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Downed Dead Wood Fuel and Biomass in the Northern Rocky Mountains
Abstract
Weights and volumes of downed woody material in diameter classes of
one-fourth to 1, 1 to 3, and greater than 3 inches and forest floor duff
depths were summarized from extensive inventories in nothern Idaho and
Montana. Biomass loadings are shown by cover types and habitat types
within National Forests. Total downed woody biomass ranged from 5 tons
per acre in ponderosa pine to 33 tons per acre in cedar-hemlock.
Loadings generally increased with increased productivity, but varied
greatly with stand age. Fuels tended to become predictably high in
overmature stands but unpredictable in young, immature, and mature
stands. Forest fuel succession is discussed in relation to tree
mortality, fuel buildup, and depletion.
... But fuel loadings vary greatly from site to site, even within groups of similar habitat types. Brown and See (1981) found that total downed woody fuel loading in the Northern Rocky Mountains was positively correlated with potential forest yield capability, although great variation occurred within groups of habitat types. They listed the habitat type series that occur in northern Idaho, from lowest to highest fuel loadings, as follows: whitebark pine, Douglas-fir, subalpine fir, grand fir, western redcedar, and western hemlock. ...
... There is little evidence, however, that heavy postfire fuels increase the likelihood of ignition or fire spread (Anonymous 1931). Brown and See (1981) found two patterns in forest fuel loadings in succession: (1) until the trees in a stand begin to decline in vigor and soundness, fuel MT, 1962(Lyon 1984. quantities cannot be predicted; and (2) fuel quantities become high as trees begin to decline. ...
... Fuels-The amount of fuel in seral lodgepole pine stands varies (Brown and See 1981 . 7), stand development, and effects of insects and diseases. ...
Provides information on fire ecology in forest habitat and community types occurring in northern Idaho. Identifies fire groups based on presettlement fire regimes and patterns of succession and stand development after fire. Describes forest fuels and suggests considerations for fire management.
... We estimated density of large logs (defined as ≥30.5 cm midpoint diameter and ≥2.44 m in length) by forest type and compared those estimates to U.S. Forest Service (USFS) management guidelines for retention of large logs in the Southwestern Region (Reynolds andothers 1992, USDA 1996). We estimated biomass of logs and stumps using estimates of wood density from Brown and See (1981). We used their estimate for sound material (25 lbs/ft 3 ) for logs in decay class 1 and stumps in decay classes 1 and 2, their estimate for rotten material (19 lbs/ft 3 ) for logs in decay class 3 and stumps in decay classes 4 and 5, and an intermediate value (22 lbs/ft 3 ) for logs in decay class 2 and stumps in decay class 3. We compared the resulting estimates to recommendations for biomass of CWD in these forest types (USDA 1999, Brown andothers 2003). ...
... Estimated values for fuel loads in these forest types generally fell within the range of values reported previously for mixed-conifer (21.5-62 tonnes/ha; Sackett 1979, Brown and See 1981, Knapp and others 2005, Stephens and Moghaddas 2005 and ponderosa pine forest (3-23.2 tonnes/ha; Sackett 1979, Brown and See 1981, Robertson and Bower 1999, Stephens 2004, Stephens and others 2007. ...
... Estimated values for fuel loads in these forest types generally fell within the range of values reported previously for mixed-conifer (21.5-62 tonnes/ha; Sackett 1979, Brown and See 1981, Knapp and others 2005, Stephens and Moghaddas 2005 and ponderosa pine forest (3-23.2 tonnes/ha; Sackett 1979, Brown and See 1981, Robertson and Bower 1999, Stephens 2004, Stephens and others 2007. Many mixed-conifer plots fell within recommended ranges for biomass of CWD (USDA 1999, Brown andothers 2003), but a substantial proportion fell above recommended levels. ...
Coarse woody debris (CWD) provides important ecosystem services in forests and affects fire behavior, yet information on amounts and types of CWD typically is limited. To provide such information, we sampled logs and stumps in mixed-conifer and ponderosa pine (Pinus ponderosa) forests in north-central Arizona. Spatial variability was prominent for all CWD parameters. Correlations between amounts of CWD and current forest structure (tree density and basal area) were relatively weak. Most plots in mixed-conifer forest exceeded current USFS guidelines for retention of large logs. In contrast, 50% of ponderosa pine plots contained no large logs, and only 37% met current guidelines for log retention. Biomass of CWD in mixed-conifer forest typically fell within or above recommended levels for this forest type, whereas biomass of CWD in ponderosa pine forest typically fell within or below recommended levels. These results provide empirical data on amounts and types of CWD in this area and establish a baseline for monitoring CWD. The pronounced spatial variability in CWD parameters argues for managing CWD at broad spatial scales, rather than attempting to maintain average characteristics on every piece of ground.
... DWD increases due to mortality during life cycle processes such as natural thinning as immature stands grow, and stand break-up of over-mature stands. It also increases due to periodic natural disturbances including wind throw, insect outbreaks and snow damage (Brown and See 1981). DWD decomposition, on the other hand, is influenced by patterns of temperature, moisture and substrate quality (Harmon et al. 1986). ...
... Summarising DWD fuel loading is complicated, and additional factors including small scale disturbance events and silvicultural practices further confound national scale summaries (Woodall and Liknes 2008). Disturbance patterns that occur at the stand level can strongly influence DWD accumulation rates (Moroni 2006), which may result in weak DWD relationships to landscape scale ecosystem characteristics like species type and climate (Brown and See 1981). This may be why some forest types required classification to the ecozone level to capture added variability due to either the widespread distribution of some species or greater influence of stand scale processes across Canadian forested lands. ...
In Canada, fire behaviour is modelled based on a fuel classification system of 16 fuel types. Average fuel loads are used to represent a wide range of variability within each fuel type, which can lead to inaccurate predictions of fire behaviour. Dead and down woody debris (DWD) is a major component of surface fuels affecting surface fuel consumption, potential crown fire initiation, and resulting crown fuel consumption and overall head fire intensity. This study compiled a national database of DWD fuel loads and analysed it for predictive driving variables. The database included DWD fuel loads for all dominant Canadian forest types at three size classes: fine (<1 cm), medium (1–7 cm) and coarse (>7 cm). Predictive models for DWD fuel load by size classes individually and collectively for various forest types and ecozones were analysed. Bioclimatic regime, age, spatial position, drainage, and structural components including diameter at breast height and stem density were significant variables. This study provides tools to improve our understanding of the spatial distribution of DWD across Canada, which will enhance our ability to represent its contribution within fire behaviour and fire effects models.
... Fuel succession patterns in fire-prone forests are reflective of fire behavior and effects and the subsequent ability of fuels to accumulate over time. Few studies have examined longer-term fuel succession patterns following fire, but previous research has highlighted substantial variation within and among forest types (Brown and See 1981;Lotan et al. 1985). In forests that experience a high-severity fire, post-fire fuel succession typically has pulses of fine fuel accumulating during the early and late stages of stand development (Fahnestock 1976;Agee and Huff 1987;Kashian et al. 2013). ...
... The patterns of fuel succession in Baker cypress were consistent with previous findings from other empirical studies following stand-replacing fire, providing further evidence that time since fire or stand age can be a useful predictor of fuel patterns over time (Fahnestock 1976;Brown and See 1981;Agee and Huff 1987). Fine-fuel loading across the 147-year chronosequence in our study indicated a Ushaped pattern. ...
Background
Increasing frequency and size of wildfires over the past few decades have prompted concerns that populations of obligate seeding species may be vulnerable to repeat, short-interval fires that occur prior to these species reaching maturity. The susceptibility of populations to this risk is partially dependent on the amount and characteristics of fuel loading over time and their influence on fire behavior and effects. This study characterized fuel dynamics and modeled fire behavior across a time-since-fire chronosequence in stands of the rare, serotinous conifer, Baker cypress ( Hesperocyparis bakeri [Jeps.] Bartel), ranging in age between 3 and 147 years post fire.
Results
Litter and fine woody fuel loading (1- to 100-hour) were highest in the 10-year-old and 147-year-old stands, while coarse fuel loading (1000-hour) peaked in the 10-year-old stand and subsequently decreased with time since fire. Duff loading consistently increased with time since fire. Cone production had not occurred in the first 10 yr of stand development. Foliar moisture content in Baker cypress was inversely correlated with stand age, and older foliage had lower moisture content than younger foliage. Modeled surface fire behavior was highest in the 10-year-old and 107-year-old stands in accordance with higher litter, fine woody fuel, or shrub fuel accumulation. While foliar moisture content was higher in younger stands and influenced the critical fireline intensity, we did not observe changes in fire type.
