Bending of a conifer branch at subfreezing temperatures: implications for snow interception

1990 ◽  
Vol 20 (8) ◽  
pp. 1251-1253 ◽  
Author(s):  
R. A. Schmidt ◽  
J. W. Pomeroy
Keyword(s):  
Modulus Of Elasticity ◽  
Lodgepole Pine ◽  
Ice Crystals ◽  
Subalpine Fir ◽  
Linear Decrease ◽  
Model Predictions ◽  
Snow Loads ◽  
In Cells

Ice crystals in cells of frozen wood increase the wood's modulus of elasticity so that branches become more rigid at colder temperatures. As temperature increases after a snowstorm, melting of crystals within the cells allows increased bending of branches under intercepted snow loads. Measurements of the force that produced a 10-cm deflection of branch tips of subalpine fir (Abieslasiocarpa (Hook.) Nutt.) and lodgepole pine (Pinuscontorta var. latifolia Engelm.) showed a linear decrease as temperature rose from −12 to 0 °C. Model predictions for the bending of a tapered branch supported the hypothesis that increased bending can explain unloading of intercepted snow under certain conditions when warming occurs after snowstorms.

scholarly journals Severity of Overstory Mortality Influences Conifer Recruitment and Growth in Mountain Pine Beetle-Affected Forests

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 536 ◽  
Author(s):  
Kristen Pelz ◽  
Charles Rhoades ◽  
Robert Hubbard ◽  
Frederick Smith
Keyword(s):  
High Mortality ◽  
Mountain Pine Beetle ◽  
Lodgepole Pine ◽  
Basal Area ◽  
Tree Regeneration ◽  
Forest Recovery ◽  
Subalpine Fir ◽  
Advance Regeneration ◽  
Mountain Pine ◽  
Pine Beetle

The severity of lodgepole pine mortality from mountain pine beetle outbreaks varies with host tree diameter, density, and other structural characteristics, influencing subcanopy conditions and tree regeneration. We measured density and leader growth of shade-intolerant lodgepole pine, shade-tolerant Engelmann spruce, and very shade-tolerant subalpine fir regeneration beneath stands that experienced moderate and high overstory lodgepole pine mortality (average 40% and 85% of total basal area) a decade earlier. Lodgepole comprised >90% of the overstory basal area and mature spruce and fir were present in both mortality levels, though live basal area and disturbance history differed. Post-beetle outbreak recruitment was high in both mortality levels, but there were more lodgepole in high than moderate mortality plots (1140 stems ha−1 vs. 60 stems ha−1) and more subalpine fir in moderate than high mortality plots (4690 stems ha−1 vs. 2870 stems ha−1). Pine advance regeneration, established prior to outbreak, was more dense in high mortality than moderate mortality sites (930 stems ha−1 vs. 310 stems ha−1), but the trend was generally the opposite for the other conifers. Lodgepole recruitment increased and subalpine fir decreased with greater forest floor light availability. All species grew faster in high mortality areas than their counterparts in moderate mortality areas. However, in high mortality areas pine grew faster than the more shade tolerant species, and in moderate mortality areas spruce and fir grew faster than pine. These species-specific responses to the degree of overstory mortality will influence future stand composition and rate of forest recovery after mountain pine beetle outbreaks.

Snowfall interception on branches of three conifer species

1991 ◽  
Vol 21 (8) ◽  
pp. 1262-1269 ◽  
Author(s):  
R. A. Schmidt ◽  
David R. Gluns
Keyword(s):  
Specific Gravity ◽  
Growth Form ◽  
Lodgepole Pine ◽  
Growth Curves ◽  
Conifer Species ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
Elastic Rebound ◽  
Snow Crystals ◽  
Sigmoidal Growth

Measuring the mass of snow on cut branch tips soon after snowfalls during two winters provided comparisons of catch by Engelmann spruce (Piceaengelmannii Parry), subalpine fir (Abieslasiocarpa (Hook.) Nutt.), and lodgepole pine (Pinuscontorta var. latifolia Engelm.). Analysis of these and other reported measurements confirmed (i) snow bridging by cohesion, (ii) bouncing of snow crystals by elastic rebound, and (iii) branch bending as mechanisms that determine the sigmoidal growth curves characterizing snow interception relative to snowfall. The fraction of snowfall intercepted by the branches was largest when storm accumulations were 3–4 mm water equivalent, with low specific gravity (0.04–0.07). Percent catch in snowfalls with 10 mm water and low specific gravity was near 50% for Engelmann spruce and about 45% for subalpine fir and lodgepole pine, but values decreased to near 30% in 20-mm storms. Catch was inversely proportional to the density of snow accumulations in the specific gravity range 0.04–0.13. Average branch catch was only about 10% of a storm with 10 mm water equivalent at 0.13 specific gravity. Meteorological conditions were more important than branch growth form in determining snow interception amounts on the conifers tested. The results suggest, as a hypothesis, a computational function for the fraction of snowfall caught on conifer crowns.

