Impact of feeding damage by the porcupine on western hemlock – Sitka spruce forests of north-coastal British Columbia

1986 ◽  
Vol 16 (3) ◽  
pp. 642-647 ◽  
Author(s):  
Thomas P. Sullivan ◽  
William T. Jackson ◽  
James Pojar ◽  
Allen Banner
Keyword(s):  
British Columbia ◽  
Small Diameter ◽  
Sitka Spruce ◽  
Control Measures ◽  
Western Hemlock ◽  
Feeding Damage ◽  
Red Cedar ◽  
Total Percentage ◽  
Second Growth ◽  
Coastal British Columbia

This study measured the incidence of feeding damage by porcupines (Erethizondorsatum Allen) within the second-growth western hemlock (Tsugaheterophylla Raf. (Sarg.)) – Sitka spruce (Piceasitchensis (Bong.) Carr.) forest of Khutzeymateen Inlet, 45 km northeast of Prince Rupert, British Columbia. Tree mensuration and damage assessments were conducted in 69 sample plots located on four transects. Western hemlock, which composed 67% of sampled stands, was the most severely (52.7% of trees, of which 5.1% were newly attacked) damaged species followed by Sitka spruce with minor (7.8%) damage. The less frequent amabilis fir (Abiesamabilis (Dougl.) Forbes) and western red cedar Thujaplicata Donn.) were not attacked. The total percentage of girdled (mortality) hemlock stems was 30.9%. Hemlock trees with a dbh > 27.4 cm had 55.9% of stems girdled. Porcupines attacked and girdled a significantly greater proportion of large than small diameter hemlock trees. Stems smaller than 125.5 cm dbh had little (3.7%) damage. Significantly more damage wounds were recorded in the middle and upper thirds of hemlock stems than in the lower bole. Dominant and codominant hemlock were preferred by porcupines in their feeding attacks. In combination with porcupine control measures, these stands clearly require some form of silvicultural treatment, such as sanitation spacing, conducted initially as an operational trial on at least a 20-ha block.

Feeding damage by bears in managed forests of western hemlock–western red cedar in midcoastal British Columbia

1993 ◽  
Vol 23 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Thomas P. Sullivan
Keyword(s):  
British Columbia ◽  
Black Bears ◽  
Western Hemlock ◽  
Grizzly Bears ◽  
Feeding Damage ◽  
Managed Forests ◽  
Red Cedar ◽  
Total Percentage ◽  
Second Growth ◽  
Western Red Cedar

This study measured the incidence of feeding damage in 1989 and 1990 by black bears (Ursusamericanus Pallas), and possibly by grizzly bears (Ursusarctos L.), within managed and unmanaged second-growth western hemlock (Tsugaheterophylla (Raf.) Sarg.)–western red cedar (Thujaplicata Donn) forest stands near Jennis Bay, 39 km northwest of Port Hardy, British Columbia. Tree mensuration (1989) and damage assessments (1989 and 1990) were conducted in 69 sample plots located in stands that were spaced in 1980 to 1982, when the trees were juvenile, and in 19 plots located in a nearby unspaced (control) stand. Western red cedar, which represented 13.6% of the managed stands, was the most severely damaged species (cumulative attack of 63.8% in 1989, increasing to 69.1% in 1990). Western hemlock, the major tree species, had <0.5% of trees attacked, and amabilis fir (Abiesamabilis (Dougl.) Forbes) was not attacked. Cumulative incidence of damage to red cedar in the control stand was 66.7% in 1989, increasing to 71.4% in 1990. The annual incidence of attack in 1990 was 18.1% in the spaced stands and 16.7% in the control stand. The total percentage of girdled cedar stems (mortality) was 10.7% in the control and 23.3% in the spaced stands overall. Bear damage clearly declined during 1990, which may be related to dispersal or removal (hunting) of animals from the general area or to a declining number of cedar trees (30%) that remain unattacked by bears. Crop tree selection against red cedar in future spacing projects could alleviate bear attacks.