Conclusions
Fine-fuel loading in Baker cypress stands followed a U-shaped pattern over time (first decreasing, then stable, then increasing), consistent with findings in other forests with stand-replacing fire regimes. Our results indicated that early-successional stages of Baker cypress forests have sufficient fuels to allow for the spread of wildfire and 10-year-old stands could burn with substantive fire behavior prior to cone production. Whenever possible, we recommend suppressing wildfire in stands less than 20 yr old to avoid substantial decreases or local extirpation of these rare Baker cypress populations. Our results highlight the importance of knowing the cone production patterns, fuel dynamics, and corresponding fire behavior over the development of obligate-seeder species to assess the risk of population loss due to short-interval fires.
... Coarse woody debris amounts vary depending on forest age. In mature subalpine forests in Idaho and Montana, CWD can range from 22 to 55 Mg/ha (13 to 25 tons/ac) (Brown and See 1981;Graham and others 1994). In young forests where lodgepole pine dominates the site as an early-seral species, up to 40 percent of the soil surface can be composed of CWD and rotten wood (Brown and See 1981;Harmon and others 1986) (fig. ...
... In mature subalpine forests in Idaho and Montana, CWD can range from 22 to 55 Mg/ha (13 to 25 tons/ac) (Brown and See 1981;Graham and others 1994). In young forests where lodgepole pine dominates the site as an early-seral species, up to 40 percent of the soil surface can be composed of CWD and rotten wood (Brown and See 1981;Harmon and others 1986) (fig. 3). ...
Recent estimates indicate that nearly 40.5 million ha (100 million ac) of forest lands that were historically burned by frequent surface fires in the western United States may benefit from the restoration of surface fire. An additional 4.5 million ha (11 million ac) of forests need to be treated to protect communities from wildfire (Aplet and Wilmer 2003). Rummer and others (2003) estimate that over 26.7 million ha (66 million ac) of forestlands could benefit from fuel reduction. Even with uncertainties in these estimates and arguments as to their precision and accuracy, they clearly illustrate the staggering number of hectares (acres) that need fuel treatments in order to modify fire behavior and burn severity. Access and operability issues further limit the options available on a large portion of western forests. Costs and lack of industrial infrastructure to use small diameter material are other critical factors influencing treatment possibilities. We, the authors, recognize that theoretically, all forests of the western United States could be treated in one way or another to modify wildfire behavior and burn severity. Many of the principles and concepts we discuss are relevant for fuel treatments within other forests and locales; however, we will emphasize forest treatments applicable for use in the cold, dry, and moist forests of the inland western United States. We will discuss forest treatments that influence watershed processes, defined as those that occur when water transports sediment, woody debris, chemicals, heat, flora, or fauna away from a site and deposits it on another site. We define a cumulative effect as one that results from the incremental effects of an event when added to other past, present, and reasonable projected future effects regardless of the triggering action or event (Reid 1988).
... The length, diameter at each end, and the decomposition class of each log encountered was recorded (Bate et al., 2004). The volume of the 1000-hr fuels was calculated as a frustum of a paraboloid (Harmon and Sexton, 1996;Bate et al., 2004) with specific gravity of sound (0.4) and rotten (0.3) wood (Brown and See, 1981). ...
... The majority of woody fuels in mulched areas were 1-hr and 10-hr fuels (<2.54 cm in diameter), composing between 67 to 78% of total woody fuel loadings. Addition of woody material to the needle litter resulted in a shift from a needle fuelbed with typical bulk densities below 100 kg m -3 in untreated areas (Brown and See, 1981;van Wagtendonk, 1998; to a compact woody/needle fuelbed. These compact, small particles wood-laden fuelbeds would likely alter potential surface fire behavior and fire effects. ...
Over the past several years, fire managers have increased their use of mastication treatments, the on-site disposal of shrubs and small-diameter trees through chipping and shredding. Mastication is a relatively untested management practice that alters the chemical and physical conditions of the forest floor and may influence vegetation regrowth and fuel development for years or decades. Eighteen sites were established across four ecosystems of the southern Rocky Mountains and the Colorado Plateau: lodgepole pine (Pinus contorta), mixed conifer (Pinus ponderosa, Pseudotsuga menziesii, Pinus flexilis, and Pinus contorta), ponderosa pine (Pinus ponderosa), and pinyon pine/juniper (Pinus edulis/Juniperus sp.). These sites were distributed across a wide geographic range throughout Colorado and represent treatments across several federal, state, and other land agencies. The sites were mulched between 2004 and 2006 and first measured in 2007 or 2008. The mechanical treatment added a substantial amount of 1-hr and 10-hr woody fuel (
... The patchy distribution of fuels across a stand or landscape often confounds development of effective measurement protocols, fuel classifications, and spatial fuel data layers suitable for fire management applications at all scales. Fuel loadings, for example, are so highly variable that they often can't be correlated to vegetation characteristics, topographic variables, or climate parameters (Brown and See 1981;Rollins and others 2004;Cary and others 2006). ...
... It is both the magnitude and variability of that characteristic that governs impacts on ecosystems, and nowhere is that more evident than in wildland fuels. Fuel properties, such as loading (Brown and See 1981), heat content (Van Wagtendonk and others 1998), specific gravity (Harmon and others 2008), size (Van Wagtendonk and others 1996), and moisture (Agee and others 2002), are astonishingly variable in time and in space, and this variability ultimately influences wildland fire effects and behavior. Fire spread, for example, is greatly influenced by the spatial distribution of fuels (Rocca 2009;Parsons and others 2010); fine-scale patches without fuels can dictate the direction, speed, and intensity of fire spread (Finney 1998b;Agee and others 2000;King and others 2008;Thaxton and Platt 2006). ...
We investigated the spatial variability of a number of wildland fuel characteristics
for the major fuel components found in six common northern Rocky Mountain
ecosystems. Surface fuel characteristics of loading, particle density, bulk density, and
mineral content were measured for eight fuel components—four downed dead woody
fuel size classes (1, 10, 100, 1000 hr), duff, litter, shrub, and herb—on nested plots
located within sampling grids to describe their variability across spatial scales. We also
sampled canopy bulk density, biomass, and cover for each plot in the grid. The spatial
distribution and variability of surface and canopy fuel characteristics are described
using the variance, spatial autocorrelation, semi-variograms, and Moran’s I. We found
that all fuels had high variability in loading (two to three times the mean), and this
variability increased with the size of fuel particle. We also found that fuel components
varied at different scales, with fine fuels varying at scales of 1 to 5 m, coarse fuels at
10 to 150 m, and canopy fuels at 100 to 500 m. Findings and data from this study
can be used to sample, describe, and map fuel characteristics, such as loading, at
the appropriate spatial scales to accommodate the next generation of fire behavior
prediction models.
... Pfister and others (1977). Fuel loading versus productivity trends are adapted from Brown and See (1981). Fire cycles were adapted from Martin (1982). ...
... Other key factors that determine consumption in a specific fuel type are preburn amounts, mineral soil incorporation, degree of consumption of a<ljacent fuels, weather conditions, and ignition technique. Because the largest quantity of fuel (organic matter) at most northern Rocky Mountain sites occurs as duff and large woody material (Brown and See 1981), the influence of fire on these fuel groups is of great interest. These fuel types are potential sources of soil heating and provide much of the nutrient base that determines long-term site productivity (Harvey and others 1989). ...
Presettlement fire played an important role in nutrient cycling, plant succession, diversity, and stand dynamics in coniferous forests of western North America. Prescribed fire can maintain site quality and contribute to control of insect and disease problems while reducing wildfire hazard. Fire effects on soils are largely governed by interactions between fuel consumption and soil characteristics that influence soil heating. Many impacts on vegetation and site productivity are also related to soil heating.
... Coarse woody debris amounts vary depending on forest age. In mature subalpine forests in Idaho and Montana, CWD can range from 22 to 55 Mg/ha (13 to 25 tons/ac) (Brown and See 1981;Graham and others 1994). In young forests where lodgepole pine dominates the site as an early-seral species, up to 40 percent of the soil surface can be composed of CWD and rotten wood (Brown and See 1981;Harmon and others 1986) (fig. ...
