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• 71. [Article] Nutrient Uptake by Intact and Disturbed Roots of Loblolly Pine Seedlings

  Most measurements of nutrient uptake use either hydroponic systems or soil-grown roots that have been disturbed by excavation. The first objective of this study was to test how root excavation affects ...

  Citation × Citation Citation Abstract Copy Title: Nutrient Uptake by Intact and Disturbed Roots of Loblolly Pine Seedlings Author: Lucash, Melissa S., Yanai, Ruth D., Joslin, J. Devereux Year: 2008 Most measurements of nutrient uptake use either hydroponic systems or soil-grown roots that have been disturbed by excavation. The first objective of this study was to test how root excavation affects nitrate uptake. Rates of NO3− uptake by mycorrhizal loblolly pine (Pinus taeda L.) seedlings were measured in intact sand-filled columns, hydroponics, and disturbed sand-filled columns. Total nitrate uptake in intact sand-filled columns was higher than in disturbed columns, indicating that disturbance lowers uptake. Transferring plants from the sand-filled columns to hydroponics had little effect on NO3− uptake beyond delaying uptake for an hour. The second objective of this study was to determine whether NH4+, Ca2+, Mg2+ and K+ uptake could be studied using sand-filled columns, since previous studies had tested this method only for nitrate uptake. Uptake rates of NH4+ and K+ were positive, while Ca2+ and Mg2+ uptake rates were negative in intact sand-filled columns, indicating that net efflux may occur even without physical disturbance to the root system. The sand-filled column approach has some limitations, but holds promise for conducting nutrient uptake studies with minimal disturbance to the root system. Title: Nutrient Uptake by Intact and Disturbed Roots of Loblolly Pine Seedlings Author: Lucash, Melissa S., Yanai, Ruth D., Joslin, J. Devereux Year: 2008 Most measurements of nutrient uptake use either hydroponic systems or soil-grown roots that have been disturbed by excavation. The first objective of this study was to test how root excavation affects nitrate uptake. Rates of NO3− uptake by mycorrhizal loblolly pine (Pinus taeda L.) seedlings were measured in intact sand-filled columns, hydroponics, and disturbed sand-filled columns. Total nitrate uptake in intact sand-filled columns was higher than in disturbed columns, indicating that disturbance lowers uptake. Transferring plants from the sand-filled columns to hydroponics had little effect on NO3− uptake beyond delaying uptake for an hour. The second objective of this study was to determine whether NH4+, Ca2+, Mg2+ and K+ uptake could be studied using sand-filled columns, since previous studies had tested this method only for nitrate uptake. Uptake rates of NH4+ and K+ were positive, while Ca2+ and Mg2+ uptake rates were negative in intact sand-filled columns, indicating that net efflux may occur even without physical disturbance to the root system. The sand-filled column approach has some limitations, but holds promise for conducting nutrient uptake studies with minimal disturbance to the root system. Close

• 72. [Article] Natural Area Stewardship Volunteers: Motivations, Attitudes, Behaviors

  To better understand the value of those who engage in environmental stewardship of natural areas, we studied volunteer steward's motivation to participate, their sustainable behaviors and attitudes toward ...

  Citation × Citation Citation Abstract Copy Title: Natural Area Stewardship Volunteers: Motivations, Attitudes, Behaviors Author: Handelman, Corinne Year: 2013 To better understand the value of those who engage in environmental stewardship of natural areas, we studied volunteer steward's motivation to participate, their sustainable behaviors and attitudes toward stewardship-related constructs. Specifically, we designed and conducted a survey of volunteers who work as stewards in urban natural areas in Portland, Oregon. We hypothesize that as volunteer frequency increases: participants will be more motivated to participate for environmental reasons, volunteers will be more likely to feel a strong connection to the stewardship site, participants will be more likely to engage in public pro-environmental behaviors, and their level of environmental literacy will increase. Participants were sampled using a face-to-face survey methodology over the course of late winter and spring of 2012 during 18 different Portland Parks and Recreation sponsored stewardship events. We examined the motivations, attitudes and behaviors of the volunteers, and devised appropriate management implications for those organizing volunteer efforts. We equated a three-tiered typology of environmental literacy, based upon the frequency of volunteer participation, and analyzed our survey data using a principal component analysis, generalized linear models, and a qualitative coding analysis. The most frequent participants showed a higher likelihood of participation in public environmental behaviors, whereas participants at all frequency levels were also likely to participate in private environmental behaviors, such as removing invasive plants in one's yard. Volunteers across all frequencies of participation were motivated to engage in stewardship events by a desire to help the environment. By understanding volunteers' motivations and linked behaviors, park managers may gain insights about the recruitment, retention, and messaging of volunteers upon whom they may depend to achieve restoration goals. We recommend considering volunteers' motivations and benefits derived from participation in messaging to recruit and retain volunteers. Additionally, park managers should take advantage of educational opportunities linked to stewardship events, such as training programs and chances for volunteer mentorship. Title: Natural Area Stewardship Volunteers: Motivations, Attitudes, Behaviors Author: Handelman, Corinne Year: 2013 To better understand the value of those who engage in environmental stewardship of natural areas, we studied volunteer steward's motivation to participate, their sustainable behaviors and attitudes toward stewardship-related constructs. Specifically, we designed and conducted a survey of volunteers who work as stewards in urban natural areas in Portland, Oregon. We hypothesize that as volunteer frequency increases: participants will be more motivated to participate for environmental reasons, volunteers will be more likely to feel a strong connection to the stewardship site, participants will be more likely to engage in public pro-environmental behaviors, and their level of environmental literacy will increase. Participants were sampled using a face-to-face survey methodology over the course of late winter and spring of 2012 during 18 different Portland Parks and Recreation sponsored stewardship events. We examined the motivations, attitudes and behaviors of the volunteers, and devised appropriate management implications for those organizing volunteer efforts. We equated a three-tiered typology of environmental literacy, based upon the frequency of volunteer participation, and analyzed our survey data using a principal component analysis, generalized linear models, and a qualitative coding analysis. The most frequent participants showed a higher likelihood of participation in public environmental behaviors, whereas participants at all frequency levels were also likely to participate in private environmental behaviors, such as removing invasive plants in one's yard. Volunteers across all frequencies of participation were motivated to engage in stewardship events by a desire to help the environment. By understanding volunteers' motivations and linked behaviors, park managers may gain insights about the recruitment, retention, and messaging of volunteers upon whom they may depend to achieve restoration goals. We recommend considering volunteers' motivations and benefits derived from participation in messaging to recruit and retain volunteers. Additionally, park managers should take advantage of educational opportunities linked to stewardship events, such as training programs and chances for volunteer mentorship. Close

