Search

Restoration goals in fire-prone conifer forests include mitigating fire hazard while restoring forest structural components linked to disturbance resilience and ecological function. Restoration of overstory spatial pattern in forests often falls short of management objectives due to complexities in implementation, regulation, and available data. When historic data is available, it is often collected at plots sizes too small to inform coarse-scale metrics like gap size and tree patch structure (e.g., 1 ha). Principles of ecological forestry typically emphasize overstory removal patterns that emulate those of natural disturbances, thus low- and moderate-severity portions of contemporary wildfires may serve as a guide to restoration treatments where mixed-severity fires occur. Here, we compare forest spatial pattern and configuration in 15 mechanical restoration treatments and low- and moderate- severity portions of three wildfires in ponderosa pine forests to determine how they differ in spatial pattern. We obtained satellite imagery of restoration treatments and wildfires and used supervised classification to differentiate canopy and openings. We assessed elements of landscape structure including canopy and gap cover, gap attributes, and landscape heterogeneity for each disturbance type. We found that both mechanical restoration treatments and low- and moderate severity portions of wildfires had reduced forest cover, increased gap cover, and altered pattern and arrangement of gaps relative to undisturbed areas, though the magnitude of changes were greatest in the burned sites we examined. Low- and moderate-severity wildfire consistently increased landscape heterogeneity while mechanical treatments did not, suggesting that a greater emphasis on increasing gap and patch spatial structure may make mechanical treatments more congruent with natural disturbances. Outcomes of low and moderate-severity portions of wildfires may provide important information upon which to base management prescriptions where reference data on landscape patterns is unavailable.

In response to large, severe wildfires in historically fire-adapted forests in the western US, policy initiatives, such as the USDA Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP), seek to increase the pace and scale of ecological restoration. One required component of this program is collaborative adaptive management, in which monitoring data are used to iteratively evaluate and improve future management actions. Here, we assess the success of seven CFLRP treatments, implemented on 2,300 ha during the first three years of the Colorado Front Range Landscape Restoration Initiative (LRI) at achieving desired forest structure by comparing pre- and post-treatment conditions. We also compare post-treatment conditions with reconstructions of historical (ca. 1860) forest conditions to contextualize the magnitude of treatment effects. Restoration projects moved stands toward desired conditions by reducing basal area, tree density, and canopy cover and increasing average tree diameter, large gap cover, and abundance of small- to medium-sized tree groups. Post-treatment stands were similar to historical stands with respect to basal area of ponderosa pine; however, they had higher total tree density and fewer gaps than historical reference conditions, suggesting that restoration prescriptions may be improved with increased flexibility for density reduction of Douglas-fir and increased gap creation. This examination of early CFLRP treatment outcomes as they relate to desired conditions informs potential areas of adjustments to future treatments and provides baseline data to evaluate the evolution of treatments over the program’s lifespan. We also identify and discuss several scientific, social, and logistical constraints to large-scale restoration success and make several recommendations to improve restoration outcomes.

Ecological restoration treatments are being implemented at an increasing rate in ponderosa pine and other dry conifer forests across the western United States, via the USDA Forest Service’s Collaborative Forest Landscape Restoration (CFLR) program. In this program, collaborative stakeholder groups work with National Forests (NFs) to adaptively implement and monitor ecological restoration treatments intended to offset the effects of many decades of anthropogenic stressors. We initiated a novel study to expand the scope of treatment effectiveness monitoring efforts in one of the first CFLR landscapes, Colorado’s Front Range. We used a Before/After/Control/Impact framework to evaluate the short-term consequences of treatments on numerous ecological properties. We collected pre-treatment and one year post-treatment data on NF and partner agencies’ lands, in 66 plots distributed across seven treatment units and nearby untreated areas. Our results reflected progress toward several treatment objectives: treated areas had lower tree density and basal area, greater openness, no increase in exotic understory plants, no decrease in native understory plants, and no decrease in use by tree squirrels and ungulates. However, some findings suggested the need for adaptive modification of both treatment prescriptions and monitoring protocols: treatments did not promote heterogeneity of stand structure, and monitoring methods may not have been robust enough to detect changes in surface fuels. Our study highlights both the effective aspects of these restoration treatments, and the importance of initiating and continuing collaborative science-based monitoring to improve the outcomes of broad-scale forest restoration efforts.

