Are mixed-species stands more productive than single-species stands: an empirical test of three forest types in British Columbia and Alberta

2003 ◽  
Vol 33 (7) ◽  
pp. 1227-1237 ◽  
Author(s):  
H YH Chen ◽  
K Klinka ◽  
A -H Mathey ◽  
X Wang ◽  
P Varga ◽  
...  
Keyword(s):  
Pinus Contorta ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
Empirical Test ◽  
Single Species ◽  
Growth Patterns ◽  
Thuja Plicata ◽  
Larix Occidentalis ◽  
Mixed Species ◽  
Stand Volume

Stand volumes were determined for naturally established, even-aged, single- and mixed-species stands involving three combinations of shade-tolerant and shade-intolerant conifers on similar sites: (i) western redcedar – western hemlock (Thuja plicata Donn ex D. Don – Tsuga heterophylla (Raf.) Sarg.), (ii) lodgepole pine – western larch (Pinus contorta Dougl. ex Loud. – Larix occidentalis Nutt.), and (iii) lodgepole pine – black spruce (Pinus contorta – Picea mariana (Mill.) BSP). Stand volume was significantly increased with site index and breast-height age in all three studies. Stand volume was also related to relative stand density in the lodgepole pine – black spruce study. When both species were shade tolerant (hemlock–redcedar), stand volume increased linearly with the proportion of hemlock; the mixed-species stands had intermediate volume compared with single-species stands. The combination of two shade-intolerant species (pine–larch) had lower stand volume than that anticipated from single-species stands, implying that one species may inhibiting the growth of the other. Mixtures of shade-intolerant and shade-tolerant species with different growth patterns (spruce–pine) may be more productive than single-species stands in specific ecological contexts and developmental stages. The effect of one species on the productivity of another species is tree-species and site specific: at maturity, even-aged, mixed-species coniferous stands are not necessarily more productive than single-species stands.

Black Bear Damage to Thinned Timber Stands in Northwest Montana

1989 ◽  
Vol 4 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Andrew C. Mason ◽  
David L. Adams
Keyword(s):  
Pinus Contorta ◽  
Black Bear ◽  
Tsuga Heterophylla ◽  
Thuja Plicata ◽  
Abies Lasiocarpa ◽  
Pinus Monticola ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Engelmann Spruce ◽  
Northwest Montana

Abstract Bear damage was at least five times higher in thinned blocks than in adjacent unthinned blocks of western larch (Larix occidentalis), lodgepole pine (Pinus contorta), and Engelmann spruce (Picea engelmannii) on the Kootenai National Forest in northwest Montana. Western larch suffered the greatest damage (63% of all trees damaged and 92% of the trees killed). Damaged larch ranged from 4 to 13 in. dbh; the 4 to 8-in. dbh class accounted for 85% of the damage. Douglas-fir (Pseudotsuga menziesii), western redcedar (Thuja plicata), subalpine fir (Abies lasiocarpa), western white pine (Pinus monticola), and western hemlock (Tsuga heterophylla) were not damaged. Stand projections showed up to a 17% reduction in board-foot yield from bear damage, after 50 years, compared with hypothetical undamaged stands. West. J. Appl. For. 4(1):10-13, January 1989.

scholarly journals Larch Seed Trees Sustain Arboreal Lichens and Encourage Recolonization of Regenerating Stands

2007 ◽  
Vol 22 (2) ◽  
pp. 94-98 ◽  
Author(s):  
Fred L. Bunnell ◽  
Trevor Goward ◽  
Isabelle Houde ◽  
Curtis Björk
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Road Dust ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Source Tree ◽  
Winter Food ◽  
The Difference

Abstract In many areas Bryoria lichen is a major winter food for deer and caribou. We examined the role of western larch (Larix occidentalis) seed trees in retaining arboreal lichens and encouraging recolonization of regenerating stands by Bryoria. Although exposed to desiccation, Bryoria was sustained in significant amounts in larch seed trees. Other than a reduction near roads, apparently by alkaline road dust, arboreal forage lichens were relatively uniformly distributed throughout the regenerating stands. There was little difference in abundance up to 135 m from the source tree. The sorediate form of the lichens did better on lodgepole pine (Pinus contorta), and larger, nonsorediate fragments were more abundant on western larch. We attribute the difference to bark pH. Scattered western larch seed trees were effective at retaining lichens and facilitating recolonization of the regenerating stand.