• 73. [Article] The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

  The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of ...

  Citation × Citation Citation Abstract Copy Title: The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon Author: Broshot, Nancy Ellen Year: 1999 The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of plant and avian communities at 25 sites, 24 which were in Forest Park and surrounding areas and one which was in the Ancient Forest Preserve (old-growth stand) northwest of Forest Park. Data were analyzed using multiple regression, ANOV A, and Bonferonni/Dunn. Seven variables were selected representing different urbanization gradients. An additional covariable coded for the old-growth stand, allowing it to be used as a control. Many tree variables, especially those related to shade-tolerant species, were positively correlated with both the distance from downtown Portland and the number of houses in the surrounding area, and negatively correlated with the distance from the nearest forest edge; however, many shrub and herbaceous variables were negatively correlated with the distance from downtown Portland. Species diversity for herbaceous and shrub species was greater at more urban sites, but diversity of trees was lower at more urban sites. There were significantly more non-native species of plants in the city section. I found significantly fewer saplings and small trees, especially shade-tolerant species, in the section of Forest Park closest to downtown Portland, although tree mortality was positively correlated with distance from Portland. Summer bird data revealed significant increases in the abundances of urban and edge species at more urban sites, with concomitant reductions in forest species. There were significantly more ground gleaning birds and short distance migratory species. I also found a significantly greater abundance of birds in the old-growth stand during the winter. This increase was positively correlated with the depth of snow in the nearby Cascade Mountains. My results indicate that Forest Park is apparently progressing in a normal successional pattern with the exception of the city section. The reduction in shade tolerant saplings and small trees in the city section suggest that rate of succession has been slower at more urban sites. Avian data suggest that urbanization affects bird species abundance and guild composition in the more urban areas. Title: The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon Author: Broshot, Nancy Ellen Year: 1999 The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of plant and avian communities at 25 sites, 24 which were in Forest Park and surrounding areas and one which was in the Ancient Forest Preserve (old-growth stand) northwest of Forest Park. Data were analyzed using multiple regression, ANOV A, and Bonferonni/Dunn. Seven variables were selected representing different urbanization gradients. An additional covariable coded for the old-growth stand, allowing it to be used as a control. Many tree variables, especially those related to shade-tolerant species, were positively correlated with both the distance from downtown Portland and the number of houses in the surrounding area, and negatively correlated with the distance from the nearest forest edge; however, many shrub and herbaceous variables were negatively correlated with the distance from downtown Portland. Species diversity for herbaceous and shrub species was greater at more urban sites, but diversity of trees was lower at more urban sites. There were significantly more non-native species of plants in the city section. I found significantly fewer saplings and small trees, especially shade-tolerant species, in the section of Forest Park closest to downtown Portland, although tree mortality was positively correlated with distance from Portland. Summer bird data revealed significant increases in the abundances of urban and edge species at more urban sites, with concomitant reductions in forest species. There were significantly more ground gleaning birds and short distance migratory species. I also found a significantly greater abundance of birds in the old-growth stand during the winter. This increase was positively correlated with the depth of snow in the nearby Cascade Mountains. My results indicate that Forest Park is apparently progressing in a normal successional pattern with the exception of the city section. The reduction in shade tolerant saplings and small trees in the city section suggest that rate of succession has been slower at more urban sites. Avian data suggest that urbanization affects bird species abundance and guild composition in the more urban areas. Close

• 74. [Article] The Impact of Fine Sediment on Stream Macroinvertebrates in Urban and Rural Oregon Streams

  Urbanization, often characterized by high impervious surface area, can result in excessive inputs of fine sediments into urban streams. Excessive fine sediments can blanket the stream bed filling the interstitial ...

