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Vole Use of Coarse Woody Debris and Implications for Habitat and Fuel Management
Abstract
Woody debris is an increasing management focus in forests, representing multiple and sometimes conflicting values. Fuel management may prioritize removal of coarse woody debris (CWD) to minimize wildfire occurrence, intensity, or both. Conversely, management for wildlife habitat or other ecological values often focuses on retention of CWD. We modeled and quantified CWD use by red-backed voles (Clethrionomys gapperi), tested whether voles move selectively in portions of forest stands with greater CWD, and correlated stand-level measures of CWD as habitat to fuel loads, providing a basis of comparison for CWD quantitative guidelines. Voles used CWD at a greater rate than expected based on availability and traveled in portions of stands with greater CWD coverage (21-27 trails made by individual voles in each of 5 forest stands). A strong correlation between stand-measure CWD coverage and fuel-load measure (r = +0.96) provides a basis for comparing CWD guidelines. We concluded that current guidelines from different research fields disagree. Only 2 of the 5 stands we sampled fit with guidelines for fuel management and ectomycorrhizae in the northern Rocky Mountains. Coarse woody debris coverage in all of our stands was well below recommendations for small mammals in coastal forests.
... The authors in [60] used CWD coverage for modelling the temporal and spatial dynamics affected by various clearcutting and fire regimes over a 1000-yr period. The coverage of WD was also evaluated in studies dealing with the activities of small mammals [61,62]. Greater coverage of CWD increased the occurrence of red-backed voles (Clethrionomys gapperi) [62]. ...
... The coverage of WD was also evaluated in studies dealing with the activities of small mammals [61,62]. Greater coverage of CWD increased the occurrence of red-backed voles (Clethrionomys gapperi) [62]. The authors in [61] recommended coverage of downed CWD between 15 and 20 percent for favouring communities of small animals. ...
... Deadwood coverage values, which were found in our study were either below or at the bottom threshold of the suggested range (mean deadwood coverage values at individual disturbed areas ranged from 7.27% to 17.91%, while coarse woody debris covered between 2.5% and 6.91% of the sample plot area, and fine woody debris covered from 4.77% to 11% (Figure 2)). However, as [62] pointed out, the threshold values of biomass amount depend on the management goal. While diversity studies aim at increasing deadwood, fuel management tends to reduce CWD in forests to minimise the risk of wildfire occurrence and/or intensity. ...
Deadwood is an important component of forests that fulfils many ecosystem functions. The occurrence, amount and spatial distribution of deadwood in forest ecosystems depend on tree species composition, historical development and past management. In this presented study, we assessed the total amount of deadwood, including fine and coarse woody debris at five areas of predominantly broadleaved forests within the University Forest Enterprise of the Technical University in Zvolen, Slovakia that had been disturbed by windstorm Žofia in 2014. Windthrown wood was salvaged between May 2014 and October 2015. In the year 2018, we performed an inventory of deadwood that remained on-site after salvage logging. The mean volume of deadwood recorded at sample plots fluctuated between 35.96 m3/ha and 176.06 m3/ha and mean deadwood coverage values at individual disturbed areas ranged from 7.27 to 17.91%. In the work, we derived several models for the estimation of deadwood volume based on deadwood coverage and/or diameter, which showed that these characteristics are good proxies of deadwood volume. The tests, involving close-range photogrammetry methods for deadwood quantification, revealed that the number of pieces and the coverage of deadwood recorded in photos was significantly lower than the values derived from field measurements.
... We characterized vole habitat with 12 variables that represented anti-predator cover (Ucitel et al. 2003, Pearce & Venier 2005b or reflected food availability for red-backed voles (Orrock & Pagels 2002, Boonstra & Krebs 2006 We measured tree basal area at each feeding station using a 2× prism (Grosenbaugh 1952). Basal area of saplings (m 2 /ha) was estimated from the dbh of saplings (i.e., ≤ 9 cm dbh and ≥ 1.30 m height) in 10 2 × 2 m quadrats, at each feeding station. ...
... According to the asset-protection principle (sensu Clark 1994), voles should display the weakest antipredatory behavior in mesic habitats (Ekman & Ulliendahl 1993, Ydenberg et al. 1995, Olsson & Molokwu 2007. Moreover, forest harvesting generally reduces anti-predator cover (Ucitel et al. 2003, Fuller et al. 2004, which increases predation risk for 97 small-mammals (Morris & Davidson 2000, Verdolin 2006, Eccard et al. 2008). On the basis of changes in habitat quality and availability of anti-predator cover, we predicted that predation costs, i.e. ∆GUD between risky and safe food patches, would increase with logging intensity in xeric habitats (Ucitel et al. 2003, Fuller et al. 2004), but would be less affected and could even decrease with logging intensity in mesic habitats (Clark 1994, Olsson & Molokwu 2007. ...
... Moreover, forest harvesting generally reduces anti-predator cover (Ucitel et al. 2003, Fuller et al. 2004, which increases predation risk for 97 small-mammals (Morris & Davidson 2000, Verdolin 2006, Eccard et al. 2008). On the basis of changes in habitat quality and availability of anti-predator cover, we predicted that predation costs, i.e. ∆GUD between risky and safe food patches, would increase with logging intensity in xeric habitats (Ucitel et al. 2003, Fuller et al. 2004), but would be less affected and could even decrease with logging intensity in mesic habitats (Clark 1994, Olsson & Molokwu 2007. Our results are consistent with these expectations. ...
... Small mammals use CWD for travel pathways, which may help them avoid predators (McCay 2000, Ucitel et al. 2003, Zollner and Crane 2003. It is possible that the low amount of deciduous leaf litter in pine stands, with a concomitant reduction in movement-related noise, may reduce predation risk to small mammals, therefore reducing their dependence on CWD as travel corridors (Roche et al. 1999, McCay 2000. ...
... Standardization of methodology and definition would help make studies directly comparable. Measurements of CWD have been taken using line transects (McCay 2000;Greenberg 2002) and circular plots (Ucitel et al. 2003, Loeb 1999, Fuhrman 2004. Fuhrman (2004) compared the variability of estimates of CWD (including snags) using 0.1-ha circular plots and 71-m transects. ...
... While it is possible that small mammal use of CWD is more or less correlated to its availability (Loeb 1999, Ucitel et al. 2003, neither presence nor abundance of small mammals has yet been firmly tied to CWD levels (Menzel et al. 1999), and, for at least some small mammal species, CWD may have more impact on distribution within stands than on presence or abundance (Greenberg 2002). Consequently, future research should strive to separate obligatory relationships between CWD and small mammals from preferential ones. ...
The conservation of biological diversity is a high priority in managed forests of the southern United States. Forest certification programs require participants to have biodiversity management programs in place supported by up-to-date science and, in some cases, to have guidelines for retention of important stand-level habitat features important to wildlife. To meet this information need, we reviewed the scientific literature for information on relationships between stand-level habitat features and wildlife communities. Within this report, we give definitions and general characteristics of habitat features considered particularly important to wildlife management in southern forests. Because of the prominence of pine plantation management in the southern U.S., particular attention is paid to research performed in southern pine systems. We follow with a comprehensive examination of wildlife relationships to each habitat feature and an analysis of information gaps and research needs. We selected five habitat features for review: coarse woody debris (CWD), snags, den trees, isolated wetlands, and streamside management zones (SMZs). These features have demonstrated potential for impacting diversity, though their contributions in pine systems are not always well-documented. There were indications of other features with potential impact (e.g., fork-topped pines, roads), but there was as yet little evidence of their importance. Coarse woody debris (CWD) is used by a great number of wildlife species; however, few manipulative experiments have been performed in southern pines to determine whether this use is obligatory or facultative. While some species have shown responsiveness to CWD, benefits supplied by pine litter may substantially overlap those supplied by CWD in other forest types. Snags increase wildlife species diversity and richness by providing nesting and roosting sites for cavity-nesting species and foraging sites for insectivores. The effects of snag density are generally well-documented, at least for avian communities; however, the impact of snag distribution on communities of snag-dependent wildlife, both within stands and across the landscape, has not been adequately investigated. Den trees are mostly confined to hardwood species, and can contribute multiple habitat values such as mast and vertical structure. Den users are often highly selective, and may take into account features of the den itself, the immediate habitat, or the surrounding landscape. Den tree research in pine-dominated landscapes is almost completely lacking, and study of den trees in SMZs and retention patches could provide much-needed information regarding optimum density, juxtaposition, and distribution. Isolated wetlands, while individually managed at the stand level, involve definite landscape-scale considerations as well. Species associated with isolated wetlands may spend most of their life cycle in adjacent uplands, requiring knowledgeable management of both wetland and upland to insure their contribution to biodiversity. The impacts of silvicultural practices on communities associated with isolated wetlands are not well known, and most of the research conducted in pine systems is of limited scope. Long-term manipulative experiments, complete with pre-treatment data and adequate replication, are critical to understanding the disturbance regimes to which wildlife communities associated with isolated wetlands in different regions are best suited. Streamside management zones also involve both stand- and landscape-scale consideration. Because they contain a heterogeneous mix of habitat elements not always found in pine plantations, SMZs have the potential to greatly increase biodiversity in pine-dominated landscapes, to provide refuges for disturbance sensitive species, and to serve as population sources for recolonization of disturbed sites. Studies regarding the impact of SMZ width in pine-dominated landscapes have produced inconsistent and even conflicting results, and it seems unlikely that a single recommended width will suffice for all situations. Management of sites adjacent to SMZs may have as much or greater impact than SMZ width. We suggest research goals and methodology to address information gaps and research directions in southern pine forests. Long-term manipulative experiments are encouraged both to increase the power of researchers to test hypotheses and to account for long-term variation in wildlife populations. Wildlife responses to habitat manipulations should be measured using demographic characteristics rather than density alone. Statistical methods such as multivariate analyses should be brought to bear on questions of community ecology and response to habitat characteristics. Studies performed in natural pine and pine-hardwood forests can provide baseline material for comparisons with managed pines. There also is a need to improve knowledge of the impact of silvicultural actions, including herbicide use, on the dynamics of snags and CWD, and to develop reliable landscape-scale models to predict the results of management on stand-level habitat features. © 2008 by the National Council for Air and Stream Improvement, Inc.
... We characterized vole habitat using 12 variables that represented anti-predator cover (Ucitel et al., 2003;Pearce and Venier, 2005) or reflected food availability for red-backed voles (Orrock and Pagels, 2002;Boonstra and Krebs, 2006). Of the 12 variables, five also provided a quantitative measure of habitat alteration [basal area of black spruce trees, ground cover of moss, bare ground cover, ground cover of fungi, ground cover of fruits available for red-backed voles (i.e. ...
... According to the assetprotection principle (sensu Clark, 1994), voles should display the weakest anti-predatory behaviour in habitats with high soil fertility (Ekman and Ulliendahl, 1993;Ydenberg et al., 1995;Olsson and Molokwu, 2007). Moreover, forest harvesting generally reduces anti-predator cover (Ucitel et al., 2003;Fuller et al., 2004), which increases predation risk for small mammals (Morris and Davidson, 2000;Verdolin, 2006;Eccard et al., 2008). On the basis of changes in habitat quality and availability of anti-predator cover, we predicted that predation costs (i.e. ...