Interactive effects of light and stratification on the germination of some British Columbia conifers

1994 ◽  
Vol 72 (11) ◽  
pp. 1635-1646 ◽  
Author(s):  
X. J. Li ◽  
P. J. Burton ◽  
C. L. Leadem
Keyword(s):  
British Columbia ◽  
Seed Germination ◽  
Pseudotsuga Menziesii ◽  
Seed Weight ◽  
Pinus Contorta ◽  
Picea Sitchensis ◽  
Thuja Plicata ◽  
Pinus Monticola ◽  
Larix Occidentalis ◽  
Tree Seed

Pregermination stratification treatment was generally more important than the effects of light on seed germination by 14 conifer species and varieties native to British Columbia. Nevertheless, there were some strong species differences in the response of germination to light. Final germination percentage after 21 days (28 days for Abies spp.) for both stratified and unstratified seeds of Picea glauca, Picea sitchensis, and Tsuga heterophylla showed no response to light during germination. Seed germination by Abies grandis, Pinus contorta var. contorta, Pinus contorta var. latifolia, Pinus ponderosa, Pseudotsuga menziesii var. glauca, and Pseudotsuga menziesii var. menziesii responded positively to light if unstratified but was not significantly affected by light when stratified. For Thuja plicata seeds, germination responded positively to light regardless of stratification pretreatment. Light appeared to reduce germination of stratified seeds of Abies amabilis, Abies lasiocarpa, Larix occidentalis, and Pinus monticola, although stratification conditions for these species were suboptimal. The germination rate of stratified seeds of all species and unstratified seeds of most species was increased by light. Results showed no significant relationship between germination response to light and shade-tolerance ranking or mean seed weight of the species. In six seed lots of Pinus contorta var. latifolia, however, we detected a weak negative correlation between mean seed weight and unstratified light responsivity measured after 1 week but a significant positive correlation when measured after 3 weeks. Very low light levels in closed-canopy forests or in the forest floor may prolong tree seed germination but are unlikely to constrain final germination levels after most seeds have been naturally stratified by moist, cool winter conditions. The importance of differences in the rate and timing of tree seed germination under natural conditions remains to be demonstrated. Key words: conifer biology, forest regeneration, light response, lodgepole pine, Pinus contorta, seed germination, stratification.

Inonotus weirii. [Descriptions of Fungi and Bacteria].

1972 ◽  
Author(s):  
D. N. Pegler
Keyword(s):  
Geographical Distribution ◽  
Pinus Contorta ◽  
Tsuga Heterophylla ◽  
Picea Engelmannii ◽  
Thuja Plicata ◽  
Western Canada ◽  
Larix Occidentalis ◽  
Ring Rot ◽  
Infected Material ◽  
Root Contact

Abstract A description is provided for Inonotus weirii. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Abies amabilis, A. grandis, A. lasiocarpa, Chamaecyparis spp., Larix occidentalis, Picea engelmannii, P. sitchensis, Pinus contorta, P. monticola, P. ponderosa, Pseudotsuga menziesii, Thuja plicata, Tsuga heterophylla. DISEASE: Laminated butt rot and yellow ring rot of conifers. GEOGRAPHICAL DISTRIBUTION: North America (Western Canada, Oregon, Washington); Japan. TRANSMISSION: The disease is spread by root contact with infected material in the soil; there appears to be little spread of the fungus by growth through the soil. It is likely that infection of freshly exposed wounds takes place through airborne basidiospores.

Tree-size diversity between single- and mixed-species stands in three forest types in western Canada

2005 ◽  
Vol 35 (3) ◽  
pp. 593-601 ◽  
Author(s):  
Pàl Varga ◽  
Han YH Chen ◽  
Karel Klinka
Keyword(s):  
Lodgepole Pine ◽  
Structural Diversity ◽  
Single Species ◽  
Tree Size ◽  
Western Hemlock ◽  
Stand Age ◽  
Western Canada ◽  
Mixed Species ◽  
Western Redcedar ◽  
Size Diversity

Mixed-species stands are hypothesized to be more structurally diverse because of inherent differences in growth rates between tree species. We investigated three combinations of even-aged, single- and mixed-species coniferous stands in western Canada: (i) shade-tolerant western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata (Donn ex D. Don) Spach), (ii) shade-intolerant lodgepole pine (Pinus contorta Dougl. ex Loud.) and western larch (Larix occidentalis Nutt.), and (iii) shade-intolerant lodgepole pine and shade-tolerant black spruce (Picea mariana (Mill.) BSP). We quantified stand structural diversity based on tree diameter and height by using Shannon's index and the coefficient of variation. Regression analysis was applied to examine the relationships between structural diversity, species composition, and stand age. Mixed-species stands of western hemlock and western redcedar had similar structural diversity to their respective single-species stands. Pine–larch and pine–spruce mixed-species stands had higher tree-size diversity than their respective single-species stands. Stand age was a significant factor for tree-size diversity, but its effect changed in different ways depending on the type of mixtures and index used to measure diversity.

