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Epidemiological studies have shown that high levels of fine particulate matter (PM) are correlated with adverse human health effects. Approximately one-third of PM emissions in Canada originate from forest fires. However, air quality concerns are not typically included in resource allocation decisions in fire management. In this paper we examine the economic magnitude of these health concerns and compare them to other costs of forest fires using the 2001 fire in Chisholm, Alberta, as a case study. We construct an empirical air dispersion model to estimate the concentration of PM arising from the fire. Benefit transfer methods were used to determine the health impacts associated with elevated PM from the fire and to value these impacts. The economic impacts appear to be substantial, second only to timber losses. The approaches used in this case study can be extended to construct a map that identifies the values at risk from health effects. The use of monetary values of these impacts helps in comparison and aggregation of the values at risk.

In the Pacific Northwest, the process of conifer development after stand-replacing disturbance has important implications for many forest processes (e.g., carbon storage, nutrient cycling, and biodiversity). This paper examines conifer development in the Coast Range Province and Western Cascades Province of Oregon using repeat interpretation of historic aerial photographs from 1959 to 1997 to examine the canopy cover change of different life forms: shrubs, hardwood trees, and conifer trees. Ninety-four stands from the Western Cascades Province and 59 stands from the Coast Range Province were photointerpreted in roughly 5-year intervals. A Chapman–Richards growth function was used to model conifer cover development for all sample stands. Based on the photo data and the Chapman–Richards function, these stands were classified into one of seven early forest successional trajectories defined by the vegetation physiognomy. Succession in the Coast Range Province and Western Cascades Province were compared using parameters derived from the Chapman–Richards growth function. Our results echo previous studies in that rates and densities of conifer regeneration varied markedly among sites; however, our results also indicate that early forest succession differs in the two study regions in terms of both trajectories and rates. Conifer regeneration in the Western Cascades Province tends to have longer delays in establishing and slower rates compared with the Coast Range Province.

The detection of release events in the annual growth increments of trees has become a central and widely applied method for reconstructing the disturbance history of forests. While numerous approaches have been developed for identifying release events, the preponderance of these methods relies on running means that compare the percent change in growth rates. These methods do not explicitly account for the autocorrelation present within tree-ring width measurements and may introduce spurious events. This paper utilizes autoregressive integrated moving-average (ARIMA) processes to model tree-ring time series and incorporates intervention detection to identify pulse and step outliers as well as changes in trends indicative of a deterministic exogenous influence on past growth. This approach is evaluated by applying it to three chronologies from the Forest Responses to Anthropogenic Stress (FORAST) project that were impacted by prior disturbance events. The examples include a hemlock (Tsuga canadensis (L.) Carrière) chronology from New Hampshire, a white pine (Pinus strobus L.) chronology from Pennsylvania, and an American beech (Fagus grandifolia Ehrh.) chronology from Virginia. All three chronologies exhibit a clustering of step, pulse, and trend interventions subsequent to a known or likely disturbance event. Time-series analysis offers an alternative approach for identifying prior forest disturbances via tree rings based on statistical methods applicable across species and disturbance regimes.

This paper presents a growth model for dominant-height and site-quality estimations for Pyrenean oak (Quercus pyrenaica Willd.) stands. The Bertalanffy–Richards function is used with the generalized algebraic difference approach to derive a dynamic site equation. This allows dominant-height and site-index estimations in a compatible way, using any desirable base age and allowing estimations to be time independent, which are important properties for site models. The database contains all possible height-growth intervals. The model is fitted considering residual autocorrelation, giving more efficient parameter estimates. Finally, the model behavior is analyzed by calculating error statistics from dominant-height and site-index estimations at different ages.

This paper considers the statistical analysis of fire-interval charts based on fire-scar data. Estimation of the fire interval (expected time between scar-registering fires at any location) by maximum likelihood is presented. Because fires spread, causing a lack of independence in scar registration at distinct sites, an overdispersed binomial model is used, leading to a two-variable quasi-likelihood function. From this, point estimates, standard errors, and approximate confidence intervals for fire interval and related quantities can be derived. Methods of testing for the significance of spatial and temporal differences are also discussed. A simple example using artificial data is given to illustrate the computational steps involved, and an analysis of real fire-scar data is presented.

Airtankers are widely employed in wildland fire control operations. This paper presents a spreadsheet procedure for modeling airtanker initial-attack performance within a protection region. Easily written and modified, this spreadsheet-based model provides the user with substantial flexibility when specifying the spatial distribution of fire occurrence within the initial-attack zone of an airtanker base. Once this spatial distribution has been specified, the expected flight distance from the airtanker base to a random fire ignition point as well as higher moments of the flight distance distribution are readily computed and applied using the spreadsheet. The chief advantages of this spreadsheet approach are described. Calculation procedures and potential applications of flight distance moments including the optimization of airbase location are illustrated. Detailed numerical examples and opportunities for future development are indicated.

Nothofagus pumilio (Poepp et Endl.) Krasser, is a deciduous tree species that grows in Chile and adjacent Argentina between 36 and 56°S, often forming the Andean tree line. This paper presents the first eight tree-ring chronologies from N. pumilio at its northern range limit in the central Andes of Chile (36–39°S) and the first precipitation reconstruction for this region. Samples were taken from upper tree-line stands (1500–1700 m elevation) in three study areas: Vilches, Laguna del Laja, and Conguillío. Results indicate that, at the northern sites (Vilches and Laguna del Laja), the tree-ring growth of N. pumilio is positively correlated with late-spring and early summer precipitation and that higher temperatures reduce radial growth, probably because of an increase in evapotranspiration and decrease in water availability. At the southern Conguillío study area, radial growth was negatively correlated with late-spring and early summer precipitation. The presence of volcanic activity in this latter study area, which might have masked the climate signal, did not seem to have a significant influence on radial growth. A reconstruction of November–December (summer) precipitation for the period 1837–1996 from N. pumilio tree-ring chronologies accounted for 37% of instrumentally recorded precipitation variance. This is the first precipitation reconstruction from N. pumilio chronologies. Only temperature and snow cover have previously been reconstructed using this species. The reconstruction indicates that the driest and wettest 25-year periods within the past 160 years are 1890–1914 and 1917–1941, respectively.

This paper presents mathematical equations describing the relationships between the amount of stemflow per canopy layer per storm and the amount of gross rain per storm for four different canopy layers in a multi-storied forest community. The curves representing the relationships were curvilinear; for three of the canopy layers stemflow per storm increased at an increasing rate as gross rain per storm increased, approaching a constant rate of increase. Numerical values of the equation coefficients varied with canopy level in the forest stand profile and with variations in vegetal structure within the forest community. The lowest canopy in the vegetal profile, a fern canopy, had the most marked effect on rainfall redistribution.