Recent evidence of range expansion and host transition by mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) has suggested that MPB may not primarily breed in their natal host, but will switch hosts to an alternate tree species. As MPB populations expanded in lodgepole pine forests in the southern Rocky Mountains, we investigated the potential for movement into adjacent ponderosa pine forests. We conducted field and laboratory experiments to evaluate four aspects of MPB population dynamics and host selection behavior in the two hosts: emergence timing, sex ratios, host choice, and reproductive success. We found that peak MPB emergence from both hosts occurred simultaneously between late July and early August, and the sex ratio of emerging beetles did not differ between hosts. In two direct tests of MPB host selection, we identified a strong preference by MPB for ponderosa versus lodgepole pine. At field sites, we captured naturally emerging beetles from both natal hosts in choice arenas containing logs of both species. In the laboratory, we offered sections of bark and phloem from both species to individual insects in bioassays. In both tests, insects infested ponderosa over lodgepole pine at a ratio of almost 2:1, regardless of natal host species. Reproductive success (offspring/female) was similar in colonized logs of both hosts. Overall, our findings suggest that MPB may exhibit equally high rates of infestation and fecundity in an alternate host under favorable conditions.

"Wildfires have become larger and more severe over the past several decades on Colorado's Front Range, catalyzing greater investments in forest management intended to mitigate wildfire risks. The complex ecological, social, and political context of the Front Range, however, makes forest management challenging, especially where multiple management goals including forest restoration exist. In this report, we present a science-based framework for managers to develop place-based approaches to forest restoration of Front Range ponderosa pine and dry mixed-conifer forests. We first present ecological information describing how Front Range forest structure and composition are shaped at multiple scales by interactions among topography, natural disturbances such as fire, and forest developmental processes. This information serves as a foundation for identifying priority areas for treatment and designing restoration projects across scales. Treatment guidelines generally reduce forest densities and surface and crown fuels, enhance spatial heterogeneity across scales, and retain drought- and fire-tolerant species, old trees, and structures important for wildlife. Implementation of these guidelines is expected to enhance forest resilience to disturbance and climate change, as well as sustain important ecosystem services. Finally, this report emphasizes the importance of adaptive management and learning through monitoring and experimentation to address uncertainties inherent in the restoration process."

Eruptive mountain pine beetle ( Dendroctonus ponderosae , MPB) populations have caused widespread mortality of pines throughout western North America since the late 1990s. Early work by A.D. Hopkins suggested that when alternate host species are available, MPB will prefer to breed in the host to which it has become adapted. In Colorado, epidemic MPB populations that originated in lodgepole pine expanded into mixed-conifer stands containing ponderosa pine, a related host. We evaluated the susceptibility of both hosts to successful MPB colonization in a survey of 19 sites in pine-dominated mixed-conifer stands spanning 140 km of the Front Range, CO, USA. In each of three 0.2-ha plots at each site, we (1) assessed trees in the annual flights of 2008–2011 to compare MPB-caused mortality between lodgepole and ponderosa pine; (2) recorded previous MPB-caused tree mortality from 2004–2007 to establish baseline mortality levels; and (3) measured characteristics of the stands (e.g. tree basal area) and sites (e.g. elevation, aspect) that might be correlated with MPB colonization. Uninfested average live basal area of lodgepole and ponderosa pine was 74% of total basal area before 2004. We found that for both species, annual percent basal area of attacked trees was greatest in one year (2009), and was lower in all other years (2004–2007, 2008, 2010, and 2011). Both pine species had similar average total mortality of 38–39% by 2011. Significant predictors of ponderosa pine mortality in a given year were basal area of uninfested ponderosa pine and the previous year’s mortality levels in both ponderosa and lodgepole pine. Lodgepole pine mortality was predicted by uninfested basal areas of both lodgepole and ponderosa pine, and the previous year’s lodgepole pine mortality. These results indicate host selection by MPB from lodgepole pine natal hosts into ponderosa pine the following year, but not the reverse. In both species, diameters of attacked trees within each year were similar, and were progressively smaller the last four years of the study period. Our results suggest that, in contrast to previous reports, ponderosa and lodgepole pine were equally susceptible to MPB infestation in the CO Front Range during our study period. This suggests that forest managers may anticipate similar impacts in both hosts during similar environmental conditions when epidemic-level MPB populations are active in mixed-pine stands.

In 2009, the federal Joint Fire Science Program (JFSP) initiated a national network of boundary organizations,known as regional fire science consortia, to accelerate the awareness, understanding, and use of wildland firescience. Needs assessments conducted by consortia in eight regions of the United States are synthesized hereusing a case survey approach. Although regions used different methods based on their different ecosystems,geography, and demography, results showed striking similarities in how fire science is accessed and used,barriers to its use, and research information needed. Use of Internet-based information is universally high;however, in-person knowledge exchange is preferred. Obstacles to fire science application include lack of time,resources, and access to the most relevant information as well as communication barriers between scientists andmanagers. Findings show a clear need for boundary organizations to span fire science and management to (a)organize and consolidate fire science information through easily accessible websites and (b) strengthenrelationships between scientists and managers to facilitate production and communication of science relevant tomanagers’ concerns. This article contributes to boundary spanning theory by underscoring and documenting theadvantages of regionally focused boundary organizations in meeting user needs and building bridges betweenfire scientists and managers.Keywords: fire science, boundary organization, fire management, Joint Fire Science Program, technologytransfer