Tree species selection revisited for plantations in the Interior Cedar Hemlock zone of southern British Columbia

2013 ◽  
Vol 89 (03) ◽  
pp. 382-391 ◽  
Author(s):  
Alan Vyse ◽  
Michelle R. Cleary ◽  
Ian R. Cameron
Keyword(s):  
British Columbia ◽  
Lodgepole Pine ◽  
Douglas Fir ◽  
Species Selection ◽  
Thuja Plicata ◽  
Pinus Monticola ◽  
White Pine ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Western White Pine

We provide results from two trials comparing performance of species of known provenance planted on logged sites in the southern Interior Cedar Hemlock biogeoclimatic zone of southern British Columbia 20 and 26 years after establishment. The commonly used plantation species, lodgepole pine (Pinus contorta var. latifolia), interior spruce (a naturally occurring hybrid between Picea glauca and P. engelmannii) and Douglas-fir (Pseudotsuga menziesii var. glauca), survived as well as, but grew more slowly than, western larch (Larix occidentalis), western white pine (Pinus monticola) and ponderosa pine (Pinus ponderosa), and faster than western redcedar (Thuja plicata). Site index values were generally higher than published values for similar sites. Numerous pests affected all species in the trials. Mountain pine beetle (Dendroctonus ponderosae) caused heavy mortality in lodgepole pine in part of one trial, and Armillaria root disease caused widespread damage to western larch and Douglas-fir in the other trial. Western white pine from local seed sources were severely damaged by white pine blister rust (Cronartium ribicola) in both trials but a rust-resistant seed source used in one trial survived better. Frost damage reduced survival and growth of Douglas-fir in one trial and may have affected western white pine. Survival of two planted broadleaves (Betula papyrifera) and a hybrid of black cottonwood (Populus trichocarpa) and black poplar (Populus nigra) was severely reduced by drought. The results support ongoing efforts to broaden the number of species used in British Columbia reforestation programs.

scholarly journals Growth of Coniferous Seedlings on a Drained and Mounded Peatland in Central Alberta

2000 ◽  
Vol 17 (2) ◽  
pp. 71-79 ◽  
Author(s):  
Sam K. Takyi ◽  
Graham R. Hillman
Keyword(s):  
Picea Glauca ◽  
Pinus Contorta ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
White Spruce ◽  
Diameter Growth ◽  
Larix Laricina ◽  
Growing Seasons ◽  
Collar Diameter ◽  
Survival And Growth

Abstract Artificial reforestation experiments compared survival and growth of five species of coniferous containerized seedlings, and seedling browsing by ungulates on a clearcut, drained, and mounded peatland in the boreal forest. Six to seven growing seasons after planting, 91% of all seedlings had survived. Height and diameter growth in five species were ranked as follows: Siberian latch (Larix sibirica Ledeb.) > lodgepole pine (Pinus contorta var. latifolia Engelm.) > tamarack (Larix laricina [Du Roi] K. Koch) > black spruce (Picea mariana [Mill.] B.S.P.) = white spruce(Picea glauca [Moench] Voss). Overall, tamarack height and diameter growth was twice that of either spruce species. Height and diameter growth of tamarack, black spruce, and white spruce planted in the spring was 65% to 97% greater than that of the more robust seedlings for the same species planted in the fall of the same year. Repeated winter browsing by ungulates did not affect survival and growth of the five species. In an experiment where survival and growth of tamarack and black spruce seedlings planted on the mounds were compared with that of seedlings planted on the flat areas between mounds, there were no differences in survival, height, or root collar diameter growth between the two planting sites. In the event that suitable peatlands are used to augment existing timber supplies, lowering the water table through ditching, combined with mound-planting, is a feasible method of reforesting timber-harvested, boreal wet sites with Siberian latch, lodgepole pine, and white spruce. Tamarack and black spruce, however, survive and grow well on drained peatlands without mound-planting. North. J. Appl. For. 17(2):71-79.