  Citation × Citation Citation Abstract Copy Title: The Impact of Fine Sediment on Stream Macroinvertebrates in Urban and Rural Oregon Streams Author: Hoy, Raymond S. Year: 2001 Urbanization, often characterized by high impervious surface area, can result in excessive inputs of fine sediments into urban streams. Excessive fine sediments can blanket the stream bed filling the interstitial space in the substratum, which may have adverse effects on stream biota. A field survey was conducted in Oregon urban and non-urban basins to investigate the relationship between fine sediments and stream macroinvertebrates. Physical, chemical, and biological data were collected from 59 stream sites in two urban and two rural streams. The stream sites fulfilled a continuous sediment gradient, which ranged from a low of 2% of fine sediment in the substrate to a high of 64% with an average of 22%. The % fines, in Clear Creek (rural basin) was significantly lower than in the urban basins (Johnson Creek and Tryon Creek) (p=0.005). Johnson Creek (mean=23%) had approximately three times more fine sediment than Clear Creek (mean=7%), while Tryon Creek (mean=32%) had nearly five times as much fine sediment as Clear Creek. EPT taxa richness was significantly higher in both rural streams than in both urban streams (p0.05). For example, regression analysis of EPT taxa richness vs. % fine sediments displayed a coefficient of determination (r2) value of 0.2. Other macro invertebrates metrics displayed similar patterns. The lack of significant correlations may be due to the cumulative effect of basin-wide "historical land use past". Past land use activity may have resulted in long-term reductions of sensitive taxa in the basin taxa pool and efforts to improve local habitats may not be quickly colonized by pollution sensitive taxa. Long-term degradation to the urban streams resulted in a relatively homogenous assemblage of macro invertebrates, which may have confounded the quantitative relationship between sediments and macroinvertebrates. This study suggests there is a clear difference between urban and non-urban streams in terms of macro invertebrates, which may be likely due to sediments, but the quantitative relationship between fine sediments and macro invertebrates is weak. Title: The Impact of Fine Sediment on Stream Macroinvertebrates in Urban and Rural Oregon Streams Author: Hoy, Raymond S. Year: 2001 Urbanization, often characterized by high impervious surface area, can result in excessive inputs of fine sediments into urban streams. Excessive fine sediments can blanket the stream bed filling the interstitial space in the substratum, which may have adverse effects on stream biota. A field survey was conducted in Oregon urban and non-urban basins to investigate the relationship between fine sediments and stream macroinvertebrates. Physical, chemical, and biological data were collected from 59 stream sites in two urban and two rural streams. The stream sites fulfilled a continuous sediment gradient, which ranged from a low of 2% of fine sediment in the substrate to a high of 64% with an average of 22%. The % fines, in Clear Creek (rural basin) was significantly lower than in the urban basins (Johnson Creek and Tryon Creek) (p=0.005). Johnson Creek (mean=23%) had approximately three times more fine sediment than Clear Creek (mean=7%), while Tryon Creek (mean=32%) had nearly five times as much fine sediment as Clear Creek. EPT taxa richness was significantly higher in both rural streams than in both urban streams (p0.05). For example, regression analysis of EPT taxa richness vs. % fine sediments displayed a coefficient of determination (r2) value of 0.2. Other macro invertebrates metrics displayed similar patterns. The lack of significant correlations may be due to the cumulative effect of basin-wide "historical land use past". Past land use activity may have resulted in long-term reductions of sensitive taxa in the basin taxa pool and efforts to improve local habitats may not be quickly colonized by pollution sensitive taxa. Long-term degradation to the urban streams resulted in a relatively homogenous assemblage of macro invertebrates, which may have confounded the quantitative relationship between sediments and macroinvertebrates. This study suggests there is a clear difference between urban and non-urban streams in terms of macro invertebrates, which may be likely due to sediments, but the quantitative relationship between fine sediments and macro invertebrates is weak. Close

• 75. [Article] Effectiveness of Fuel Treatments for Mitigating Wildfire Risk and Sequestering Forest Carbon: A Case Study in the Lake Tahoe Basin

  Fuel-reduction treatments are used extensively to reduce wildfire risk and restore forest diversity and function. In the near future, increasing regulation of carbon (C) emissions may force forest managers ...

