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Old-growth forests of Engelmann spruce (Picea engelmannii Parry ex. Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) dominate much of the landscape of the Rocky Mountains. We characterized the structure, biomass and production of 18 old-growth (200-450-year-old) spruce/fir forests in Rocky Mountain National Park, Colorado, as well as the stand-level supply and use of light and nitrogen. Stands were chosen to span a broad range of elevation, aspect, and topography. Aboveground tree biomass in these old-growth forests averaged 253 Mg/ha (range 130-488 Mg/ha), with aboveground net primary production of 3700 kg ha-1 yr-1 (range from 2700 to 5200 kg ha-1 yr-1). Within stands, trees >35 cm in diameter accounted...
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The rapid growth of housing in and near the wildland–urban interface (WUI) increases wildfirerisk to lives and structures. To reduce fire risk, it is necessary to identify WUI housing areas that are more susceptible to wildfire. This is challenging, because wildfire patterns depend on fire behavior and spread, which in turn depend on ignition locations, weather conditions, the spatial arrangement of fuels, and topography. The goal of our study was to assess wildfirerisk to a 60,000 ha WUI area in northwesternWisconsin while accounting for all of these factors. We conducted 6000 simulations with two dynamic fire models: Fire Area Simulator (FARSITE) and Minimum Travel Time (MTT) in order to map the spatial pattern...
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Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total...
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Contemporary forest management practices are increasingly designed to optimize novel objectives, such as maximizing biomass feedstocks and/or maintaining ecological legacies, but many uncertainties exist regarding how these practices influence forest carbon (C) cycling. We examined the responses of soil respiration (Rs) to biomass harvesting and green-tree retention in an effort to empirically assess their impacts on C cycling. We measured Rs and soil microclimatic variables over four growing seasons following implementation of these management practices using a fully replicated, operational-scale experiment in aspen-dominated forests in northern Minnesota. Treatments included three levels of biomass removal within...
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The diverse forest types of the southwestern US are inseparable from fire. Across climate zones in California, Nevada, Arizona, and New Mexico, fire suppression has left many forest types out of sync with their historic fire regimes. As a result, high fuel loads place them at risk of severe fire, particularly as fire activity increases due to climate change. A legacy of fire exclusion coupled with a warming climate has led to increasingly large and severe wildfires in many southwest forest types. Climate change projections include an extended fire season length due to earlier snowmelt and a general drying trend due to rising temperatures. This suggests the future will be warmer and drier regardless of changes in...
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Pacific Northwest salmonids are adapted to natural disturbance regimes that create dynamic habitat patterns over space and through time. However, human land use, particularly long-term fire suppression, has altered the intensity and frequency of wildfire in forested upland and riparian areas. To examine the potential impacts of wildfire on aquatic systems, we developed stream-reach-scale models of freshwater habitat for three life stages (adult, egg/fry, and juvenile) of spring Chinook salmon (Oncorhynchus tshawytscha) in the Wenatchee River subbasin, Washington. We used variables representing pre- and post-fire habitat conditions and employed novel techniques to capture changes in in-stream fine sediment, wood,...
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California experienced severe drought from 2012 to 2016, and there were visible changes in the forest canopy throughout the State. In 2014, unprecedented foliage dieback was recorded in giant sequoia (Sequoiadendron giganteum) trees in Sequoia National Park, in the southern California Sierra Nevada mountains. Although visible changes in sequoia canopies can be recorded, biochemical and physiological responses to drought stress in giant sequoia canopies are not well understood. Ground-based measurements provide insight into the mechanisms of drought responses in trees, but are often limited to few individuals, especially in trees of tall stature such as giant sequoia. Recent studies demonstrate that remotely measured...