... On the basis of changes in habitat quality and availability of anti-predator cover, we predicted that predation costs (i.e. ∆GUD between risky and safe food patches) would increase with logging intensity in sites with low soil fertility (Ucitel et al., 2003;Fuller et al., 2004), but would be affected less and could even decrease with logging intensity in sites with high soil fertility (Clark, 1994;Olsson and Molokwu, 2007). Our results are consistent with these expectations. ...
Hypotheses: (1) Intra- and inter-specific competition should increase with anthropogenic disturbances that reduce habitat quality. (2) In forested ecosystems, predation risk for small consumers should increase with the intensity of disturbance. (3) For the same level of disturbance, foragers living in higher-quality habitats should protect their assets by investing more in anti-predatory behaviours than those living in low-quality habitats. Organisms: Red-backed voles (Myodes gapperi) living in sympatry with deer mice (Peromyscus maniculatus). Place and time: Twenty-nine pairs of natural and logged habitats sampled during 2006 in managed boreal forest, Province of Québec, Canada. Methods: We identified a gradient of habitat disturbance along principal components summarizing 12 habitat variables. We estimated competition by measuring the giving-up density of rodents along the gradient of habitat disturbance. We assessed predation risk by measuring the giving-up density of rodents foraging in safe and risky patches. We tested for differences with multi-level statistical modelling. Conclusions: Competition and predation risk increased with habitat disturbance in the boreal forest studied. Foragers living in higher-quality habitats experienced higher predation costs than foragers living in low-quality habitats. Intra- and inter-specific competition, rather than predation, was the main mechanism responsible for the decline of red-backed vole populations associated with forest harvesting.
... Once lying on the ground, CWD continues to provide habitat (Harmon et al., 1986). Many mammals and amphibians use CWD for shelter (Harmon et al., 1986;Bull and Heater, 2000;Butts and McComb, 2000;Ucitel et al., 2003), and volume of CWD was found http://dx.doi.org/10.1016/j.foreco.2014.12.008 0378-1127/Published by Elsevier B.V. to be correlated to forest arthropod community structure (Ferrenberg et al., 2006). CWD also plays a role in forest nutrient cycling, and although the proportion of total nutrients stored in logs is often relatively small (Harmon et al., 1986;Laiho and Prescott, 2004), decomposing logs are linked to increased microbial activity (Busse, 1994). ...
... This tension between dead wood as habitat and dead wood as fuel has raised the question of how much wood is appropriate in fire-dependent forested ecosystems (Brown et al., 2003;Ucitel et al., 2003;Lehmkuhl et al., 2007;Scheller et al., 2011;Ritchie et al., 2013). Because wood is readily consumed by fire, one likely consequence of fire exclusion in unlogged forests where fire was historically frequent is an excess of coarse woody debris (Skinner, 2002). ...
... While numerous terrestrial vertebrate and invertebrate species use CWD for cover, movement, or food (Harmon et al., 1986), strength of associations between abundance and CWD measures vary. Red-backed voles (Clethrionomys gapperi) have been shown to use CWD at a greater rate than expected based on availability (Ucitel et al., 2003;Thomson et al., 2009), and Goodwin and Hungerford (1979) reported a strong positive relationship between density of deer mice (Peromyscus maniculatus) and cover of downed wood. Several studies have reported the strongest associations to occur in stands with relatively low overall abundance of decayed CWD and other structures that provide cover (Bowman et al., 2000;Ucitel et al., 2003). ...
... Logs serve as substrates and environments for fungi, lichens, and invertebrates, which provide forage and prey items to many species (Bunnell et al. 1997;Evans et al. 2003;Hayes et al. 1986;Maser and Trappe 1984;Rambo and Muir 1998). Use of downed wood as physical cover for nests or dens (Bull et al. 1997;Maser and Trappe 1984;McCay 2000;Thompson 1996) and travel paths McCay 2000;McMillan and Kaufman 1995;Ucitel et al. 2003;Zollner and Crane 2003) has been documented for some species, although the value of downed wood to many species is unknown. ...
... Further, we examined if use of downed wood differed between females and males, between summer and autumn, and with the quantity of wood in the environment. Given the importance of downed wood to path selection of eastern chipmunks (Tamias striatus-Zollner and Crane 2003), shrews (Sorex-Craig 1995), deermice (Peromyscus- Barnum et al. 1992;Carter 1993;McCay 2000;McMillan and Kaufman 1995), and southern red-backed voles (Myodes [formerly Clethrionomys] gapperi- Ucitel et al. 2003), we hypothesized that Townsend's chipmunks would disproportionately select paths with downed wood. Further, because populations, home ranges, and habitat selection of individual small mammals are sometimes related to stage of decay, size, and other characteristics of downed wood (Carey and Johnson 1995;Hayes and Cross 1987;McCay 2000;Tallmon and Mills 1994;Thompson 1996), we hypothesized that chipmunks would select larger-diameter wood and wood that was elevated because it can provide paths under the logs that could function as protective cover (Hayes and Cross 1987). ...
... Our study is the 1st to document the importance of downed wood in path selection by Townsend's chipmunks and con-tributes to the growing knowledge base that downed wood is selected as travel paths by many species of small mammals including deermice Carter 1993;McCay 2000;McMillan and Kaufman 1995), shrews (Craig 1995), southern red-backed voles (Ucitel et al. 2003), and eastern chipmunks (Zollner and Crane 2003). Interestingly, downed wood influences path selection and habitat use by individual Townsend's chipmunks even though Townsend's chipmunk populations do not consistently seem to respond to downed wood in the environment (Carey 1995(Carey , 2000Doyle 1990;Hayes et al. 1995;Morrison and Anthony 1989;Rosenberg and Anthony 1993). ...
Dead wood is important to small mammals and is hypothesized to be used as travel paths. We evaluated the likelihood of different a priori models regarding sex- and season-specific differences and if quantity of wood in the environment influenced path selection of 41 Townsend's chipmunks (Tamias townsendii) in coniferous forests of western Oregon with the spool-and-line method using an information-theoretic approach. On average, 50% (SD = 4%) of the surficial portion of a chipmunk's path was associated with downed wood and 79% (SD = 10%) was on top of logs. Chipmunks disproportionately selected paths with downed wood relative to its availability and the model indicating that quantity of wood in the environment influenced path selection was 22.6 times more likely than the null model. At average wood densities (paths with 26% wood), a chipmunk was 3.0 times more likely to select locations with downed wood than locations without downed wood (95% confidence interval [95% CI] = 2.5–3.5). Furthermore, chipmunks selected wood that averaged 1.2 times larger in diameter than randomly available wood (95% CI = 1.1–1.3). Our findings document that Townsend's chipmunks preferentially use downed wood and we hypothesize that downed wood may influence fitness or survival of individual chipmunks.
... In these habitats, populations of southern red-backed voles show sensitivity to canopy removal (Keinath and Hayward 2003) and habitat fragmentation (Bayne and Hobson 1998). In addition to a continuous overstory, red-backed voles prefer stands with abundant down wood and vegetative cover in the understory (Ucitel et al. 2003). ...
... Down wood.-Red-backed vole use of habitats was positively and linearly associated with availability of down wood (Ucitel et al. 2003). Hard logs with branches may act as effective barriers against predators and Andruskiw et al. (2008) suggested that red-backed voles may reduce their visibility to avian predators by moving along pieces of down wood. ...
The Tongass National Forest in southeast Alaska previously relied on timber volume, a measure related to timber production and economics, to provide information on forest structure, ecosystem diversity, and wildlife habitat. The Forest Service developed a measure (Size Density Model [SDM]) based on tree density and mean tree diameter as a more comprehensive assessment of these key characteristics. To fully incorporate the SDM into planning and management of wildlife habitat and populations, information was needed on the relationship of land cover classes described by the SDM and habitat for wildlife species of conservation concern.
... More generally, some of the greatest differences in small mammal communities occur between recently clearcut and adjacent uncut mature forest. This was true for the southern red-backed vole (Myodes gapperi), which tends to be relatively abundant in mature forests (Ucitel et al., 2003), and thus often has been labelled an old-growth "indicator" species (NatureServe, 2015), and long-tailed vole (Microtus longicaudus) and chipmunks (Tamias amoenus) which are more prevalent in disturbed areas (Klenner and Sullivan, 2003;Sullivan and Sullivan, 2012). But differences are not as apparent when less intensive silvicultural methods are studied or when reserve strategies are employed to retain some habitat complexity (Moses and Boutin, 2001;Klenner and Sullivan, 2003;Ransome et al., 2009;). ...
... Substantial differences in responses to woody debris loads have been reported for several species including voles, mice, lemmings, and shrews (Butts and McComb, 2000;Fauteux et al., 2012, Ucitel et al., 2003. Deer mice may be less sensitive to woody debris than to living vegetation (Craig et al., 2006), but red-backed voles use coarse woody debris disproportionately across an array of MMC potential vegetation types including subalpine fir/beadlily (ABLA/CLUN) and grand fir/ beadlily (ABGR/CLUN). ...
Moist, mixed conifer (MMC) forests, which encompass more than 11 million ha in the Inland Northwest, USA and adjacent Canada, were extensively modified after Euro-american occupation by now-outdated forestry practices and wildfire suppression. Those activities homogenized tree composition and density, modified forest soils, increased risks to insect and disease epidemics, and, in combination with longer drought periods ultimately increased the prevalence of unusually severe wildfires to further homogenize landscapes. Recommendations for restoring structure and function include re-establishing natural fire regimes and disturbance-patch size distributions across landscapes, as well as restoring and maintaining large, old early-seral dominant trees (LOEST), large snags and coarse woody debris, while accounting for physiographic influences. Implementing such recommendations with sensitivity to wildlife conservation requires additional details to account for habitat needs at the planning levels of national forests and districts. We synthesized silviculture-specific literature for wildlife species of greatest conservation concern listed in the strategic wildlife conservation plans of Inland Northwest states ("strategy" species), others of social and economic importance ("focal" species), and some others that are either important in the ecologies of strategy species or otherwise offer literature having particular relevance to MMC silviculture ("facilitative" species). Evaluations of habitat selection behavior and comparisons of species-specific habitat values to tree-stocking guidelines used by silviculturists indicated that most species reviewed are likely to respond positively to restoration, and that a wide array of extant silvicultural methods can be used, provided that large snags and acceptable levels of coarse woody debris are recruited or retained. Thinning followed by routine prescribed burning will be problematic for some wildlife species. Knowledge of wildlife responses to variation in the size distribution of disturbance patches is limited, as is knowledge of wildlife population responses to intentional forestry. Coupling new wildlife research to forest modeling and manipulative experiments within adaptive management and monitoring frameworks will improve predictions of wildlife population responses over the long time frames and multiple spatial scales associated with strategic planning.