  Citation × Citation Citation Abstract Copy Title: Effectiveness of Fuel Treatments for Mitigating Wildfire Risk and Sequestering Forest Carbon: A Case Study in the Lake Tahoe Basin Author: Loudermilk, E. Louise, Stanton, Alison, Scheller, Robert M., Dilts, Thomas E., Weisberg, Peter J., Skinner, Carl, Yang, Jian Year: 2014 Fuel-reduction treatments are used extensively to reduce wildfire risk and restore forest diversity and function. In the near future, increasing regulation of carbon (C) emissions may force forest managers to balance the use of fuel treatments for reducing wildfire risk against an alternative goal of C sequestration. The objective of this study was to evaluate how long-term fuel treatments mitigate wildfires and affect forest C. For the Lake Tahoe Basin in the central Sierra Nevada, USA, fuel treatment efficiency was explored with a landscape-scale simulation model, LANDIS-II, using five fuel treatment scenarios and two (contemporary and potential future) fire regimes. Treatment scenarios included applying a combination of light (hand) and moderate (mechanical) forest thinning continuously through time and transitioning from these prescriptions to a more mid-seral thinning prescription, both on a 15 and 30 year rotation interval. In the last scenario, fuel treatments were isolated to around the lake shore (nearby urban settlement) to simulate a low investment alternative were future resources may be limited. Results indicated that the forest will remain a C sink regardless of treatment or fire regime simulated, due to the landscape legacy of historic logging. Achievement of a net C gain required decades with intensive treatment and depended on wildfire activity: Fuel treatments were more effective in a more active fire environment, where the interface between wildfires and treatment areas increased and caused net C gain earlier than as compared to our scenarios with less wildfire activity. Fuel treatments were most effective when continuously applied and strategically placed in high ignition areas. Treatment type and re-application interval were less influential at the landscape scale, but had notable effects on species dynamics within management units. Treatments created more diverse forest conditions by shifting dominance patterns to a more mixed conifer system, with a higher proportion of fire-tolerant species. We demonstrated that a small amount of wildfire on the landscape resulted in significant changes in the C pool, and that strategically placed fuel treatments substantially reduced wildfire risk, increased fire resiliency of the forest, and is beneficial for long-term C management. Implications for landscape management included consideration for prioritization of treatment areas and creating ideal re-entry schedules that meet logistic, safety, and conservation goals. In forests with a concentrated wildland urban interface, fuel treatments may be vital for ensuring human welfare and enhancing forest integrity in a fire-prone future. Title: Effectiveness of Fuel Treatments for Mitigating Wildfire Risk and Sequestering Forest Carbon: A Case Study in the Lake Tahoe Basin Author: Loudermilk, E. Louise, Stanton, Alison, Scheller, Robert M., Dilts, Thomas E., Weisberg, Peter J., Skinner, Carl, Yang, Jian Year: 2014 Fuel-reduction treatments are used extensively to reduce wildfire risk and restore forest diversity and function. In the near future, increasing regulation of carbon (C) emissions may force forest managers to balance the use of fuel treatments for reducing wildfire risk against an alternative goal of C sequestration. The objective of this study was to evaluate how long-term fuel treatments mitigate wildfires and affect forest C. For the Lake Tahoe Basin in the central Sierra Nevada, USA, fuel treatment efficiency was explored with a landscape-scale simulation model, LANDIS-II, using five fuel treatment scenarios and two (contemporary and potential future) fire regimes. Treatment scenarios included applying a combination of light (hand) and moderate (mechanical) forest thinning continuously through time and transitioning from these prescriptions to a more mid-seral thinning prescription, both on a 15 and 30 year rotation interval. In the last scenario, fuel treatments were isolated to around the lake shore (nearby urban settlement) to simulate a low investment alternative were future resources may be limited. Results indicated that the forest will remain a C sink regardless of treatment or fire regime simulated, due to the landscape legacy of historic logging. Achievement of a net C gain required decades with intensive treatment and depended on wildfire activity: Fuel treatments were more effective in a more active fire environment, where the interface between wildfires and treatment areas increased and caused net C gain earlier than as compared to our scenarios with less wildfire activity. Fuel treatments were most effective when continuously applied and strategically placed in high ignition areas. Treatment type and re-application interval were less influential at the landscape scale, but had notable effects on species dynamics within management units. Treatments created more diverse forest conditions by shifting dominance patterns to a more mixed conifer system, with a higher proportion of fire-tolerant species. We demonstrated that a small amount of wildfire on the landscape resulted in significant changes in the C pool, and that strategically placed fuel treatments substantially reduced wildfire risk, increased fire resiliency of the forest, and is beneficial for long-term C management. Implications for landscape management included consideration for prioritization of treatment areas and creating ideal re-entry schedules that meet logistic, safety, and conservation goals. In forests with a concentrated wildland urban interface, fuel treatments may be vital for ensuring human welfare and enhancing forest integrity in a fire-prone future. Close

• 76. [Article] Disequilibrium of Fire-prone Forests Sets the Stage for a Rapid Decline in Conifer Dominance during the 21st Century

  As trees are long-lived organisms, the impacts of climate change on forest communities may not be apparent on the time scale of years to decades. While lagged responses to environmental change are common ...

