Silvicultural Alternatives Research Articles

Growth ofPseudotsuga menziesiiandTsuga heterophyllaseedlings along a light gradient: resource allocation and morphological acclimation

Silvicultural alternatives that differ in the degree of overstory removal may create shady environments that will be problematic for the regeneration of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Gradients of light in the field were used to compare mortality, growth, and leaf morphological acclimation of two conifer species of contrasting shade tolerances: Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.). Results after two growing seasons indicated that Douglas-fir mortality occurred mainly at relative light intensity (RLI) below 20%, while western hemlock mortality was evenly distributed along the light gradient. Height, diameter, and biomass of the planted seedlings increased with increasing light for both species but at different rates, and maximum biomass accumulation always occurred in the open. Douglas-fir allocated more resources to stem biomass than western hemlock, which accumulated more foliage biomass. Increases in specific leaf area for Douglas-fir seedlings occurred at RLI ≤ 0.4 and red/far red (R/FR) ratio ≤ 0.6, which appear to be the minimal optimum light levels for growth. Conversely, western hemlock seedlings adjusted their leaf morphology in a more regular pattern, and changes were less pronounced at low light levels. These results, along with early mortality results for Douglas-fir, suggest that the most successful way to artificially regenerate this species may be by allowing at least 20% of RLI for ensuring survival and at least 40% RLI for optimum growth. Key words: light, light quality, leaf morphology, acclimation.

A Decision Tree to Evaluate Silvicultural Alternatives for Mature Aspen in the Northern Lake States

A Decision Tree to Evaluate Silvicultural Alternatives for Mature Aspen in the Northern Lake States

Growing-season microclimate variability within an old-growth Douglas-fir forest

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 08:21-34 (1997) - DOI: https://doi.org/10.3354/cr008021 Growing-season microclimate variability within an old-growth Douglas-fir forest Chen J, Franklin JF Physical properties of old-growth Douglas-fir [Pseudotsuga menziesii(Mirb.) Frankco] forests in the west coast regions of North America have received very little attention aver 30 yr of extensive research. This study was aimed at characterizing the forest microclimate and its variability over the growing season (June to October). Three 200 m line transects in the interior area of an old-growth Douglas-fir forest of the Wind River Experimental Forest, Gifford Pichot National Forest, Washington, USA, were used to install randomly 8 automatic-recording systems to quantify growing-season microclimate and variability in 1990 and 1992, including air and surface soil temperature (Ta and Ts), relative humidity (h), wind speed (v), and solar radiation (Rt). The maximum differences in Ta, Ts, h, Rt, and v recorded over 40 sampling days were 2.7°C, 5.9°C, 7.6%, 0.8 kW m-2, and 0.5 m s-1, respectively; clear diurnal patterns were detected for all 5 variables with greater variability during the day than at night; changes in temperatures and relative humidity over time appeared to be more predictable than those in wind speed and solar radiation. Local weather condition was linearly related to the above variability and, therefore, can be used as a reliable independent variable to predict a forest's microclimate and variability. Results concluded in this study are essential in providing microclimatic perspective in evaluating silvicultural alternatives for the region in creation of old-growth-like forest structure. Microclimate · Old growth · Variability · Douglas fir Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 08, No. 1. Publication date: March 27, 1997 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 1997 Inter-Research.

Using Alternative Silvicultural Systems to Integrate Mountain Caribou and Timber Management in British Columbia

Even-aged forest management using the clearcutting silvicultural system as it is currently applied threatens mountain caribou habitat in British Columbia. Since neither complete preservation nor maximum development of timber resources are socially acceptable alternatives, forest managers are anxious to find integrated management options. We describe alternative silvicultural systems currently being tested, including single-tree and group selection. All the treatments have the goal of periodically extracting viable timber volumes while perpetually retaining stand characteristics necessary for caribou. The effects of these logging prescriptions on lichen biomass and growth rates are being tested. Alternative silvicultural systems may become part of a larger strategy to maintain caribou habitat in managed forests.