... CWD has repeatedly been interpreted as important for redbacked voles, deer mice, and jumping mice by providing environmental and predatory protection, nesting sites, moisture sources, and fungal food (e.g., Pauli et al. 2006;Bowman et al. 2000;Orrock and Pagels 2002;Ucitel et al. 2003). Deer mice and red-backed voles use CWD for movement within subnivea, and it provides them with significant thermal insulation and predator protection (Evernden and Fuller 1972;Miller and Getz 1977;Korslund and Steen 2006;Sullivan et al. 2012). ...
... The relationship between CWD and deer mice may have been obfuscated from the deer mouse population irruption similar to that observed by Bowman et al. (2001c). Red-backed vole densities displayed a moderate, positive relationship to CWD, which corroborates with previous research (e.g., Bondrup-Nielson 1987;Bowman et al. 2000;Ucitel et al. 2003;Kaminski et al. 2007). Woodland jumping mice were always negatively associated with number of fresh CWD pieces (decay classes 1 and 2) but were positively associated with number of well-decayed CWD pieces during summer. ...
We assessed whether commercially thinning (CT) spruce (Picea spp.) plantations (40% basal area removal) can cause structural changes in fine woody debris (FWD) and understory vegetation to improve habitat quality for small rodents in northwestern New Brunswick, Canada.Wecreated three contrasting environments (FWD rich – understory vegetation rich, FWD poor – understory vegetation rich, and FWD poor – understory vegetation poor) by establishing CT with debris retention (merchantable trunk removal), CT with all debris removed (full tree removal), and non-CT (plantation without CT) in six midrotation white spruce (Picea glauca (Moench) Voss) plantations. We live-trapped small mammals in each plantation during spring and summer of 2011 and 2012 and estimated animal density and survival with capture–recapture models. Southern red-backed vole (Myodes gapperi (Vigors, 1830)) density was two to three times greater in CT with debris retention than in either non-CT or CT with debris removal, and their survival rate was twice that in CT with debris removal. Woodland jumping mouse (Napaeozapus insignis (Miller, 1891)) density was two to five times greater in non-CT than in either CT treatment. Deer mice (Peromyscus maniculatus (Wagner, 1845)) did not show any treatment effect. Productivity and demographics were not affected by CT treatment for any species. We found evidence that midrotation spruce plantations are used differently by small mammal species based on stand condition and recommend that managers maintain plantations in CT and non-CT states.
... Specifically, they require accumulations of coarse woody debris for foraging and resting activities. This material can provide access to subnivean small mammal prey in winter (Sherburne and Bissonette 1994;Andruskiw 2003), shelter from overhead predators (Thompson and Harestad 1994), thermally efficient den sites (Martin 1987;Taylor and Buskirk 1994), and good habitat for their prey (Ucitel et al. 2003). In addition, overhead cover and vertical structure, such as well-distributed tree stems, are important for predator avoidance and escape (Baker 1992;Coffin 1994;Drew 1995;Potvin et al. 1999). ...
... The most abundant subnivean prey on our study site included red-backed voles (Clethrionomys gapperi), meadow voles (Microtus pennsylvanicus), and deer mice (Peromyscus maniculatus) (Poole et al. 2004). These species would be expected to need logs (red-backed voles; Ucitel et al. 2003) or a combination of logs and grass (meadow voles and deer mice; Banfield 1974). Instead, we found that marten selected hard snags during foraging and avoided hard stumps, neither of which seems pertinent to sheltering marten prey or intercepting snow to facilitate access to them. ...
American marten (Martes americana (Turton, 1806)) are often associated with old-growth forests, but have been detected living in a young deciduous forest in northern British Columbia, where a previous coarse-scale analysis failed to detect significant habitat selection. To address this paradox, we examined fine-scale habitat selection for specific activities. We used radiotelemetry and snowtracking to identify sites that appeared to have been used for resting, foraging, scent marking, and traveling during the winters of 19981999 and 19992000. Then we conducted vegetation surveys at these activity sites and at nearby random locations and used logistic regression to measure selection. Based on the number of significant variables and model fit, we detected more selectivity by marten for resting than for foraging and scent-marking sites, and no selectivity for traveling. Marten exhibited selection for several habitat structures that are characteristic of older forests (e.g., rootballs and wide-diameter snags), but that can be retained in some manipulated forests. With the exception of wide-diameter snags (selected at both resting sites and scent marks), marten selected different habitat structures for each type of activity. These results may help to explain why marten are able to survive in this and other sites that provide seemingly unsuitable habitat.
... Snags contribute to gradual chemical cycling while providing habitat for numerous species of birds and mammals (Thomas 1979;Raphael and White 1984;Harmon et al. 1986;Rabe et al. 1998;Meyer et al. 2005). When snags fragment or fall, the resulting logs provide denning habitat, protect movement pathways, and accelerate soil development by cycling carbon and nutrients at a faster rate than snags (Harmon et al. 1986;Bull and Heater 2000;Butts and McComb 2000;Ucitel et al. 2003;Cousins et al. 2015). Intersecting or stacked logs (sensu Lutz et al. 2021;their Figure 8) can spread fire, potentially killing vegetation and altering soil characteristics (Monsanto and Agee 2008;Knapp 2015). ...
Background
Snags, standing dead trees, are becoming more abundant in forests as tree mortality rates continue to increase due to fire, drought, and bark beetles. Snags provide habitat for birds and small mammals, and when they fall to the ground, the resulting logs provide additional wildlife habitat and affect nutrient cycling, fuel loads, and fire behavior. Predicting how long snags will remain standing after fire is essential for managing habitat, understanding chemical cycling in forests, and modeling forest succession and fuels. Few studies, however, have quantified how fire changes snag fall dynamics.
Results
We compared post-fire fall rates of snags that existed pre-fire ( n = 2013) and snags created during or after the fire ( n = 8222), using 3 years of pre-fire and 5 years of post-fire data from an annually monitored, 25.6-ha spatially explicit plot in an old-growth Abies concolor–Pinus lambertiana forest in the Sierra Nevada, CA, USA. The plot burned at low to moderate severity in the Rim Fire of 2013. We used random forest models to (1) identify predictors of post-fire snag fall for pre-existing and new snags and (2) assess the influence of spatial neighborhood and local fire severity on snag fall after fire. Fall rates of pre-existing snags increased 3 years after fire. Five years after fire, pre-existing snags were twice as likely to fall as new snags. Pre-existing snags were most likely to persist 5 years after fire if they were > 50 cm in diameter, > 20 m tall, and charred on the bole to heights above 3.7 m. New snags were also more likely to persist 5 years after fire if they were > 20 m tall. Spatial neighborhood (e.g., tree density) and local fire severity (e.g., fire-caused crown injury) within 15 m of each snag barely improved predictions of snag fall after fire.
Conclusions
Land managers should expect fall rates of pre-existing snags to exceed fall rates of new snags within 5 years after fire, an important habitat consideration because pre-existing snags represent a wider range of size and decay classes.
... The most commonly assessed physical fuel attribute is the load (kg m −2 ). Fuel load is a required input to nearly all fire behavior and effects models and is coupled to terrestrial carbon inventories and wildlife habitat assessments [1][2][3][4]. Fuel inventory approaches have traditionally assumed that spatial variability in fuel load is of little consequence for management decisions and thus focus on providing estimates of the spatially averaged fuel load for a given area based on a limited set of sampled locations. Yet, recent studies highlight that fine-scale variability in the fuel complex, as exists in virtually all wildland fuel beds, exerts considerable influence on many ecologically relevant fire behavior and effects metrics [5][6][7][8][9][10][11][12]. ...
Patterns of spatial heterogeneity in forests and other fire-prone ecosystems are increasingly recognized as critical for predicting fire behavior and subsequent fire effects. Given the difficulty in sampling continuous spatial patterns across scales, statistical approaches are common to scale from plot to landscapes. This study compared the performance of four spatial interpolation methods (SIM) for mapping fine-scale fuel loads: classification (CL), multiple linear regression (LR), ordinary kriging (OK), and regression kriging (RK). These methods represent commonly used SIMs and demonstrate a diversity of non-geostatistical, geostatistical, and hybrid approaches. Models were developed for a 17.6-hectare site using a combination of metrics derived from spatially mapped trees, surface fuels sampled with an intensive network of photoload plots, and topographic variables. The results of this comparison indicate that all estimates produced unbiased spatial predictions. Regression kriging outperformed the other approaches that either relied solely on interpolation from point observations or regression-based approaches using auxiliary information for developing fine-scale surface fuel maps. While our analysis found that surface fuel loading was correlated with species composition, forest structure, and topography, the relationships were relatively weak, indicating that other variables and spatial interactions could significantly improve surface fuel mapping.
... Thus, successfully balancing fuel treatment and biodiversity considerations remains a challenge facing managers in fire-prone ecosystems around the globe (Haslem et al., 2011;James and M'Closkey, 2003;Kennedy et al., 2008;Ucitel et al., 2003). In the present study, we hypothesize that the biodiversity loss resulting from the removal of vegetation in areas designated for firebreak placement can be offset by the reduction in biodiversity loss due to the firebreaks' protective action. ...
A solution approach is proposed to optimize the selection of landscape cells for inclusion in firebreaks. It involves linking spatially explicit information on a landscape’s ecological values, historical ignition patterns and fire spread behavior. A firebreak placement optimization model is formulated that captures the tradeoff between the direct loss of biodiversity due to the elimination of vegetation in areas designated for placement of firebreaks and the protection provided by the firebreaks from losses due to future forest fires. The optimal solution generated by the model reduced expected losses from wildfires on a biodiversity combined index due to wildfires by 30% relative to a landscape without any treatment. It also reduced expected losses by 16% compared to a randomly chosen solution. These results suggest that biodiversity loss resulting from the removal of vegetation in areas where firebreaks are placed can be offset by the reduction in biodiversity loss due to the firebreaks’ protective function.
... Accurate fine-scale fuel maps can be used for a variety of applications to improve forest management, including quantifying biomass and carbon storage capacity (e.g., Smithwick et al 2009), identifying important wildlife habitat (e.g., North et al. 1999, Roberts et al. 2011, Ucitel et al. 2003, and to inform fire and forest management. Fuel maps are essential for fire research and management to model fuel treatment effectiveness, smoke emissions, and fire spread. ...
Fire regimes in National parks of the Pacific Northwest: Implications for Climate Change.
Chapter 1) A checkered past: the history of a mixed-severity fire regime on a mountain landscape in the Cascade Range, Stehekin, WA, USA.
Chapter 2) Fuel characteristics of Mount Rainier National park, WA, USA: Mapping with a combination of field, environmental, and LiDAR data.
Chapter 3) Fire-climate interactions: local controls and management implications for moist and dry conifer forests of the Pacific Northwest.
... Note that probability of use (y-axis) changes scales between plots. (Ucitel et al. 2003, Pauli et al. 2006, Fauteux et al. 2012, Sullivan et al. 2017, from which martens appear to acquire sensory cues that aid in locating prey (Corn andRaphael 1992, Andruskiw et al. 2008). Other prey items, such as Douglas' squirrel (Tamiasciurus douglasii), build and occupy cone caches in large logs where they may be susceptible to marten predation , Ruggiero et al. 1998. ...