  Citation × Citation Citation Abstract Copy Title: Disequilibrium of Fire-prone Forests Sets the Stage for a Rapid Decline in Conifer Dominance during the 21st Century Author: Serra-Diaz, Josep M., Maxwell, Charles, Lucash, Melissa S., Scheller, Robert M., Laflower, Danelle M., Miller, Adam D., Tepley, Alan J., Epstein, Howard E., Anderson-Teixeira, Kristina J., Thompson, Jonathan R. Year: 2017 As trees are long-lived organisms, the impacts of climate change on forest communities may not be apparent on the time scale of years to decades. While lagged responses to environmental change are common in forested systems, potential for abrupt transitions under climate change may occur in environments where alternative vegetation states are influenced by disturbances, such as fire. The Klamath mountains (northern California and southwest Oregon, USA) are currently dominated by carbon rich and hyper-diverse temperate conifer forests, but climate change could disrupt the mechanisms promoting forest stability– regeneration and fire tolerance— via shifts in the fire regime in conjunction with lower fitness of conifers under a hotter climate. Understanding how this landscape will respond to near-term climate change (before 2100) is critical for predicting potential climate change feedbacks and to developing sound forest conservation and management plans. Using a landscape simulation model, we estimate that 1/3 of the Klamath could transition from conifer forest to shrub/hardwood chaparral, triggered by an enhanced fire activity coupled with lower post-fire conifer establishment. Such shifts were more prevalent under higher climate change forcing (RCP 8.5) but were also simulated under the climate of 1950-2000, reflecting the joint influences of early warming trends and historical forest legacies. Our results demonstrate that there is a large potential for loss of conifer forest dominance—and associated carbon stocks and biodiversity-- in the Klamath before the end of the century, and that some losses would likely occur even without the influence of climate change. Thus, in the Klamath and other forested landscapes subject to similar feedback dynamics, major ecosystem shifts should be expected when climate change disrupts key stabilizing feedbacks that maintain the dominance of long-lived, slowly regenerating trees. Title: Disequilibrium of Fire-prone Forests Sets the Stage for a Rapid Decline in Conifer Dominance during the 21st Century Author: Serra-Diaz, Josep M., Maxwell, Charles, Lucash, Melissa S., Scheller, Robert M., Laflower, Danelle M., Miller, Adam D., Tepley, Alan J., Epstein, Howard E., Anderson-Teixeira, Kristina J., Thompson, Jonathan R. Year: 2017 As trees are long-lived organisms, the impacts of climate change on forest communities may not be apparent on the time scale of years to decades. While lagged responses to environmental change are common in forested systems, potential for abrupt transitions under climate change may occur in environments where alternative vegetation states are influenced by disturbances, such as fire. The Klamath mountains (northern California and southwest Oregon, USA) are currently dominated by carbon rich and hyper-diverse temperate conifer forests, but climate change could disrupt the mechanisms promoting forest stability– regeneration and fire tolerance— via shifts in the fire regime in conjunction with lower fitness of conifers under a hotter climate. Understanding how this landscape will respond to near-term climate change (before 2100) is critical for predicting potential climate change feedbacks and to developing sound forest conservation and management plans. Using a landscape simulation model, we estimate that 1/3 of the Klamath could transition from conifer forest to shrub/hardwood chaparral, triggered by an enhanced fire activity coupled with lower post-fire conifer establishment. Such shifts were more prevalent under higher climate change forcing (RCP 8.5) but were also simulated under the climate of 1950-2000, reflecting the joint influences of early warming trends and historical forest legacies. Our results demonstrate that there is a large potential for loss of conifer forest dominance—and associated carbon stocks and biodiversity-- in the Klamath before the end of the century, and that some losses would likely occur even without the influence of climate change. Thus, in the Klamath and other forested landscapes subject to similar feedback dynamics, major ecosystem shifts should be expected when climate change disrupts key stabilizing feedbacks that maintain the dominance of long-lived, slowly regenerating trees. Close

• 77. [Article] Type and Timing of Stream Flow Changes in Urbanizing Watersheds in the Eastern U.S.

  Linking the type and timing of hydrologic changes with patterns of urban growth is essential to identifying the underlying mechanisms that drive declines in urban aquatic ecosystems. In six urbanizing ...

