Physical Sciences and Mathematics | Open Access Articles

Clean-Energy Policy Community Town Hall: Part A, Al Gore, Harry Reid, T. Boone Pickens, Cathy Zoi

National Clean Energy Summit

Moderator: John D. Podesta, President & CEO, Center for American Progress Action Fund

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Special Remarks By President Bill Clinton, Bill Clinton

National Clean Energy Summit

Special remarks by President Bill Clinton

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Roundtable: Building The Clean-Energy Economy: Part B, Neal Smatresk, Harry Reid, Al Gore, John D. Podesta

National Clean Energy Summit

Moderator: Tim Wirth, Former Colorado Senator, United Nations Foundation

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2009 National Clean Energy Summit Event Video Highlights And Press Tour Photos

National Clean Energy Summit

Video highlights & press tour photos

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Efficient Simulation Of Fluid Flow, David Hannasch, Monika Neda

Undergraduate Research Opportunities Program (UROP)

We are computationally investigating fluid flow models for physically correct predictions of flow structures. Models based on the idea of filtering the small scales/structures and also the Navier-Stokes equations which are the fundamental equations of fluid flow, are numerically solved via the continuous finite element method. Crank-Nicolson and fractional-step theta scheme are used for the discretization of the time derivative, while the Taylor-Hood and Mini elements are used for the discretization is space. The effectiveness of these numerical discretizations in time and space are examined by studying the accuracy of fluid characteristics, such as drag, lift and pressure drop.

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Long Distance Microbial Transport In Air: Global Change Implications, Bradley J. Davey, J. C. Bruckner, Jenny C. Fisher, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

The first manifestations of global change will most likelv be observed in the Earth's atmosphere. Changing wind patterns, for example, may effect the long distance dispersal of microor-g anisms. The overall objective of this research is to correlate molecular assessments of microbial community structure from cloud water and snow samples, obtained from DRI's Storm Peak Laboratory atop Mt. Werner in Colorado, with atmospheric data and calculated air mass back trajectories. Our activities for summer of 2009 will be a focused proof-of-concept exercise to determine if intact microbial DNA and viable cells can be recovered from cloud water and alpine snow …

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Point And Nonpoint Source Analysis Of Nutrients, Metals, And Pathogens In The Sediment And Water Column In Las Vegas Wash, Christine Simmons, Kumud Acharya

Undergraduate Research Opportunities Program (UROP)

Formerly an ephemeral watercourse, Las Vegas Wash is now a perennial system due to urban runoff and wastewater treatment plant (WWP) effluent. Las Vegas Wash flows into Lake Mead, where the discharge point is only a few miles upstream of Las Vegas’ main water intake. This small water cycle establishes the necessity to evaluate water quality especially due to non point sources pollution, wherein my research lies. Several points along Las Vegas Wash upstream and downstream of WWP have been chosen to represent different landuse types such as commercial, residential, wastewater treatment plants, etc. At each location, parameters including arsenic, …

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The Effects Of Pressure On Wide Bandgap Gan Semiconductors, William Kang, Linda Tran, Eunja Kim

Undergraduate Research Opportunities Program (UROP)

Gallium nitride (GaN) is a group-III nitride semiconductor; which may prove useful in developing optical instruments that operate under high ambient pressures. The purpose of this project is to examine the properties of GaN under varying conditions. The methods used in this experiment consist of modeling free energy as a function of lattice constants; calculating bond lengths, bond strengths, and bulk moduli; and comparing the resultant data with values in published literature. We will also compare these results with experimental data drawn from x-ray diffraction scans. By doing so, we hope to determine whether gallium nitride is suitable for use …

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Martian Life Detection With Amino Acid Enantiomers, Ali Jamil, Gaosen Zhang, Henry J. Sun

Undergraduate Research Opportunities Program (UROP)

The Viking mission showed that Martian soil can degrade a heterotrophic medium to carbon dioxide as if live microorganisms were present. The result is considered inconclusive, however, because abiotic oxidants, such as superoxides, may also exist on Mars and would explain the Viking result. One way to resolve this ambiguity is to repeat the Viking experiment with a isomerically pure medium. The consumption of one isomer, either D or L, would indicate biological activity. Indiscriminate destruction of both isomers would indicate abiotic redox processes. This idea was validated for glucose by REU research last summer (Sun et al. 2009). The …

