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.

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.

STUDIES IN FOREST PATHOLOGY: VIII. DECAY OF WESTERN HEMLOCK ON THE QUEEN CHARLOTTE ISLANDS, BRITISH COLUMBIA

1951 ◽  
Vol 29 (5) ◽  
pp. 479-521 ◽  
Author(s):  
R. E. Foster ◽  
A. T. Foster
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Total Loss ◽  
Western Hemlock ◽  
Site Quality ◽  
Forest Pathology ◽  
Old Growth ◽  
Queen Charlotte Islands ◽  
Dead Trees ◽  
Understory Trees

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) on the Queen Charlotte Islands, British Columbia, has shown that decay losses in old-growth stands are appreciable, amounting to 13.9, 8.0, and 10.7% of the gross volume of Grades 1, 2, and 3 logs respectively. Total loss, including dead trees, amounted to 25.5% of the gross volume. Twenty-seven decay-producing fungi have been isolated. The most important of these are Fomes pinicola (Sw.) Cke., F. pini (Thore) Lloyd, F. annosus (Fr.) Cke., and Polyporus sulphureus Bull. ex Fr. Echinodontium tinctorium E. & E. apparently does not occur in the region. Scars provided the most frequent, and roots the most important, avenue of entrance for decay. The logs of 2318 western hemlock were analyzed in detail. Decay was found to increase progressively with diameter, age, and decreasing site quality. Maximum net periodic increment was reached between 350 and 400 years of age and between 35 and 40 in. in diameter. Color of bark was found to provide an added indication of tree maturity. Understory trees were found to give a substantial yield of sound wood.

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.

scholarly journals Sitka Spruce and Western Hemlock Stand and Tree Growth 10 Years after Precommercial Thinning in Southeast Alaska

2012 ◽  
Vol 27 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Mike Newton ◽  
Liz Cole
Keyword(s):  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Diameter Growth ◽  
Southeast Alaska ◽  
Steady Rate ◽  
Increasing Trend ◽  
Naturally Regenerated Stands ◽  
Understory Plant

Abstract Ten years after precommercially thinning 16–18-year-old naturally regenerated stands of Sitka spruce (Picea sitchensis [Bong.] Carr.) and western hemlock (Tsuga heterophylla [Raf.] Sarg.) in southeast Alaska, neither species responded in height growth to spacing. Spruce diameter growth increased significantly following all thinning treatments, and among thinning treatments, there was a weak but increasing trend toward more rapid diameter growth at the wider spacings. Spruce basal areas increased almost twice as fast after thinning as without thinning, and radial growth continued to increase, whereas unthinned stands grew at a slower but steady rate. Western hemlock also showed a trend for increased diameter, but growth response was less than for spruce. Shrub control to enhance understory plant development for deer forage did not improve growth of either tree species. Branch diameter of Sitka spruce increased with spacing. Pruning led to epicormic sprouting in the 3 years following pruning with numbers inversely related to spacing. Sprouts developed and persisted in stands thinned to 200 or fewer stems per acre. Overall, pruning led to a small reduction in diameter growth at breast height.

Economic Evaluation of Thinning Alternatives in a Western Hemlock-Sitka Spruce Forest

1988 ◽  
Vol 3 (1) ◽  
pp. 14-17
Author(s):  
Loren D. Kellogg ◽  
Eldon D. Olsen
Keyword(s):  
Pacific Northwest ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Base Case ◽  
Projection Model ◽  
Net Worth ◽  
Study Results ◽  
Rotation Age

Abstract As part of a multidisciplinary study on managing young western hemlock (Tsuga heterophylla)-Sitka spruce (Picea sitchensis) stands in the Pacific Northwest, a present net worth analysis of thinning impacts on financial returns at final harvest was completed. Two 32-year-old precommercially thinned stands were selectively and strip thinned with a skyline logging system, and stand growth was projected to rotation age 70 years with a stand-table projection model. A harvest simulation model was then used to estimate harvest costs and revenues from clearcutting at rotation age. Regardless of model assumptions, present net worth was highest for the control (no thinning). A sensitivity analysis of variations from base-case assumptions did not alter the outcome. Study results suggest that if density of managed western hemlock-Sitka spruce stands has been sufficiently controlled with precommercial thinning, they will develop adequately to a rotation-age harvest without intermediate thinning. West. J. Appl. For. 3(1):14-17, January 1988.

