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The Fuel Characteristic Classification System (FCCS) is a systematic catalog of inherent physical properties of wildland fuelbeds that allows land managers, policy makers, and scientists to build and calculate fuel characteristics with complete or incomplete information. The FCCS is equipped with a set of equations to calculate the potential of any real-world or simulated fuelbed to spread fire across the surface and in the crowns, and consume fuels. FCCS fire potentials are a set of relative values that rate the intrinsic physical capacity of a wildland fuelbed to release energy and to spread, crown, consume, and smolder under known or benchmark weather and fuel moisture conditions. The FCCS reports eight component fire potentials for every fuelbed, arranged in three categories: surface fire behaviour (reaction intensity, spread rate, and flame length), crown fire potential (torching and active crown fire), and available fuel potential (flaming, smouldering, and residual smouldering). FCCS fire potentials may be used to classify or compare fuelbeds that differ because of location, structure, passage of time, or management action, based on expected fire behavior or effect outcomes. As a classification tool, they are offered as an objective alternative to categorizing bulk properties of fuelbeds or stylized model inputs.

The Fuel Characteristic Classification System (FCCS) includes equations that calculate energy release and one-dimensional spread rate in quasi-steady state fires in heterogeneous but spatially-uniform wildland fuelbeds, using a reformulation of the widely used Rothermel fire spread model. This reformulation provides an automated means to predict fire behavior under any environmental conditions in any natural, modified, or simulated wildland fuelbed. The formulation may be used to compare potential fire behavior between fuelbeds that differ in time, space, or as a result of management, and provides a means to classify and map fuelbeds based on their expected surface fire behavior under any set of defined environmental conditions (i.e., effective wind speed and fuel moisture content). Model reformulation preserves the basic mathematical framework of the Rothermel fire spread model, reinterprets data from two of the original basic equations in his model, and offers a new conceptual formulation that allows the direct use of inventoried fuel properties instead of stylized fuel models. Alternative methods for calculating the effect of wind speed and fuel moisture, based on more recent literature, are also provided. This reformulation provides a framework for the incremental improvement in quantifying fire behaviour parameters in complex fuelbeds and for modeling fire spread.

Fuel mapping is a complex and often multidisciplinary process, involving remote sensing, ground-based validation, statistical modelling, and knowledge-based systems. The scale and resolution of fuel mapping depend both on objectives and availability of spatial data layers. We demonstrate use of the Fuel Characteristic Classification System (FCCS) for fuel mapping at two scales and resolutions: the conterminous USA (CONUS) at 1 km resolution and the Wenatchee National Forest, in Washington State, at 25 m resolution. We focus on the classification phase of mapping — assigning a unique fuelbed to each mapped cell in a spatial data layer. Using a rule-based method, we mapped 112 fuelbeds onto 7.8 million 1 km cells in the CONUS, and mapped 34 fuelbeds onto 18 million 25 m cells in the Wenatchee National Forest. These latter 34 fuelbeds will be further subdivided based on quantitative spatial data layers representing stand structure and disturbance history. The FCCS maps can be used for both modelling and management at commensurate scales. Dynamic fuel mapping is necessary as we move into the future with rapid climatic and land-use change, and possibly increasing disturbance extent and severity. The rule-based methods described here are well suited for updating with new spatial data, to keep local, regional, and continental scale fuel assessments current and inform both research and management.

Until recently, natural dynamics of mixedwood stands have been largely ignored, resulting in the transformation of many North American mixedwoods into conifer- or hardwood-dominated stand types. The goal of this study was to examine canopy gap dynamics in balsam fir ( Abies balsamea (L.) Mill.) – yellow birch ( Betula alleghaniensis Britt.) mixedwoods to better understand possible mechanisms for species coexistence. Gap proportion in 12 study stands varied between 9% and 30% of the total stand area, while gap size varied from 20 to 2100 m2. Balsam fir mortality was the primary cause of gap formation. Balsam fir and mountain maple ( Acer spicatum Lamb.) dominated the tree and shrub regeneration layers, respectively. Shrub competition slows the natural filling of gaps by tree species. Our results indicate that yellow birch is most abundant in gaps over 800 m2 and balsam fir in those under 200 m2. Transition models showed that the greater longevity of yellow birch than balsam fir ensured its maintenance as a dominant. Dominant species coexistence thus results from divergent use of available resources through time and space. Forest management should maintain variability in harvest timing and size because the use of one gap size or a single rotation age will lead to an imbalance in species proportion relative to natural stands.

