Understory conifer seedling response to a gradient of root and ectomycorrhizal fungal contact

2005 ◽  
Vol 83 (6) ◽  
pp. 638-646 ◽  
Author(s):  
J M Kranabetter
Keyword(s):  
Picea Glauca ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Forest Understory ◽  
Western Hemlock ◽  
Scarce Resources ◽  
Full Contact ◽  
Mycorrhizal Network ◽  
Mycorrhizal Networks ◽  
Common Mycorrhizal Network

The possible benefit of common mycorrhizal network linkages to seedling growth was tested in a low light partial-cut forest understory. Naturally regenerated western hemlock (Tsuga heterophylla Raf.) and hybrid spruce (Picea glauca × Picea sitchensis [Moench] Voss) seedlings were transplanted directly into soil or within bags of different pore sizes to restrict the amounts of root and ectomycorrhizal contact. The 5-year study included "full contact" (no bag), "moderate contact" (250-µm openings), and "low contact" (4-µm openings) treatments. Height increment was lowest for full contact seedlings over most of the experiment, and highest for low contact seedlings by years 4 and 5. Full contact seedlings also had slightly lower foliar N content than moderate and low contact seedlings. There were no significant interactions in growth detected between tree species and treatments, despite the higher potential for common mycorrhizal network linkages between a western hemlock understory and canopy. Fifty-eight ectomycorrhizal fungal morphotypes were identified on the seedlings, including many with smooth mantles or with only sparse emanating hyphae, which likely reduced the potential for common mycorrhizal network linkages. These results would support the more traditional concepts of competition for scarce resources by isolated seedlings as the primary interaction for the understory of these mature forests.Key words: common mycorrhizal networks, facilitation, shade tolerance, competition.

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.

Ten-year postharvest effects of silviculture systems on soil-resource availability and conifer nutrition in a northern temperate forest

2004 ◽  
Vol 34 (4) ◽  
pp. 800-809 ◽  
Author(s):  
J M Kranabetter ◽  
K D Coates
Keyword(s):  
Tree Growth ◽  
Forest Floor ◽  
Light Availability ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Net N Mineralization ◽  
Mature Trees ◽  
Foliar N

Silviculture systems (clear-cut, partial-cut, and unharvested forest) were compared 9–10 years after harvesting to determine their effects on conifer nutrition and the availability of soil resources, especially nitrogen. These results were used to discuss the effects of silviculture systems on tree growth in relation to the more commonly described effects of light. Differences in soil properties across the silviculture treatments were most apparent in the forest floor. Depth and C/N ratio of the forest floor had decreased slightly in clearcuts, and forest-floor moisture was highest under partial-cut forest. Despite these differences in soil chemistry and soil moisture, no differences were detected in mineralizable N (anaerobic incubation) or in situ net N mineralization among treatments. Height growth and foliar mass were reduced under the low-light conditions of the partial-cut forest, but there were no differences in foliar N concentrations of hybrid white spruce (Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carrière), western redcedar (Thuja plicata Dougl. ex D. Don), or western hemlock (Tsuga heterophylla (Raf.) Sarg.) saplings. Mature western hemlock trees in partial-cut forest also had concentrations of foliar N equal to that of mature trees in the unharvested forest. Overall, we detected only minor effects of silviculture systems on soils after 10 years, and we conclude that light availability is likely more responsible for the current differences in tree growth.

Trees are larger on southern slopes in late-seral conifer stands in northwestern British Columbia

2019 ◽  
Vol 49 (11) ◽  
pp. 1349-1356
Author(s):  
Nathan J. Kuyek ◽  
Sean C. Thomas
Keyword(s):  
British Columbia ◽  
Picea Glauca ◽  
Pinus Contorta ◽  
Tree Height ◽  
Tsuga Heterophylla ◽  
Snow Accumulation ◽  
Western Hemlock ◽  
Stem Volume ◽  
Published Data ◽  
Canopy Tree