When wildlife species exhibit unexpected associations with vegetation, replication of studies in different locales can illuminate whether patterns of use are consistent or divergent. Our objective was to describe fine‐scale forest conditions used by Pacific martens ( Martes caurina ) at 2 study sites in northern California that differed in forest composition and past timber harvest. We identified denning and resting locations of radio‐marked martens and sampled structure‐ and plot‐level vegetation using standardized forest inventory methods between 2009–2021. Woody structures used by martens were significantly larger than randomly available structures across types (e.g., live tree, snag, log) and at both study sites. Den and rest structures occurred in areas characterized by higher numbers of logs and snags, lower numbers of live trees and stumps, larger diameter live trees and logs, and greater variation in live tree and log diameter. Features of denning and resting locations were largely consistent across study sites and were generally representative of fine‐scale forest heterogeneity and increased structural complexity, conditions that martens have been widely associated with at broader spatial scales (i.e., home range or landscape). The spatial occurrence of denning and resting locations may indicate that fine‐scale structural complexity facilitates marten foraging while reducing predation risk. Our work offers timely and directed information that can guide forest management in the context of increased landscape change.
... Thus, successfully balancing fuel treatment and biodiversity considerations remains a challenge facing managers in fire-prone ecosystems around the globe (Haslem et al., 2011;James and M'Closkey, 2003;Kennedy et al., 2008;Ucitel et al., 2003). In the present study, we hypothesize that the biodiversity loss resulting from the removal of vegetation in areas designated for firebreak placement can be offset by the reduction in biodiversity loss due to the firebreaks' protective action. ...
... We show species using log complexes in a diverse manner, but most of the animal activities are associated to movement (i.e., log crossing). Small mammals such as Townsend's Chipmunks, Deer Mice, Shrews (Sorex spp.), and Southern Red-backed Voles preferentially use downed wood in forests as movement paths (Waldien et al. 2006;McMillan and Kaufman 1995;Craig 1995;Ucitel et al. 2003). In addition, small and meso-carnivores are also known to select paths containing downed wood in forests (Buskirk and Zielinski 2003). ...
Until the 1980s, large wood removal from streams was widely promoted across North America because in-stream logs were considered undesirable. At present, millions of dollars are invested annually to place large wood back in streams owing to its importance for the geomorphology of channels, stream discharge, sediment deposits, and habitat for fish. Yet, little is known about the role of large wood in streams for wildlife. Here, we used 12 months of camera trap videos (effort of 4703 camera days) to document wildlife biodiversity and animal activities at several log complexes located in Rock Creek, Wil-lamette River basin, Oregon. Our dataset (1921 independent videos) documented up to 40 species including small mammals, aquatic and terrestrial birds, meso-carnivores, large carnivores, and semi-aquatic mammals. We found a strong seasonality in detections and species richness with the highest values occurring in summer and spring, and the lowest values in winter. There were idiosyncratic responses for species richness and assemblages at each large wood complex. Most common animal activities included movement (68%), rest (18%), and food handling/eating (9%) suggesting that large wood structures in streams act as lateral corridors connecting terrestrial habitats year-round for wildlife. Collectively, we reveal multiple functions that large wood plays to support wildlife biodiversity across the aquatic-terrestrial interface demonstrating the value of restoration projects that involve wood placement into streams.
... Primary decomposers that contribute to nutrient cycling in forests, such as beetles and fungi, rely on CWD as an energy source and are found in greater abun-dance in areas with greater CWD (Zhou et al. 2007). Small mammals, such as the red-backed vole (Ucitel et al. 2003), are reliant on CWD, as it provides nesting habitat, thermal shelter and cover from predators (McComb 2009). In British Columbia, Canada, alone, 51 vertebrates are known to be supported by CWD (Keisker 2000). ...
Coarse woody debris (CWD) is a meaningful contributor to forest carbon cycles, wildlife habitat, and biodiversity and can influence wildfire behavior. Using airborne laser scanning (ALS), we map CWD across a range of natural forest stand types in north-central British Columbia, Canada, providing forest managers with spatially detailed information on the presence and volume of ground-level woody biomass. We describe a novel methodology that isolates CWD returns from large diameter logs (>30cm) using a refined grounding algorithm, a mixture of height and pulse-based filters and linear pattern recognition, to transform ALS returns into measurable, vectorized shapes. We then assess the accuracy of CWD detection at the individual log level and predict CWD volume at the plot level. We detected 64% of CWD logs and 79% of CWD volume within our plots. Increased elevation of CWD significantly aided detection (P = 0.04), whereas advanced stages of decay hindered detection (P = 0.04). ALS-predicted CWD volume totals were compared against field-measured CWD and displayed a strong correlation (R = 0.81), allowing us to expand the methodology to map CWD over a larger region. The expanded CWD volume map compared ALS volume predictions between stands and suggests greater volume in stands with older and more heterogeneous stand structure.
Study Implications
A methodology is presented to extract returns associated with large diameter coarse woody debris (CWD) directly from an ALS point cloud. These returns are transformed into measurable shapes and their volume estimated based on the height of the returns. The procedure is implemented over a large forested area to produce a map of local CWD volume. Production of these maps can be used to generate inventory of CWD over a range of natural forest stands to support a more well-rounded understanding of carbon levels associated with downed trees, wildlife habitat attributes, and fuel loading in the terrestrial biosphere.
... For example, the Canada lynx selectively use outbreak stands with large diameter trees, and its prey, the snowshoe hare, prefers understory connectivity in subalpine stands (Squires et al., 2020). In addition, small mammals, such as the red-backed vole (Clethrionomys gapperi), selectively use areas with abundant coarse woody debris (Ucitel et al., 2003). Fuel reduction treatments aimed at reducing fire behavior may have negative implications for listed wildlife species. ...
Due to the shifting global climate, the frequency and severity of disturbances are increasing, inevitably causing an increase in disturbances overlapping in time and space. Bark beetle epidemics and wildfires have historically shaped the disturbance regimes of Western North American forests. Their interactive effects on stand dynamics and recovery are inadequately studied in Picea engelmannii (Engelmann spruce)-Abies lasiocarpa (subalpine fir) dominant forests; understanding these interactions is imperative to the management and health of forested ecosystems. This study focuses on the effects of epidemic Dendroctonus rufipennis (spruce beetle) outbreaks, high-severity fires, and the subsequent species and structural diversity of subalpine forest regeneration and structure in Northern Colorado and Southern Wyoming. We compared tree seedling densities and species composition, surface fuel loading, and stand structure characteristics across 80 sites that experienced either high tree mortality from epidemic spruce beetle outbreaks (>50% affected basal area), high-severity wildfire, post-outbreak high-severity wildfire (1-3 years post-outbreak), or no disturbance (control). The beetle outbreak sites span multiple years post-outbreak from 1996 to 2017, ultimately comprising a chronosequence of beetle-affected stands. Analyses indicate a significant increase in fuel loading over time-since-outbreak, as aerial fuels are transferred to the forest floor following high tree mortality. Tree seedling densities among outbreak and control sites differ significantly from burned areas, indicating that wildfires override the effects of repeated disturbances on regeneration. There was consistent Engelmann spruce seedling survival following beetle outbreaks, providing evidence for stable forest recovery following a single disturbance. However, fire was a dominate force in determining post-disturbance species composition, indicating continued prevalence of high severity fire may prove detrimental for the persistence of spruce-fir species, while promoting shifts toward more drought and fire tolerant tree species (e.g., Pinus contorta). It is critical to understand post-disturbance fuel dynamics and stand recovery to identify hazards for subsequent fire suppression, implement treatments to enhance forest resilience, and to understand the potential consequences of climate-induced shifts in disturbance regimes on forest health.
... Dead woody material plays important roles in forest ecosystems, such as providing organic matter and nutrients (Jia-bing et al., 2008), habitat for animals (Ucitel et al., 2003), carbon stocks (Woodall and Liknes, 2008), facilitating regeneration of trees (Ripple and Larsen, 2001), and supporting biological diversity (Nally et al., 2001;Nordén et al., 2004). Woody debris can also be used as a parameter to determine whether fuel management is needed or not (Knapp et al., 2005). ...
... Woody debris-dead trees and branches-is a key element of forest ecosystems, providing nutrient cycling, carbon storage, microhabitats, and overall forest structure, and can feature prominently in studies of wildlife habitat [1], forest fuel load [2], bioenergy [3], and forest disturbances [4]. Coarse woody debris (CWD) can be distinguished from fine woody debris on the basis of length (at least 1 m) and diameter (at least 10 cm at the largest end) [5]. ...
Coarse woody debris (CWD; large parts of dead trees) is a vital element of forest ecosystems, playing an important role in nutrient cycling, carbon storage, fire fuel, microhabitats, and overall forest structure. However, there is a lack of effective tools for identifying and mapping both standing (snags) and downed (logs) CWD in complex natural settings. We applied a random forest machine learning classifier to detect CWD in centimetric aerial imagery acquired over a 270-hectare study area in the boreal forest of Alberta, Canada. We used a geographic object-based image analysis (GEOBIA) approach in the classification with spectral, spatial, and LiDAR (light detection and ranging)-derived height predictor variables. We found CWD to be detected with great accuracy (93.4 ± 4.2% completeness and 94.5 ± 3.2% correctness) when training samples were located within the application area, and with very good accuracy (84.2 ± 5.2% completeness and 92.2 ± 3.2% correctness) when training samples were located outside the application area. The addition of LiDAR-derived variables did not increase the accuracy of CWD detection overall (<2%), but aided significantly (p < 0.001) in the distinction between logs and snags. Foresters and researchers interested in CWD can take advantage of these novel methods to produce accurate maps of logs and snags, which will contribute to the understanding and management of forest ecosystems.
... The remains of dead trees and large branches on the forest floor, known as downed coarse woody debris (DCWD), contribute to the structure and function of forest ecosystems. In recent decades, there has been growing recognition of the influence of DCWD on many ecological characteristics and processes including wildlife habitat (Hagan and Grove 1999, McComb and Lindenmayer 1999, Ucitel et al. 2003, fuel loads and fire behavior (Schoennagel et al. 2004), runoff and erosion (Gurnell et al. 1995), water holding capacity and soil moisture (Harmon andSexton 1995, Goldin andHutchinson 2014), seedling establishment and regeneration (Harmon and Franklin 1989), carbon storage (Magn usson et al. 2016), nutrient cycling (Shortle et al. 2012, Yuan et al. 2017, and biodiversity (Freedman et al. 1996, Siitonen 2001, Stokland et al. 2012. Because DCWD decomposes relatively slowly, it represents a long-term carbon storage pool. ...
