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Full-Text Articles in Plant Sciences

Understory Cover Responses To Piñon-Juniper Treatments Across Tree Dominance Gradients In The Great Basin, Bruce A. Roundy, Richard F. Miller, Robin J. Tausch, Kert Young, April Hulet, Benjamin Rau, Brad Jessop, Jeanne C. Chambers, Dennis Eggett Sep 2014

Understory Cover Responses To Piñon-Juniper Treatments Across Tree Dominance Gradients In The Great Basin, Bruce A. Roundy, Richard F. Miller, Robin J. Tausch, Kert Young, April Hulet, Benjamin Rau, Brad Jessop, Jeanne C. Chambers, Dennis Eggett

Articles

Piñon (Pinus spp.) and juniper (Juniperus spp.) trees are reduced to restore native vegetation and avoid severe fires where they have expanded into sagebrush (Artemisia tridentata Nutt.) communities. However, what phase of tree infilling should treatments target to retain desirable understory cover and avoid weed dominance? Prescribed fire and tree felling were applied to 8–20-ha treatment plots at 11 sites across the Great Basin with a tree-shredding treatment also applied to four Utah sites. Treatments were applied across a tree infilling gradient as quantified by a covariate tree dominance index (TDI = tree cover/[tree + shrub + …


Mechanical Mastication Of Utah Juniper Encroaching Sagebrush Steppe Increases Inorganic Soil N, Kert R. Young, Bruce A. Roundy, Dennis L. Eggett Apr 2014

Mechanical Mastication Of Utah Juniper Encroaching Sagebrush Steppe Increases Inorganic Soil N, Kert R. Young, Bruce A. Roundy, Dennis L. Eggett

Articles

Juniper (Juniperus spp.) has encroached on millions of hectares of sagebrush (Artemisia spp.) steppe. Juniper mechanical mastication increases cover of understory species but could increase resource availability and subsequently invasive plant species. We quantified the effects of juniper mastication on soil resource availability by comparing total C, total N, C : N ratio, Olsen extractable P, sulfate S, and pH using soil samples and inorganic N (NO3-+NH4+) using ion exchange membranes. We compared resource availability in paired masticated and untreated areas in three juniper-dominated sagebrush and bunchgrass ecosystems in the Utah portion …


Hydrologic And Erosion Responses To Wildfire Along The Rangeland-Xeric Forest Continuum In The Western Us: A Review And Model Of Hydrologic Vulnerability, Christopher Jason Williams, Frederick B. Pierson, Peter R. Robichaud, Jan Boll Feb 2014

Hydrologic And Erosion Responses To Wildfire Along The Rangeland-Xeric Forest Continuum In The Western Us: A Review And Model Of Hydrologic Vulnerability, Christopher Jason Williams, Frederick B. Pierson, Peter R. Robichaud, Jan Boll

Articles

The recent increase in wildfire activity across the rangeland–xeric forest continuum in the western United States has landscape-scale consequences in terms of runoff and erosion. Concomitant cheatgrass (Bromus tectorum L.) invasions, plant community transitions and a warming climate in recent decades along grassland–shrubland–woodland–xeric forest transitions have promoted frequent and large wildfires, and continuance of the trend appears likely if warming climate conditions prevail. These changes potentially increase overall hydrologic vulnerability by spatially and temporally increasing soil exposure to runoff and erosion processes. Plot and hillslope-scale studies demonstrate burning may increase event runoff or erosion by factors of 2–40 over …


Resilience To Stress And Disturbance, And Resistance To Bromus Tectorum L. Invasion In Cold Desert Shrublands Of Western North America, Jeanne C. Chambers, Bethany A. Bradley, Cynthia S. Brown, Carla D'Antonio, Matthew J. Germino, James B. Grace, Stuart P. Hardegree, Richard F. Miller, David A. Pyke Nov 2013

Resilience To Stress And Disturbance, And Resistance To Bromus Tectorum L. Invasion In Cold Desert Shrublands Of Western North America, Jeanne C. Chambers, Bethany A. Bradley, Cynthia S. Brown, Carla D'Antonio, Matthew J. Germino, James B. Grace, Stuart P. Hardegree, Richard F. Miller, David A. Pyke

Articles

Alien grass invasions in arid and semi-arid ecosystems are resulting in grass–fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked questions about (a) …


Diffuse Migratory Connectivity In Two Species Of Shrubland Birds: Evidence From Stable Isotopes, Steven T. Knick, Matthias Leu, John T. Rotenberry, Steven E. Hanser, Kurt A. Fesenmyer Oct 2013

