Duff mound consumption and cambium injury for centuries-old western larch from prescribed burning in western Montana

2013 ◽  
Vol 22 (3) ◽  
pp. 359 ◽  
Author(s):  
Michael G. Harrington

Western larch is one of the most fire-adapted conifers in western North America. Its historical perpetuation depended upon regular fire disturbances, which creates open stand conditions and mineral seedbeds. A stand of 200- to 500-year-old larch in western Montana with deep duff mounds resulting from an unusually long 150-year fire-free period was mechanically thinned and prescribed burned to reduce the probability of high intensity wildfire near a community and increase opportunities for larch regeneration. Little documentation is available regarding basal damage to larch from lengthy duff mound burning; therefore this study was established to assess: duff consumption from prescribed burning and resulting cambial damage and tree vitality. Ninety trees averaging 91-cm diameter at breast height were selected, half with duff mounds measured and burned in autumn and half with mounds removed. Duff depths nearest the bole averaged 20 cm and mound consumption approached 100% including large amounts of the basal bark with smouldering combustion lasting 18–24 h. Cambial mortality ranged from 0 to 36% of the basal circumference but no trees had died after 7 years. The cambium mortality was likely due to the spatially infrequent coincident of deep duff and thinner bark. Under similar site and environmental conditions removal of the potential duff consumption injury hazard appears unwarranted.

2000 ◽  
Vol 30 (2) ◽  
pp. 324-328 ◽  
Author(s):  
Kevin L O'Hara ◽  
Narayanan I Valappil

Western larch (Larix occidentalis Nutt.) trees in western Montana, U.S.A., were monitored for 6 years following pruning to assess incidence of epicormic sprouting. Trees were pruned to either 2.4 or 5.5 m. Epicormic sprouts were more prevalent in smaller diameter trees and in trees pruned to shorter live crown lengths than larger or longer crowned trees. Number of sprouts declined since pruning, but over 30% of trees still had epicormic sprouts 6 years after pruning. Sprouts that did not extend from the bole were prone to becoming dormant or dying over time. Extended sprouts were more persistent and will probably form wood-quality defects that remain outside the defect core. Pruning of western larch may still be successful for enhancing clearwood production if trees are pruned to retain at least a 50% live crown ratio and if pruning is delayed until trees reach about 16 cm diameter at breast height for a short pruning lift (2.4 m) or 22 cm for a higher pruning lift (5.5 m).


2018 ◽  
Vol 48 (1) ◽  
pp. 42-57 ◽  
Author(s):  
Geoffrey M. Williams ◽  
Andrew S. Nelson ◽  
David L.R. Affleck

Western larch (Larix occidentalis Nutt.) is an endemic pioneer species in northwestern North America and unique as a deciduous conifer and the most shade-intolerant, fastest growing, and most fire-resistant species in the northwestern United States. To better understand its production ecology, we used a multilevel modeling approach to analyze the intrinsic dynamics of western larch vertical foliage distribution and compared it with other species. We found that western larch allocates foliage into a more diffuse distribution as the crown lengthens, whereas shade-tolerant evergreens concentrate foliage into a more monolayered distribution higher within the crown as it lengthens. Crown foliar biomass scaled linearly with diameter at breast height, indicating that western larch does not fill volume in the crown with foliage at an increasing rate like other conifers. Our model supports the hypothesis that foliar shade intolerance and water stress jointly influence foliage allocation in this deciduous conifer. These results also highlight intrinsic foliage distribution as a factor potentially contributing to the inability of western larch to survive light-limiting conditions and its preference for mesic sites. The models developed here provide a basic framework that may be built upon to study the morphological response of western larch to modified stand conditions such as disturbance and silvicultural treatment.