Both the size and the density of gaps affect seedling growth, but these two parameters have a reciprocal relationship at a given gap ratio. The objective of the present study was to clarify the appropriate gap mosaic coarseness required to facilitate the growth of Quercus gilva Blume seedlings in Cryptomeria japonica D. Don plantations. The spatial heterogeneity of the photosynthetic photon flux density on the forest floor was predicted using mimicked hemispherical diagrams under five levels of gap mosaic coarseness ranging from the finest gap mosaic with a gap size of 25 m2 and a gap density of 100·ha–1 to the coarsest mosaic of 400 m2 and 6.25·ha–1. Photosynthetic potentials (PP) were calculated by combining the predicted photosynthetic photon flux density and photosynthetic relationships of Q. gilva and two nontree major competitors ( Mallotus japonicus (Thunb.) Muell. Arg. and Miscanthus sinensis Anderss.). The coarser gap mosaic formed a more heterogeneous and bimodal PP frequency and resulted in a wider site in which the three species had high growth potential without considering competition among species. However, an intermediate mosaic with a gap width to mean canopy height ratio of 0.7 formed the widest realized niche in which Q. gilva would show good growth with a relative PP > 70%, whereas the competitor species would be suppressed with a relative PP < 70%.

Variants of partial harvesting are gaining favour as means to balance ecosystem management and timber production objectives on managed boreal forest landscapes. Understanding how residual trees respond to these alternative silvicultural treatments is a critical step towards evaluating their potential from either a conservation or a wood supply perspective. We used dendroecological techniques combined with a chronosequence approach to quantify the temporal radial growth response pattern of residual black spruce ( Picea mariana (Mill.) BSP) trees to partial harvest in northeastern Ontario. At its peak, 8–9 years after harvest, radial growth of residual trees had doubled. The growth pattern was characterized by a 2-year phase of no response, a subsequent period of increase 3–9 years after harvest, and a stage of declining rates 10–12 years after harvest. The magnitude of tree growth response depended strongly on tree age: peak postharvest growth was substantially higher for young trees, while old trees displayed only modest growth increases. Both the large magnitude and the time delay in postharvest growth responses have important implications for the development of more accurate quantitative tools to project future yields and, more generally, for determining whether partial harvesting is a viable management option for the boreal forest.

Forest litter and soil may contain >10 × 106individual nematodes·m–2and, regionally, >400 species. Root-feeding nematodes may be pathogenic to young plants; microbial-feeding nematodes may increase turnover of the microbial pool; predacious and omnivorous nematodes represent higher trophic levels. The spatial distribution and abundance of nematode species in forests reflect soil type, soil fertility, climate, canopy and understorey plant species, litter depth, forest age, and management. Nematodes may be important in forest nurseries; they occur throughout the rooting depth of forest trees; hyphal-feeding species may influence mycorrhizae; and insect-vectored Bursaphelenchus species are a quarantine risk. Nematode populations interact with those of other soil animals (e.g., mites, tardigrades, enchytraeids, and protozoa). The diversity and abundance of the nematode assemblage make nematodes a useful indicator of soil condition and soil processes. Information available from forest systems suggests that, as long as physical disturbance is minimized and remaining trees or herb layer moderate the microclimate, logging and other forestry operations have only transitory effects on nematode populations. Extreme disturbance, such as bulldozing and slash-and-burn management, can significantly reduce nematode abundance and diversity. In contrast, management that enhances growth of understorey or herb layer can stimulate nematode populations. Each of these changes can be related to changes in food resource availability and environmental conditions, such as soil temperature and moisture. Although details of soil nematode contributions to nutrient processes in forest soils are sparse, that their populations are maintained through cycles of moderate management practices suggest that their beneficial contributions will also be maintained.

Wildfires and prescribed burns constitute widespread and potentially destructive disturbances in forest ecosystems. Fire-related effects on aboveground ecosystem components are well established, and it is known that fire can have both a direct and an indirect influence on the edaphic environment, but the effects of fire on soil-dwelling fungi are poorly understood. We review the disparate literature relating to fire effects on soil fungi, with emphasis on forest environments. A variety of effects have been reported, including altered fungal community structure along with increased or decreased mycorrhizal colonization of roots. Such effects, along with their duration, appear to be site- and (or) fire-specific, but are likely to be greater in the upper soil horizons. Where repeated burning occurs, the effects on soil fungal communities appear to be more pronounced with more frequent burning. Although fire may effect structural changes in soil fungal communities, the functional significance of such changes at the ecosystem level remains difficult to assess.