Diffuse Migratory Connectivity In Two Species Of Shrubland Birds: Evidence From Stable Isotopes, Steven T. Knick, Matthias Leu, John T. Rotenberry, Steven E. Hanser, Kurt A. Fesenmyer

Articles

Connecting seasonal ranges of migratory birds is important for understanding the annual template of stressors that influence their populations. Brewer’s sparrows (Spizella breweri) and sagebrush sparrows (Artemisiospiza nevadensis) share similar sagebrush (Artemisia spp.) habitats for breeding but have different population trends that might be related to winter location. To link breeding and winter ranges, we created isoscapes of deuterium [stable isotope ratio (δ) of deuterium; δ 2H] and nitrogen (δ 15N) for each species modeled from isotope ratios measured in feathers of 264 Brewer’s and 82 sagebrush sparrows and environmental …


The Economics Of Fuel Management: Wildfire, Invasive Plants, And The Dynamics Of Sagebrush Rangelands In The Western United States, Michael H. Taylor, Kimberly Rollins, Mimako Kobayashi, Robin J. Tausch May 2013

The Economics Of Fuel Management: Wildfire, Invasive Plants, And The Dynamics Of Sagebrush Rangelands In The Western United States, Michael H. Taylor, Kimberly Rollins, Mimako Kobayashi, Robin J. Tausch

Articles

In this article we develop a simulation model to evaluate the economic efficiency of fuel treatments and apply it to two sagebrush ecosystems in the Great Basin of the western United States: the Wyoming Sagebrush Steppe and Mountain Big Sagebrush ecosystems. These ecosystems face the two most prominent concerns in sagebrush ecosystems relative to wildfire: annual grass invasion and native conifer expansion. Our model simulates long-run wildfire suppression costs with and without fuel treatments explicitly incorporating ecological dynamics, stochastic wildfire, uncertain fuel treatment success, and ecological thresholds. Our results indicate that, on the basis of wildfire suppression costs savings, fuel …


Risk Assessment Of Erosion From Concentrated Flow On Rangelands Using Overland Flow Distribution And Shear Stress Partitioning, Osama Z. Al-Hamdan, Frederick B. Pierson, Mark A. Nearing, Christopher Jason Williams, Jeffry J. Stone, Patrick R. Kormos, Jan Boll, Mark A. Weltz Feb 2013

Risk Assessment Of Erosion From Concentrated Flow On Rangelands Using Overland Flow Distribution And Shear Stress Partitioning, Osama Z. Al-Hamdan, Frederick B. Pierson, Mark A. Nearing, Christopher Jason Williams, Jeffry J. Stone, Patrick R. Kormos, Jan Boll, Mark A. Weltz

Articles

Erosion rates of overland flow on rangelands tend to be relatively low, but under certain conditions where flow is concentrated, soil loss can be significant. Therefore, a rangeland site can be highly vulnerable to soil erosion where overland flow is likely to concentrate and exert high shear stress on soil grains. This concept is commonly applied in cropland and wildland soil erosion modeling using predictions of flow effective shear stress (shear stress applied on soil grains). However, historical approaches to partition shear stress in erosion models are computationally complex and require extensive parameterization. Furthermore, most models are not capable of …


Concentrated Flow Erodibility For Physically Based Erosion Models: Temporal Variability In Disturbed And Undisturbed Rangelands, Osama Z. Al-Hamdan, Frederick B. Pierson, Mark A. Nearing, C. Jason Williams, Jeffry J. Stone, Patrick R. Kormos, Jan Boll, Mark A. Weltz Jul 2012

Concentrated Flow Erodibility For Physically Based Erosion Models: Temporal Variability In Disturbed And Undisturbed Rangelands, Osama Z. Al-Hamdan, Frederick B. Pierson, Mark A. Nearing, C. Jason Williams, Jeffry J. Stone, Patrick R. Kormos, Jan Boll, Mark A. Weltz

Articles

Current physically based overland flow erosion models for rangeland application do not separate disturbed and undisturbed conditions in modeling concentrated flow erosion. In this study, concentrated flow simulations on disturbed and undisturbed rangelands were used to estimate the erodibility and to evaluate the performance of linear and power law equations that describe the relationship between erosion rate and several hydraulic parameters. None of the hydraulic parameters consistently predicted the detachment capacity well for all sites, however, stream power performed better than most of other hydraulic parameters. Using power law functions did not improve the detachment relation with respect to that …