  Citation × Citation Citation Abstract Copy Title: Type and Timing of Stream Flow Changes in Urbanizing Watersheds in the Eastern U.S. Author: Hopkins, Kristina G., Morse, Nathaniel B., Bain, Daniel J., Bettez, Neil D., Grimm, Nancy B., Morse, Jennifer L., Palta, Monica M. Year: 2015 Linking the type and timing of hydrologic changes with patterns of urban growth is essential to identifying the underlying mechanisms that drive declines in urban aquatic ecosystems. In six urbanizing watersheds surrounding three U.S. cities (Baltimore, MD, Boston, MA, and Pittsburgh, PA), we reconstructed the history of development patterns since 1900 and assessed the magnitude and timing of stream flow changes during watershed development. Development reconstructions indicated that the majority of watershed development occurred during a period of peak population growth, typically between 1950 and 1970. Stream flow records indicated significant increases in annual frequency of high-flow events in all six watersheds and increases in annual runoff efficiency in five watersheds. Annual development intensity during the peak growth period had the strongest association with the magnitude of changes in high-flow frequency from the pre- to post-development periods. Results suggest the timing of the peak growth period is particularly important to understanding hydrologic changes, because it can set the type of stormwater infrastructure installed within a watershed. In three watersheds there was a rapid (~10-15 years) shift toward more frequent high-flow events, and in four watersheds there was a shift toward higher runoff efficiency. Breakpoint analyses indicated these shifts occurred between 1969 and 1976 for high-flow frequency and between 1962 and 1984 for runoff efficiency. Results indicated that the timing of high-flow changes were mainly driven by the development trajectory of each watershed, whereas the timing of runoff-efficiency changes were driven by a combination of development trajectories and extreme weather events. Our results underscore the need to refine the causes of urban stream degradation to incorporate the impact of gradual versus rapid urbanization on hydrologic changes and aquatic ecosystem function, as well as to recognize that the dominant drivers of hydrologic changes are heterogeneous among urban watersheds and vary over time. Title: Type and Timing of Stream Flow Changes in Urbanizing Watersheds in the Eastern U.S. Author: Hopkins, Kristina G., Morse, Nathaniel B., Bain, Daniel J., Bettez, Neil D., Grimm, Nancy B., Morse, Jennifer L., Palta, Monica M. Year: 2015 Linking the type and timing of hydrologic changes with patterns of urban growth is essential to identifying the underlying mechanisms that drive declines in urban aquatic ecosystems. In six urbanizing watersheds surrounding three U.S. cities (Baltimore, MD, Boston, MA, and Pittsburgh, PA), we reconstructed the history of development patterns since 1900 and assessed the magnitude and timing of stream flow changes during watershed development. Development reconstructions indicated that the majority of watershed development occurred during a period of peak population growth, typically between 1950 and 1970. Stream flow records indicated significant increases in annual frequency of high-flow events in all six watersheds and increases in annual runoff efficiency in five watersheds. Annual development intensity during the peak growth period had the strongest association with the magnitude of changes in high-flow frequency from the pre- to post-development periods. Results suggest the timing of the peak growth period is particularly important to understanding hydrologic changes, because it can set the type of stormwater infrastructure installed within a watershed. In three watersheds there was a rapid (~10-15 years) shift toward more frequent high-flow events, and in four watersheds there was a shift toward higher runoff efficiency. Breakpoint analyses indicated these shifts occurred between 1969 and 1976 for high-flow frequency and between 1962 and 1984 for runoff efficiency. Results indicated that the timing of high-flow changes were mainly driven by the development trajectory of each watershed, whereas the timing of runoff-efficiency changes were driven by a combination of development trajectories and extreme weather events. Our results underscore the need to refine the causes of urban stream degradation to incorporate the impact of gradual versus rapid urbanization on hydrologic changes and aquatic ecosystem function, as well as to recognize that the dominant drivers of hydrologic changes are heterogeneous among urban watersheds and vary over time. Close

• 78. [Article] Understanding the Links Between Cyanobacteria Physiology and Hydrodynamics may Help Find Adaption Strategies for Toxic Blooms

  Even though we are managing lakes to decrease algal blooms overall, harmful algal blooms seem to be showing up more and more frequently. Although the word “blooms” connotes dominance and rapid growth, ...