The U.S. Fish and Wildlife Service, along with the global conservation community, has recognized that the conservation challenges of the 21st century far exceed the responsibilities and footprint of any individual agency or program. The ecological effects of climate change and other anthropogenic stressors do not recognize geopolitical boundaries and, as such, demand a national geographic framework to provide structure for cross-jurisdictional and landscape-scale conservation strategies. In 2009, a new map of ecologically based conservation regions in which to organize capacity and implement strategic habitat conservation was developed using rapid prototyping and expert elicitation by an interagency team of U.S. Fish and Wildlife Service and U.S. Geological Survey scientists and conservation professionals. Incorporating Bird Conservation Regions, Freshwater Ecoregions, and U.S. Geological Survey hydrologic unit codes, the new geographic framework provides a spatial template for building conservat...

Pine forest in northern Colorado and southern Wyoming, USA, are experiencing the most severe mountain pine beetle epidemic in recorded history, and possible degradation of drinking-water quality is a major concern. The objective of this study was to investigate possible changes in soil and water chemistry in Grand County, Colorado in response to the epidemic, and to identify major controlling influences on stream-water nutrients and C in areas affected by the mountain pine beetle. Soil moisture and soil N increased in soils beneath trees killed by the mountain pine beetle, reflecting reduced evapotranspiration and litter accumulation and decay. No significant changes in stream-water NO 3 - or dissolved organic C were observed; however, total N and total P increased, possibly due to litter breakdown or increased productivity related to warming air temperatures. Multiple-regression analyses indicated that % of basin affected by mountain pine beetles had minimal influence on stream-water NO 3 - and dissolved organic C; instead, other basin characteristics, such as percent of the basin classified as forest, were much more important.

Some species of animals provide directed dispersal of plant seeds by transporting them nonrandomly to microsites where their chances of producing healthy seedlings are enhanced. We investigated whether this mutualistic interaction occurs between granivorous rodents and Jeffrey pine (Pinus jeffreyi) in the eastern Sierra Nevada by comparing the effectiveness of random abiotic seed dispersal with the dispersal performed by four species of rodents: deer mice (Peromyscus maniculatus), yellow-pine and long-eared chipmunks (Tamias amoenus and T. quadrimaculatus), and golden-mantled ground squirrels (Spermophilus lateralis). We conducted two caching studies using radio-labeled seeds, the first with individual animals in field enclosures and the second with a community of rodents in open forest. We used artificial caches to compare the fates of seeds placed at the range of microsites and depths used by animals with the fates of seeds dispersed abiotically. Finally, we examined the distribution and survival of naturally establishing seedlings over an eight-year period. Several lines of evidence suggested that this community of rodents provided directed dispersal. Animals preferred to cache seeds in microsites that were favorable for emergence or survival of seedlings and avoided caching in microsites in which seedlings fared worst. Seeds buried at depths typical of animal caches (5-25 mm) produced at least five times more seedlings than did seeds on the forest floor. The four species of rodents differed in the quality of dispersal they provided. Small, shallow caches made by deer mice most resembled seeds dispersed by abiotic processes, whereas many of the large caches made by ground squirrels were buried too deeply for successful emergence of seedlings. Chipmunks made the greatest number of caches within the range of depths and microsites favorable for establishment of pine seedlings. Directed dispersal is an important element of the population dynamics of Jeffrey pine, a dominant tree species in the eastern Sierra Nevada. Quantifying the occurrence and dynamics of directed dispersal in this and other cases will contribute to better understanding of mutualistic coevolution of plants and animals and to more effective management of ecosystems in which directed dispersal is a keystone process.

Food stored by animals can either be recovered by the hoarder or pilfered, but it is very difficult to distinguish between these possibilities under natural conditions. We tested the hypothesis that yellow pine chipmunks, Tamias amoenus, have a recovery advantage (i.e. a greater probability of finding a cached item than does a naive forager). We allowed chipmunks to cache radiolabelled pine seeds and then established artificial caches nearby. Paired artificial and real caches were identical in number of seeds, depth and microsite. Caches (393 pairs at 10 sites) were monitored during autumn 1997, 1999 and 2002. Removal of real caches represented the activity of the hoarder, foraging using spatial memory, plus the activities of pilferers, whereas the removal of artificial caches represented the activities of pilferers. We used these two measures in a competing risks model, which estimated that seed-caching chipmunks retrieved 74% of the food they stored in 1997 and 56% of the food they stored in 1999–2002. Seed-hoarding chipmunks were removed at four of the 10 sites immediately after they prepared caches. Where the seed-hoarders remained, animals took real caches 3.4 to 6.5 times faster than artificial caches, an effect that we attribute to the activity of the hoarder. Where the caching chipmunk was removed, there were no significant differences in the rates of removal of real versus artificial caches. We suggest that artificial caches can be used to estimate the proportion of caches retrieved by a seed-hoarding animal versus the proportion discovered by pilferers.