... In mature subalpine forests in Idaho and Montana, CWD can range from 22 to 55 Mg/ha (13 to 25 tons/ac) (Brown and See 1981;Graham and others 1994). In young forests where lodgepole pine dominates the site as an early-seral species, up to 40 percent of the soil surface can be composed of CWD and rotten wood (Brown and See 1981;Harmon and others 1986) (fig. 3). ...
... Coarse woody debris quantities may not always reach their maximum values in old-growth forests, and several trends in CWD quantity with forest age have been reported. Brown and See (1981) described different trends in CWD mass with forest age for each of three studies of Pinus contorta forests. One trend was a general increase with increasing age, peaking in old growth.Another was an inverse U-shaped curve, with maximum CWD mass occurring in mature (110-160 years old) forests. ...
... The third trend was a U-shaped curve with maximum values occurring in the youngest as well as the oldest forests. These same three trends were also found by Brown and See (1981) within four studies of Abies lasiocarpa forests, and similar variation occurs within other published studies. Of these trends, U-shaped curves, similar to those described by van Wagner (1983), have been found to be the most common in B.C. (e.g., Muraro 1971;Wells and Trofymow 1997;Clark et al. 1998), similar to results in the adjacent U.S. Pacific Northwest (e.g., Fahnestock 1976;Agee and Huff 1987;Spies et al. 1988). ...
This paper synthesizes data extracted from the literature and data collected in various studies by the author on the quantity, characteristics, and functional importance of coarse woody debris (CWD) in the old-growth forests of British Columbia (B.C.). There is little agreement in the literature about the minimum diameter of CWD or the number of decay classes recognized. In western North America, five decay classes are commonly used, but recent studies suggest fewer decay classes are preferable. Comparisons among decay classes and biogeoclimatic zones and subzones in B.C. reveal that quantities and volumes are greatest (up to approximately 60 kg/m2 and approximately 1800 m3/ha, respectively), and CWD persists the longest (sometimes in excess of 1000 years) in the Coastal Western Hemlock (CWH) biogeoclimatic zone. The quantity and ground cover of CWD increase with forest productivity. Persistence of CWD has varied from less than 100 to over 800 years in two coastal (CWH and Mountain Hemlock (MH)) and three interior (Interior Douglas-fir (IDF), Interior CedarHemlock (ICH), and Engelmann Spruce Subalpine Fir (ESSF)) biogeoclimatic zones. Trends in CWD quantity with forest age in managed coastal B.C. forests suggest a U-shaped curve, with greater quantities occurring in recent cutovers than in old-growth forests, and lowest quantities occurring in middle-aged forests. This may be the normal trend in CWD with forest age, with departures from this trend resulting from disturbance- or environment-specific factors. Relatively large amounts of data exist on the characteristics of CWD in the CWH, IDF, ICH, ESSF, and Boreal White and Black Spruce (BWBS) biogeoclimatic zones, but such data for the Coastal Douglas-fir, Sub-Boreal PineSpruce, Sub-Boreal Spruce (SBS), and SpruceWillowBirch biogeoclimatic zones appear relatively sparse. There have been few studies of the functional role of CWD in B.C. forests, but those studies that have been completed indicate that CWD is an important habitat component for some plant and animal species. A total of 169 plant species, including >95% of all lichens and liverworts, were found to grow on CWD in old-growth forests in the CWH, MH, IDF, ICH, and ESSF biogeoclimatic zones. One third of these species were restricted to CWD. Studies in several biogeoclimatic zones have found that CWD provided preferred habitat for and was associated with higher populations of some small animal species, such as shrews, some voles, and some salamanders, in old-growth forests, but the effects varied with species and biogeoclimatic zone. The nutrient cycling role of CWD is not yet well known, but it currently appears to be relatively insignificant in B.C. old-growth forests. Although it has been considered that CWD could increase mineral soil acidification and eluviation, no evidence for this was found in a study of the CWH, MH, IDF, ICH, ESSF, BWBS, and SBS biogeoclimatic zones. Future studies of the functional role of CWD should consider both scale (square metre vs. hectare) and temporal (changes in CWD with forest age) issues, as studies including these are sparse and both may be important. Key words: biogeoclimatic zones, British Columbia, coarse woody debris, old-growth forests.
... In recently treated northern Rocky Mountain ponderosa pine stands (i.e., <10 years), Keane et al. (2012) reported mean log loading ranging from 1.23 to 2.92 ac-1 (0.276-0.657 kg m -2 ), loadings similar or lower to our observations. Finally, Brown and See (1981) reported mean log loading of 5.3 tons ac -1 (1.18 kg m -2 ) and standard deviation of 14.0 tons ac -1 (3.14 kg m -2 ) in ponderosa pine cover types on the Bitterroot National Forest. These examples indicate the high variability of log loading in northern Rocky Mountain ponderosa pine forests. ...
... Σύμφωνα με τους Brown and See (1981) και Rothermel (1991a), τα δασικά καύσιμα μπορούν να ταξινομηθούν, με κριτήριο τη θέση τους στο δασικό οικοσύστημα. Ο χούμος, οι ρίζες, τα σάπια κλαδιά και οι κορμοί συνιστούν τα υπεδάφια δασικά καύσιμα τα οποία -στις κατάλληλες συνθήκες υγρασίας -συντηρούν ατελή καύση πολύ μικρής ταχύτητας διάδοσης (υπόγεια πυρκαγιά). ...
Η φωτιά αποτελεί έναν σημαντικό φυσικό παράγοντα της λειτουργίας των Μεσογειακών οικοσυστημάτων, όμως οι δασικές πυρκαγιές κατά τις τελευταίες δεκαετίες, προξενούν σημαντικές καταστροφές στο ανθρωπογενές και το φυσικό περιβάλλον των Μεσογειακών χωρών (Πορτογαλία, Ισπανία, νότια τμήματα της Γαλλίας, Ιταλία, Ελλάδα και Κύπρος) αλλά και του Καναδά, των Ηνωμένων Πολιτειών της Αμερικής (Η.Π.Α.) και της Αυστραλίας.
... Accumulation of C in CWD in the boreal forest is significantly affected by TSD and can follow several different pathways that are largely influenced by stand species composition (Hély et al. 2000;Arseneault 2001): a continuous increase with age (Hély et al. 2000), an inverse U-shaped curve (Brown & See 1981) or a U-or Sshaped curve (Sturtevant et al. 1997;Clark et al. 1998;Pedlar et al. 2002;Brais et al. 2005;Martin et al. 2005). The most common of these in the boreal forest is the Ushaped CWD accumulation curve (Figure 4). ...
Large amount of carbon (C) stored in boreal forest ecosystems plays an important role in the global carbon cycle. Forest ecosystem C is stored in four major pools: live vegetation (above- and belowground), dead woody material (snags, down woody debris, and stumps), organic soil horizons (forest floor), and mineral soil. Carbon cycling among these pools is mainly determined by disturbance. A large portion of previously fire-driven ecosystems in boreal North American forest are now managed. How C cycling of managed stands differs from that of natural stands strongly influences boreal forest carbon balance. In this thesis I first synthesize literature on carbon dynamics in North American boreal forests followed by a study about aboveground biomass C dynamics in boreal mixedwoods after wildfire and clearcut harvest.
Carbon pool dynamics in forest ecosystems after stand replacing wildfire are described and compared with carbon dynamics after clearcut harvesting. Following a stand replacing disturbance, 1) live biomass increases rapidly leading to the maximal biomass stage, then stabilizes at stand maturation; 2) dead woody material carbon generally follows a ‘U’ or ‘S’ shaped pattern during succession; 3) Forest floor carbon increases throughout stand development; 4) mineral soil carbon is the largest terrestrial organic carbon pool and is highly variable, but an overall increase over time has been observed. These pools are connected and throughout stand development C allocation form one pool to another takes place. Wildfire and harvesting differ in many ways, fire being more as a chemical and harvesting as a mechanical disturbance. Fire consumes forest floor and small live vegetation and foliage while during logging much of large size biomass is removed and forest floor is mechanically disturbed. Another major difference is the absence of coarse woody debris after logging. Also, regeneration of the new stand is different after wildfire and logging. Fire often destroys advanced regeneration while it is less affected by logging, resulting different species composition and therefore different stand C dynamics. Overall, the manner in which different types of disturbance effect C dynamics in boreal forest is poorly understood. Further studies following wildfire but especially forest harvesting are needed to improve understanding of the effect of disturbance on C dynamics.