The Frying Pan Or The Fire: Public Attitudes About Using Herbicides To Manage Invasive Weeds, Mariah Evans, Kimberly Rollins Jan 2012

The Frying Pan Or The Fire: Public Attitudes About Using Herbicides To Manage Invasive Weeds, Mariah Evans, Kimberly Rollins

Articles

How do we balance risks? This paper assesses hypotheses derived from instrumental rationality and risk society theories about the reasoning strategies that people will use to develop views supportive or oppositional to the use of herbicides to manage cheatgrass (Bromus tectorum), an invasive weed. Cheatgrass is well-known in the population of the American West to increase wildfire risks substantially and to harm the environment in other ways. But are the cures worse than the disease? One demonstrably effective method of cheatgrass suppression is the use of herbicides, and the paper explores sources of support for and opposition to …


Economic And Social Impacts Of Wildfires And Invasive Plants In American Deserts: Lessons From The Great Basin, Mark W. Brunson, John Tanaka Sep 2011

Economic And Social Impacts Of Wildfires And Invasive Plants In American Deserts: Lessons From The Great Basin, Mark W. Brunson, John Tanaka

Articles

Research on the impacts of wildfire and invasive plants in rangelands has focused on biophysical rather than human dimensions of these environmental processes. We offer a synthetic perspective on economic and social aspects of wildfire and invasive plants in American deserts, focusing on the Great Basin because greater research attention has been given to the effects of cheatgrass expansion than to other desert wildfire/invasion cycles. We focus first on impacts at the level of the individual decision-maker, then on impacts experienced at the human community or larger socio-political scales. Economic impacts of wildfire differ from those of invasive grasses because …


Developing A Model Framework For Predicting Effects Of Woody Expansion And Fire On Ecosystem Carbon And Nitrogen In A Pinyon-Juniper Woodland, Benjamin M. Rau, Robin J. Tausch, Alicia Reiner, Dale W. Johnson, Jeanne C. Chambers, Robert R. Blank Jul 2011

Developing A Model Framework For Predicting Effects Of Woody Expansion And Fire On Ecosystem Carbon And Nitrogen In A Pinyon-Juniper Woodland, Benjamin M. Rau, Robin J. Tausch, Alicia Reiner, Dale W. Johnson, Jeanne C. Chambers, Robert R. Blank

Articles

Sagebrush-steppe ecosystems are one of the most threatened ecosystems in North America due to woodland expansion, wildfire, and exotic annual grass invasion. Some scientists and policy makers have suggested that woodland expansion will lead to increased carbon (C) storage on the landscape. To assess this potential we used data collected from a Joint Fire Sciences Program demonstration area to develop a Microsoft Excel™ based biomass, carbon, and nitrogen (N) spreadsheet model. The model uses input for tree cover, soil chemistry, soil physical properties, and vegetation chemistry to estimate biomass, carbon, and nitrogen accumulation on the landscape with woodland expansion. The …


Woodland Expansion's Influence On Belowground Carbon And Nitrogen In The Great Basin U.S., Benjamin M. Rau, Dale W. Johnson, Robert R. Blank, Robin J. Tausch, Bruce A. Roundy, Richard F. Miller, Todd G. Caldwell, Annmarie Lucchesi May 2011

Woodland Expansion's Influence On Belowground Carbon And Nitrogen In The Great Basin U.S., Benjamin M. Rau, Dale W. Johnson, Robert R. Blank, Robin J. Tausch, Bruce A. Roundy, Richard F. Miller, Todd G. Caldwell, Annmarie Lucchesi

Articles

Vegetation changes associated with climate shifts and anthropogenic disturbance can have major impacts on biogeochemical cycling and soils. Much of the Great Basin, U.S. is currently dominated by sagebrush (Artemisia tridentate (Rydb.) Boivin) ecosystems. Sagebrush ecosystems are increasingly influenced by pinyon (Pinus monophylla Torr. & Frém and Pinus edulis Engelm.) and juniper (Juniperus osteosperma Torr. and Juniperus occidentalis Hook.) expansion. Some scientists and policy makers believe that increasing woodland cover in the intermountain western U.S. offers the possibility of increased organic carbon (OC) storage on the landscape; however, little is currently known about the distribution of OC …


The Landscape Similarity Toolbox: New Tools For Optimizing The Location Of Control Sites In Experimental Studies, Thomas E. Dilts, Jian Yang, Peter J. Weisberg Nov 2010