Downed coarse woody debris, also known as coarse woody detritus or downed dead wood, is challenging to estimate for many reasons, including irregular shapes, multiple stages of decay, and the difficulty of identifying species. In addition, some properties are commonly not measured, such as wood density and carbon concentration. As a result, there have been few previous evaluations of uncertainty in estimates of downed coarse woody debris, which are necessary for analysis and interpretation of the data. To address this shortcoming, we quantified uncertainties in estimates of downed coarse woody debris volume and carbon storage using data collected from permanent forest inventory plots in the northeastern United States by the Forest Inventory and Analysis program of the USDA Forest Service. Quality assurance data collected from blind remeasurement audits were used to quantify error in diameter measurements, hollowness of logs, species identification, and decay class determination. Uncertainty estimates for density, collapse ratio, and carbon concentration were taken from the literature. Estimates of individual sources of uncertainty were combined using Monte Carlo methods. Volume estimates were more reliable than carbon storage, with an average 95% confidence interval of 15.9 m³/ha across the 79 plots evaluated, which was less than the mean of 31.2 m³/ha. Estimates of carbon storage (and mass) were more uncertain, due to poorly constrained estimates of the density of wood. For carbon storage, the average 95% confidence interval was 11.1 Mg C/ha, which was larger than the mean of 4.6 Mg C/ha. Accounting for the collapse of dead wood as it decomposes would improve estimates of both volume and carbon storage. On the other hand, our analyses suggest that consideration of the hollowness of downed coarse woody debris pieces could be eliminated in this region, with little effect. This study demonstrates how uncertainty analysis can be used to quantify confidence in estimates and to help identify where best to allocate resources to improve monitoring designs.
... The fuel properties presented here can also be used as inputs to ecosystem models to simulate future decomposition (Keane 2008a). The data may also provide information that is useful for wildlife habitat description (Pilliod et al. 2006;Ucitel et al. 2003), erosion control (Kokaly et al. 2007;Robichaud et al. 2007), and site productivity longevity (Harvey et al. 1989). ...
Mastication is a wildland fuel treatment technique that is rapidly becoming the preferred method for many fire hazard reduction projects, especially in areas where reducing fuels with prescribed fire is particularly challenging. Mastication is the process of mechanically modifying the live and dead surface and canopy biomass by chopping and shredding vegetation to reduce canopy bulk density, raise canopy base height, lower surface fuelbed depth, and increase surface fuelbed bulk density, thereby reducing fire hazard. However, little is known about the properties of masticated fuelbeds as they age. In 2013, we began a comprehensive study called MASTIDON (MASTIcated fuelbed Decomposition Operational Network) to measure the diverse characteristics of masticated fuelbeds at treatment sites of different ages across the western U.S. Rocky Mountains. Our primary objective was to evaluate effects of aging of masticated fuelbeds on fire behavior, fuel moisture dynamics, soil heating, and smoldering combustion. Results from these investigations could then be used to build fire behavior fuel models for use in operational fire management. This report concerns a small facet of the MASTIDON study, where summaries of the physical and chemical fuel properties of the sampled masticated fuelbeds are presented and the relationships of these properties to fuel age are explored. We document masticated fuelbed characteristics and correlate these characteristics to age. In general, we found that there were few changes in physical and chemical properties over the short 10 years represented by the sites in this study, primarily due to confounding factors of low decomposition rates, diverse mastication techniques, wide range of biophysical conditions, and high variability in fuel properties across disparate sites. However, we feel it will take more than 10 years for decomposition to mitigate the negative impacts of wildfires burning in masticated fuelbeds. These summaries can be used to understand how different types of masticated fuelbeds might burn if ignited and as inputs to fire behavior and effects models.
... Microclimatic conditions are seasonally and diurnally more variable following clear cuts (Chen et al., 1993;Carlson and Groot, 1997;Gray et al., 2002). This increased fluctuation in surface conditions may limit the use of these sites for some species, and retained CWD may supplant some of the shelter provided by canopy cover prior to harvest (Grialou et al., 2000;Fauteux et al., 2012), help maintain moisture for species subject to desiccation (Getz, 1961;Jaeger, 1980;Brannon, 2002), provide travel pathways (McCay, 2000;Ucitel et al., 2003;Zollner and Crane, 2003;Jones et al., 2009) and provide the habitat structure present in mature forests (Gustafsson et al., 2010). Snags also promote mammal diversity by providing a habitat for arboreal species such as squirrels and tree-roosting bats (Loeb, 1996;Perry et al., 2007;Jones, 2009). ...
... This snag habitat is ephemeral, however, with most snags falling to the ground within 5-15 years (Keen 1955. Once on the ground, dead wood can provide cover and continue to be important for wildlife (harmon et al. 1986, Butts and McComb 2000, Ucitel et al. 2003. however, downed wood is also fuel, which can cause subsequent fires to burn at higher intensities, particularly when the large downed logs are rotten (Passovoy andFule 2006, Knapp 2015). ...
Timber is frequently salvage-logged following high-severity stand-replacing wildfire, but the practice is controversial. One concern is that compound disturbances could result in more deleterious impacts than either disturbance individually, with mechanical operations having the potential to set back recovering native species and increase invasion by non-native species. Following the 2002 Cone Fire on the Lassen National Forest, three replicates of five salvage treatments were applied to 15 units formerly dominated by ponderosa pine, covering a range of disturbance intensities from unsalvaged to 100% salvaged. Understory species richness and cover data were collected every two years between 2006 and 2012. Richness of both native and non-native species did not differ among salvage treatments, but both showed strong changes over time. While cover of forbs and graminoids did not differ with salvage treatment, cover of shrubs was significantly reduced at the higher salvage intensities. The three main shrub species are all stimulated to germinate by fire, potentially leaving seedlings vulnerable to any mechanical disturbance occurring immediately postgermination. Many other native perennial species emerge from rhizomes or other deeply buried underground structures and appear to be less affected by salvage harvest. Over time, the plant community in all salvage treatments shifted from dominance by shrubs and forbs to shrubs and grasses. Most of the grasses were native, except Bromus tectorum (cheatgrass), which was found in 4% of measurement quadrats in 2006 and 52% in 2012. Our results indicated that understory vegetation change 4–10 years post-high-severity wildfire appeared to be influenced more strongly by factors other than salvage logging.
... Perkins and Conner (2004) used a MANOVA on Euclidean distances to compare distances between animal locations from each habitat with expected distances (see also Conner et al. 2003 for a discussion of this method). Ucitel (2003) used simple linear regression through the origin to relate use and availability of woody debris by red-backed voles (Clethrionomys gapperi). Roloff et al. (2001) compared fixed-kernel utilization distributions from elk telemetry data to a simulated, random habitat-utilization distribution using a volume of intersection index statististic defined by Seidel (1992). ...
Classified study designs for comparing resource (food, habitat) use and availability into 3 basic types. Design 1 permits investigation of resource selectivity only at the population level because individual animals are not identified. Designs 2 and 3 measure use by individuals and thus allow examination of the variation in resource selection strategies. Resource availabilities are measured for each individual in Design 3 but not in Design 2. Graphical plots illustrating individual selection are recommended for data resulting from Designs 2 and 3 to assess variability and possible sex or age differences. The authors recommend a method for determining the number of random points required to bound the probable error in estimating resource availability proportions simultaneously, rather than individually. Four problem areas in the use of statistical methods for evaluating resource selectivity are identified: dependencies among observations, misuse of the Chi-square goodness-of-fit test when availabilities are estimated, tests that do not control experimentwise error rates, and the sensitivity of tests to the subjective inclusion or exclusion of resources. -Authors
... This reflected the four-fold difference in volume of downed woody debris across treatments. Mechanical removal of trees during logging led to an incidental and rapid accumulation of downed branches, debris used by small mammals for breeding, foraging, and predator avoidance (Harmon et al. 1986;Ucitel et al. 2003). Dead trees on the control remained standing two to three years post-fire and had not yet replaced downed woody debris consumed during the fire. ...
We investigated how post-fire salvage logging of Ponderosa Pine (Pinus ponderosa) affected populations of cavity-nesting birds and small mammals in southeastern Montana in 2004 and 2005. We examined two salvage and two control plots with three point-count stations and one small mammal trap site randomly distributed across each plot. We used point counts and distance sampling methods to estimate density of cavity-nesting birds on each treatment. We also searched each plot for nests and used program MARK to construct a set of candidate models to investigate variations in nest survival related to treatment, year, and time. We used live traps arranged in webs centered on trapping sites and distance sampling methods to estimate small mammal density. Habitat characteristics were also quantified on each plot. Density of all cavity-nesting birds combined and of Hairy Woodpeckers (Picoides villosus) in particular were higher on the control than the salvage treatment. Density of large trees and abundance of active cavities were higher on the control treatment. Nest cavities on the salvage treatment were most often located in non-logged watersheds. Nest survival estimates were uniformly high, with only marginal variations attributed to treatment and year. Density of Deer Mice (Peromyscus maniculatus) was higher on the salvage than the control treatment, reflecting the amount of downed woody debris created during harvest.
... Microclimatic conditions are seasonally and diurnally more variable following clear cuts (Chen et al., 1993;Carlson and Groot, 1997;Gray et al., 2002). This increased fluctuation in surface conditions may limit the use of these sites for some species, and retained CWD may supplant some of the shelter provided by canopy cover prior to harvest (Grialou et al., 2000;Fauteux et al., 2012), help maintain moisture for species subject to desiccation (Getz, 1961;Jaeger, 1980;Brannon, 2002), provide travel pathways (McCay, 2000;Ucitel et al., 2003;Zollner and Crane, 2003;Jones et al., 2009) and provide the habitat structure present in mature forests (Gustafsson et al., 2010). Snags also promote mammal diversity by providing a habitat for arboreal species such as squirrels and tree-roosting bats (Loeb, 1996;Perry et al., 2007;Jones, 2009). ...
Within young pine (Pinus spp.) plantations, coarse woody debris (CWD) and green trees are important habitat structures that may be impacted by the
production of biofuel feedstock. Therefore, we compared site preparation procedures associated with switchgrass (Panicum virgatum L.) intercropping to determine effects on CWD and green trees in stands (n = 24) site-prepared for intercropping, with switchgrass only, or pine plantation in Mississippi, USA. Following site preparation,
CWD dispersal or volume did not differ between intercropped and control stands. Intercropped stands had significantly fewer
retained trees and snags. Switchgrass monocultures had no retained trees or piles and significantly fewer pieces and less
volume of CWD than the other treatments. Our results suggest switchgrass intercropping may provide similar habitat quality
to traditional pine plantations for wildlife species using these areas in the year following disturbance, but may provide
a less suitable habitat for species that require snags. However, the relationship between snag reduction and wildlife population
response in an intercropped setting is not clear and should be further investigated. Regardless, if retaining snags is a desired
outcome, site preparation for switchgrass should be restricted to the interbed area where it will be cultivated as opposed
to extensive debris removal from the entire site.