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Researching Nitrite Oxidation At High Temperatures, Dolores A. Huang, Jeremy A. Dodsworth, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

15N-nitrate (NO3 -) pool dilution experiments show that ammonia (NH3) is oxidized to nitrate in geothermal springs up to at least 85C; however, nitrite (NO2 -)- oxidizing microorganisms are only known to grow up to 66°C. We hypothesize that thermophilic microorganisms oxidize nitrite to nitrate at high temperatures. Alternatively, it is possible that nitrite is oxidized abiotically. We propose to test these hypotheses by setting up microbial enrichments designed to grow thermophilic nitrite oxidizing bacteria by varying incubation temperature (50, 65, 80°C), oxygen concentration (20% and 5%), and cultivation media. A negative control consisting of filtered spring water (0.1 μm) …

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Temperature Links To Compositional Variations At Mutnovsky Volcano, Kamchatka, Russia, Lindsey Clark, Adam Simon, Kelly L. Robertson, Sean Mulcahy

Undergraduate Research Opportunities Program (UROP)

Full petrographic descriptions of fifty two rock samples collected from one hundred thousand year old Mutnovsky Volcano, Kamchatka, Russia are being studied to determine the magma compositions of the volcano through time. I expect that the composition will change with time owing to variation in input at the base of the volcano pluming system, above the subducting Pacific Ocean crust. This variation in composition, including the abundance of important atmospheric gases, water, and carbon dioxide, may play a key role in the abundance and type of greenhouse gases being emitted. The samples will also be analyzed by using electron probe …

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Baseline Microbial Characterizations Of An Imperiled Aquatic Diversity Hotspot: Ash Meadows National Wildlife Refuge, Jessica Newburn, Jim Bruckner, Jenny C. Fisher, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

Located in the discharge zone of the Death Valley Flow System, Ash Meadows National Wildlife Refuge is a spring-fed desert oasis and biodiversity hotspot about 90 miles northwest of Las Vegas. These critical wetlands are potentially threatened by groundwater pumping, exotic species invasions, and climate change. Although a major component of the lower food web, very little is known about the microbial makeup of this ecosystem. As a first step towards understanding the microbial and biogeochemical aspects of this system, a detailed molecular-based characterization of microbial communities, baseline chemistry, and physical characteristics of various springs of Ash Meadows will be …

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Martian Life Detection With Xylose Enantiomers, Arturo White, Gaosun Zhang, Henry J. Sun

Undergraduate Research Opportunities Program (UROP)

Ability of Martian soil to degrade carbohydrates, shown by the Viking mission, has two interpretations. One possibility is that the soil harbors living microorganisms. Alternatively, the soil is sterile but chemically oxidizing, i.e. it is laden with photochemical oxidants. It was shown by REU research last summer that these two possibilities can be distinguished by the use of glucose enantiomers. Life is selective: Earth organisms use D-glucose, but ignore Lglucose. This stereo selectivity is absent in chemical reactions. The goal of this project is to test if xylose, a five carbon sugar, is also suitable for chiral life detection. Mixed …

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Undergraduate Research Opportunities Program, University Of Nevada Las Vegas, College Of Sciences

Undergraduate Research Opportunities Program (UROP)

No abstract provided.

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Fuel Loads, Fire Severity, And Tree Mortality In Florida Keys Pine Forests, Jay Sah, Mike S. Ross, Danielle Ogarcak, Jim R. Snyder

North American Forest Ecology Workshop

In fire dependent forested ecosystems, fire managers are greatly interested in predicting the consequences of their management-oriented prescribed burnings on post-fire tree mortality. While fire intensity is believed to be a strong predictor of tree mortality, fire behavior itself largely depends on fuel characteristics, including both their structure and spatial distribution. We examined the type and distribution of fuels, their effects on fire behavior, and the effects of fire on tree mortality in slash pine forests in the Florida Keys. We conducted a burning experiment in six blocks, and burned eleven plots, three in winter and eight in summer, over …

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Overstory Dynamics In An Uncut Pine-Hardwood Stand: Lessons From Seventy Years Of Passive Management, Don Bragg, Michael G. Shelton