The Landscape Similarity Toolbox: New Tools For Optimizing The Location Of Control Sites In Experimental Studies, Thomas E. Dilts, Jian Yang, Peter J. Weisberg

Articles

Large‐scale manipulative experiments are critically important for linking ecological theory with land management at a relevant spatial scale. Statistically powerful inferential approaches such as the before‐after‐control‐impact design involve pairing a small number of treatment sites with control sites of analogous ecological structure and landscape context. Pairing treatment and control sites that are as analogous as possible is an important step to ensuring that differences are due to a treatment effect. The Landscape Similarity Toolbox provides tools for optimizing the location of potential control sites based upon the spatial characteristics of the treatment site.


Influence Of Prescribed Fire On Ecosystem Biomass, Carbon, And Nitrogen In A Pinyon Juniper Woodland, Benjamin M. Rau, Robin Tausch, Alicia Reiner, Dale W. Johnson, Jeanne C. Chambers, Robert R. Blank, Annmarrie Lucchesi Mar 2010

Influence Of Prescribed Fire On Ecosystem Biomass, Carbon, And Nitrogen In A Pinyon Juniper Woodland, Benjamin M. Rau, Robin Tausch, Alicia Reiner, Dale W. Johnson, Jeanne C. Chambers, Robert R. Blank, Annmarrie Lucchesi

Articles

Increases in pinyon and juniper woodland cover associated with land-use history are suggested to provide offsets for carbon emissions in arid regions. However, the largest pools of carbon in arid landscapes are typically found in soils, and aboveground biomass cannot be considered long-term storage in fire-prone ecosystems. Also, the objectives of carbon storage may conflict with management for other ecosystem services and fuels reduction. Before appropriate decisions can be made it is necessary to understand the interactions between woodland expansion, management treatments, and carbon retention. We quantified effects of prescribed fire as a fuels reduction and ecosystem maintenance treatment on …


Sensitivity Of Wtp Estimates To Definition Of 'Yes': Reinterpreting Expressed Response Intensity, Mimako Kobayashi, Kimberly Rollins, M. D. R. Evans Feb 2010

Sensitivity Of Wtp Estimates To Definition Of 'Yes': Reinterpreting Expressed Response Intensity, Mimako Kobayashi, Kimberly Rollins, M. D. R. Evans

Articles

Willingness to pay (WTP) estimation typically involves some strategy for mapping nondichotomous contingent valuation (CV) responses onto a dichotomous yes/no dependent variable. We propose a new approach to selecting which responses qualify as ‘yes.’ We apply the proposed method to polychotomous CV data for preventative land management programs in the Great Basin. We also estimate WTP using other methods of response recoding found in the literature. By contrasting the results under different approaches, we demonstrate how and why WTP point estimates vary across recoding methods and discuss the comparative advantages of our more generalized recoding approach that is based on …


Sagebrush Steppe Treatment Evaluation Project (Sagestep): Restoration Research With Practical Applications, Summer Olsen Apr 2008

Sagebrush Steppe Treatment Evaluation Project (Sagestep): Restoration Research With Practical Applications, Summer Olsen

Articles

Sagebrush rangelands cover millions of acres in the Great Basin including parts of Oregon, California, Idaho, Nevada, and Utah. This land provides a variety of important services, including wildlife habitat, clean water, recreation, and economic opportunities; it also serves as the primary forage base for the western livestock industry. Healthy sagebrush rangelands are rapidly being lost due to a variety of factors including severe wildfires, woodland expansion, invasion of non-native species, urban development, and drought. This loss can have significant impacts on those who depend on the land for goods and services.


Rangeland Fires And Cheatgrass: Values At Risk And Support For Preservation, M. D. R. Evans, Kim Rollins Apr 2008

Rangeland Fires And Cheatgrass: Values At Risk And Support For Preservation, M. D. R. Evans, Kim Rollins

Articles

The high desert sagebrush ecosystems of the Great Basin evolved with fire. However, the introduction of cheatgrass (t. bromus), a highly flammable invasive annual grass, has contributed to the increased intensity and frequency of wildfires we have seen in recent years. Cheatgrass-fueled fires often kill native perennials, which creates openings for further cheatgrass expansion. Winters with more moisture than usual result in more cheatgrass and increased fire risk. Over time the result is ever larger areas dominated by cheatgrass and other invasive weeds that burn with greater frequency, and increasingly severe fire seasons.