2008 ◽  
Vol 38 (4) ◽  
pp. 844-850 ◽  
Author(s):  
Gregory Peters ◽  
Anna Sala

Thinning and thinning followed by prescribed fire are common management practices intended to restore historic conditions in low-elevation ponderosa pine ( Pinus ponderosa Dougl. ex P. & C. Laws.) forests of the northern Rocky Mountains. While these treatments generally ameliorate the physiology and growth of residual trees, treatment-specific effects on reproductive output are not known. We examined reproductive output of second-growth ponderosa pine in western Montana 9 years after the application of four treatments: thinning, thinning followed by spring prescribed fire, thinning followed by fall prescribed fire, and unthinned control stands. Field and greenhouse observations indicated that reproductive traits vary depending on the specific management treatment. Cone production was significantly higher in trees from all actively managed stands relative to control trees. Trees subjected to prescribed fire produced cones with higher numbers of filled seeds than trees in unburned treatments. Seed mass, percentage germination, and seedling biomass were significantly lower for seeds from trees in spring burn treatments relative to all others and were generally higher in trees from fall burn treatments. We show for the first time that thinning and prescribed-burning treatments can influence reproductive output in ponderosa pine.


2020 ◽  
Vol 11 (1) ◽  
pp. 41-49
Author(s):  
Lucio Di Cosmo ◽  
Patrizia Gasparini

Predicting diameter at breast height (DBH) of trees from stump information may be necessary to reconstruct silvicultural practices, to assess harvested timber and wood, or to estimate forest products’ losses caused by illegal cuttings or natural disasters (disturbances). A model to predict DBH of felled trees was developed by the first Italian National Forest Inventory in 1985 (IFNI85). The model distinguished between the two broad groups of conifers and broadleaves and used stump diameter as the sole quantitative variable. Using an original dataset containing data from about 1200 trees of sixteen species recorded throughout Italy, we assessed the performance of that model. To improve the prediction of the DBH of removed trees over large areas and for multiple species, we developed new models using the same dataset. Performance of the new models was tested through indices computed on cross-validated data obtained through the leave-one-out method. A new model that performs better than the old one was finally selected. Compared to the old NFI model, the selected model improved DBH prediction for fourteen species up to 31.28%. This study proved that species specification and stump height are variables needed to improve the models’ performance and suggested that data collection should be continued to get enhanced models, accurate for different ecological and stand conditions.


1999 ◽  
Vol 14 (3) ◽  
pp. 137-143 ◽  
Author(s):  
Dayna M. Ayers ◽  
Donald J. Bedunah ◽  
Michael G. Harrington

Abstract In many western Montana ponderosa pine (Pinus ponderosa) stands, fire suppression and past selective logging of large trees have resulted in conditions favoring succession to dense stands of shade-tolerant, but insect- and disease-prone Douglas-fir (Pseudotsuga menziesii). Stand thinning and understory prescribed burning have been proposed as surrogates for pre-Euro-American settlement ecological processes and as potential treatments to improve declining forest condition and reduce the probability of severe wildfire. To test the effectiveness of these silvicultural techniques on overstory and understory conditions, research is ongoing in the Lick Creek Demonstration Site in the Bitterroot National Forest, Montana. Our research examined the response (mortality and vigor) of the dominant browse species, antelope bitterbrush (Purshia tridentata) and Scouler's willow (Salix scouleriana), to a ponderosa pine stand restoration project utilizing four treatments: (1) a shelterwood cut that removed 53% of the tree basal area; (2) a shelterwood cut with a low fuel consumption burn; (3) a shelterwood cut with a high fuel consumption burn; and (4) a control. Prior to the application of treatments, 1,856 bitterbrush and 871 willow were located, and their survival and vigor subsequently monitored for 2 yr posttreatment. The cut and burn treatments resulted in the greatest reduction in antelope bitterbrush and Scouler's willow density averaging 66% and 24% of pretreatment density, respectively. The shelterwood cut reduced bitterbrush and Scouler's willow density by 35% and 14%, respectively. On treatments receiving a shelterwood cut (all treatments but the control), but where antelope bitterbrush and Scouler's willow did not have fire damage, mortality was 45% for bitterbrush and 20% for willow, respectively. For bitterbrush and Scouler's willow plants that received fire damage, mortality was 72% for bitterbrush and 19% for willow. Although the burn and shelterwood harvest treatments resulted in reduced density of antelope bitterbrush and Scouler's willow 2 yr posttreatment, these treatments increased vigor of both species and created mineral seedbeds that may be necessary for establishment of seedlings. West. J. Appl. For. 14(3):137-143.