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.

STUDIES IN FOREST PATHOLOGY: VII. DECAY IN WESTERN HEMLOCK AND FIR IN THE FRANKLIN RIVER AREA, BRITISH COLUMBIA

1949 ◽  
Vol 27c (6) ◽  
pp. 312-331 ◽  
Author(s):  
D. C. Buckland ◽  
R. E. Foster ◽  
V. J. Nordin
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Forest Pathology ◽  
Abies Amabilis ◽  
Armillaria Mellea ◽  
Forest Region ◽  
Volume Increment ◽  
Juan De Fuca

An investigation of decay in western hemlock (Tsuga heterophylla (Raf.) Sarg.) and fir (mainly Abies amabilis (Loud.) Forb.) in the Juan de Fuca forest region of British Columbia has shown that the major organisms causing root and butt rots are the same in both species. These are Poria subacida (Peck) Sacc., Fomes annosus (Fr.) Cke., Armillaria mellea Vahl ex Fr., Polyporus sulphureus Bull. ex Fr., and P. circinatus Fr. Those organisms causing trunk rots of western hemlock, in decreasing order of importance, are Fomes pinicola (Sw.) Cke., F. Pini (Thore) Lloyd, Stereum abietinum Pers., Fomes Hartigii (Allesch.) Sacc. and Trav., and Hydnum sp. (H. abietis). These same organisms causing trunk rots of fir, in decreasing order of importance, are Fomes pinicola, Stereum abietinum, Hydnum sp. (H. abietis), Fomes Pini, and Fomes Hartigii. The logs of 963 western hemlock were analyzed in detail. Maximum periodic volume increment was reached between 225 and 275 years of age. Maximum periodic volume increment was reached between 275 and 325 years of age in the 719 fir that were analyzed. Scars were the most frequent avenue of entrance for infection. In 59% of the cases of infection studied the fungus had entered through wounds.

What influences the long-term development of mixtures in British forests?

2020 ◽  
Vol 93 (4) ◽  
pp. 545-556 ◽  
Author(s):  
W L Mason ◽  
T Connolly
Keyword(s):  
Functional Traits ◽  
Scots Pine ◽  
Shade Tolerance ◽  
Basal Area ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Silver Birch ◽  
Western Hemlock ◽  
Larix Kaempferi ◽  
Pure Stand

Abstract Six experiments were established between 1955 and 1962 in different parts of northern and western Britain which used replicated randomized block designs to compare the performance of two species 50:50 mixtures with pure stands of the component species. The species involved were variously lodgepole pine (Pinus contorta Dougl.), Japanese larch (Larix kaempferi Lamb. Carr.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth.), Sitka spruce (Picea sitchensis Bong. Carr.) and western hemlock (Tsuga heterophylla Raf. Sarg.). The first four species are light demanding, while Sitka spruce is of intermediate shade tolerance and western hemlock is very shade tolerant: only Scots pine and silver birch are native to Great Britain. In three experiments (Bickley, Ceannacroc, Hambleton), the mixtures were of two light-demanding species, while at the other three sites, the mixture tested contained species of different shade tolerance. The experiments were followed for around 50 years, similar to a full rotation of even-aged conifer stands in Britain. Five experiments showed a tendency for one species to dominate in mixture, possibly reflecting differences in the shade tolerance or other functional traits of the component species. In the three experiments, the basal area of the mixtures at the last assessment was significantly higher than predicted based on the performance of the pure stands (i.e. the mixture ‘overyielded’). In two of these cases, the mixture had had a higher basal area than found in the more productive pure stand indicating ‘transgressive overyielding’. Significant basal area differences were generally more evident at the later assessment date. The exception was in a Scots pine: western hemlock mixture where greater overyielding at the earlier date indicated a nursing (‘facilitation’) effect. In the remaining experiments, the performance of the mixture conformed to predictions from the growth of the component species in pure stands. Taken overall, the results suggest that functional traits can be used to interpret the performance of mixtures but prediction of the outcome will require better understanding of the interplay between species and site characteristics plus the influence of silvicultural interventions.

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