Mid-latitude forests commonly show increased productivity and ultimately produce larger trees on shaded, northern aspects compared with those on sunny, southern aspects. Little research has been conducted on this phenomenon at higher latitudes where solar radiation is less available. We examined patterns of canopy tree size in a set of 142 naturally regenerated, late-seral conifer stands in northwestern British Columbia, Canada, at latitudes of 54°N–56°N. The height, diameter, and total stem volume of three shade-tolerant conifers (western hemlock (Tsuga heterophylla (Raf.) Sarg.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and hybrid spruce (Picea glauca × engelmannii (Moench) Voss)) and shade-intolerant lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) were analyzed. In contrast to most previous studies, mean canopy tree height, diameter, and volume were greatest on southern aspects and lowest on northern aspects for the subset of sites with pronounced slopes (≥30%). There was some variation in patterns among species, with western hemlock responding most strongly to topography, and species-specific effects of topography on height–diameter allometry. We suggest that decreased levels of radiation at northern latitudes and increased light and warmer temperatures on steeper, southern aspects promote growth. In contrast, colder, shaded, northern aspects with increased snow accumulation, delayed snowmelt, and decreased nitrogen mineralization inhibit growth. Our results, together with published data, suggest that a latitudinal shift from higher forest productivity on northern aspects to higher productivity on southern aspects typically occurs between 40°N and 50°N.

Modeling the incidence and severity of hemlock dwarf mistletoe in 110-year-old wind-disturbed forests in Southeast Alaska

1998 ◽  
Vol 28 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
L M Trummer ◽  
P E Hennon ◽  
E M Hansen ◽  
P S Muir
Keyword(s):  
Basal Area ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Managed Forests ◽  
Coastal Forests ◽  
Dwarf Mistletoe ◽  
Infection Level ◽  
Southeast Alaska ◽  
Preliminary Validation

Amodel was developed to predict the severity of dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones) in western hemlock trees (Tsuga heterophylla (Raf.) Sarg.) that developed within forests of Southeast Alaska that experienced near-catastrophic windthrow in the late 1800s. The model suggests that the degree of dwarf mistletoe severity on western hemlock trees was significantly and positively correlated with levels of dwarf mistletoe infection and basal area (m2/ha) in large and small residual trees that survived the wind disturbance. No significant relationships were found between severity level and any other factors, including site productivity, density of coexisting Sitka spruce (Picea sitchensis (Bong.) Carr.), or slope. The model demonstrates the overriding importance of infected residual trees to predict future severity of dwarf mistletoe; greater size and infection level of residual trees results in greater dwarf mistletoe levels on regenerating hemlock crop trees. The model, derived from 76 plots on Kuiu Island, was tested in 18 plots on Chichagof Island, providing a preliminary validation. Slower rates of dwarf mistletoe spread and intensification in forests of southeastern Alaska, as compared with similar coastal forests south of Alaska, provide an opportunity for managers to manipulate the parasite to desired levels in managed forests.

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 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.

Spatial distribution and succession of epiphytes on Tsuga heterophylla (western hemlock) in an old-growth Douglas-fir forest

2000 ◽  
Vol 78 (7) ◽  
pp. 957-968 ◽  
Author(s):  
Betsy Lyons ◽  
Nalini M Nadkarni ◽  
Malcolm P North
Keyword(s):  
Forest Canopy ◽  
Spatial Scales ◽  
Coniferous Forest ◽  
Tsuga Heterophylla ◽  
Forest Understory ◽  
Western Hemlock ◽  
Old Growth ◽  
Old Growth Forest ◽  
Crown Structure ◽  
Large Trees

We examined the distribution and abundance of nonvascular epiphytes on western hemlock trees in an old-growth coniferous forest focusing on patterns of epiphyte distribution at different spatial scales, epiphyte abundance amongst trees differing in size, and crown structures associated with epiphyte abundance. Total epiphyte cover was greatest in four canopy microhabitats: the upper canopy strata, crowns of large trees, lower crown branches, and inner branch plots. Epiphyte functional groups were stratified vertically within the stand and horizontally within branches. Alectorioid and "other" lichens were most abundant in the upper canopy and outer branch plots. Cyanolichens and Sphaerophorus globosus (Huds.) Vain. were most abundant in the lower to mid canopy. Although cyanolichens were most abundant in middle branch plots, Sphaerophorus was most abundant in inner branch plots. Bryophytes were most abundant in the lower canopy and inner branch plots. At the stand level, canopy height and tree size were the main influences on epiphytes. Within trees, plots closer to the tree trunk and lower in the crown had the greatest abundance of epiphytes. In this forest, understory trees were colonized first by bryophytes, not by alectorioid and "other" lichens as is common for small trees in young stands.Key words: epiphyte succession, lichens, western hemlock, old growth, forest canopy, crown structure.

scholarly journals Transformation of western hemlock ( Tsuga heterophylla ) tree crowns by dwarf mistletoe ( Arceuthobium tsugense , Viscaceae)

2020 ◽  
Author(s):  
Stephen J. Calkins ◽  
David C. Shaw ◽  
Yung‐Hsiang Lan
Keyword(s):  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Tree Crowns
Sign in / Sign up

Export Citation Format

Share Document