Effects of post-thinning density and repeated fertilization on the growth and development of young lodgepole pine

2005 ◽  
Vol 35 (8) ◽  
pp. 1952-1964 ◽  
Author(s):  
R P Brockley
Keyword(s):  
Growth And Development ◽  
Radial Growth ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Tree Height ◽  
Negative Effects ◽  
Stand Volume ◽  
Thinning Intensity ◽  
Positive Effects ◽  
Nutrient Additions

The effects of factorial combinations of post-thinning density and fertilization on the growth and development of young lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) were investigated in central British Columbia. The effects of density and fertilization (repeated every 5 years) on tree height were small relative to the effects on stem radial growth. Tree radial growth increased with thinning intensity, whereas per-hectare growth was greatest at the highest residual density. Fertilizer effects varied across the range of residual densities tested. Tree and stand volume gains following fertilization were less, in both relative and absolute terms, at 600 trees/ha than at 1100 or 1600 trees/ha. Vigorous response of understory vegetation to nutrient additions (and strong competition for water and nutrients) may have reduced the effectiveness of fertilization on tree growth at 600 trees/ha relative to higher stand densities. Results indicate that the combined positive effects of thinning and fertilization on the growth of young lodgepole pine will accelerate stand development, thereby shortening technical rotation length. Results also indicate that significant growth gains following fertilization of thinned lodgepole pine will partially compensate for stand volume losses due to thinning. However, fertilization may be less effective at low stand densities, where negative effects of thinning on harvest volume are greatest.

Wind tunnel measurements of crown streamlining and drag relationships for three conifer species

2004 ◽  
Vol 34 (3) ◽  
pp. 666-676 ◽  
Author(s):  
Mark Rudnicki ◽  
Stephen J Mitchell ◽  
Michael D Novak
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Pinus Contorta ◽  
Prediction Models ◽  
Lodgepole Pine ◽  
Tsuga Heterophylla ◽  
Frontal Area ◽  
Thuja Plicata ◽  
Tree Crowns ◽  
Wind Speeds

Estimating the wind force or drag acting on tree crowns is central to understanding both the chronic effects of wind and the calculation of critical wind speed in windthrow prediction models. The classical drag equation is problematic for porous, flexible tree crowns whose frontal area declines as wind speeds increase and branches streamline. Juvenile crowns of three morphologically different conifers, western redcedar (Thuja plicata Donn ex D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and lodgepole pine (Pinus contorta Dougl. ex Loud.), were exposed to wind speeds from 4 to 20 m/s in a wind tunnel. At 20 m/s, streamlining reduced the frontal area by 54% for redcedar, 39% for hemlock, and 36% for lodgepole pine. Crown drag coefficients calculated using frontal area in still air varied with wind speed. At 20 m/s, they were 0.22, 0.47, and 0.47 for these species, respectively. Drag was proportional to the product of mass and wind speed and also to the product of wind speed squared and wind speed specific frontal area. Lodgepole pine and redcedar had lower drag per unit of branch mass than did hemlock. Removing branches by pruning had little effect on drag per unit branch mass.

Forest structure altered by mountain pine beetle outbreaks affects subsequent attack in a Wyoming lodgepole pine forest, USA

2011 ◽  
Vol 41 (12) ◽  
pp. 2403-2412 ◽  
Author(s):  
Daniel M. Kashian ◽  
Rebecca M. Jackson ◽  
Heather D. Lyons
Keyword(s):  
Pinus Contorta ◽  
Mountain Pine Beetle ◽  
Stand Structure ◽  
Lodgepole Pine ◽  
Climate Change Scenarios ◽  
Cone Production ◽  
Mountain Pine ◽  
Large Trees ◽  
Pine Beetle ◽  
The 1960S

Extensive outbreaks of the mountain pine beetle ( Dendroctonus ponderosae Hopkins) will alter the structure of many stands that will likely be attacked again before experiencing a stand-replacing fire. We examined a stand of lodgepole pine ( Pinus contorta var. latifolia Engelm. ex S. Watson) in Grand Teton National Park currently experiencing a moderate-level outbreak and previously attacked by mountain pine beetle in the 1960s. Consistent with published studies, tree diameter was the main predictor of beetle attack on a given tree, large trees were preferentially attacked, and tree vigor, age, and cone production were unimportant variables for beetle attack at epidemic levels. Small trees killed in the stand were killed based mainly on their proximity to large trees and were likely spatially aggregated with large trees as a result of the previous outbreak. We concluded that the driving factors of beetle attack and their spatial patterns are consistent across outbreak severities but that stand structure altered by the previous outbreak had implications for the current outbreaks in the same location. This study should catalyze additional research that examines how beetle-altered stand structure affects future outbreaks — an important priority for predicting their impacts under climate change scenarios that project increases in outbreak frequency and extent.

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