Phospholipid fatty acid profiles were used to evaluate microbial community composition in different soil layers of sugi ( Cryptomeria japonica (L.f.) D. Don) plantations and seminatural secondary forests in southeastern Kyushu, Japan. These forests had previously been utilized as meadows or coppices. Principal components analysis and canonical correspondence analysis of the phospholipid fatty acid data demonstrated differences in microbial community structure between current vegetation (sugi plantations or seminatural forests) in the FH layer. In contrast, differences between the previous land-use types (meadows or coppices) were detected through variation in the soil microbial community structure in the upper part of the A layer (0–5 cm). However, in the deeper part of the A layer (5–10 cm), the influence of the previous land-use history on soil microbial community structure was weak and the influence of the current vegetation could be detected. In the 0–5 cm part of the A layer, the organic matter was correlated with the microbial community structure. However, it cannot be assumed that these soil chemical characteristics were the principal factors responsible for separation of the microbial communities based on previous land-use history because the difference in chemical characteristics between the sites was small.

The sustainability of exotic commercial plantations is dependent on the conservation of soil nutrients, especially on the ancient, leached soils of the tropics, particularly when limited fertilization is practiced. In Eucalyptus grandis W. Hill ex Maid. plantations in South Africa, the site is usually burned following harvest and prior to replanting, potentially causing a disruption of soil faunal function and losses of nutrients associated with burning and removal of slash residues. The aim was to study the effect of fire on nutrient dynamics and invertebrate faunal composition. The in situ nitrogen and phosphorus mineralization rates and invertebrate faunal composition were measured in six randomly located plots — three burned and three unburned — prior to and after a low-intensity fire. Results indicate that within the burned plots, phosphorus availability was enhanced 10-fold within the first month following the fire. Invertebrate faunal diversity was low both prior to and after burning, with ants constituting the highest number. Invertebrate faunal composition was more markedly influenced by season than by the fire, with millipedes present in the majority of plots in spring and ants dominating in summer.

We investigated the structure of the fungal community of evergreen broad-leaved forests dominated by evergreen oak ( Castanopsis sieboldii or Quercus myrsinaefolia ) through surveying sporocarps in urban, suburban, and rural areas of the Kanto District, Japan. In a 4 year census, 132 species of fungi were recorded and classified into five groups on the basis of growth substrate: 22 litter decomposers, 39 wood rotters, 10 rotted-wood decomposers, 23 humus decomposers, and 38 ectomycorrhizal species. A long-term survey of fungi revealed lower species richness and diversity of ectomycorrhizal fungi in the urban and suburban forest than in the rural forest. The low species diversity of ectomycorrhizal fungi in the urban forest was related to low species richness of Amanitaceae and a high frequency of some Russulaceae species such as Russula japonica . In contrast, species richness and abundance of litter decomposers and wood rotters were higher in the urban forest than in the rural forest. The uneven litter distribution on soil surfaces in the mountainous rural forest may have caused the lower species richness of litter decomposers. Rotted-wood decomposers and humus decomposers showed no significant differences among the three types of forest.

Five years after spacing a young, 11 m tall paper birch (Betula papyrifera Marsh.) stand, we examine relationships between growth of understory white spruce (Picea glauca (Moench) Voss), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and level of birch retention. Our objectives were to evaluate the effectiveness of selected measures of competition for estimating the effects of the residual birch and to evaluate the influence of residual birch densities on growth responses of naturally regenerated subalpine fir and white spruce. Basal area of Scouler willow (Salix scouler iana Barratt) and birch were found to effectively predict light transmittance (diffuse noninterceptance). The best models for predicting 4-year volume growth of subalpine fir and white spruce incorporate initial crown volume of the subject trees and transmittance as independent variables. Lorimer's index and Hegyi's index gave similar results to those obtained using basal area and transmittance, suggesting that there is little benefit in including measurements of proximity in a competition index. For both species, the correlation between basal area increment and light was substantially stronger than observed for volume increment. However, height increment of both subalpine fir and spruce was only weakly correlated with measured light levels. The ratio of height increment to volume increment decreased with both increasing initial height and transmittance for subalpine fir and white spruce.

