater than that of redcedar. The highest root density in the hemlock–redcedar mixtures may indicate the presence of overlapping and intermingling roots and intense competition for available soil resources.

TOXICITY OF SMOKE FROM SPOROPHORES OF THE INDIAN PAINT FUNGUS AND WOOD FROM WESTERN HEMLOCK TO YELLOWFEVER MOSQUITOES

1987 ◽  
Vol 119 (12) ◽  
pp. 1109-1115
Author(s):  
W.P.L. Osborn ◽  
J.H. Borden
Keyword(s):  
British Columbia ◽  
Aedes Aegypti ◽  
Combustion Products ◽  
Tsuga Heterophylla ◽  
Water Soluble ◽  
Western Hemlock ◽  
Aqueous Extracts ◽  
Smoke Water

AbstractTo mitigate the effects of mosquitoes, settlers in the Revelstoke area of British Columbia reportedly burned the sporophores of the Indian paint fungus, Echinodontium tinctorium (Ell. & Ev.) Ell. & Ev., a pathogen of western hemlock, Tsuga heterophylla (Raf.) Sarg., and true firs, Abies spp. Larval and adult yellowfever mosquitoes, Aedes aegypti (L.), were exposed to aqueous extracts of smoke (smoke-waters) from E. tinctorium sporophores, and from western hemlock sapwood and heartwood. Smoke-waters were of approximately equal toxicity to larvae. Fungus smoke-water, but not sapwood or heartwood smoke-waters, lost 50% of its potency in 5 months. Vapors from fungus smoke-water were significantly more toxic to adult mosquitoes than those from sapwood or heartwood. Thus smoke from E. tinctorium sporophores and T. heterophylla wood apparently contain different water-soluble combustion products toxic to A. aegypti.

Sign in / Sign up

Export Citation Format

Share Document