North American Forest Ecology Workshop

Long-term demonstration projects on experimental forests can be adapted from their original goals to provide insights into contemporary research questions. For instance, a 32.4-hectare cutover parcel on the Crossett Experimental Forest, the eventual Reynolds Research Natural Area (RRNA), was reserved in 1936 to act as a control for more intensively managed study areas. Over the last 70+ years, the RRNA has been allow to develop under 'natural' conditions that include no harvesting or other human interventions-with the notable exception of fire control. From 1937 until the most recent measurement in 2007, overall stand basal increased from about 20 to 36 …

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What Drives Decomposition Rates Of Coarse Woody Debris (Cwd)?, Steffen Herrmann, Jurgen Bauhus

North American Forest Ecology Workshop

Currently increasing efforts are made to manage CWD as a habitat component and a carbon store in forest ecosystems. For this a basic understanding of patterns and rates of dead wood decomposition in different forests is crucial. The decomposition rate of CWD is mainly dependent on climatic (wood temperature, wood moisture) and substrate specific (tree species, decay stage, diameter) variables. Here, we analysed the influence of these factors using a combined approach. 1) We assessed the decay rate of Fagus sylvatica, Picea abies and Pinus sylvestris in three diameter classes (10-20 cm, 20-40 cm, >40 cm) along a climatic/altitudinal gradient …

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Seed Release In Lodgepole Pine Forests After Mountain Pine Beetle Outbreak, Francios Teste, Vic J. Lieffers, Simon M. Landhausser

North American Forest Ecology Workshop

Serotinous lodgepole pine (Pinus contorta var. latifolia) usually regenerates after fire or harvesting provided conditions that are warm enough to open the cones. There are concerns that large-scale stand mortality due to mountain pine beetle (MPB) outbreak could greatly reduce natural regeneration of lodgepole pine because the closed cones are held in place in the tree canopy without any seed release. We selected 15 stands (five gray-attacked, five red-attacked, and five green) in the Sub-Boreal Spruce biogeoclimatic zone of British Columbia to determine loss of canopy seed via breakage of twig-bearing cones and cone opening (i.e., loss of serotiny) throughout …

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Potential Effects Of Climate Change On Mixed Severity Fire Regimes, Jessica Halofsky, Dave L. Peterson

North American Forest Ecology Workshop

The frequency, severity, and extent of wildfire are strongly related to climate, and increasing temperatures with climate change will likely lead to changes in fire regimes in many types of ecosystems. Increased spring and summer temperatures with climate change will result in relatively early snowmelt, lower summer soil and fuel moisture, and longer fire seasons in the West. These conditions will lead to increased fire frequency and extent. Higher temperatures may also interact with vegetation and fuel characteristics to increase fire intensity and severity. Mixed severity fire regimes may be uniquely influenced by these climate-induced changes in the frequency, extent, …

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Assessment Of Prescribed Burning Effects In Paludified Black Spruce Forests In Ontario’S Clay Belt Region, Sebastien Renard, Sylvie Gauthier, Nicole Fenton, Yves Bergeron, David Pare

North American Forest Ecology Workshop

Paludification, the accumulation of poorly decomposed organic matter principally originating from Sphagnum, transforms black spruce forests to forested peatlands in the prolonged absence of fire. High-severity wildfires reverse this process by burning the organic matter layer and thus restart forest succession; in contrast low severity wildfires remove only the tree layer and do not reduce paludification. On the Ontario Clay Belt, a physiogeographic region prone to paludification due to its cold climate and poor drainage, current forest harvest practices (Careful Logging Around Advanced Growth; CLAAG) mimic low severity fires by removing trees but lacking forest floor and soil disturbances caused …

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An Integrated Study Investigating Masticated Fuel Treatments In The Rocky Mountains, Robert Keane, Helen Y. Smith

North American Forest Ecology Workshop

Many coniferous forests in the western US once supported frequent, low intensity fires, but due to a century of fire exclusion and other factors, severe wildfires have now become common. With the goal of lowering fire intensities and severities, one possible fuel treatment that is currently gaining favor in with many land managers is mastication which breaks, shreds, or grinds canopy (seedlings, saplings and pole trees) and surface fuel (fine and coarse woody material) into smaller sizes and deposits the treated fuel on the ground. However, very little is known concerning the effects of this treatment on the resulting fire …