The current spruce bark beetle (Dendroctonus rufipennis Kirby) epidemic in interior Alaska is leaving large expanses of dead spruce with little spruce regeneration. Many of these areas are habitat for moose (Alces alces). To establish spruce regeneration and improve browse production for moose, paper birch (Betula papyrifera Marsh), willow (Salix spp.), and three stocktypes (plug+1 bareroot, and 1+0 plugs from two nurseries) of white spruce (Picea glauca (Moench) Voss) were planted in freshly cutover areas on Fort Richardson, near Anchorage. Four vegetation- management treatments were compared: broadcast site preparation with herbicides, banded site preparation with herbicides, mechanical scarification, and untreated control. Spruce seedlings had the greatest growth in the broadcast site preparation treatment (p < 0.01). Stocktype was the most important factor in spruce growth, with bareroot transplant seedlings being the tallest and largest 5 years after planting ( p < 0.001). In the first 3 years, relative stem volume growth was greater for plug seedlings than for bareroot seedlings (p < 0.001). By year 4, relative growth rates were similar among all stocktypes. Treatment effects for paper birch and willow were confounded by moose browsing. Results indicate spruce can be regenerated and moose browse enhanced simultaneously in forests in interior Alaska. Resume : L'epidemie actuelle de dendroctone de l'epinette (Dendroctonus rufipennis Kirby) dans la partie interieure de l'Alaska est a l'origine de grandes etendues de pessiere morte ou la regeneration de l'epinette s'avere faible. Plusieurs de ces regions sont habitees par l'orignal (Alces alces). Dans le but de favoriser l'etablissement de la regeneration en epinette et d'ameliorer la production de broutilles pour l'orignal, des bouleaux blancs ( Betula papyrifera Marsh), des saules (Salix spp.) et trois types de plants d'epinette blanche ( Picea glauca (Moench) Voss) (semis en douille de 1 an a racines nues et semis en douille 1+0 provenant de deux pepinieres) ont ete plantes sur des aires recemment coupees a blanc a Fort Richardson, pres d'Anchorage. Quatre traitements de preparation de terrain ont ete compares : preparation extensive avec herbicides, preparation par bandes avec herbicides, scarification mecanique et temoin non traite. Les semis d'epinette du traitement de preparation extensive montraient la croissance la plus forte ( p < 0,01). Le facteur le plus important pour la croissance de l'epinette etait le type de plants, les semis a racines nues etant les plus grands et les plus gros 5 ans apres la plantation (p < 0,001). Pendant les trois premieres annees, la croissance relative en volume des tiges etait plus elevee chez les semis en douille que chez les semis a racines nues ( p < 0,001). Des la quatrieme annee, les taux de croissance relative etaient similaires pour tous les types de plants. Chez le bouleau blanc et le saule, l'effet des traitements etait confondu avec le broutage des orignaux. Ces resultats indiquent qu'il est possible de regenerer l'epinette et, simultanement, d'ameliorer la production de broutilles pour l'orignal dans les forets continentales de l'Alaska.

Seedlings of four geographically diverse paper birch (Betula papyrifera Marsh.) populations native to British Columbia were grown under low and high levels of water and nitrogen in a greenhouse for 3 months to examine the relative sensitivity of each population to water and nutrient availability. Nine sequential measurements on height and basal diameter growth were made, and then the seedlings were harvested for final biomass measurements. Under optimal conditions the highest elevation population ceased height growth, while the low-elevation coastal population continued to increase in height under all treatment conditions. Plants of all populations grown under high N conditions grew faster and had larger total biomass and lower root/shoot ratios than plants grown under low N conditions. Relative growth rate was significantly correlated with shoot and foliage biomass, leaf area, and root weight ratio. All populations generally responded more to low N level than to low moisture level in terms of height growth, relative growth rate, total biomass, and root/shoot ratio. This suggests that the populations observed in this study are better adapted to drought than poor soil nutrient availability. Therefore, consideration of site quality, which includes soil moisture regime and soil nutrient regime, should be a primary concern when allocating birch seed lots in a planting program.

Widespread paper birch (Betulapapyrifera Marsh.) mortality associated with the activity of the bronze birch borer (Agrilusanxius Gory) was observed across northern Michigan in 1991. This mortality occurred at two study sites on which paper birch growth has been intensively monitored since 1985. Recent warmer than normal growing seasons and lower than normal moisture availability are statistically associated with a reduction in annual diameter growth. On one study site 62% of the paper birch study trees were dead and 13% were visibly declining; on the other study site, although no trees were dead, 25% of the paper birch study trees were visibly declining. Growth reductions since 1985 suggest that the species was under climatic stress, making it more vulnerable to pest–pathogen activity. The evidence of the role of climatic conditions acting as a precursor to decline and mortality on these sites is of serious concern given recent projections of warmer temperatures and lower precipitation for this region by several global-climate models.