1989 ◽  
Vol 19 (7) ◽  
pp. 930-932 ◽  
Author(s):  
James N. Long ◽  
Frederick W. Smith

For a given species, differences in the relation between leaf area and sapwood cross-sectional area at breast height have been attributed to the effects of varying stand density and site quality. When leaf area of Abieslasiocarpa (Hook.) Nutt. is estimated as a function of sapwood cross-sectional area at breast height and distance from breast height to the midpoint of the crown, the apparent effects of stand density and site quality are eliminated. A comparison of these results with those for Pinuscontorta Dougl. suggests this model form should provide unbiased estimates of leaf area for a variety of species and stand conditions.


1987 ◽  
Vol 17 (10) ◽  
pp. 1234-1239 ◽  
Author(s):  
Mark D. McGregor ◽  
Gene D. Amman ◽  
Richard F. Schmitz ◽  
Robert D. Oakes

Partial cutting prescriptions were applied in the fall of 1978 through the early winter of 1980 to lodgepole pine stands (Pinuscontorta Douglas var. latifolia Engelmann) threatened by mountain pine beetle (Dendroctonusponderosae Hopkins) in the Kootenai and Lolo National Forests in western Montana, U.S.A. Partial cutting prescriptions consisted of removing from separate stands all trees 17.8, 25,4, and 30.5 cm and larger diameter at breast height (dbh), and prescriptions leaving 18.4, 23.0, and 27.6 m2 basal area per hectare. In thinned stands, the first 5 years' results following cutting showed greatly reduced tree losses to mountain pine beetle when compared with untreated stands (P < 0.01) on both forests. There were no significant differences in tree losses among partial cut treatments (P > 0.05). Post treatment mortality of lodgepole pine 12.7 cm and larger dbh to mountain pine beetle averaged 4.0 to 38.6% on the Kootenai and 6.0 to 17.1% on the Lolo in treated stands, compared with averages of 93.8 and 73.1% in untreated stands. Partial cutting appears to be useful for reducing lodgepole losses to mountain pine beetle.


Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 482
Author(s):  
James E. Steed ◽  
Sara A. Goeking

Substantial shifts in the distribution of western larch (Larix occidentalis Nutt.) are predicted during the coming decades in response to changing climatic conditions. However, it is unclear how the interplay between direct climate effects, such as warmer, drier conditions, and indirect climate effects, such as predicted increases in fire disturbance, will impact fire-adapted species such as western larch. The objectives of this study were (1) to compare the relative importance of stand, site, and indirect versus direct climatic factors in determining western larch seedling recruitment; (2) to determine whether seedling recruitment rates have changed in recent years in response to disturbance, post-fire weather, and/or climate; and (3) to determine whether seedlings and mature trees are experiencing niche differentiation based on recent climatic shifts. We addressed these objectives using data collected from 1286 national forest inventory plots in the US states of Idaho and Montana. We used statistical models to determine the relative importance of 35 stand, site, and climatic factors for larch seedling recruitment. Our results suggest that the most important predictors of larch seedling recruitment were indicative of early-seral stand conditions, and were often associated with recent fire disturbance and cutting. Despite indications of climatic niche compression, seedling recruitment rates have increased in recent decades, likely due to increased fire disturbance, and were unrelated to post-fire weather. Compared to sites occupied by mature trees, seedling recruitment was positively associated with cooler, drier climatic conditions, and particularly with cooler summer temperatures, but these climatic factors were generally less important than biotic stand variables such as stand age, basal area, and canopy cover. These results suggest that, for fire-dependent species such as western larch, increased heat and drought stress resulting from climatic change may be offset, at least in the near term, by an increase in early-seral stand conditions resulting from increased fire disturbance, although localized range contraction may occur at warm, dry extremes.


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