Live biomass carbon (C) pool dynamics are central to understanding carbon sequestration of forest ecosystems. Despite its importance, how aboveground live C pools change with stand development of boreal mixedwoods is poorly understood, in particular in relation to different disturbance origins. I quantified above ground live biomass C pools in a postfire chronosequence ranging from 1 to 203 years and a post-logging chronosequence ranging from 1 to 27 years in boreal mixedwood forest in central Canada. Stands were chosen along a successional sequence in boreal mixedwoods. Total live biomass C was significantly affected by time since disturbance and stand origin with time since disturbance explaining most of the variation. The biomass C dynamics was largely determined by overstory tree dynamics as it constituted most of stand biomass. Biomass in postfire stands reached maximum (109.18 Mg C/ha) at the age of 92 years after fire and then declined in older age classes. Post-logged stands had significantly more biomass C compared to postfire stands with the biggest difference at 27 years after disturbance when post-logged stands had 38.5 Mg C/ha more C than postfire stands.
... reached during the post-epidemic phase as CWD decomposes (Jenkins 2011). In this, the generality that downed woody fuels accumulate over time may not always be true (Brown and See 1981). ...
The increase in both southern pine beetle (SPB) (Dendroctonus frontalis Zimm) outbreak and wildfire occurrence in recent decades has resulted in a growing concern regarding possible interactions. Few studies have quantified fuel characteristics of SPB-killed stands, and none has studied the dynamics of this fuel complex over time. Moreover, how changes in these fuels affect fire behavior remains unknown. To address this lack of empirical data, field measurements and modeling were combined to study fuel dynamics and potential fire behavior within control and post-outbreak loblolly pine-dominated forest stands across a chronosequence ranging from 0 to 8 years since outbreak. Fuels data were collected on three study areas within the Piedmont of Georgia and South Carolina, USA. Fuel loading was significantly greater in post-outbreak stands than in control stands for several types of fuels. Stand structure was altered between stand types, containing fewer live pines and more hardwoods in post-outbreak stands. The Fuel Characteristic Classification System (FCCS) was used to construct representative fuelbeds from the measured data. The customized fuelbeds were then used to model surface fire behavior as a measure of the change in fuel loading and stand structure resulting from SPB outbreak. Flame length and rate of spread (ROS) were derived as metrics of predicted surface fire behavior. BehavePlus was used to further understand the consequences of these fuel changes. Both FCCS and BehavePlus predicted faster ROS and higher flame lengths in post-outbreak stands than in uninfested stands. Stands measured 8 years after outbreak under extremely dry moisture conditions were predicted to have the most extreme fire behavior. These results were compared to existing standard fuel models and discussed in the context of management implications for SPB-killed Piedmont forests.
... Surface fuel loads are notoriously di cult to predict because variability is very high across a landscape and even within a stand. Reinhardt et al. (2010) quoted Brown and See (1981), who analyzed fuel data from thousands of plots in the Rocky Mountains and found that "very little of the observed variation in loading was explained by any of the factors" such as stand age, aspect, slope, elevation, habitat type, and cover type. erefore, it is very di cult to predict how fast surface fuels will accumulate a er a fuel treatment. ...
Fuel treatments are common and are generally regarded as beneficial for reducing fire behavior, as well as for ecological reasons such as increasing understory diversity and reducing competition among trees for nutrients and water. What remains unclear is how long such fuel treatments are effective in reducing undesirable fire behavior. This working paper addresses the following management questions regarding fuel treatment longevity: What factors influence fuel treatment longevity? How long will fuel treatments last before sites need to be retreated? Do some types of treatments last longer than others?
... If the variation we encountered is typical of streams in other regions, few studies have measured coarse wood with sufficient intensity to reasonably characterize mean volume of pieces or total volume in segments. Biomass estimation may be even more problematic because wood density varies with species, age, and stage of decomposition (Brown and See, 1981;Hardy, 1996), which are rarely assessed. Consequently, counts may serve as the most efficient metric for describing coarse wood loads in small streams. ...
The importance of coarse wood to aquatic biota and stream channel structure is widely recognized, yet characterizations of large-scale patterns in coarse wood dimensions and loads are rare. To address these issues, we censused instream coarse wood (>= 2 m long and >= 10 cm minimum diameter) and sampled riparian coarse wood and channel characteristics in and along 13 streams in western Montana. Instream coarse wood tended to be shorter but of larger diameter than riparian pieces, presumably because of fluvial processing. Instream coarse wood also displayed highly variable spatial patterns. Most segments lacked significant spatial correlation in coarse wood abundance in adjacent 50 m reaches and when present, coarse wood patch sizes (100-1200 m) were specific to particular streams. Estimation of instream and riparian piece dimensions within 25% of the mean required samples of 13-314 pieces, whereas estimation of wood loads instream segments required samples of 8-210 reaches (400-10 500 m). If these results are representative of other systems, few previous studies have used sample sizes adequate to characterize instream coarse wood loads. (c) 2006 Elsevier B.V. All rights reserved.
... In the cedar/ hemlock forests of the Northern Rocky Mountains an average of 66 Mg per ha (29.4 tons per acre) of CWD has accumulated. In the ponderosa pine forests an average of 23 Mg per ha (10.3 tons per acre) of CWD has accumulated (Brown and See 1981). During the last 100 years, the fire frequencies in all of the Rocky Mountain ecosystems have been greatly extended, potentially increasing CWD accumulations. ...
Coarse woody debris is a major component of Rocky Mountain forests. Debris has many functions ranging from soil protection to wildlife and microbial habitat. The management of coarse woody debris is critical for maintaining functioning ecosystems in the Rocky Mountains. These forests have great diversity, with each forest habitat type developing and retaining different amounts of debris. Fourteen habitat types were examined, ranging from ponderosa pine (Pinus ponderosa) habitat types of Arizona to subalpine fir (Abies asiocarpa) habitat types of western Montana. Coarse woody debris management recommendations were developed by using ectomycorrhizae as a bioindicator of healthy, productive forest soils. These recommendations are intentionally conservative to ensure that enough organic matter is available after timber harvest to maintain long-term forest productivity.
... After the monsoons end in September and October there is another peak in fire activity, though fires occur throughout the growing season (Grissino-Mayer et al. 2004). Further north in the Rocky Mountains, monsoon weather has less impact and fires are most common in July (Brown e Typical fuel loads in mixed conifer forests based on inventories of ten national forests in the Northern Rocky Mountains averaged 9.6 tons per acre (Brown and See 1981 (Robertson andBowser 1999, Baker et al. 2007). Brown and colleagues (2003) recommend retaining 5 to 10 tons per acre of CWM in warm-dry ponderosa pine-Douglas-fir types and 10 to 20 tons per acre of CWM in cool Douglas-fir types. ...
The goal of this guide is to provide a resource for managers of mixed conifer forests of the Southwestern plateaus and uplands, the Central and Southern Rocky Mountains, the Sierra Nevada, and the Transverse and Peninsular Ranges in Southern California. Mixed conifer forests have different species, structures, and spatial patterns in these regions but, in general, we focus on forests with a mix of ponderosa or Jeffrey pine, Douglas-fir, true firs, and aspen. The guide includes a comprehensive review of historic conditions, past land use, natural fire regimes, impacts of altered fire regimes, and future prospects, given climate change, for mixed conifer forests. The second half of the guide addresses fuels treatment objectives, techniques, barriers, and successes across a range of ownerships. Before Euro-American settlement of the West, fires in mixed conifer forests burned on intervals that averaged between eight and 25 years for the Sierra Nevada, Southern Rockies, and Southwestern mixed conifer. Low-severity fires were more frequent in some mixed conifer forests; but, in general, mixed conifer forests have historically tended to be heterogeneous mixtures in which species composition, forest structure, and fuel loads change over short distances. Since Euro-American settlement, many mixed conifer forests have become more homogeneous and can therefore facilitate larger, higher-severity fires than those that occurred historically. Increasing heterogeneity in mixed conifer forests at the landscape scale to approximate historic conditions is important for achieving many management objectives, from fuel reduction to wildlife habitat. Restoration and wildfire hazard reduction are not synonymous, but restoration treatments can reduce the risk of uncharacteristic high-severity fire, i.e., standreplacing fire covering a large portion of the landscape. This report discusses prescribed fire, silvicultural treatments, and combinations of cutting and burning. In most mixed conifer forests, thinning that treats both the canopy and understory (crown and low thinnings) combined with prescribed fire is the most effective way to reduce wildfire hazard. However, land management objectives or external constraints can make other tools, such as mastication or prescribed fire alone, more appropriate. Treatments must be maintained for their fuel reduction effect to be sustained, and no single treatment will reverse a long history of fire exclusion. After about ten years, fuels begin building up towards pretreatment levels in many mixed conifer forests. Interviews with 75 managers and experts helped identify numerous complications and barriers to implementing fuels treatments in mixed conifer forests. Smoke management and wildlife habitat protections are two common issues that can make these treatments more complicated, though not impossible. This report also discusses institutional challenges, such as the loss of local expertise and experience with fire that occurs with retirement. Another institutional challenge to returning natural mixed-severity fire regimes that include patches of high-severity fire to mixed conifer landscapes is the need to build confidence within an organization. Organizations and the public can be wary of prescriptions that include patches of high-severity fire, but landscape-level treatments that reduce wildfire hazard and increase the ability to control fires help build confidence that prescribed mixed-severity fires can be implemented safely.