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A Post-Fire Index For Describing Mixed Severity Outcomes After Wildfire, Theresa Jain, Russel T. Graham, David S. Pilliod, Leigh Lentile

North American Forest Ecology Workshop

Kimmins (1997) argues that “words” and their correct usage are important and that the “careless use of language often causes confusion and misunderstanding and is a factor in many conflicts.” The public often lacks the technical knowledge to understand and interpret the use of inconsistent terminology and each discipline within resource science and management has developed their own definitions and application of specific terms. The fire community is no different. The only consistent component in the fire literature is the interchangeable use of the terms fire intensity, fire severity, and burn severity. Moreover, within each of these definitions, the terms …

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Mechanical Mastication Showed Fewer Negative Above-And Belowground Impacts Than Slash Pile Burning, Suzanne Neal, Carolyn H. Sieg, Catherine A. Gehring, Matthew A. Bowker

North American Forest Ecology Workshop

Management designed to reduce wildfire risk must consider both above- and belowground factors in order to promote native plant growth and reduce soil erosion. This goal is challenging because current methods, such as tree thinning and burning the resulting slash, can create soil disturbances that favor exotic plants. We compared mechanical mastication to slash pile burning (both 6-months and 2.5-years post treatment) and untreated controls in pinyon-juniper (Pinus edulis-Juniperus osteosperma) woodland and measured soil properties, arbuscular mycorrhizal fungi (AMF) and understory plant composition. Our results showed slash pile burns had severely degraded soil properties, low plant and AMF abundance and …

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The Influence Of Mastication On Soils And Fuels In Moist And Dry Forests Of The Northern Rocky Mountains, Theresa Jain, Russel T. Graham

North American Forest Ecology Workshop

We evaluated the applicability of mastication as a fuel treatment alternative within Northern Rocky Mountain moist and dry forests to treat post-harvest activity slash (moist forest) and standing trees (dry forest). On the moist forest site, we compared four different slash treatments, mastication, machine grapple piling, lop and scatter, and a control within a wildland urban interface setting to determine the effects of these treatments on soil nutrition, forest floor depth, and woody debris distributions. We randomly assigned the slash treatments and controls to 12 one-acre plots. Nitrogen, soil carbon, and magnesium concentrations within the soil components were not significantly …

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Aspen Mortality In The Intermountain West: What Forest Inventory And Analysis Plots Tell Us, Fred Baker, John D. Shaw

North American Forest Ecology Workshop

Reports of a long-term decline in area dominated by aspen forests, coupled with increased mortality attributed to long term drought, have lead to concerns of increased mortality in aspen forests. We examined data collected by USDA Forest Service Inventory and Analysis (FIA) to quantify aspen mortality. Most aspen stands in the Intermountain West are older than 80 years, a recommended rotation age for the best sites. Plot mortality rate was not related to site index or stand age. Many stands, however, have stem density greater than one would expect for self-thinning stands. At a given latitude, aspen plots with mortality …

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Ecosystem Recovery Following A Mountain Pine Beetle Outbreak In Northern British Columbia: A Case Of Shifting Values, Craig Delong, Bennita Kaytor, Bruce J. Rogers

North American Forest Ecology Workshop

The massive Mountain Pine Beetle (MPB) outbreak in northern British Columbia created a unique opportunity to examine ecosystem change over time in response to this disturbance. Prior to this outbreak, the dominant disturbance agents were wildfire and harvesting. A key question is how timber and habitat value will change over time in response to this disturbance and how this might be impacted by extensive clearcut salvage harvest. We have established 48 permanent sample plots in MPB impacted stands. Changes in stand structure, vegetation and functional wildlife habitat along with tree mortality and growth are being monitored. There has been almost …

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Surface Fuel Loadings In Mulching Treatments In Colorado Coniferous Forests, Mike Battaglia, Chuck Rhoades, Monique E. Rocca, Michael G. Ryan