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Avian territory densities were determined from 20 Breeding Bird Censuses in mature (>30 years) bottomland hardwood stand: and 18 Breeding Bird Censuses in young (6-9 years old) cottonwood (Populas deltoides) plantations in the Mississippi Alluvial Valley. Avian species richness, diversity, and territory density were greater (p < 0.01) in bottomland hardwood stands than in intensively-managed cottonwood stands but these parameters were not impacted by selective timber harvest within bottomland hardwood stands nor by method of regeneration within cottonwood plantations (p > 0.05). Even so, detrended correspondence analysis based on avian territory densities readily segregated forest types and silvicultural treatments....
Old-growth forests of Engelmann spruce (Picea engelmannii Parry ex. Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) dominate much of the landscape of the Rocky Mountains. We characterized the structure, biomass and production of 18 old-growth (200?450-year-old) spruce/fir forests in Rocky Mountain National Park, Colorado, as well as the stand-level supply and use of light and nitrogen. Stands were chosen to span a broad range of elevation, aspect, and topography. Aboveground tree biomass in these old-growth forests averaged 253 Mg/ha (range 130?488 Mg/ha), with aboveground net primary production of 3700 kg ha?1 yr?1 (range from 2700 to 5200 kg ha?1 yr?1). Within stands, trees >35 cm in diameter accounted...
We examined changes in small mammal habitat and densities of four small mammal species, including deer mice (Peromyscus maniculatus), gray-collared chipmunks (Tamias cinereicollis), golden-mantled ground squirrels (Spermophilus lateralis), and Mexican woodrats (Neotoma mexicana), 2?3 years after thinning and prescribed fire treatments in ponderosa pine (Pinus ponderosa) forests of northern Arizona, US. These treatments were designed to simultaneously reduce high-severity fire risk while returning forests to conditions more representative of pre-European settlement structure and function. Treatments resulted in changes in important components of small mammal habitat, including increased herbaceous vegetation, decreased...
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Over the last century, fire exclusion in the forests of the Sierra Nevada has allowed surface fuels to accumulate and has led to increased tree density. Stand composition has also been altered as shade tolerant tree species crowd out shade intolerant species. To restore forest structure and reduce the risk of large, intense fires, managers have increasingly used prescription burning. Most fires prior to EuroAmerican settlement occurred during the late summer and early fall and most prescribed burning has taken place during the latter part of this period. Poor air quality and lack of suitable burn windows during the fall, however, have resulted in a need to conduct more prescription burning earlier in the season....
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Pathogens and insect pests have become increasingly important drivers of tree mortality in forested ecosystems. Unfortunately, understanding the relative contributions of multiple mortality agents to the population decline of trees is difficult, because it requires frequent measures of tree survival, growth, and recruitment, as well as the incidence of mortality agents. We present a population model of whitebark pine (Pinus albicaulis), a high-elevation tree undergoing rapid decline in western North America. The loss of whitebark pine is thought to be primarily due to an invasive pathogen (white pine blister rust; Cronartium ribicola) and a native insect (mountain pine beetle; Dendroctonus ponderosae). We utilized...
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Forested ecosystems contain the majority of the world’s terrestrial carbon, and forest management has implications for regional and global carbon cycling. Carbon stored in forests changes with stand age and is affected by natural disturbance and timber harvesting. We examined how harvesting and disturbance interact to influence forest carbon stocks over the Superior National Forest, in northern Minnesota. Forest inventory data from the USDA Forest Service, Forest Inventory and Analysis program were used to characterize current forest age structure and quantify the relationship between age and carbon stocks for eight forest types. Using these findings, we simulated the impact of alternative management scenarios and...
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The quantity of spruce-fir forest and some conifer-associated breeding bird abundances in the Atlantic Northern Forest have declined in recent decades emphasizing the need to better understand avian responses to forest management and to identify options that proactively conserve habitat for birds during the breeding and post-breeding period. We conducted avian point counts and vegetation surveys on publicly and privately-owned lands with known management histories to assess relationships between avian assemblages in harvest and postharvest treatments that could provide habitat for passerine birds associated with the spruce-fir forest type. We sampled regenerating conifer-dominated stands 5–41 years-since-harvest...