... Surface fuel loads are notoriously diicult to predict because variability is very high across a landscape and even within a stand. Reinhardt et al. (2010) quoted Brown and See (1981), who analyzed fuel data from thousands of plots in the Rocky Mountains and found that " very little of the observed variation in loading was explained by any of the factors " such as stand age, aspect, slope, elevation, habitat type, and cover type. erefore, it is very diicult to predict how fast surface fuels will accumulate aer a fuel treatment. ...
Dry forests of the western United States have been
altered by long-term fire exclusion, resulting in a
more dense forest structure and an increased risk of
crown fire. Recently, thinning and prescribed fire
treatments have been implemented in these forests
for two main reasons: ecological restoration and
fire hazard reduction. Ecological restoration is a
holistic endeavor that focuses on restoring ecological
patterns, processes, and functions. Ecological
restoration goals often include restoring the process
of fire to forested ecosystems and changing forest
structure to fall within the historical range of
variability as indicated by reference information.
While fire hazard reduction is often a goal or an
outcome of ecological restoration, not all treatments
specifically designed to reduce fuels also restore
ecosystem patterns, processes, and functions
(Reinhardt et al. 2008). Fire hazard reduction
treatments are designed specifically to reduce fire
intensity, reduce fire severity, and increase the ability
of firefighters to control wildfires (Table 1).
Fuel treatments are common and are generally
regarded as beneficial for reducing fire behavior,
as well as for ecological reasons such as increasing
understory diversity and reducing competition
among trees for nutrients and water. What remains
unclear is how long such fuel treatments are effective
in reducing undesirable fire behavior. This working
paper addresses the following management questions
regarding fuel treatment longevity: What factors
influence fuel treatment longevity? How long will fuel
treatments last before sites need to be retreated? Do
some types of treatments last longer than others?
... In terrestrial environments there are several trends in which the quantity of wood can vary in association with forest age, forest stand dynamics and in response to natural disturbances (Feller 2003). In forest types similar to the southcentral interior of British Columbia, Brown and See (1981) identified three different temporal patterns of wood loading in different lodgepole pine (Pinus contorta) forests in western Montana and Northern Idaho. The first pattern involved an increasing amount of wood as the forest aged, with peak loads occurring in old-growth forest stands. ...
... While the importance of woody detritus to the ecological health of many forested ecosystems is undeniable, it is also recognized that in seasonally dry forests a balance is necessary so that excessive fire hazard does not result (Brown and See, 1981; Brown et al., 2003; Lehmkuhl et al., 2007 ). A substantial proportion of lightingignited fires start in snags (Komarek, 1968 ). ...
... The biophysical environment is important because site-related ecological processes such as productivity, decomposition, and fire regime often govern fuel loadings and fuel characteristics (Brown and Bevins 1986). Species composition is important because branchfall and leaffall rates are unique to many forest and range communities and their accumulation rates coupled with varied woody morphology can create unique fuelbed characteristics See 1981, Brown andBevins 1986). Stand structure is critical because it describes the vertical arrangement of live and dead biomass above the ground surface (O'Hara et al. 1996). ...
Fuel input layers for the FARSITE fire growth model were created for all lands in and around the Gila Na-tional Forest, New Mexico, using satellite imagery, terrain modeling, and biophysical simulation. FARSITE is a spatially explicit fire growth model used to predict the growth of wildland fires in terms of size, intensity, and spread. It requires eight data layers as input; fire behavior fuel model, crown closure, crown base height, stand height, crown bulk density, eleva-tion, aspect, and slope. These input layers were cre-ated from a digital terrain model (elevation, aspect, and slope) and from base vegetation layers of biophysi-cal settings, cover type, and structural stage using a methodology designed to be easily replicated by other fire management agencies. Biophysical settings de-scribe long-term environmental conditions and this layer was created from a vegetation-based potential vegetation type classification modeled from hierarchi-cal topographic rulebase terrain models. Cover type and structural stage layers were created from 1993 and 1997 satellite Thematic Mapper (TM) imagery of southwestern New Mexico. Fire behavior fuel models were assigned to each biophysical setting, cover type and structural stage category combination from an analysis of comprehensive field databases created by extensive plot sampling of the entire study area. An extensive accuracy assessment of the layers showed accuracy ranges from 25 to 87 percent for the poten-tial vegetation type, cover type, and structural stage layers. Accuracy for the crown and surface fuels lay-ers is between 40 to 70 percent. This paper was written and prepared by US Govern-ment employees on official time and therefore is in the public domain and not subject to copyright. The use of trade or firm names in the publication is for reader information and does not imply endorsement by the U. S. Department of Agriculture of any product or ser-vice.
... The fuel map was derived from a national land cover characteristics map produced by the Earth Resources (EROS) Data Center (Loveland and others 1991). Because the classification is well defined, the fuel type map can be used for ignition probability estimation, including duff depth (Brown and See 1981). Fuel moisture is also available from WIMS. ...
The Authors Don Latham received his B.A. degree in physics from Pomona College in 1960. In 1964 and 1967 , he received the M.S. and Ph.D. degrees in earth science, specializing in atmospheric electricity and weather radar . He subsequently taught these and other subjects in atmospheric science in the Rosenteil School of Marine and Atmospheric Sciences of the University of Miami, FL. While there, he held grants from the National Science Foundation and the U.S. Air Force. In 1976, he moved to the Northern Forest Fire Laboratory of the USDA Forest Service's Intermountain Research Station where he began work on ignition of forest fuels by lightning discharges and the location of lightning discharges. He has.Ior the past 10 years, also been working in the field of artificial intelligence, particu larly as applied to fire sciences and related fields. He is currently studying wind-fire interact ion.
... The parameters of a fuel model are fuel loading (the mass of the fuel per unit area), surface-to-volume ratio (representing the reactivity of fuels to fire), fuel depth, a percentage of extinction moisture beyond which fire does not spread, and heat content (heat of combustion) of the dead and live fuel. Fuel loading is divided into the standard fuel classification system of the U.S. Forest Service (Brown 1974, andBrown andSee 1981): 1 hour fuels (Mg/ha, <0.6 cm in diameter of fuels), 10 hour fuels (Mg/ha, >0.6 and <2.5 cm in diameter), 100 hour fuels (Mg/ha, >2.5 and <7.5 cm in diameter), and 1000 h fuels (Mg/ha, >7.5 cm in diameter). Surface-to-volume ratio represents how fast fuels are burned. ...
... Studies of naturally regenerated forests typically report U-shaped distributions of CWD (Spies et al. 1988;Spies 1997;Sturtevant et al. 1997;Janisch and Harmon 2002;Brais et al. 2005), as was evident for jack pine in our study. Other temporal patterns have also been noted, however, including S curves (Hely et al. 2000;Martin et al. 2005), inverted-U shapes (Brown and See 1981), a mirrored-J shape (Duvall and Grigal 1999), or linear increases over time (Hely et al. 2000). Occasionally, stands exhibit no clear temporal pattern at all, as seen in red pine stands in our study and naturally regenerated Scots pine (Pinus sylvestris L.) stands in Karelia (Karjalainen and Kuuluvainen 2002). ...