The abiotic environment often influences the ways in which animals interact. By affecting the cues associated with buried seeds, the type of substrate used by seed-caching rodents may alter the relative probabilities of cache pilferage and cache retrieval. We predicted that, after a wildfire, the presence of ash would impair rodents’ ability to smell pine seeds on the forest floor. In a laboratory experiment, we compared the foraging success, caching frequency, and cache recovery of chipmunks (six Tamias amoenus and six T. quadrimaculatus) in ash versus sand substrates. Initial results supported our hypothesis: chipmunks found only 2.3% of 108 caches of Jeffrey pine (Pinus jeffreyi) seeds that we buried in ash but found 98% of caches in sand. However, chipmunks made as many or more of their own caches in ash compared with sand (48% for T. amoenus, 73% for T. quadrimaculatus.) When foraging for seeds cached in ash by themselves and by other individuals, they found significantly higher proportions of their own caches (62%) than of caches made by others (25%). However, when foraging in sand, they found high proportions both of their own caches and those of others (86 versus 81%). These results suggest that olfaction is less effective in ash than in sand, that spatial memory enables chipmunks to recover their own caches in ash, and that caching in ash may allow animals to avoid pilferage of stored food. As chipmunks are important dispersers of seeds, changes in their foraging patterns or competitive interactions after fire could significantly affect pine regeneration. Key words: ash, caching, chipmunks, foraging, Jeffrey pine, olfaction, pilferage, Pinus jeffreyi, spatial memory, scatter hoarding, Tamias. [Behav Ecol 15:666–672 (2004)]

Olfaction plays an important role in the foraging behavior of rodents, but little is known about how this sense varies among taxa that evolved in different ecological settings. Field experiments were conducted in 10- by 10-m enclosures to test for interspecific differences in foraging success for ponderosa pine (Pinus ponderosa) or sunflower seeds, based on olfaction, of 4 rodent species: 2 heteromyid rodents (Panamint kangaroo rat, Dipodomys panamintinus, and Great Basin pocket mouse, Perognathus parvus) and 2 nonheteromyid rodents (yellow pine chipmunk, Tamias amoenus, and deer mouse, Peromyscus maniculatus). All species found large, shallow caches more frequently than small, deep caches. Chipmunks had the lowest foraging success for buried sunflower seeds under dry conditions. Deer mice did as well as the heteromyid rodents on large shallow caches but found relatively few small, deep caches. The heteromyids were the only species that found small, deep sunflower seed caches under dry conditions, and Panamint kangaroo rats always found more caches than did Great Basin pocket mice. These results confirm that olfaction plays an important role in foraging of rodents for buried seeds and support the notion that the olfactory sense of rodent species has evolved greater sensitivity to seeds in different ecological contexts.

Wildfire behavior depends on the type, quantity, and condition of fuels, and the effect that bark beetle outbreaks have on fuels is a topic of current research and debate. Remote sensing can provide estimates of fuels across landscapes, although few studies have estimated surface fuels from remote sensing data. Here we predicted and mapped field-measured canopy and surface fuels from light detection and ranging (lidar) and Landsat time series explanatory variables via random forest (RF) modeling across a coniferous montane forest in Colorado, USA, which was affected by mountain pine beetles (Dendroctonus ponderosae Hopkins) approximately six years prior. We examined relationships between mapped fuels and the severity of tree mortality with correlation tests. RF models explained 59%, 48%, 35%, and 70% of the variation in available canopy fuel, canopy bulk density, canopy base height, and canopy height, respectively (percent root-mean-square error (%RMSE) = 12–54%). Surface fuels were predicted less accurately, with models explaining 24%, 28%, 32%, and 30% of the variation in litter and duff, 1 to 100-h, 1000-h, and total surface fuels, respectively (%RMSE = 37–98%). Fuel metrics were negatively correlated with the severity of tree mortality, except canopy base height, which increased with greater tree mortality. Our results showed how bark beetle-caused tree mortality significantly reduced canopy fuels in our study area. We demonstrated that lidar and Landsat time series data contain substantial information about canopy and surface fuels and can be used for large-scale efforts to monitor and map fuel loads for fire behavior modeling at a landscape scale.

A current pine beetle infestation has caused extensive mortality of lodgepole pine ( Pinus contorta ) in forests of Colorado and Wyoming; it is part of an unprecedented multispecies beetle outbreak extending from Mexico to Canada. In United States and European watersheds, where atmospheric deposition of inorganic N is moderate to low (