Using Image-capture Technology to Assess Scenic Value at the Urban/Forest Interface: a Case Study

Urban expansion to the edge of managed forest lands is creating new problems for resource managers as home owners protest at the effects of timber management. Strategies to resolve urban/forest interface conflicts require that all participants are equally informed about the impacts of silvicultural alternatives. In cases where scenic values are a prime consideration, computer "image-capture" technology (ICT) offers opportunities to level the information base, especially when experimental or non-traditional forestry practices are being considered. This paper describes a pilot study in which forest-adjacent home owners in Oregon viewed ICT-generated slides simulating the view from their own homes if various silvicultural practices were used on the adjacent forest. The study sought to evaluate the utility of ICT for displaying possible localized impacts of timber management, and to determine whether adjacent land owners would express willingness to pay for scenic easements. The method showed promise, although generating slides for individual home sites was cumbersome. A majority of land owners were willing to pay for scenic-protection measures that would restrict timber-harvest options on adjacent properties.

Considering costs and revenues in long‐term forecasts of timber yields

In Sweden, long‐term forecasts of timber yields have traditionally dealt with the production of timber, without consideration of costs and revenues. A system for long‐term forecasting (HUGIN) has been further developed with incorporation of calculations of costs for logging and silviculture together with revenues from timber and pulp wood. The forecasts of HUGIN are based on sample plot data from the Swedish National Forest Inventory. After the specification of alternative silviculture and logging programs in HUGIN, the user can study costs, revenues and number of man‐days for each program. By using quality functions and price lists, the HUGIN system calculates the highest possible revenue for the individual tree by optimizing the division into assortments. The HUGIN system will be improved further in the future to include calculations of road transport costs, improved quality functions and revenues from other forest resources than timber.

Modelling the yield of Pinus radiata on a site limited by water and nitrogen

A process-based model is described and applied to a range of Pinus radiata D. Don stands, aged 9–12 years, growing on stabilised sand dunes in a stocking × fertiliser experiment in Woodhill State Forest, New Zealand. The model requires inputs of daily weather data (maximum and minimum air temperatures and rainfall), physical characteristics of the site (longitude, latitude, rootzone depth and relationship between root-zone soil matric potential and volumetric water-content) and crop (stocking, crown dimensions and leaf-area index) and crop physiological parameters (e.g., maximum stomatal conductance). The model was used to simulate components of the forest water-balance and annual net photosynthesis for a defined crop canopy architecture. Simulated daily root-zone water storage in both open and closed canopy stands generally agreed with monthly measurements made over a complete year. Simulated net annual photosynthesis ranged from 23 to 33 t C ha −1 year −1 and comparison with measured stem-volume increments of 12–38 m 3 ha −1 year −1 over the same time periods resulted in a strong positive correlation. Ratios of stem-volume increment to net photosynthesis suggested that fertilised and unfertilised stands had a 26 and 14%, respetively, allocation of C to stem growth. Simulations using weather data for a dry year with 941 mm year −1 rainfall indicated that annual net photosynthesis and transpiration of fully stocked stands were reduced by 41 and 45%, respectively, compared to those in a wet year with 153 mm year −1 rainfall. Operational applications of the model to forest management in quantifying environmental requirements for stand growth and examining silvicultural alternatives are discussed.

Winter Logging on the Tanana River Flood Plain in Interior Alaska

Abstract Flood plains in interior Alaska support an important forest resource. Silvicultural alternatives for these sites depend on access and on the effect of timber harvesting on the residual stand and site. Some aspects (i.e., road access, logging damage to residual stand, and effect of logging on snow pack) of winter logging of white spruce on an island in the Tanana River were observed. Winter roads of snow and ice were easily developed over a variety of surface conditions and appeared to have little lasting impact. Damage to uniformly spaced residual shelterwood trees was variable. Much of this damage could be eliminated by better sale administration, methods of sale layout, and harvesting methods. Logging activity created two distinct snow layers—an upper layer mixed with logging debris and a lower, compacted layer that showed little evidence of being physically disturbed. The compacted layer could provide good physical protection to seedlings and protect the forest floor frown disturbance. North. J. Appl. For. 4:11-16, Mar. 1987.