... There are many fuel component attributes, such as heat content, mineral content, and density, but the most commonly used attribute across most fire management applications is fuel loading or the biomass per unit area (Brown and Bevins, 1986;Harmon et al., 1986;Pyne et al., 1996). Fuel loads are required as inputs to nearly all fire applications (Burgan, 1987;Krivtsov et al., 2009), and they are also important for the quantification of carbon inventories (de Groot et al., 2007), site productivity (Neary et al., 1999), and wildlife habitat (Ucitel et al., 2003). This paper evaluates three surface fuel classifications used for the prediction of fire effects, such as fuel consumption, smoke production, and soil heating, that describe actual fuel loadings on the ground and can, therefore, also be used for fuel description, inventory, and monitoring. ...
Fuel Loading Models (FLMs) and Fuel Characteristic Classification System (FCCSs) fuelbeds are used throughout wildland fire science and management to simplify fuel inputs into fire behavior and effects models, but they have yet to be thoroughly evaluated with field data. In this study, we used a large dataset of Forest Inventory and Analysis (FIA) surface fuel estimates (n = 13,138) to create a new fuel classification called Fuel Type Groups (FTGs) from FIA forest type groups, and then keyed an FLM, FCCS, and FTG class to each FIA plot based on fuel loadings and stand conditions. We then compared FIA sampled loadings to the keyed class loading values for four surface fuel components (duff, litter, fine woody debris, coarse woody debris) and to mapped FLM, FCCS, and FTG class loading values from spatial fuel products. We found poor performances (R-2 < 0.30) for most fuel component loadings in all three classifications that, in turn, contributed to poor mapping accuracies. The main reason for the poor performances is the high variability of the four fuel component loadings within classification categories and the inherent scale of this variability does not seem to match the FIA measurement scale or LANDFIRE mapping scale. Published by Elsevier B.V.
... Wildlife responses to thinning may decline 4 to 5 years post-thinning as the canopy closes; thus, periodic thinning may be necessary if continued wildlife use is a management priority (Bender et al. 1997). An advantage of thinning over burning may be the ability to selectively retain snags or coarse woody debris that benefit certain wildlife species (Ucitel et al. 2003). For example, black bears appear to benefit from habitat shifts to early successional stages that provide forage and cover during the active season, but that benefit can be maximized by also retaining hollow logs which are used for denning during winter (Pilliod et al. 2006). ...
Fuels reduction decisions are made within a larger context of resource management characterized by multiple
objectives including ecosystem restoration, wildlife management, commodity production (from timber to
nontraditional forest products), and provision of recreation opportunities and amenity values. Implementation of fuels treatments is strongly influenced by their perceived influence on and compatibility with overarching management objectives. In some cases these objectives may be complementary while in others they may involve difficult tradeoffs. Such tradeoffs are only further complicated by institutional mandates, limited availability of information, and complex ownership patterns. Like natural resource managers across the United States, those in the northern Lake States must balance these competing demands as they seek to build their management programs. However, there is limited information available to support these management decisions in the mixed red (Pinus resinosa Ait.) and eastern white pine (P. strobus L.) forests of the northern Lake States.
This report informs fuels management decisions in the northern Lake States by synthesizing existing knowledge from the fields of silviculture, forest ecology, wildlife ecology, forest economics, public acceptance, and decision science. We provide an overview of forests and fire regimes in the northern Lake States followed by a description of different fuels treatment techniques and their expected outcomes. We then include a discussion of comprehensive management principles to consider in developing fire and fuels management programs for the region.
... 2011). CWD is an important habitat component for many wildlife species (Enge & Marion, 1986;Conant & Collins, 1991;Lohr, Gauthreaux, & Kilgo, 2002;Hicks & Pearson, 2003;Ucitel, Christian, & Graham, 2003;Todd & Andrews, 2008). CWD also aids in maintaining soil fertility (Ellert & Gregorich, 1995), moderates thermal extremes in clear-cuts (Harpole & Haas, 1999), increases moisture retention (Johnson & Crossley, 1996), and reduces soil erosion (Stevens, 1997). ...
Information regarding how site preparation techniques affect residual woody structure is lacking for the southern United States in spite of the importance of such structure for many wildlife species. Therefore, we documented retained structure in young loblolly pine (Pinus taeda L.) plantations established using four common site preparation regimes: mechanical only, chemical only, chemical + mechanical, or chemical + prescribed burning. Herbicides reduced live tree density and increased snag density relative to mechanical methods. Prescribed burning reduced density of coarse woody debris (CWD) along with density and volume of piled CWD relative to chemical and mechanical methods. Our results provide a baseline for further studies of wildlife and retained structure in southern pine forests.
... In this context, it is likely that tree retention groups will facilitate recruitment of dead trees of all decomposition classes in the future. With their higher CWD content, the tree retention groups could serve as "life boats" for saproxylic and non-vascular species (Söderström, 1988;Rambo & Muir, 1998), which prefer CWD as a substrate, and for small mammals (Loeb, 1999;Ucitel, Christian & Graham, 2003;LeMaître et al., 2010), which use CWD as cover, nesting sites, and travel routes. Consequently, the possibility of having CWD over the short-and mediumterm within the tree retention groups, resulting from felled live or dead trees, will have an important effect on species that depend upon deadwood. ...
Alternatives are being sought to the widespread use of clear-cut logging in boreal forests. Group retention harvesting is a silvicultural treatment in which well-distributed but relatively small residual forest patches (ca 10 m wide) are left inside cutover sites. The objective of this study was to compare vascular plant communities, tree species regeneration, and dead wood retention in tree retention groups and adjacent clear-cuts with soil protection. Our results indicate that plant diversity is relatively similar inside tree retention groups and the adjacent clear-cut area. This result may be explained by the important spatial variability observed among the stands, which were located in different geographical locations, the fact that soils were little disturbed during harvesting in clear-cuts and few opportunities were present for the establishment of pioneer species, and the relatively short time span since harvesting. Using a functional trait approach, we found that shade tolerance still plays a significant but relatively minor role in explaining species abundance between the 2 environments. Tree retention groups also retain a greater quantity and greater variability of dead wood materials compared with clear-cuts, and a higher abundance of regenerating trees, which is likely explained in part by the direct damage caused by the harvesting operations outside tree retention groups. Overall, retention groups do not appear to confer superior protection for late-successional plants compared with traditional clear-cut logging with soil protection. Their ecological value mostly consists in ensuring a minimal input of dead woody materials for saproxylic species.
... Characteristics of fuel components can be described by many variables, such as heat content, mineral content and density, but the most common variable used across most fire management applications is fuel loading or the biomass per unit area (Pyne et al. 1996). Fuel loads and related properties are required as inputs to nearly all fire applications (Burgan 1987;Fernandes 2009), and they are also important for other land management concerns, such as the quantification of carbon inventories (de Groot et al. 2007), site productivity (Neary et al. 1999) and wildlife habitat (Ucitel et al. 2003). ...
Wildland fuelbeds are exceptionally complex, consisting of diverse particles of many sizes, types and shapes with abundances and properties that are highly variable in time and space. This complexity makes it difficult to accurately describe, classify, sample and map fuels for wildland fire research and management. As a result, many fire behaviour and effects software prediction systems use a generalised description of fuels to simplify data collection and entry into various computer programs. There are several major fuel description systems currently used in the United States, Canada and Australia, and this is a source of confusion for many in fire management. This paper (1) summarises the challenges of describing fuels, (2) contrasts approaches (association, classification and abstraction) for developing fuel description systems and (3) discusses possible future directions in wildland fuel description and science to transition to a universal fuel description system. Most discussion centres on surface fuel loadings as the primary descriptive characteristic. This synthesis paper is intended to provide background for understanding surface fuel classification and description systems and their use in simulating fire behaviour and effects, quantifying carbon inventories and evaluating site productivity.
... No voles were observed at sites with less than 0.2% coarse woody cover, after which densities increased until reaching a possible plateau at approximately 1% coarse woody material. Our results were consistent with previous studies documenting red-backed vole sensitivity to the amount and distribution of coarse woody debris in the understory (Keinath and Hayward 2003, Ucitel et al. 2003, Vanderwel et al. 2010. These data suggested a threshold relationship such that forest patches with less than a minimal amount of coarse woody debris did not support vole populations. ...
Mountain pine beetle (Dendroctonus ponderosae) (MPB) outbreaks are increasingly prevalent in western North America, causing considerable ecological change in pine (Pinus spp.) forests with important implications for wildlife. We reviewed studies examining wildlife responses to MPB outbreaks and postoutbreak salvage logging to inform forest management and guide future research. Our review included 16 studies describing MPB outbreak relationships with 89 bird species and 6 studies describing relationships with 11 mammalian species, but no studies of reptiles or amphibians. We included studies that compared wildlife response metrics temporally (before versus after the outbreak) and spatially (across sites that varied in severity of outbreak) in relation to beetle outbreaks. Outbreaks ranged in size from 20,600 to ≥107 ha and studies occurred 1–30 years after the peak MPB outbreak, but most studies were conducted over the short-term (i.e., ≤6 years after the peak of MPB-induced tree mortality). Birds were the only taxa studied frequently; however, high variability existed among those studies to allow many inferences, although some patterns were evident. Avian studies concluded that cavity-nesting species responded more favorably to beetle-killed forests than species with open-cup nests, and species nesting in the shrub layer favored outbreak forests compared with ground and open-cup canopy nesters that generally showed mixed relationships. Bark-drilling species as a group clearly demonstrated a positive short-term association with MPB epidemics compared with that of other foraging assemblages. Cavity-nesting birds that do not consume bark beetles (i.e., secondary cavity-nesting species and nonbark-drilling woodpeckers) also exhibited some positive responses to MPB outbreaks, although not as pronounced or consistent as those of bark-drilling woodpeckers. Mammalian responses to MPB outbreaks were mixed. Studies consistently reported negative effects of MPB outbreaks on red squirrels (Tamiasciurus hudsonicus). However, there is evidence that red squirrels can persist after an outbreak under some conditions, e.g., when nonhost tree species are present. For small mammal species associated with forest understories, responses may be most pronounced during the postepidemic period (>6 years after the peak of beetle-induced tree mortality) when snags fall to produce coarse woody debris. Postoutbreak salvage logging studies (n = 6) reported results that lacked consensus. Postoutbreak salvage logging may have an impact on fewer wildlife species than postfire salvage logging, probably because only host-specific tree species are removed after beetle outbreaks.
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... Perkins and Conner (2004) used a MANOVA on Euclidean distances to compare distances between animal locations from each habitat with expected distances (see also Conner et al. 2003 for a discussion of this method). Ucitel (2003) used simple linear regression through the origin to relate use and availability of woody debris by red-backed voles (Clethrionomys gapperi). Roloff et al. (2001) compared fixed-kernel utilization distributions from elk telemetry data to a simulated, random habitat-utilization distribution using a volume of intersection index statististic defined by Seidel (1992). ...
Wildlife management studies often compare relative use and availability of resources
(e.g., habitats). When resources. are used disproportionately to availability, use is said
to be selective. Designs and analyses for resource selection studies are reviewed and
compared with respect to the type of data collected, underlying assumptions, weighting
of observations, distributional requirements and usefulness in comparing selection among
subgroups or time periods. Common misuses of analyses are noted. Practical problems
in studying resource selection, such as which resources to consider, the choice of study
area, and spatial and temporal dependencies, are discussed and suggestions for future
development are given.