  Citation × Citation Citation Abstract Copy Title: Understanding the Links Between Cyanobacteria Physiology and Hydrodynamics may Help Find Adaption Strategies for Toxic Blooms Author: Rueter, John Year: 2016 Even though we are managing lakes to decrease algal blooms overall, harmful algal blooms seem to be showing up more and more frequently. Although the word “blooms” connotes dominance and rapid growth, dangerous accumulations of cyanobacteria can occur because of combinations of physiological advantages and particular weather and hydrodynamic conditions. I am particularly interested in specific conditions that might favor Aphanizomenon versus those that might favor Microcystis in Upper Klamath and Agency Lakes. Aphanizomenon is a nuisance and large blooms can lead to oxygen depletion and fish deaths. Microcystis can both be a nuisance and is toxic. The comparison of the physiologies of these two cyanobacterial strains could lead to an understanding of both short term adaptation and mitigation tactics as well as long term lake restoration strategies. Ideally, we would like to employ lake restoration strategies and see constant improvement leading to safer and cleaner water. However, either because of threshold effects or ineffective lake management approaches, we might have to take short-term manipulations that can reduce local accumulations of cyanobacteria to protect the health of humans and other species. These short term tactics must have three characteristics: First, we need to find mitigation techniques that might knock down or stall a bloom of algae from occurring. Second, we have to have ways to model and monitor these manipulations over relevant time and space scales. Third, any short-term techniques we employ should not substantial interfere with the long term goals of lake restoration, i.e. the quick fix shouldn’t undermine the solving the problem. I will present several potential short-term solutions based algal physiology and hydrodynamics. Then I will describe how we have used temperature datalogging (10 minute intervals) and high-resolution transects (1 meter spatial resolution) to understand impacts on accumulation processes. Then finally, I will describe a framework for supporting fast and cheap methods to adapt to cyanobacteria accumulations that don’t result in unintended consequences or interfere with lake restoration efforts. Title: Understanding the Links Between Cyanobacteria Physiology and Hydrodynamics may Help Find Adaption Strategies for Toxic Blooms Author: Rueter, John Year: 2016 Even though we are managing lakes to decrease algal blooms overall, harmful algal blooms seem to be showing up more and more frequently. Although the word “blooms” connotes dominance and rapid growth, dangerous accumulations of cyanobacteria can occur because of combinations of physiological advantages and particular weather and hydrodynamic conditions. I am particularly interested in specific conditions that might favor Aphanizomenon versus those that might favor Microcystis in Upper Klamath and Agency Lakes. Aphanizomenon is a nuisance and large blooms can lead to oxygen depletion and fish deaths. Microcystis can both be a nuisance and is toxic. The comparison of the physiologies of these two cyanobacterial strains could lead to an understanding of both short term adaptation and mitigation tactics as well as long term lake restoration strategies. Ideally, we would like to employ lake restoration strategies and see constant improvement leading to safer and cleaner water. However, either because of threshold effects or ineffective lake management approaches, we might have to take short-term manipulations that can reduce local accumulations of cyanobacteria to protect the health of humans and other species. These short term tactics must have three characteristics: First, we need to find mitigation techniques that might knock down or stall a bloom of algae from occurring. Second, we have to have ways to model and monitor these manipulations over relevant time and space scales. Third, any short-term techniques we employ should not substantial interfere with the long term goals of lake restoration, i.e. the quick fix shouldn’t undermine the solving the problem. I will present several potential short-term solutions based algal physiology and hydrodynamics. Then I will describe how we have used temperature datalogging (10 minute intervals) and high-resolution transects (1 meter spatial resolution) to understand impacts on accumulation processes. Then finally, I will describe a framework for supporting fast and cheap methods to adapt to cyanobacteria accumulations that don’t result in unintended consequences or interfere with lake restoration efforts. Close

• 79. [Article] Bending the Carbon Curve: Fire Management for Carbon Resilience under Climate Change

  Context: Forest landscapes are increasingly managed for fire resilience, particularly in the western US which has recently experienced drought and widespread, high-severity wildfires. Fuel reduction treatments ...

  Citation × Citation Citation Abstract Copy Title: Bending the Carbon Curve: Fire Management for Carbon Resilience under Climate Change Author: Loudermilk, E. Louise, Scheller, Robert M., Weisberg, Peter J., Kretchun, Alec M. Year: 2017 Context: Forest landscapes are increasingly managed for fire resilience, particularly in the western US which has recently experienced drought and widespread, high-severity wildfires. Fuel reduction treatments have been effective where fires coincide with treated areas. Fuel treatments also have the potential to reduce drought-mortality if tree density is uncharacteristically high, and to increase long-term carbon storage by reducing high-severity fire probability. Objective: Assess whether fuel treatments reduce fire intensity and spread and increase carbon storage under climate change. Methods: We used a simulation modeling approach that couples a landscape model of forest disturbance and succession with an ecosystem model of carbon dynamics (Century), to quantify the interacting effects of climate change, fuel treatments and wildfire for carbon storage potential in a mixed-conifer forest in the western USA. Results: Our results suggest that fuel treatments have the potential to ‘bend the C curve’, maintaining carbon resilience despite climate change and climate-related changes to the fire regime. Simulated fuel treatments resulted in reduced fire spread and severity. There was partial compensation of C lost during fuel treatments with increased growth of residual stock due to greater available soil water, as well as a shift in species composition to more drought- and fire-tolerant Pinus jeffreyi at the expense of shade-tolerant, fire-susceptible Abies concolor. Conclusions: Forest resilience to global change can be achieved through management that reduces drought stress and supports the establishment and dominance of tree species that are more fire- and drought-resistant, however, achieving a net C gain from fuel treatments may take decades. Title: Bending the Carbon Curve: Fire Management for Carbon Resilience under Climate Change Author: Loudermilk, E. Louise, Scheller, Robert M., Weisberg, Peter J., Kretchun, Alec M. Year: 2017 Context: Forest landscapes are increasingly managed for fire resilience, particularly in the western US which has recently experienced drought and widespread, high-severity wildfires. Fuel reduction treatments have been effective where fires coincide with treated areas. Fuel treatments also have the potential to reduce drought-mortality if tree density is uncharacteristically high, and to increase long-term carbon storage by reducing high-severity fire probability. Objective: Assess whether fuel treatments reduce fire intensity and spread and increase carbon storage under climate change. Methods: We used a simulation modeling approach that couples a landscape model of forest disturbance and succession with an ecosystem model of carbon dynamics (Century), to quantify the interacting effects of climate change, fuel treatments and wildfire for carbon storage potential in a mixed-conifer forest in the western USA. Results: Our results suggest that fuel treatments have the potential to ‘bend the C curve’, maintaining carbon resilience despite climate change and climate-related changes to the fire regime. Simulated fuel treatments resulted in reduced fire spread and severity. There was partial compensation of C lost during fuel treatments with increased growth of residual stock due to greater available soil water, as well as a shift in species composition to more drought- and fire-tolerant Pinus jeffreyi at the expense of shade-tolerant, fire-susceptible Abies concolor. Conclusions: Forest resilience to global change can be achieved through management that reduces drought stress and supports the establishment and dominance of tree species that are more fire- and drought-resistant, however, achieving a net C gain from fuel treatments may take decades. Close