North American Forest Ecology Workshop

Recent large-scale, severe wildfires in the western United States have prompted extensive fuel treatment programs to reduce potential wildfire size and severity. Often, unmerchantable material is mechanically masticated because removing the material is cost-prohibitive. Mastication treatments involve shredding, chopping, or chipping small trees and/or shrubs into small chunks and leaving the material on site. While it is obvious that mechanical treatments will increase surface fuel loads, few studies have addressed how treatments alter fuel particle size and quantity. We examined how mastication treatments alter the distribution of woody material size by comparing paired masticated and untreated sites in lodgepole pine …

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Regeneration Dynamics In Mountain Pine Beetle-Disturbed Forests: Lessons From The Current And The 1978-82 Flathead Epidemics, Dave Coates

North American Forest Ecology Workshop

There are two dominant mechanisms for development of a new tree layer and subsequent canopy recruitment after major canopy mortality events. First, regeneration may develop from a pulse of new post-disturbance recruitment. Alternatively, regeneration can be from the existing seedling bank that survived the canopy mortality event. The timing and extent of post-disturbance recruitment from seed and the relative importance of the existing seedling bank is poorly understood in MPB-disturbed forests. The recruitment of post-MPB seedlings is a function of seed-source availability, seedbed substrate, overstory structure, and time since MPB attack. In the northern interior, post-MPB recruitment was sparse in …

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Patterns Of Structural Response To Simulated Partial Harvesting Of Boreal Mixedwood Stands, Mark Vanderwel, John P. Caspersen, Jay R. Malcolm

North American Forest Ecology Workshop

Partial harvesting has been proposed as an approach for maintaining late-successional structure within managed boreal mixedwood stands. Although little long-term data is available to evaluate its effects in this stand type, recent advances in individual tree-based stand modeling provide an opportunity to simulate post-harvest stand development following different retention harvests. Using the stand dynamics model SORTIE-ND, we examined 40-year patterns of structural change in response to different intensities (30%, 50%, and 70% removal) and spatial patterns (uniform, small patch, large patch) of harvesting in aspen-dominated mixedwood stands. We assessed structural dynamics through a suite of variables representing the distribution of …

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Stand Density In South Florida Tropical Forests: Implications For The Function And Management Of Everglades Tree Islands, M. Ross, P. L. Ruiz, J. P. Sah, L. Lopez, N. Colbert

North American Forest Ecology Workshop

Within the continental US, the broadleaved forests of south Florida are exceptional in the abundance and diversity of tree species of tropical origin. Dry tropical forests are regionally most extensive in the upper Florida Keys, but are also represented on the mainland as fragments on limestone rocklands, and as “tree islands” embedded in the Everglades marsh. The exposed Everglades tree islands have a history of human use reaching back thousands of years, and are subject to frequent disturbance from tropical storms and hurricanes. They are sensitive to the hydrology of the surrounding marsh, which can lead to gradual changes in …

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Full-Text Articles in Physical Sciences and Mathematics

Clean-Energy Policy Community Town Hall: Part A, Al Gore, Harry Reid, T. Boone Pickens, Cathy Zoi

National Clean Energy Summit

Special Remarks By President Bill Clinton, Bill Clinton

National Clean Energy Summit

Roundtable: Building The Clean-Energy Economy: Part B, Neal Smatresk, Harry Reid, Al Gore, John D. Podesta

National Clean Energy Summit

2009 National Clean Energy Summit Event Video Highlights And Press Tour Photos

National Clean Energy Summit

Efficient Simulation Of Fluid Flow, David Hannasch, Monika Neda

Undergraduate Research Opportunities Program (UROP)

Long Distance Microbial Transport In Air: Global Change Implications, Bradley J. Davey, J. C. Bruckner, Jenny C. Fisher, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

Point And Nonpoint Source Analysis Of Nutrients, Metals, And Pathogens In The Sediment And Water Column In Las Vegas Wash, Christine Simmons, Kumud Acharya

Undergraduate Research Opportunities Program (UROP)

The Effects Of Pressure On Wide Bandgap Gan Semiconductors, William Kang, Linda Tran, Eunja Kim

Undergraduate Research Opportunities Program (UROP)

Martian Life Detection With Amino Acid Enantiomers, Ali Jamil, Gaosen Zhang, Henry J. Sun

Undergraduate Research Opportunities Program (UROP)