... Woody biomass harvest includes the extraction of downed woody material (DWM), such as treetops, limbs, slash and felled small trees, during traditional silvicultural harvest of live trees (Rudolphi and Gustafsson, 2005). Although biomass harvest has not been studied extensively, numerous studies have emphasized that retention of residual woody structure on the forest floor may reduce negative impacts of timber harvesting on forest biota and ecosystem function (Payer and Harrison, 2003;Ucitel et al., 2003;McKenny et al., 2006;Riffell et al., 2011). Woody biomass harvest has the potential to exacerbate negative effects of timber harvesting on forest biota and ecosystem function because it involves additional removal of woody organic matter (Rudolphi and Gustafsson, 2005;Bunnell and Houde, 2010). ...
... Concern about wildfire has initiated programs to control fuel (removal of downed woody materials and under story vegetation). Within forests, numerous small mammals use the downed woody material (Loeb 1999, Menszel et al. 1999, Ucitel et al. 2003. Removal of these materials has potential to reduce prey abundance that may cause fishers to hunt elsewhere, or reduce overall abundance of fishers if the fuel treatments are on a wide scale. ...
We characterized the diet of fisher in the Klamath/North Coast Bioregion of northern California by collecting 388 fecal remains at four distinct study areas within the Klamath Bioregion and analyzing differences between the warmer,and drier interior sites and the marine influenced coastal sites. Ma mmals, especially Sciuridae, were the most frequent food items (98.0% and 26.8% frequency of occurrence, respectively), which
... In contrast, vole densities were consistently lower at sites with higher percent cover of conifer seedlings (live and dead) ; in the spring, they were lower at sites with an abundant ground cover of moss. Coarse woody debris ( CWD) has been reported as a significant correlate of vole abundance in montane coniferous forests of western North America ( Keinath and Hayward, 2003 ;Nordyke and Buskirk, 1991 ;Ucitel et al. , 2003 ) and coniferous or mixedwood forest in the northeastern United States (Miller and Getz, 1973) ( Wywialowski , 1987 ) . Keinath and Hayward (2003 ) reported that C . ...
We studied red-backed vole Clethrionomys gapperi and Keen' s mouse Peromyscus keeni populations in the Alexander Archipelago to test predictions regarding habitat relations in temperate rain forest of southeastern Alaska during August - September 1998 and 2000 and April - May 1999 and 2000. We measured 26 vegetative and structural features to correlate abundance among and microhabitat use within gap-phase old growth, multi-cohort old growth, pre-commer- cially thinned young (23-yr-old) growth, and peatland mixed-conifer forests ... Populations of both species were higher in 1998 than 1999 and 2000. Both species used microhabitats randomly in 1998 4 but were highly selective in 1999 - 2000. Correlates of microhabitat use varied between seasons and among habitats, but C. gapperi captures were most often posi- tively correlated with the percent cover of deciduous shrubs in the understory. Microhabitats used by P. keeni had less moss cover on the forest floor, but in gap-phase were directly related to the probability of capturing a C. gapperi . Density of both species during both seasons was directly correlated with decayed downed wood in the understory. Density of P. keeni in spring explained 62 % of the variation in C. gapperi density, which in turn explained 89 % of the variation in P. keeni density. Our results corroborate the findings of earlier studies that P. keeni in southeastern Alaska flourishes in a variety of habitats, especially early sera1 forests; but, departed from the general conclusion that C. gapperi populations in western landscapes achieve their highest densities in late-sera1 coniferous forests. Unlike populations elsewhere in north- western North America, C. gapperi may be able to persist in rain forest patches where the overstory has been removed. Peatland mixed-conifer forest contributed little to breeding populations of C. gapperi or P. keeni and thus is unlikely to mitigate any impacts of broad-scale clearcut logging of productive old-growth rainforests ( Acta Zoologica Sinica 51 (6) : $!b%o ~~l'l@~~T 26 ~~@i~~&I$~~l2~%#
... Because of conXicting interests, this is indeed a politically diYcult topic. For instance, in Wre-prone forest ecosystems there is the potential for a conXict between biodiversity enhancement as well as forest regeneration facilitation through deadwood retention and Wre risk reduction through fuel management (e.g. Ucitel et al. 2003; Bury 2004; Sanchez-Flores and Yool 2004; Donato et al. 2006; Passovoy and Fulé 2006). In regions aZicted by storms, the numerous damaged trees in a windthrow area, although desirable for all the reasons discussed in this review, can become a source of infestation by bark beetles (Wichmann and Ravn 2001; Eriksson et al. 2005), with perceived risk rates of further infestation often signiWcantly higher than actual ones (e.g. ...
Wood-decaying fungi are essential for the functioning of forest ecosystems. They provide habitat for many other organisms and enable the regeneration of forests throughout the world. Since wood decomposition is a decisive process in nutrient recycling, soil formation and the carbon budget of forest ecosystems, it is receiving increasing attention from forest ecologists, pathologists and managers. Research has focussed on the factors driving the species-richness of wood-decomposing organisms and is moving on to analyse the effects of this species-richness on ecosystem functioning. Coarse woody debris (CWD) and its associated wood-decaying organisms have been drastically reduced in abundance and diversity by forestry and so these features often have potential as conservation indicators. Protective measures at a landscape level are needed for threatened wood-inhabiting fungi. These include restricting salvage operations in windthrow stands, actively encouraging the accumulation of deadwood in forests, and facilitating decay in standing trees by inoculating them with fungi. Here, we aim to collect and summarize recently produced work on deadwood ecology, pointing out research gaps and perspectives.
... At least 55 of the 81 southeastern mammal species make some use of CWD (Loeb 1996). Small mammals use CWD for travel pathways, which may help them avoid predators (McCay 2000, Ucitel et al. 2003, Zollner and Crane 2003. It is possible that the low amount of deciduous leaf litter in pine stands, with a concomitant reduction in movement-related noise, may reduce predation risk to small mammals, thereby reducing their dependence on CWD as travel corridors (Roche et al. 1999, McCay 2000. ...
Forest certification programs require management of stand-level habitat elements supported by up-to-date science. Coarse woody debris (CWD) and snags have shown potential for impacting diversity, although their contributions in pine systems are not always well documented. We reviewed the scientific literature for information on relationships between wildlife communities and these habitat elements, with particular emphasis on southern pine systems, and offer analyses of information gaps and research needs. There is a need to improve knowledge of the impact of silvicultural actions, including herbicide use, on snag and CWD dynamics, and to develop reliable predictive models connecting management to stand-level habitat features and associated wildlife communities. Multivariate analyses should be used in studies of community ecology and response to habitat characteristics. We encourage long-term experiments to increase the power of hypothesis testing and account for temporal variation in wildlife populations. Wildlife responses should be measured using demographic characteristics rather than mere density.
... little relation between abundance of small mammal species and down wood (Corn and Bury 1991a;West 1991); weak relations for a few species (r s or r 2 < 0.40; Gilbert and Alwine 1991;Maquire 2002); abundance of Pacific water shrews (Sorex bendirii) positively correlated with log densities ; shrews responded to down wood by concentrating their movements within 1 m of pieces of down wood, but this effect was not evident in amounts of down wood on 1 ha plots (Craig 1995); Ucitel et al. (2003) obtained similar findings for red-backed voles (Myodes gapperi); four small mammal species showed positive responses to abundance of down wood in managed stands, but not in old-growth stands (Carey and Johnson 1995); on inland Douglas-fir sites, small mammals, including deer mice (Peromyscus maniculatus) were more abundant on sites where down wood was more abundant (van Woudenberg 1992); on others there was no response of deer mice to volume of down wood (Craig et al. 2006). in Englemann spruce (Picea englemanii) sites, deer mice appeared to be more closely related to vegetation cover than to down wood (Craig et al. 2006). The variability in response precludes estimating threshold amounts. ...
Many species require or use down wood (fine and coarse woody debris) as habitat. Where forestry has been practiced for several rotations large proportions of these species are considered threatened. Key attributes determining the suitability of down wood as habitat are decay stage, tree species, and size, specifically diameter. Both quantity and distribution of suitable down wood influence species' presence and abundance. We present a simple framework describing use of down wood based on broad natural history features, derive predictions from the framework, then test these by review and summary of literature. Our focus is terrestrial vertebrates, particularly in the Pacific Northwest. Species other than vertebrates are addressed to ensure that metrics derived for vertebrates also are appropriate for other organisms. Basic metrics are the same, but appropriate values span a larger range among nonvertebrates. Current evidence suggests that the "extinction debt" apparent for nonvertebrates is approaching for vertebrates. Predictions derived from underlying natural history hold when tested. From that basis we derive broad guidelines for forest planning and practice, and suggest how regional target values can be derived.
... Perkins and Conner (2004) used a MANOVA on Euclidean distances to compare distances between animal locations from each habitat with expected distances (see also Conner et al. 2003 for a discussion of this method). Ucitel (2003) used simple linear regression through the origin to relate use and availability of woody debris by red-backed voles (Clethrionomys gapperi). Roloff et al. (2001) compared fixed-kernel utilization distributions from elk telemetry data to a simulated, random habitat-utilization distribution using a volume of intersection index statististic defined by Seidel (1992). ...
We classified study designs for comparing resource (food, habitat) use and availability into 3 basic types. Design 1 permits investigation of resource selectivity only at the population level because individual animals are not identified. Designs 2 and 3 measure use by individuals and thus allow examination of the variation in resource selection strategies. Resource availabilities are measured for each individual in Design 3 but not in Design 2. Graphical plots illustrating individual selection are recommended for data resulting from Designs 2 and 3 to assess variability and possible sex or age differences. We recommend a method for determining the number of random points required to bound the probable error in estimating resource availability proportions simultaneously, rather than individually. Four problem areas in the use of statistical methods for evaluating resource selectivity are identified: dependencies among observations, the misuse of the Chi-square goodness-of-fit test when availabilities are estimated, tests that do not control experimentwise error rates, and the sensitivity of tests to the subjective inclusion or exclusion of resources.
Successional, second-growth forests dominate much of eastern North America, thus patterns of biomass accumulation in standing trees and downed wood are of great interest for forest management and carbon accounting. The timing and magnitude of biomass accumulation in later stages of forest development are not fully understood. We applied a “chronosequence with resampling” approach to characterize live and dead biomass accumulation in sixteen northern hardwood stands in the White Mountains of New Hampshire. Live aboveground biomass increased rapidly and leveled off at about 350 Mg/ha by 145 years. Downed wood biomass fluctuated between 10 and 35 Mg/ha depending on disturbances. The species composition of downed wood varied predictably with overstory succession, and total mass of downed wood increased with stand age and the concomitant production of larger material. Fine woody debris peaked at 30-50 years during the self-thinning of early-successional species, notably pin cherry. Our data support a model of northern hardwood forest development wherein live tree biomass accumulates asymptotically and begins to level off at ~140-150 years. Still, 145-year-old second-growth stands differed from old-growth forests in their live (p = 0.09) and downed tree diameter distributions (p = 0.06). These patterns of forest biomass accumulation would be difficult to detect without a time series of repeated measurements of stands of different ages.