Repeat photography samples were used to analyze how the structure and site-specific distribution of forests may or may not have changed during the past century in the San Juan Mountains, Colorado. Systematic evaluation of 146 photosets was combined with field observations to identify trends in vegetation change. Both conifers and deciduous trees (e.g., aspen) have increased in extent. Forest recovery from large disturbances that occurred during Euro-American settlement contributed substantially to this increase. Trees also encroached into grass/shrublands, but less than half of photosets show tree invasion, and invasion is more common in small grass/shrubland openings interspersed with forest than in large openings....
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Current goals for prescription burning are focused on measures of fuel consumption and changes in forest density. These benchmarks, however, do not address the extent to which prescription burning meets perceived ecosystem needs of heterogeneity in burning, both for overstory trees and understory herbs and shrubs. There are still questions about how closely prescribed fires mimic these patterns compared to natural wildfires. This study compared burn patterns of prescribed fires and managed unplanned wildfires to understand how the differing burning regimes affect ecosystem properties. Measures of forest structure and fire severity were sampled in three recent prescribed fires and three wildfires managed for resource...
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Globally, there is widespread interest in using forest-derived biomass as a source of bioenergy. While conventional timber harvesting generally removes only merchantable tree boles, harvesting biomass feedstock can remove all forms of woody biomass (i.e., live and dead standing woody vegetation, downed woody debris, and stumps) resulting in a greater loss of biomass and nutrients as well as more severe habitat alteration. To investigate the potential impacts of this practice, this study examined the initial impacts (pre- and post-harvest) of various levels of slash and live-tree retention on biomass and nutrient stocks, including carbon (C), nitrogen (N), calcium (Ca), potassium (K), and phosphorus (P), in Populus...
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The fisher was extirpated from much of the Pacific Northwestern United States during the mid- to late-1900s and is now proposed for federal listing as a threatened species in all or part of its west coast range. Following the translocation of 90 fishers from central British Columbia, Canada, to the Olympic Peninsula of Washington State from 2008 to 2010, we investigated the landscape-scale habitat selection of reintroduced fishers across a broad range of forest ages and disturbance histories, providing the first information on habitat relationships of newly reintroduced fishers in coastal coniferous forests in the Pacific Northwest. We developed 17 a priori models to evaluate several habitat-selection hypotheses...
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The fire history of Piñon–Juniper (Pinus edulis–Juniperus osteosperma) woodlands in much of the southwestern United States is poorly understood, and as a result, fire management decisions are being made without a rigorous ecological underpinning. We investigated the historic fire regimes in Piñon–Juniper woodlands on the Mesa Verde cuesta utilizing stand and age structures. All Piñon trees in eight stands were aged and stand age was extrapolated to the surrounding landscapes using digital imagery, creating a time-since-fire map of the 1995 landscape. Six sampled stands were over 400 years, while two were between 200 and 300 years. Stand-replacing fire with a rotation of 400 years or longer characterized this Piñon–Juniper...


map background search result map search result map Historical and recent fire regimes in Piñon–Juniper woodlands on Mesa Verde, Colorado, USA Impacts of post-harvest slash and live-tree retention on biomass and nutrient stocks in <i>Populus tremuloides</i> Michx.-dominated forests, northern Minnesota, USA Potential increases in natural disturbance rates could offset forest management impacts on ecosystem carbon stocks Climate change, fire management, and ecological services in the southwestern US Initial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region Historical and recent fire regimes in Piñon–Juniper woodlands on Mesa Verde, Colorado, USA Impacts of post-harvest slash and live-tree retention on biomass and nutrient stocks in <i>Populus tremuloides</i> Michx.-dominated forests, northern Minnesota, USA Potential increases in natural disturbance rates could offset forest management impacts on ecosystem carbon stocks Initial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region Climate change, fire management, and ecological services in the southwestern US