A parsimonious model of capacity expansion is proposed for the United States paper and paperboard industries. The work grows out of Tobin's q theory, which suggested that the ratio between market value and replacement cost of capital is crucial in investment decision making. The model assumes that firms in the two industries are price takers, with a marginal cost of production equal to the average cost. The q values for the paper and paperboard industries were calculated as the ratios of the shadow price of existing capacity to the cost of new capacity. Annual data from 1958 to 1988 were used for estimation, with static and dynamic models of capacity changes. The results showed that a single dynamic equation using the q ratios alone explained most of the gross changes in capacity in both the paper and paperboard industries of the United States during the period considered.

Les organisateurs (George Askew, Tom Blush et Barbara McCutchan) du programme 1994 de la rencontre du SRIEG (Groupe regional d'echange d'informations du Sud) ont invite 18 auteurs afin de passer en revue les attitudes, les donnees, les methodes, les plans, les reglements et les strategies relativement a la diversite genetique des peuplements forestiers. Ces presentations, presentes durant une rencontre de 2 jours qui s'est deroulee les 19 et 20 juillet a l'Universite Clemson, a Clemson en Caroline du Sud, ont surtout aborde le contexte des plantations commerciales ou une seule espece peut servir de composante primaire majeure pour l'ecosysteme qui se developpe. Les auteurs presentent (1) une breve introduction a ces 10 presentations dont 6 sont publies dans ce numero, en plus de courts rapports concernant deux reunions satellites, dont un est publie dans le present numero (H.E. Stelzer and B. Goldfarb. 1997. Implementing clonal forestry in the southeastem United States: SRIEG satellite workshop summary remarks. J. Can. Rech. For. 27: 442-446); (2) certains sujets abordes durant les discussions informelles entre conferenciers invites et en assemblee ainsi que durant les discussions informelles pendant les pauses, ces sujets n'etant pas completement couverts dans les articles qui suivent; et (3) certaines preoccupations au sujet de la diversite genetique et de la conservation des ressources genetiques, qui demandent un suivi ou une attention additionnelle. (A propos des deux derniers volets dont les auteurs de ce rapport avaient la responsabilite, ces derniers admettent n'avoir pu participer a toutes les conversations et discussions informelles, pas plus qu'ils revendiquent avoir une connaissance complete des contenus des discussions informelles faisant l'objet de leur rapport. Ces sujets de conversation furent soumis a l'audience lors de la derniere seance de la rencontre, laissant ainsi l'opportunite aux autres participants de manifester leur desaccord ou d'ajouter certains elements manquants. Les auteurs ont tenu compte de ces commentaires en revisant et en amendant leur rapport final. Plusieurs de ces conversations et discussions informelles ont permis d'eclairer sous un jour different certains sujets, et ont rendu la rencontre plus productive a ce niveau que la seule publication independante des articles soumis. Admettant que leur rapport peut contenir des imperfections, les auteurs sont heureux d'inclure ces informations et points de vue, tout en suggerant que certains d'entre eux s'avereront utiles.).

Price equations for the following product groupings of the Canadian pulp and paper industry were estimated using data from 1955 to 1981: (i) woodpulp; (ii) newsprint; (iii) "other paper and paperboard"; and (iv) "aggregate paper and paperboard," which includes (ii) and (iii). Price equations were formed on the assumption that firms markup average costs of production to set prices. These equations show the effects of factor costs, economies of scale, and technological progress on the prices of the products. They also help understand relevant aspects of production processes. Newsprint and "other paper and paperboard" production costs and prices are most responsive to the prices of material (woodpulp), labour, and energy, while woodpulp price responds more to the prices of pulpwood and energy. Substantial economies of scale are experienced by newsprint and woodpulp sectors. Such economies in the "other paper and board" sector are nonexistent. Technological progress has also contributed to reduction in the costs of production: 4.3% in woodpulp, 4.4% in "other paper and board," and 2.6% in newsprint per annum. Reduction in the cost of obtaining pulpwood to woodpulp sector is important in reducing the cost of paper and paperboard production. Substitution of existing capital with low energy and labour using capital is also required to lower the costs. Also, efforts to modernize the whole industry and the use of available economies of scale are indicated to keep the Canadian pulp and paper industry competitive in world markets.