• 80. [Article] Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed

  Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed A watershed analysis project was undertaken to investigate the impact of urbanization on the water quality with Bronson ...

  Citation × Citation Citation Abstract Copy Title: Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed Author: Creech, Jason Cristopher Year: 2003 Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed A watershed analysis project was undertaken to investigate the impact of urbanization on the water quality with Bronson Creek; a small urban stream in the metropolitan area of Portland, Oregon. Total Maximum Daily Loads (TMDLs) have been established for several water quality parameters within the watershed. Water quality data were collected at nine sampling along Bronson Creek by Clean Water Services, a local public utility charged with storm water management and water quality protection duties. Only seven water quality parameters were included in the analysis; they were 1) temperature, 2) total phosphorous, 3) ortho-phosphate, 4) ammonia, 5) total nitrogen, 6) total suspended solids, and 7) E. Coli. Samples were taken approximately twice a month over a 7 year period from 1994 – 2001. Total impervious area (TIA) was used as the indicator of urbanization for the project. Impervious area values (TIA%) were calculated by digitizing aerial photography. Yearly TIA values were calculated for the entire watershed, as well as for its 37 subasins (subcatchement level). Water quality data were analyzed for variations along the stream and for the presence of trends (monotonic changes over time) during seasons of poor water quality. Kendall’s t was also used as the trend test statistic. Data were also analyzed to determine if an association exists between water quality at a sampling site and the upstream imperviousness (TIA%). Kendall’s t was used as the test statistic. Negative trends (improving water quality) were found throughout the watershed with nitrogen exhibiting the largest reduction. Temperature was the only parameter not to exhibit a negative trend at any location within the watershed. Results of the correlation between water quality and TIA% showed similar results, where a parameter experiencing a trend also exhibited a significant Kendall’s correlation with upstream TIA%. As TIA increased, water quality improved at least one site, for all parameters except temperature. One possible cause of the improving water quality within Bronson Creek is the implementation of best management practices within the watershed. Stormwater ponds were located in subcatchments that were adjacent to water quality sampling sites with improving water quality. The Bronson Creek watershed is also part of a pilot program to test the effectiveness of best management practices on improving water quality in the urban environment. Title: Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed Author: Creech, Jason Cristopher Year: 2003 Urbanization and its Relationship to Water Quality within the Bronson Creek Watershed A watershed analysis project was undertaken to investigate the impact of urbanization on the water quality with Bronson Creek; a small urban stream in the metropolitan area of Portland, Oregon. Total Maximum Daily Loads (TMDLs) have been established for several water quality parameters within the watershed. Water quality data were collected at nine sampling along Bronson Creek by Clean Water Services, a local public utility charged with storm water management and water quality protection duties. Only seven water quality parameters were included in the analysis; they were 1) temperature, 2) total phosphorous, 3) ortho-phosphate, 4) ammonia, 5) total nitrogen, 6) total suspended solids, and 7) E. Coli. Samples were taken approximately twice a month over a 7 year period from 1994 – 2001. Total impervious area (TIA) was used as the indicator of urbanization for the project. Impervious area values (TIA%) were calculated by digitizing aerial photography. Yearly TIA values were calculated for the entire watershed, as well as for its 37 subasins (subcatchement level). Water quality data were analyzed for variations along the stream and for the presence of trends (monotonic changes over time) during seasons of poor water quality. Kendall’s t was also used as the trend test statistic. Data were also analyzed to determine if an association exists between water quality at a sampling site and the upstream imperviousness (TIA%). Kendall’s t was used as the test statistic. Negative trends (improving water quality) were found throughout the watershed with nitrogen exhibiting the largest reduction. Temperature was the only parameter not to exhibit a negative trend at any location within the watershed. Results of the correlation between water quality and TIA% showed similar results, where a parameter experiencing a trend also exhibited a significant Kendall’s correlation with upstream TIA%. As TIA increased, water quality improved at least one site, for all parameters except temperature. One possible cause of the improving water quality within Bronson Creek is the implementation of best management practices within the watershed. Stormwater ponds were located in subcatchments that were adjacent to water quality sampling sites with improving water quality. The Bronson Creek watershed is also part of a pilot program to test the effectiveness of best management practices on improving water quality in the urban environment. Close