Boreal forests are thought to store more than 30% of the world’s terrestrial carbon (C), much of it in the form of dead wood. Harvesting, stand transformation, and climate change the storage capacity of this carbon pool and improved quantification of C storage is needed to improve the accuracy and coverage of C accounting in Canadian forests. In this study, we compared wood volumes and C storage in coarse woody debris (CWD), fine woody debris (FWD), and standing dead wood (snags) in a 94-year chronosequence of jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) stands in the Sandilands Provincial Forest, southeastern Manitoba. In our data set of 20 jack pine and 17 red pine stands, jack pine stands supported higher volumes of CWD, snags, and sparsely distributed FWD than red pine stands. Mean CWD volume and C mass were, respectively, 18.6 m3·ha−1 and 2.6 tonnes (t)·ha−1 for jack pine and 11.3 m3·ha−1 and 1.1 t·ha−1 for red pine. Snag volumes and C mass were, respectively, 1.8 m3·ha−1 and 0.25 t·ha−1 for jack pine and 0.26 m3·ha−1 and 0.04 t·ha−1 for red pine. CWD loads in jack pine stands followed a U-shaped distribution with stand age, and snag loads in jack pine increased linearly with time. No such significant trends for CWD or snags were observed in red pine. Our results confirm that stand conversion from fire-origin jack pine to red pine plantations has the potential to significantly reduce and alter temporal patterns of dead wood accumulation across the landscape.
... Hence, it is common to measure it indirectly using line-intercept methods. Having made the decision to indirectly measure wood, one has several choices: to convert the intercept data into volume or mass using either locally or literature-derived functions (e.g., Brown and See 1981), or simply to use the intercept data directly. Clearly, the least error will be associated with using the data directly, therefore the decision as to whether to convert the data is based on the reliability of the equations and the importance of the conversion. ...
The use of indices to evaluate small-mammal populations has been heavily criticized, yet a review of small-mammal studies published from 1996 through 2000 indicated that indices are still the primary methods employed for measuring populations. The literature review also found that 98% of the samples collected in these studies were too small for reliable selection among population-estimation models. Researchers therefore generally have a choice between using a default estimator or an index, a choice for which the consequences have not been critically evaluated. We examined the use of a closed-population enumeration index, the number of unique individuals captured (Mt+1), and 3 population estimators for estimating simulated small populations (N = 50) under variable effects of time, trap-induced behavior, individual heterogeneity in trapping probabilities, and detection probabilities. Simulation results indicated that the estimators produced population estimates with low bias and high precision when the estimator reflected the underlying sources of variation in capture probability. However, when the underlying sources of variation deviated from model assumptions, bias was often high and results were inconsistent. In our simulations, Mt+1 generally exhibited lower variance and less sensitivity to the sources of variation in capture probabilities than the estimators.L'utilisation d'indices pour évaluer les populations de petits mammifères est très critiquée et pourtant les études publiées entre 1996 et 2000 sur les petits mammifères démontrent que l'utilisation d'indices est toujours la méthode la plus courante d'évaluation des populations. Dans la littérature, 98 % des échantillons recueillis pour les études étaient trop petits pour permettre le choix judicieux d'un modèle d'estimation de population. Les chercheurs se retrouvent donc devant un choix à faire entre une méthode par défaut ou un indice, choix dont les conséquences n'ont pas été évaluées de façon formelle. Nous avons examiné les résultats de l'utilisation d'un indice de dénombrement d'une population fermée, du nombre d'individus particuliers capturés (Mt+1), et de 3 estimateurs de population pour estimer de petites populations simulées (N = 50) soumises à des effets divers du temps, du comportement relié au piégeage, de l'hétérogénéité dans la probabilité de capture des individus et des probabilités de détection. Les résultats de cette simulation ont démontré que les estimateurs donnent des évaluations qui comportent peu d'erreur et qui sont d'une grande précision lorsque l'estimateur utilisé reflète les sources de variation sous-jacentes des probabilités de capture. Cependant, lorsque les sources de variation sous-jacentes s'éloignent des présuppositions du modèle, les chances d'erreur sont souvent élevées et les résultats sont changeants. Dans nos simulations, Mt+1 a généralement une faible variance et manifeste moins de sensibilité aux sources de variation des probabilités de capture que les autres estimateurs.[Traduit par la Rédaction]
... The median amount of coarse woody debris >7.6 cm that is expected to be on the ground is 64.2 Mg/ha (MAD = 28.5). The historical range of coarse downed woody debris loads found in Montana lodgepole pine forests is suggested to be 27-58 Mg/ha (Brown and See, 1981). However, Tinker and Knight (2000) reported higher amounts of coarse woody debris, including snags, in lodgepole pine forests; a range of 41-284 Mg/ha for burned lodgepole pine stands in Yellowstone National Park, Wyoming and 52-123 Mg/ha for previously clearcut stands in the Medicine Bow National Forest, WY. ...
Lodgepole pine (Pinus contorta Dougl. ex Loud.)-dominated ecosystems in north-central Colorado are undergoing rapid and drastic changes associated with overstory tree mortality from a current mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak. To characterize stand characteristics and downed woody debris loads during the first 7 years of the outbreak, 221 plots (0.02 ha) were randomly established in infested and uninfested stands distributed across the Arapaho National Forest, Colorado. Mountain pine beetle initially attacked stands with higher lodgepole pine basal area, and lower density and basal area of Engelmann spruce (Picea engelmannii [Parry]), and subalpine fir (Abies lasiocarpa (Hook.) Nutt. var. lasiocarpa) compared to uninfested plots. Mountain pine beetle-affected stands had reduced total and lodgepole pine stocking and quadratic mean diameter. The density and basal area of live overstory lodgepole declined by 62% and 71% in infested plots, respectively. The mean diameter of live lodgepole pine was 53% lower than pre-outbreak in infested plots. Downed woody debris loads did not differ between uninfested plots and plots currently infested at the time of sampling to 3 or 4–7 years after initial infestation, but the projected downed coarse wood accumulations when 80% of the mountain pine beetle-killed trees fall indicated a fourfold increase. Depth of the litter layer and maximum height of grass and herbaceous vegetation were greater 4–7 years after initial infestation compared to uninfested plots, though understory plant percent cover was not different. Seedling and sapling density of all species combined was higher in uninfested plots but there was no difference between infested and uninfested plots for lodgepole pine alone. For trees ≥2.5 cm in diameter at breast height, the density of live lodgepole pine trees in mountain pine beetle-affected stands was higher than Engelmann spruce, subalpine fir, and aspen, (Populus tremuloides Michx.), in diameter classes comprised of trees from 2.5 cm to 30 cm in diameter, suggesting that lodgepole pine will remain as a dominant overstory tree after the bark beetle outbreak.
... Forests of the northern Rockies had stocks of DWM biomass/C nearly equivalent to those of the Pacific Northwest, but with FWD representing a greater proportion of total DWM. Fire can reduce the DWM biomass in these forests (Brown and See, 1981); however, the cold and/or dry environments of the northern Rockies may slow decomposition allowing CWD accumulation (Kueppers et al., 2004). Recent mortality in this region due to drought and beetle infestation (Klutsch et al., 2009) may be reflected in this study's estimates of DWM for this region. ...
... Fuel loading categories include four downed woody size classes, live and dead shrub and herbaceous biomass, duff and litter depth, and crown fuel characteristics. Many studies have noted that high variation of fuel loading across temporal and spatial scales often precludes correlations with vegetation characteristics (see Bevins 1986 andSee 1981). We examined this variance across and between fuel categories to identify clusters of fuel loading that might facilitate fire effects fuel model mapping. ...
... Errors identified by the software have been corrected; however, some errors may remain. Table 1-Average downed woody loadings, duff depths, and percentages rotten from the Forest Inventory by cover type for east and westside National Forests of the Northern Rocky Mountains (Brown and See 1981) ...
Forest management is at a critical juncture. Concepts and strategies for managing forests to produce goods and services, yet maintain functioning visually pleasing forests, are being debated, developed, and implemented. A well designed and implemented silvicultural system is basic to good forest management. Means of protecting soil and all factors affecting soil properties must be integrated into sil vicultural systems. Inappropriate silvicultural techniques can degrade forest productivity especially by compacting, displacing, or destroying soil surface layers rich in organic matter. Because both short- and long-term productivity can be influenced by changes in these layers, we make several recommendations on how to protect soil when developing prescriptions for any silvicultural system.