Regeneration of a North Queensland Rain Forest Following Felling and Burning

The regeneration modes and heights of 82 tree species reappearing the felling and burning of a tropical rain forest were observed 23 months the perturbation. Of these species, 74 had coppiced, 10 had produced root suckers, and 34 had developed from seed during the post-fire period. Those trees developing mainly from seed appeared to have the highest growth rates. The results are discussed in relation to the stability of the floristics of the tree component on the site and the problem of predicting successional sequences in the tropical rain forest environment. STUDIES OF SECONDARY SUCCESSION have been seen as essential for a solution to the problems of establishing a rational system of land use in the tropics (Richards 1955). In his study of secondary plant succession in tropical montane Mindanao, Kellman (1970) stressed that the first critical question to be answered when explaining a successional sequence was autecological. Unfortunately, autecological data for the species involved in secondary successions in the tropics are often not available. The object of this paper is to illustrate the importance of an autecological characteristic, the regeneration mode of a species felling and burning, on the floristic composition of the regenerating stand. The 100 x 100 m felled and burnt plot forming the basis for this study was established as one treatment of an experiment examining the effects of various silvicultural alternatives on the growth of planted seedlings of Flindersia brayleyanal and F. pimenteliana. The study was commenced only when it was observed that many components of the original rain forest had regenerated by coppice. Although seedlings and root suckers of some tree species in the original stand were also present, they appeared to be of lesser overall significance. The only previously published quantitative study of regeneration following severe disturbance to a tropical or subtropical rain forest in Australia is that of Williams et al. (1969). They cleared their experimental area with a bulldozer, exposing mineral soil over most of the area. The observations they made were of seedling regeneration, and the few coppice shoots were ignored. Workers outside Australia also seem to have concentrated on aspects of seedling regeneration. Nevertheless, sufficient mention is made of coppice development in the literature on secondary succession in the tropics to indicate that this feature is widespread if not universal. For example, Symington (1933) in a Malayan forest observed that after felling, coppice growth, if allowed to develop, will within a few years create a stand which, except for the absence of large trees and the presence of a few typical secondary growth species, shows little indication that the rainforest had been so recently cleared. Whitmore (1975) in his review of rain forests of the Far East mentions the coppicing habit mainly in relation to rain forests with one or more limiting environmental factors, e.g., the heath, swamp, and mon-

A dynamic programming analysis of silvicultural alternatives for red pine plantations in Wisconsin

An individual tree based stand growth model was analyzed, via dynamic programming, for thinning and final harvest strategies leading to maximum physical yields. Optimal density yield tables, indicating maximum yields and corresponding strategies, were constructed from the solution of the dynamic programming networks. Maximum yields averaged 25 – 30% higher than comparable yields reported previously for periodically thinned red pine plantations.

Stand Structure, Succession, and Use of Southern Alberta's Rocky Mountain Forest

Structural analysis of the subalpine forest in southern Alberta shows that the old—growth Picea—Abies forest has succeeded even—aged stands of Pinus contorta var. latifolia Engelm. that became established after fire 150—200 or more years ago. Because P. Contorta regeneration fails beneath its own canopy, an irregular— to uneven—aged understory of Picea engelmannii Parry x P. glaca (Moench) Voss. and Abies lasiocarpa (Hook) Nutt. becomes established. As the even—aged P. contorta overstory ages, sporadic death of overmature trees permits an irregular— to all—aged Picea—Abies forest to emerge and dominate, unless fire reinitiates the succession to even—aged P. contorta. Extensive and frequent fires in the past, mainly initiated by "dry" electrical storms, have prevented long—term successional development and have maintained most of the forest in the early P. contorta—dominated phase of the succession. Introduction of effective fire protection is now permitting progress toward the late successional phases. Widespread development of the Picea—Abies phase and the decadent Abies—Picea phase that follows are forecast. The ecological effects of such fire—protection policies are questioned. A silvicultural program of fire prescription is suggested for the maintenance of the fauna and wilderness value of the mountain national parks. Silvicultural alternatives in harmony with the ecology of the forest are suggested for the implementation of multiple—use policies in the Rocky Mountain Reserve.