Impact of feeding damage by the porcupine on western hemlock – Sitka spruce forests of north-coastal British Columbia: 15-year results

2003 ◽  
Vol 33 (10) ◽  
pp. 1983-1989 ◽  
Author(s):  
Alex J Woods ◽  
Stefan Zeglen
Keyword(s):  
British Columbia ◽  
Mixed Forest ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
North Coast ◽  
Feeding Damage ◽  
Decay Fungi ◽  
Dead Trees

American porcupine (Erithizon dorsatum L.) feed on the cambial tissues of several tree species. This study assessed feeding by porcupine over a 15-year period on midrotation age western hemlock (Tsuga heterophylla (Raf.) Sarg.) dominated stands on the north coast of British Columbia, Canada. Although four coniferous hosts were available, hemlock was, by far, the most preferred and most seriously impacted. Of 398 hemlock studied, 260 were wounded by porcupine feeding and 86 died by 2000. Porcupine attacked two-thirds of the dead trees, over 82% of which were dominant or codominant, while almost all unattacked dead trees were intermediate or suppressed. This loss resulted in a 14.6% reduction in the proportion of volume per hectare represented by hemlock and an increase in the representation by other species, all of which suffered little or no feeding damage. Results indicate that the final merchantable volume of hemlock expected at rotation age will be lower than projected and will consist mainly of damaged trees of poor form and quality due to decay fungi, such as Stereum sanguinolentum (A. & S. ex Fr.), entering through feeding wounds. Porcupine activity has led to a shift in species composition and volume from a condition where a single species, western hemlock, dominates to a mixed forest consisting of amabilis fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes), Sitka spruce (Picea sitchensis (Bong.) Carrière), and western hemlock.

Seasonal Variation of Stump Infection by Fomes Annosus in Coastal British Columbia

1970 ◽  
Vol 46 (3) ◽  
pp. 200-202 ◽  
Author(s):  
D. J. Morrison ◽  
A. L. S. Johnson
Keyword(s):  
British Columbia ◽  
Seasonal Variation ◽  
Sitka Spruce ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Lower Percentage ◽  
Fresh Cut ◽  
Coastal British Columbia ◽  
Cut Stumps

Susceptibility of fresh-cut stumps of western hemlock, amabilis fir, Douglas-fir and Sitka spruce to infection via Fomes annosus (Fr.) Karst. spores was determined at 12 consecutive monthly intervals. Over 40% of the amabilis fir, western hemlock, Douglas-fir and Sitka spruce stumps became infected throughout the year when inoculated with a basidiospore suspension. Airborne spore infection of amabilis fir was high (> 80%) throughout the year; infection of Douglas-fir was lower during the summer, whereas infection of hemlock was lower during the fall and winter. Excepting amabilis fir, natural airborne spore inoculum resulted in a lower percentage stump infection than when the stumps were inoculated with basidiospores.

scholarly journals Porcupine Feeding Damage in Precommercially Thinned Conifer Stands of Central Southeast Alaska

1997 ◽  
Vol 12 (4) ◽  
pp. 115-121 ◽  
Author(s):  
Andris Eglitis ◽  
Paul E. Hennon
Keyword(s):  
Host Selection ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Feeding Damage ◽  
Southeast Alaska ◽  
Erethizon Dorsatum ◽  
Young Growth

Abstract This study describes feeding damage by porcupines (Erethizon dorsatum) in precommercially thinned young growth stands of Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla) on Mitkof Island in central southeast Alaska. We examined 641 trees from 54 sampling plots along transect lines in three 12 to 20 yr old stands. Porcupine feeding was monitored each spring and fall from 1985 to 1987. Four categories of feeding damage are described: complete girdling of the bole, partial girdling (bole scars), branch clipping, and "tasting wounds" (small basal bole scars). Sitka spruce, the primary crop tree in these thinned stands, sustained significantly higher damage (52% of trees affected) than western hemlock (26% of trees affected). Porcupine feeding was greater on taller than shorter Sitka spruce. Although only 8 of 59 trees initially girdled in 1985 were killed, many later sustained additional feeding damage. Following the 1987 season 3 yr after thinning, nearly 30% of the spruce and 14% of the western hemlock crop trees had been partially or completely girdled. Issues deserving future attention include the role of thinning in predisposing stands to porcupine damage, methods of population assessment, and mechanisms of host selection by porcupines. West. J. Appl. For. 12(4):115-121.