... If the variation we encountered is typical of streams in other regions, few studies have measured coarse wood with sufficient intensity to reasonably characterize mean volume of pieces or total volume in segments. Biomass estimation may be even more problematic because wood density varies with species, age, and stage of decomposition (Brown and See, 1981;Hardy, 1996), which are rarely assessed. Consequently, counts may serve as the most efficient metric for describing coarse wood loads in small streams. ...
Coarse wood is widely recognized as a critical component of aquatic environments in forested ecosystems and fundamental to fish habitat formation, diversity, and stability, as well as sediment dynamics, hydrologic response, and channel complexity. Its significance has resulted in prescriptions for coarse wood abundance in streams, yet few studies have addressed the spatial variation in coarse wood counts and volumes, with many relying on samples taken from reaches of a few hundred meters. To examine these patterns and relations at the scale of individual pieces and in consecutive 50-m reaches, we continuously censused channel large wood and at 250-m intervals sampled riparian large wood along 1- to 5-km reaches in 13 western Montana basins with varying disturbance histories. Although most coarse wood in channels appeared to originate from riparian zones, frequency distributions of dimensions of channel coarse wood compared to those of riparian pieces indicated substantial in-stream processing. Despite apparent transport of coarse wood shorter than bankfull width in nearly all streams, frequency distributions of counts and volumes of channel coarse wood tended to be normal. Surprisingly, in most streams there was no correlation among counts or among volumes of wood in adjacent 50-m reaches, and although correlograms revealed large-scale coarse wood patches in several streams, patch size was unique to each stream. Finally, relations in piece counts (and volumes) between channels and riparian zones were erratic. Sample sizes necessary to estimate mean length and maximum diameter of individual pieces within 25% of the mean were modest (fewer than 30 pieces in most basins), whereas estimating piece volume required sampling over 150 pieces. To characterize coarse wood abundance with similar precision on average required sampling over 1.3 km of stream; to characterize volume required sample sizes exceeding 2.7 km. Consequently, we regard estimates from short stream reaches as unreliable predictors of total coarse wood abundance. Similarly, models predicting coarse wood abundance based on such estimates likely underestimate variation and may yield unrealistic results.
... 1931 fire origin stand comprising an overstory dominated by jack pine and, to a lesser extent, black spruce with a well-developed black spruce understory. Although the forest generally appeared uniform, there was a certain degree of spatial variation, as is inherent in any natural forest stand (Sackett 1979; Brown and See 1981). Nevertheless, it was possible to characterize the ICFME fuel complex as follows. ...
... The FEFM's were assigned to each PVT, cover type, structural stage combination based on the ground-truth data collected for this project and on fire manager assessments. Fuel loading data from Brown and Bevins (1986) and Brown and See (1981) were used to adjust some fire effects fuel models to agree with the PVT, cover type, structural stage descriptions. ...
Fuel and vegetation spatial data layers required by the spatially explicit fire growth model FARSITE were developed for all lands in and around the Selway-Bitterroot Wilderness Area in Idaho and Montana. Satellite imagery and terrain modeling were used to create the three base vegetation spatial data layers of potential vegetation, cover type, and structural stage. Fire behavior fuel models and crown characteristics were assigned to combinations of base layer categories on these maps by local fire managers, ecologists, and existing data. FARSITE fuels maps are used to simulate growth of prescribed natural fires in the wilderness area, aiding managers in the planning and allocation of resources. An extensive accuracy assessment of all maps indicated fuels layers are about 60 percent accurate. This methodology was designed to be replicated for other areas.
... The most difficult problem in mapping fuels accurately is their high variability across space (Brown and See, 1981). Extensive field data are therefore required to characterize fuel variability adequately ( Figure 10). ...
Will the global community promote actively the alliances between the natural and social sciences required to manage wildland fire effectively? We must to achieve this alliance integrate fire, climate and society variables. Meeting grand challenges in remote sensing and geographic information science (GIS) define first steps toward wildland fire management. The grandest challenge of all is, however, integrated decision support that empowers people and fire to co-exist, thus stabilize atmospheric processes and benefit from the renewal fire brings to natural systems. A Fire-Climate-Society (FCS) prototype uses the Analytical Hierarchy Process (AHP) to bring together suites of fire probability variables (e.g., fuel moistures; lightning and human ignition probabilities) and societal values at risk (e.g., property; recreation; endangered species). Resulting maps create consensus on high priority fuel treatment areas.
... Hence, it is common to measure it indirectly using line-intercept methods. Having made the decision to indirectly measure wood, one has several choices: to convert the intercept data into volume or mass using either locally or literature-derived functions (e.g., Brown and See 1981), or simply to use the intercept data directly. Clearly, the least error will be associated with using the data directly, therefore the decision as to whether to convert the data is based on the reliability of the equations and the importance of the conversion . ...
The use of indices to evaluate small-mammal populations has been heavily criticized, yet a review of small-mammal studies published from 1996 through 2000 indicated that indices are still the primary methods employed for measuring populations. The literature review also found that 98% of the samples collected in these studies were too small for reliable selection among population-estimation models. Researchers therefore generally have a choice between using a default estimator or an index, a choice for which the consequences have not been critically evaluated. We examined the use of a closed-population enumeration index, the number of unique individuals captured (Mt+1), and 3 population estimators for estimating simulated small populations (N = 50) under variable effects of time, trap-induced behavior, individual heterogeneity in trapping probabilities, and detection probabilities. Simulation results indicated that the estimators produced population estimates with low bias and high precision when the estimator reflected the underlying sources of variation in capture probability. However, when the underlying sources of variation deviated from model assumptions, bias was often high and results were inconsistent. In our simulations, Mt+1 generally exhibited lower variance and less sensitivity to the sources of variation in capture probabilities than the estimators.
... Unlike fine fuels, coarse fuels are not derived using species-specific age cohorts. Instead, stand age (the oldest age cohorts) in combination with disturbance history (time since last disturbance) is used to determine the coarse fuel accumulation for a cell (Brown and See 1981, Harmon et al. 1986, Spetich et al. 1999, Spies et al. 1988, Sturtevant et al. 1997. Coarse fuel amount is the interplay between input and decomposition (Spies et al. 1988, Sturtevant et al. 1997. ...
... Downed wood pieces ≥ 3 inch were classified as either sound or rotten and we used the specific gravities provided by Brown (1974) to obtain a weight estimate for each condition class. That is, we used 24.96 lbs/ft 3 and 18.72 lbs/ft 3 for sound and rotten wood, respectively, relative to the density of water (62.4 lbs/ft 3 ) (Brown and See 1981). Here, we present results for downed wood in four size categories: (1) < 3 inch; (2) ≥ 3 inch; ...
Most prescribed fi re plans focus on reducing wildfi re hazards with little consideration given to effects on wildlife populations and their habitats. To evaluate effectiveness of prescribed burning in reducing fuels and to assess effects of fuels reduction on wildlife, we began a large-scale study known as the Birds and Burns Net- work in 2002. In this paper we analyze changes in downed wood and forest structure (trees and snags) measured within one year after prescribed fi re treatments that were completed in ponderosa pine (Pinus ponderosa) forests in Arizona and New Mexico (Southwest region), and Idaho and Washington (Northwest region). Apparent reductions in downed wood and trees were observed in both regions. However, statistically signifi - cant reductions of downed wood were found primarily in the Northwest (p < 0.001), whereas signifi cant reductions of trees were reported only for the Southwest (p = 0.03). No signifi cant post-treatment changes were detected in snag densities, although we observed a pattern of non-signifi cant increases in all size classes. Additional fi re treat- ments are likely needed to meet fuels reduction goals. Results of this study are intended to assist managers with developing scientifi cally sound and legally defensible prescribed fi re projects that will reduce fuels and concurrently enhance wildlife habitat.
... Unburned spruce-fir forests in Colorado had 120-135 t ha -1 of stem mass (Landis and Mogren 1975) that would become coarse woody debris if the stand burned. On old-growth spruce-fir sites, where lodgepole pine mortality adds a new cohort of coarse woody debris, log biomass may exceed 100 t ha -1 (Brown and See 1981), and much of that will remain after fire passes through the stand. In these environments, decay is slow, so that 50-100 years after the fire, some snags and many logs still reflect the fire evidence (Agee and Smith 1984). ...