Nutrient release from decomposing litter in Rocky Mountain coniferous forests: influence of nutrient availability

1993 ◽  
Vol 23 (8) ◽  
pp. 1576-1586 ◽  
Author(s):  
Cindy E. Prescott ◽  
Barry R. Taylor ◽  
William F.J. Parsons ◽  
Daniel M. Durall ◽  
Dennis Parkinson
Keyword(s):  
Nutrient Availability ◽  
Lodgepole Pine ◽  
Nutrient Release ◽  
Rocky Mountain ◽  
P Uptake ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
P Loss ◽  
N Release ◽  
Forest Floors

We examined patterns of N and P uptake and release from a wide variety of litter types, including leaves, needles, moss, roots, and wood, for 4 years in three forests (lodgepole pine (Pinuscontorta Loud.), white spruce (Piceaglauca (Moench) Voss)–lodgepole pine, and Engelmann spruce (Piceaengelmannii Parry ex Engelm.)–subalpine fir (Abieslasiocarpa (Hook.) Nutt.)) and a small clearcut, in the Rocky Mountains of Alberta. Decomposition was more rapid and N release began sooner in the clearcut than in the forests, but N release began at the same stage of decomposition at all sites. In most litter types, a period of net immobilization of N was followed by a period of net release; only litter types particularly rich in N had an initial leaching phase. Each litter type initially gained or lost N depending on its original concentration, such that N contents converged after 1 or 2 years. The N content at convergence differed among litter types. Phosphorus was usually released immediately. The rate of P loss also varied according to the initial P concentration, and the P contents of all litter types converged within 1 year. The availability of N and P in the forest floor did not affect the rate of N and P release from a standard substrate placed at all sites. The concentrations of N and P in the litter influenced the rate of uptake of N or P during the first 1–3 years, but was not consistently related to nutrient availability in the forest floors at the four sites.

scholarly journals Habitat Distribution of Small Mammal Communities in Grand Teton National Park

1990 ◽  
Vol 14 ◽  
pp. 109-115
Author(s):  
Nancy Stanton ◽  
Steven Buskirk ◽  
Steve Miller
Keyword(s):  
National Park ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Abies Lasiocarpa ◽  
Fire Policy ◽  
Grand Teton National Park ◽  
Natural Fire ◽  
Subalpine Fir ◽  
Small Mammal Communities ◽  
Mammal Communities

Since Grand Teton National Park adopted a natural fire policy in the early 1970's, four major fires have burned within the park which created a chronosequence of post-burn successional ecosystems. The burns encompassed forests varying in composition from Englemann spruce (Picea englemanil) /subalpine fir (Abies lasiocarpa) /lodgepole pine (Pinus contorta) (Beaver Creek, Mystic Isle) to Englemn spruce / subalpine fir (Waterfalls Canyon) to primarily lodgepole pine (Huckleberry Mountain).

scholarly journals The Ecological Role of Fire in the Jackson Hole area, Northwestern Wyoming

1973 ◽  
Vol 3 (3) ◽  
pp. 425-443 ◽  
Author(s):  
Lloyd L. Loope ◽  
George E. Gruell
Keyword(s):  
National Parks ◽  
Fire History ◽  
Prescribed Burning ◽  
Lodgepole Pine ◽  
Major Effect ◽  
Subalpine Fir ◽  
Large Numbers ◽  
Hole Area ◽  
Jackson Hole ◽  
Forest Plans

AbstractFire-history investigations in the Jackson Hole area of northwestern Wyoming reveal that most current stands of aspen and lodgepole pine regenerated following extensive fires between 1840 and 1890 and that widespread fires occurred in the 1600s and 1700s. White man's major effect on the fire incidence has been the successful suppression during the past 30–80 yr. Successional changes in the absence of fire include the deterioration of aspen stands, massive invasions of subalpine fir in lodgepole pine stands, great increase in conifer cover, heavy fuel buildups in lodgepole pine and Douglas fir stands, and increase in sagebrush and other shrubs. Steps are being taken, starting in 1972, to allow fire to play a more natural role in Grand Teton and Yellowstone National Parks. Teton National Forest plans experimental prescribed burning to determine whether fire can stimulate successful aspen regeneration in the presence of large numbers of wintering elk.

scholarly journals Height Growth Models for High-Elevation Subalpine Fir, Engelmann Spruce, and Lodgepole Pine in British Columbia