scholarly journals Estimating the Number of Filled Seeds per Cone of Western Hemlock from Coastal British Columbia

1996 ◽  
Vol 11 (2) ◽  
pp. 44-49
Author(s):  
M. D. Meagher
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Linear Relationships ◽  
The Face ◽  
Predetermined Level ◽  
Exponential Factors ◽  
The Relationship ◽  
Coastal British Columbia ◽  
Filled Seeds

Abstract Unopened western hemlock (Tsuga heterophylla) cones from coastal British Columbia were tested for the relationship between total filled seeds per cone and the number of sound seeds exposed by slicing through the center of the cone's long axis, and with cone length. Predictive linear relationships of total number of filled seeds per cone (TFS), based on number of filled seeds cut on the face through the cone's long axis (CC), were found in a cone sample bulked from a number of trees. The regression based on CC explained about 63% of the variation in TFS. More accurate estimates of TFS were found where cone length, and exponential factors of CC and cone length, were included in the analysis. Analyses of cones from seven parents did not find statistically significant trends of TFS on CC in all cases, and differed in slope in most cases. Sample sizes (cones) to estimate TFS to a predetermined level of precision were much larger than cones needed to accept or reject a tree for study. West. J. Appl. For. (11)2:44-49.

Availability of N and P in the forest floors of adjacent stands of western red cedar–western hemlock and western hemlock–amabilis fir on northern Vancouver Island

1993 ◽  
Vol 23 (4) ◽  
pp. 605-610 ◽  
Author(s):  
C. E. Prescott ◽  
M.A. McDonald ◽  
G.F. Weetman
Keyword(s):  
Forest Floor ◽  
Forest Type ◽  
Western Hemlock ◽  
Red Cedar ◽  
Floor Layer ◽  
Second Growth ◽  
Extractable P ◽  
Western Red Cedar ◽  
Forest Floors ◽  
Floor Material

Availability of N and P was compared in the forest floors of old-growth forests of western red cedar (Thujaplicata Donn)and western hemlock (Tsugaheterophylla (Raf.) Sarg.) (CH forests), and second-growth forests of western hemlock and amabilis fir (Abiesamabilis (Dougl.) Forbes) (HA forests) of windthrow origin. Five samples of each forest floor layer (litter, fermentation (woody and nonwoody), and humus (woody and nonwoody)) were collected from three forests of each type (CH and HA). All layers of CH forest floors had smaller concentrations of total and extractable N and mineralized less N during 40-day aerobic incubations in the laboratory. Total and extractable P was lower in the litter layer of CH forest floors. Seedlings of western red cedar, Sitka spruce (Piceasitchensis (Bong.) Carr.), western hemlock, and amabilis fir grown from seed in forest floor material from CH forests grew more slowly and took up less N and P than did seedlings grown in HA forest floor material. The low supply of N and P in CH forest floors may contribute to the nutrient supply problems encountered by regenerating trees on cutovers of this forest type.

Palynology and paleoecology of postglacial sediments in an anoxic basin, Saanich Inlet, British Columbia

1983 ◽  
Vol 20 (5) ◽  
pp. 873-885 ◽  
Author(s):  
Linda E. Heusser
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Alnus Rubra ◽  
Red Cedar ◽  
Saanich Inlet ◽  
Anoxic Basin

Varved, black clayey silts deposited in the marine waters of Saanich Inlet yield unusually abundant and diverse pollen assemblages derived from the coastal Douglas-fir (Pseudotsuga) and western hemlock (Tsuga heterophylla) forests of southwestern British Columbia. The 12 000 year palynological record chronicles the development of vegetation since ice left Saanich Inlet: the succession of pine (Pinus contorta) and alder (Alnus rubra) woodlands by forests characterized by Douglas-fir and oak (Quercus) and later by western hemlock and red cedar (Thuja plicata). Rapid deposition of annual layers of pollen, charcoal, and other terrigenous particles provides detailed evidence of changes in land use during the past few hundred years: settlement, logging, farming, and urbanization. Vegetational and climatic changes inferred from pollen spectra in the marine sediments of Saanich Inlet compare favorably with changes inferred from correlative pollen assemblages previously described from adjacent parts of Vancouver Island and the Fraser River valley.

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