Disturbance dynamics differ in the three subregions of the North American boreal forest (taiga, western United States, and eastern United States) where lynx are found, resulting in a range of potential effects on lynx populations. Fire severity tends to be high in most of the forest types where lynx habitat occurs, although subsequent succession will differ among the subregions. Other distur- bance dynamics involve insects, disease, wind, and human ownership and use, such as logging, mining, agriculture, and fire suppression. The author addresses three general lynx management implications based on disturbance dynamics.
Aim of study: To evaluate the effects of two different prescribed burning strategies on ectomycorrhizal (ECM) fungal species in Pinus cubensis-dominated natural forest.
Area of study: Yateras Silvicultural Base Business Unit, Guantánamo, Cuba.
Material and methods: In June 2015, six plots (20 × 50 m) were subjected to forward or back burning. Nine interval samplings (performed 1 week before and up to 120 days after prescribed burning) were undertaken to determine the total number of sporocarps and to evaluate the effect of fire on the soil.
Main results: Eight ECM species were collected from the study plots. Suillus sp. and Amanita muscaria started fruiting 15 and 60 days after the fire, respectively. Boletus sp., Suillus brevipes, Suillus decipiens, Suillus sp., Amanita muscaria, Lactarius semisanguifluus, Scleroderma stellatum and Pisolithus arhizus were found before and after prescribed burning. Sporocarp numbers showed an increasing trend after fire and significantly recovered 75 days after forward or back burning and were significantly higher 120 days after forward burning compared to unburned plots. The ECM fungal community in the heading fire and the backfire plots did not differ significantly. However, non-metric multidimensional scaling confirmed that ECM composition differed over time. According to a Mantel test, the sampling time after prescribed burning accounted for 64% of the variation in ECM composition, followed by edaphic factors (26%) such as organic matter and Na.
Research highlights: This preliminary study suggests that low-intensity prescribed burning does not have a negative effect on ECM fungal dynamics in humid tropical forests.
In January 2020, the Wildland Fire Leadership Council (WFLC) requested that EPA, in collaboration with scientific staff in the U.S. Forest Service (USFS), the Department of the Interior (DOI) and the National Institute of Standards and Technology (NIST), conduct an assessment of air quality and health impacts of prescribed fire compared to wildfire. This assessment is described in the final report, Comparative Assessment of the Impacts of Prescribed Fire Versus Wildfire (CAIF): A Case Study in the Western U.S.
The CAIF report is organized as follows:
Executive Summary
Chapter 1: Introduction
Part I: Conceptual Framework, Background, and Context
Chapter 2: Conceptual Framework for Evaluating and Comparing Different Fire Management Strategies
Chapter 3: Fire Regimes, Fire Effects, and a History of Fuels and Fire Management in the Western U.S.
Chapter 4: Air Quality Monitoring of Wildland Fire Smoke
Chapter 5: Direct Damages from Wildland Fire
Chapter 6: Health and Ecological Effects of Wildland Fire Smoke Exposure
Part II: Quantitative Assessment of Smoke Impacts of Wildland Fire in Case Study Areas
Chapter 7: Air Quality Modeling of Case Study Fires
Chapter 8: Estimated Public Health Impacts of Smoke from Case Study Fires
Chapter 9: Integrated Synthesis
Stand-level forest structure varies spatially and surface fuels would be expected to vary as well. We measured surface fuel deposition and decomposition within old-growth Jeffery pine (Pinus jeffreyi Balf.)-mixed conifer forests to quantify rates of change and examine relationships with overstory structure and composition. Annual fuel deposition ranged from 0.7 to 20.1 Mg ha−1 for litter and 0.2 to 0.8 Mg ha−1 for woody fuels, exhibiting large temporal and spatial variation, and corresponded with annual precipitation during the study period. Surface fuel deposition had high spatial heterogeneity and was predicted by stand structure such as basal area and canopy cover, particularly for litter deposition, which was the main contributor to total fuel loadings in this system. Jeffery pine litter decomposition rate of 7 to 11% yr−1 over the six-year study period is among the lowest compared to other conifer forests in western North America. Two sites were distinguished by edaphic and structural characteristics, but exhibited similarities in fuels dynamics. Incorporating within-stand variation into fuel modeling could improve the accuracy in predicting fire behavior, fire effects, and stand progression.
We compared the potential fire behavior and smoke production of historical and current time periods
based on vegetative conditions in forty-nine 5100- to 13 5OO-hectare watersheds in six river basins in
eastern Oregon and Washington. Vegetation composition, structure, and patterns were attributed and
mapped from aerial photographs taken from 1932 to 1959 (historical) and from 1981 to 1992 (current).
Vegetation with homogeneous composition and structure were delineated as patches. Each patch was
assigned a potential rate of spread, flame length, fuel loading, and smoke production from published
information that matched the closest characteristics of the vegetation and downed fuels and assigned a
uniform fuel moisture, wind speed, and slope. Potential rate of spread of fire, flame length, and smoke
production were highly variable among sample watersheds in any given river basin. In general, rate of
spread and flame length were positively correlated with the proportion of area logged in the sample
watersheds. There were large increases in potential smoke production from the historical to the current
periods for many sample watersheds due to changes in fuel loadings associated with management activities
and, presumably, fire suppression. Wildfires were shown to produce nearly twice the amount of smoke as
prescribed fire for the current period for all river basins. Understanding these and other tradeoffs will
assist managers and society in making informed decisions about how to implement prescribed fire and
manage wildfire to address air quality and forest health problems. Because of the variability of fuel or
vegetative conditions observed among the sample watersheds, we recommend an extensive
characterization of these conditions before large-scale restoration and maintenance of fire-related processes
are undertaken.
multiple use management of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and National Grasslands, it strives—as directed by Congress—to provide increasingly greater service to a growing Nation. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, 1400
Litter loading in first rotation P. pinaster stands on high quality sites can increase by more than 4 t/ha a year and early results indicate that this accumulation continues in second rotation stands.The accumulation of litter aggravates the fire hazards and increased problems with accessibility will make silvicultural treatments more expensive. Nutritional problems may also develop on marginal sites.Where these problems have been identified, serious consideration should be given to litter reduction by the use of controlled burning.
Coarse woody debris (CWD) is an important component of temperate stream and forest ecosystems. This chapter reviews the rates at which CWD is added and removed from ecosystems, the biomass found in streams and forests, and many functions that CWD serves. CWD is added to ecosystems by numerous mechanisms, including wind, fire, insect attack, pathogens, competition, and geomorphic processes. Despite the many long-term studies on tree mortality, there are few published rates of CWD input on mass-area-1 time-1 basis. CWD is significantly transformed physically and chemically. Movement of CWD, especially in streams, is also an important but poorly documented mechanism whereby CWD is lost from ecosystems. Many factors control the rate at which CWD decomposes, including temperature, moisture, internal gas composition of CWD, substrate quality, size of CWD, and types of organisms involved. However, the importance of many of these factors has yet to be established in field experiments. CWD performs many functions in ecosystems, serving as autotrophic and heterotrophic habitat and strongly influencing geomorphic processes, especially in streams. It is also a major component of nutrient cycles in many ecosystems and is an important functional component of stream and forest ecosystems.
Publisher Summary
This chapter reviews the rates at which Coarse Woody Debris (CWD) is added and removed from ecosystems, the biomass found in streams and forests, and many functions that CWD serves. CWD is an important component of temperate stream and forest ecosystems and is added to the ecosystem by numerous mechanisms, including wind, fire, insect attack, pathogens, competition, and geomorphic processes. Many factors control the rate at which CWD decomposes, including temperature, moisture, the internal gas composition of CWD, substrate quality, the size of the CWD, and the types of organisms involved. The mass of CWD in an ecosystem ideally represents the balance between addition and loss. In reality, slow decomposition rates and erratic variations in input of CWD cause the CWD mass to deviate markedly from steady-state projections. Many differences correspond to forest type, with deciduous-dominated systems having generally lower biomass than conifer-dominated systems. Stream size also influences CWD mass in lotic ecosystems, while successional stage dramatically influences CWD mass in boat aquatic and terrestrial settings. This chapter reviews many of these functions and concludes that CWD is an important functional component of stream and forest ecosystems. Better scientific understanding of these functions and the natural factors influencing CWD dynamics should lead to more enlightened management practices.
Presents procedures for inventorying weight per unit area of living and dead surface vegetation.-from STAR, 21(12), 1983
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