Salvage logging is a controversial tool for post-wildfire management that removes fire-killed trees. We use a generalized randomized experimental design to fulfill two main objectives: (1) quantify the immediate (1-year post-harvest) effects of salvage logging on stand structure, fine and coarse woody fuel loadings; and (2) use pre-and post-empirical field data and the Fire and Fuels Extension to the Forest Vegetation Simulator (hereafter FFE-FVS; Reinhardt and Crookston 2003) to simulate post-wildfire dead woody fuel succession and snag dynamics. We compared the effects on woody fuel loadings of two salvage logging prescriptions: 1. seed tree harvest (STH), thin to 3.4 m2 ha-1; and 2. full salvage (FS) of all merchantable timber, relative to unlogged controls. There was substantial block-level variability in the implementation of the treatments and in their immediate effects on fine fuel loading, complicating comparison of the two prescriptions. Overall, salvage logging did reduce snag basal area and, relative to unlogged controls, significantly increased measured fine woody fuel loading (10- and 100-hr). Simulated snag fall was rapid, with mean predicted snag basal area loss of 61% within 10 years. Future long-term monitoring of permanent field plots will supplement model predictions and provide valuable data to inform post-wildfire management decisions.
Prescribed burning is used in fire-prone environments worldwide to reduce fuel loads and the severity and spread of future wildfires. Forest habitat structures, such as large trees, dead trees and logs are highly flammable, yet also are essential for animal species that require hollows (cavities) as den sites for shelter and reproduction. We examined the effects of experimental prescribed burns on the use of den sites by a small marsupial, the yellow-footed antechinus Antechinus flavipes, in south-eastern Australia. Specifically, we radio-tracked individual A. flavipes to identify forest habitat structures preferred as den sites and recorded the fate of known den sites following patchy prescribed burns. We found that large living trees and dead trees were used as den sites disproportionately to their relative abundance in the forest. While all marked individuals of A. flavipes survived the immediate impacts of patchy prescribed burns, almost a third (16/52) of den sites identified before burning were lost, including 17% of trees (4/23) and 48% of logs (10/21). The vulnerability of den sites to prescribed burns can be attributed to the decay-dependent effect of fire on both trees and logs, whereby, the amount of damage from fire is related to the structure’s pre-fire condition (i.e. whether dead or alive, amount of decay). Large trees and large logs are scarce in this dry forest ecosystem and their replacement is likely to take a century or more due to the slow growth rates of trees. The ecological impacts of prescribed burning on habitat structures used by A. flavipes and other hollow-using species can be moderated by: (1) carrying out patchy, rather than complete burns; (2) ensuring the inter-fire interval is sufficient to allow time for replenishment of resources; and (3) planning at a regional scale to maintain an appropriate spatial pattern of post-fire age-classes, including areas retained as long-unburned (e.g. >50 years) in which resources such as deep litter, large logs and dead trees can accumulate.
Prescribed burning to achieve management objectives is a common practice in fire-prone regions worldwide. Structural components of habitat that are combustible and slow to develop are particularly susceptible to change associated with prescribed burning. We used an experimental, 'whole of landscape' approach to investigate the effect of differing patterns of prescribed burning on key habitat components (logs, stumps, dead trees, litter cover, litter depth and understorey vegetation). Twenty-two landscapes (each ~100 ha) were selected in a dry forest ecosystem in southeast Australia. Experimental burns were conducted in 16 landscapes (stratified by burn extent) while six served as untreated controls. We measured habitat components prior to and after burning. Landscape burn extent ranged from 22-89% across the 16 burn treatments. With the exception of dead standing trees (no change), all measures of habitat components declined as a consequence of burning. The degree of loss increased as the extent to which a landscape was burnt also increased. Prescribed burning had complex effects on the spatial heterogeneity (beta diversity) of structural components within landscapes. Landscapes that were more heterogeneous pre-fire were homogenized by burning, while those that were more homogenous pre-fire tended to display greater differentiation post-burning. Thus, the notion that patch mosaic burning enhances heterogeneity at the landscape-scale depends on prior conditions. These findings have important management implications. Where prescribed burns must be undertaken, effects on important resources can be moderated via control of burn characteristics (e.g. burn extent). Longer-term impacts of prescribed burning will be strongly influenced by the return interval, given the slow rate at which some structural components accumulate (decades to centuries). Management of habitat structural components is important given the critical role they play in: (1) provision of habitat resources for diverse organisms; (2) retention of moisture and nutrients in otherwise dry, low-productivity systems; and (3) carbon storage. This article is protected by copyright. All rights reserved.
Coarse woody debris (CWD) is generally considered dead woody material in various stages of forest decomposition and has been hypothesized to be an important habitat feature for mammals in forests of the Pacific Northwest, USA. Sherman and pitfall trapping were conducted for 2 years on three paired sites with low and high amounts of CWD. Deer mice was the dominant species with a total capture of 605 (45.6%). Four species of insectivores were captured, including Sorex moncicolus, S. trowbridgii, S. vagrans, and Neurotrichus gibbsii. A Poisson regression model was used to test whether 11 CWD variables could predict insectivore captures. The volume of logs and mean decay were important variables for deer mice use of CWD. Mean distance from pieces of CWD to the capture point was significantly related to the total number of captures of trowbridge shrew (Sorex trowbridgii) and all insectivore species. Vagrant shrews (Sorex vagrans) were significantly associated with log volume. Retaining large size CWD should be part of a management plan for ground-dwelling insectivores in forests to secure their biodiversity.
Traditional, stage-based, classification systems provide a qualitative measure of decay and have been widely used to monitor and model terrestrial coarsewood and aquatic largewood dynamics. These systems are limited by subjective assignment of wood to classes, lack of measurements relating wood morphology with decay classes, and poor estimates of elapsed time-since-death within and between decay classes. To overcome these limitations, we used quantitative methods to develop a new classification system for in-stream largewood based on morphological attributes that are (1) easily measured in the field and (2) relate to the time-since-death of individual logs. Using principal components and cluster analyses, we developed a three-class system for largewood based on log length, branch order, and cover (quartile classes) of bark, vegetation, and soil. Thresholds for each attribute provided criteria that we organized in a dichotomous key that can be used to objectively and consistently assign individual pieces of largewood into mutually exclusive classes. Using time-since-death determined using dendrochronology, we verified that successive classes in our model-based decay classification represent progressive largewood decomposition through time. This model-based classification system provides an improved framework for developing management plans and modeling dynamics of in-stream largewood.
Red-shouldered hawks (Buteo lineatus) are threatened in Wisconsin and when nest sites are found during the cruising or marking stage of timber harvesting, the harvest is altered to accommodate the hawks. If nest site locations are known before initiation of timber harvest, foresters can employ a proactive approach to manage red-shouldered hawks while maintaining timber production. We searched for red-shouldered hawks nest sites on Marinette County Forest (MCF) which encompasses 94,000ha in northeastern Wisconsin and is the second largest county forest in the state. We used a comparative modeling approach to evaluate distribution and habitat relationships of red-shouldered hawk nest sites in relation to a suite of environmental variables in MCF. Models were used to develop forest management recommendations for red-shouldered hawks in Wisconsin. During the spring of 2006 and 2007, we broadcasted conspecific calls to survey 1121 calling stations along forest roads and trails. We located 20 and 25 active nesting territories in 2006 and 2007, respectively (11 of which were active in both years). To understand nest site selection, we measured 22 habitat variables within 0.04-ha plots at active nest sites (n=34) and at stratified random sites (n=61). Logistic regression with information-theoretic model selection identified a model including greater tree species richness and closeness to forested wetland as the best-approximating model. Variable selection with Discriminant Function Analysis (DFA) indicated that nest selection was best explained by greater number of tree species, closer distance to forested wetlands, greater volume of downed woody debris, fewer small sawlogs, and increased proximity to streams. Univariate comparisons identified four of the five aforementioned variables in the DFA model as significant. Red-shouldered hawks are likely more common in Wisconsin than their state status suggests. Forest management for red-shouldered hawk nest sites should focus on increasing tree species richness, increasing down woody debris volume, and protecting forested wetlands. These recommendations may assist property managers to locate and plan for continued persistence of this species on MCF.
American marten (Martes americana) are typically associated with mature coniferous forests. Some recent results, however, suggest that marten habitat selection may also operate at a finer scale. We therefore described site characteristics of 24 martens that were radio-tracked and snow-tracked between August 2002 and March 2004. From these data we developed 2 resource selection functions, one for summer and the other for winter, using logistic regressions. In summer, selected sites were mainly characterized by abundant biomass of spruces and short (≤ 30 cm) herbaceous plants and low biomass of tall (> 30 cm) herbaceous plants. Other factors, such as increased coniferous canopy closure and amount of coarse woody debris (CWD) and reduced lateral cover (LC5) were included in the composite model. In winter, sites with closed coniferous canopy and LC5, high snow sinking depth, greater amounts of CWD, greater basal area, and greater tree density were more likely to be visited by marten. These variables may be related to 3 factors that play roles in marten ecology: prey abundance, protective cover, and thermoregulation. Our results also show that, unlike clear-cutting with protection of regeneration and soils (CPRS) and pre-commercial thinning (PCT), partial logging techniques (PL) could maintain, under certain conditions, the structural elements required by pine marten in a managed forest. These elements would favour prey abundance and detection, protective cover, and rest and thermoregulation sites.
Species evaluated include Peromyscus maniculatus, Eutamius ruficaudus, Zapus princeps and Clethrionomys gapperi. P. maniculatus increased with succession; E. ruficaudus abundance varied but was generally most common in mid-successional stages; Z. princeps preferred willow-alder thickets within mid-successional stages; and C. gapperi was most abundant in the mature forest. -from Authors
Fluorescent powder frequently is used to track free-living small mammals. We investigated possible harmful effects of powdered fluorescent pigments on wild deer mice (Peromyscus maniculatus) in northcentral Colorado. We examined mice collected 3, 6, 16, and 27 days after dusting with fluorescent powder to document the location and extent of powder both internally and externally and to record changes in the amount of powder over time. We also examined tissues histologically for pathological lesions and other evidence of adverse reactions to powder and compared the incidence of these effects with those from untreated mice collected at the same time. The amount of fluorescent powder in body tissues decreased over time, with ingested particles apparently passing harmlessly through the gastrointestinal tract. Mild to moderate histiocytic pneumonia, presumably associated with inhalation of powder, was detected in one mouse from each collection period (27% of all dusted mice), whereas control animals showed no evidence of pneumonia. Most dusted mice, however, exhibited no adverse reaction to the presence of powder particles in lung or other tissues. Our results indicate that the use of fluorescent powder for tracking studies has few significant pathological effects, but we recommend that researchers minimize the exposure of respiratory tissues of study animals to large doses of powder.