2000 ◽  
Vol 15 (2) ◽  
pp. 62-69 ◽  
Author(s):  
Han Y. H. Chen ◽  
Karel Klinka
Keyword(s):  
British Columbia ◽  
Growth Models ◽  
Lodgepole Pine ◽  
Site Index ◽  
High Elevation ◽  
Logistic Function ◽  
Height Growth ◽  
Potential Productivity ◽  
Subalpine Fir ◽  
Engelmann Spruce

Abstract To estimate potential productivity of the high-elevation Engelmann Spruce and Subalpine Fir (ESSF) zone of British Columbia forests, the height growth models developed from low-elevation forests are currently used to estimate site indices of subalpine fir (Abies lasiocarpa), Engelmann spruce (Picea engelmannii), and lodgepole pine (Pinus contorta). Whether these models are adequate to describe height growth of high-elevation forests is of concern. We sampled a total of 319 naturally established, even-aged, and undamaged stands with breast height age ≥50 yr (165 for subalpine fir, 87 for Engelmann spruce, and 67 for lodgepole pine) ranging widely in climate and available soil moisture and nutrients. In each sampled stand, three dominant trees were destructively sampled for stem analysis. Height growth models developed from fitting data to a conditioned logistic function explained > 97% variation in height for all three study species. Examined by residual analysis, no models showed lack of fit. These models provided more accurate estimates of site index than the currently used models developed from low-elevation stands or different species. It is recommended that the models developed in this study be applied to estimate site index of the three species in the ESSF zone in British Columbia. West. J. Appl. For. 15(2):62-69.

scholarly journals Decline of planted lodgepole pine in the southern interior of British Columbia

2010 ◽  
Vol 86 (4) ◽  
pp. 484-497 ◽  
Author(s):  
W. Jean Mather ◽  
Suzanne W. Simard ◽  
Jean L. Heineman ◽  
Donald L. Sachs
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Forest Health ◽  
Summer Precipitation ◽  
Dominant Factor ◽  
Natural Occurrence ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
Moisture Regimes

Lodgepole pine is extensively planted across western Canada but little is known about development of these stands beyond the juvenile stage. We quantified stocking status and damage incidence in sixty-six 15- to 30-year-old lodgepole pine plantations that had previously been declared free-growing in the southern interior of British Columbia. The stands were located in six biogeoclimatic zones: Engelmann Spruce-Subalpine Fir (ESSF), Montane Spruce (MS), Interior Cedar-Hemlock (ICH), Interior Douglas-fir (IDF), Sub-Boreal Spruce (SBS), and Sub-Boreal Pine-Spruce (SBPS). Free-growing standards were no longer met on 27% of plantations, with the worst performance (70% no longer free-growing) in the Interior Cedar-Hemlock forests. Natural regeneration was common but it was half the size of lodgepole pine. Biotic damage, especially hard pine stem rusts, was the dominant factor reducing free-growing densities. Stands were at greater risk of reduced stocking where summer precipitation was higher or soil moisture regimes were wetter and where stands had been broadcast-burned prior to planting or received secondary treatments of brushing or pruning. Reforestation policies that encourage widespread planting of lodgepole pine, particularly in areas where lodgepole pine has limited natural occurrence such as in the ICH zone, should be reconsidered given that health problems are extensive and are expected to increase with climate change.Key words: Pinus contorta, lodgepole pine, free-growing, stocking, forest health, damage, disease

Response of leaf area index to density for two contrasting tree species

1991 ◽  
Vol 21 (12) ◽  
pp. 1760-1764 ◽  
Author(s):  
Steven B. Jack ◽  
James N. Long
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Tree Species ◽  
Lodgepole Pine ◽  
Stand Density ◽  
Area Index ◽  
Subalpine Fir ◽  
Wide Range ◽  
Stable Leaf ◽  
The Relationship

It is commonly assumed that mature forest stands with closed canopies support constant amounts (weight or area) of foliage, independent of stand density. For stand leaf area to be constant, mean leaf area must be plastic with respect to density. We examined the relationship between density and both leaf area index and mean leaf area for two contrasting tree species, lodgepole pine (Pinuscontorta var. latifolia Engelm.) and subalpine fir (Abieslasiocarpa (Hook.) Nutt.). In lodgepole pine, leaf area index tended to be constant over a wide range of absolute and relative densities, but in subalpine fir, leaf area index increased with density. Consistent with these results, mean leaf area of lodgepole pine was more plastic with respect to density than mean leaf area of subalpine fir. The presumption of stable leaf area index independent of stand density, therefore, may not be as general as usually assumed owing to differential responses of mean leaf area to density. Differences in plasticity between the two species were attributed to differences in relative shade tolerance and the effect of shade on competitive interactions at high densities.

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