Researching Nitrite Oxidation At High Temperatures, Dolores A. Huang, Jeremy A. Dodsworth, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Temperature Links To Compositional Variations At Mutnovsky Volcano, Kamchatka, Russia, Lindsey Clark, Adam Simon, Kelly L. Robertson, Sean Mulcahy

Undergraduate Research Opportunities Program (UROP)

Baseline Microbial Characterizations Of An Imperiled Aquatic Diversity Hotspot: Ash Meadows National Wildlife Refuge, Jessica Newburn, Jim Bruckner, Jenny C. Fisher, Duane P. Moser

Undergraduate Research Opportunities Program (UROP)

Martian Life Detection With Xylose Enantiomers, Arturo White, Gaosun Zhang, Henry J. Sun

Undergraduate Research Opportunities Program (UROP)

Undergraduate Research Opportunities Program, University Of Nevada Las Vegas, College Of Sciences

Undergraduate Research Opportunities Program (UROP)

Fuel Loads, Fire Severity, And Tree Mortality In Florida Keys Pine Forests, Jay Sah, Mike S. Ross, Danielle Ogarcak, Jim R. Snyder

North American Forest Ecology Workshop

Overstory Dynamics In An Uncut Pine-Hardwood Stand: Lessons From Seventy Years Of Passive Management, Don Bragg, Michael G. Shelton

North American Forest Ecology Workshop

What Drives Decomposition Rates Of Coarse Woody Debris (Cwd)?, Steffen Herrmann, Jurgen Bauhus

North American Forest Ecology Workshop

Seed Release In Lodgepole Pine Forests After Mountain Pine Beetle Outbreak, Francios Teste, Vic J. Lieffers, Simon M. Landhausser

North American Forest Ecology Workshop

Potential Effects Of Climate Change On Mixed Severity Fire Regimes, Jessica Halofsky, Dave L. Peterson

North American Forest Ecology Workshop

Assessment Of Prescribed Burning Effects In Paludified Black Spruce Forests In Ontario’S Clay Belt Region, Sebastien Renard, Sylvie Gauthier, Nicole Fenton, Yves Bergeron, David Pare

North American Forest Ecology Workshop

An Integrated Study Investigating Masticated Fuel Treatments In The Rocky Mountains, Robert Keane, Helen Y. Smith

North American Forest Ecology Workshop

A Post-Fire Index For Describing Mixed Severity Outcomes After Wildfire, Theresa Jain, Russel T. Graham, David S. Pilliod, Leigh Lentile

North American Forest Ecology Workshop

Mechanical Mastication Showed Fewer Negative Above-And Belowground Impacts Than Slash Pile Burning, Suzanne Neal, Carolyn H. Sieg, Catherine A. Gehring, Matthew A. Bowker

North American Forest Ecology Workshop

The Influence Of Mastication On Soils And Fuels In Moist And Dry Forests Of The Northern Rocky Mountains, Theresa Jain, Russel T. Graham

North American Forest Ecology Workshop

Aspen Mortality In The Intermountain West: What Forest Inventory And Analysis Plots Tell Us, Fred Baker, John D. Shaw

North American Forest Ecology Workshop

Ecosystem Recovery Following A Mountain Pine Beetle Outbreak In Northern British Columbia: A Case Of Shifting Values, Craig Delong, Bennita Kaytor, Bruce J. Rogers

North American Forest Ecology Workshop

Surface Fuel Loadings In Mulching Treatments In Colorado Coniferous Forests, Mike Battaglia, Chuck Rhoades, Monique E. Rocca, Michael G. Ryan

North American Forest Ecology Workshop

Regeneration Dynamics In Mountain Pine Beetle-Disturbed Forests: Lessons From The Current And The 1978-82 Flathead Epidemics, Dave Coates

North American Forest Ecology Workshop

Patterns Of Structural Response To Simulated Partial Harvesting Of Boreal Mixedwood Stands, Mark Vanderwel, John P. Caspersen, Jay R. Malcolm

North American Forest Ecology Workshop

Stand Density In South Florida Tropical Forests: Implications For The Function And Management Of Everglades Tree Islands, M. Ross, P. L. Ruiz, J. P. Sah, L. Lopez, N. Colbert

North American Forest Ecology Workshop