Virginia Dale | University of Tennessee Knoxville (original) (raw)

Papers by Virginia Dale

Agronomy for Sustainable Development, Jan 8, 2019

Environmental Management, Jun 1, 2010

Efroymson brings extensive expertise in risk assessment and environmental toxicology. Her work ha... more Efroymson brings extensive expertise in risk assessment and environmental toxicology. Her work has focused on land management, natural resources, water quality, and rare species, with recent work on benefits and risks of energy alternatives. ENVIRONMENTAL MANAGEMENT has been publishing research on the management and conservation of natural resources and habitats since 1976. Articles discuss implications for an international audience and examine a scientific or management hypothesis. As a premier scientific journal in applied and cross-cutting areas, articles come from a variety of disciplines including biology, botany, climatology, earth sciences, ecology, ecological economics, environmental engineering, fisheries, forest sciences, geography, information science, law, management science, politics, public affairs, social sciences, and zoology, most often in combinations determined by the interdisciplinary topic of the study. The journal strives to improve cross-disciplinary communication by making ideas and results available to environmental practitioners from other backgrounds. The goal of ENVIRONMENTAL MANAGEMENT is to present a wide spectrum of viewpoints and approaches, and to this end the journal consists of four main sections. Forum contains addresses, editorials, comments, and opinions about environmental matters. Articles in the

I DISCLAIMER Portions of this document may be illegible in electronic image products. Images are ... more I DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

The changes that accompany growth and development over a region are reflected in many ways. Chang... more The changes that accompany growth and development over a region are reflected in many ways. Changes to the land can be observed using data derived from remote sensing to create land-cover maps. Land-cover data provide a snapshot of the land status at a specific period of time. Hence any major growth or development in a region should reflect associated changes in the land cover. To explore causes and implications of land-cover changes, land-cover change rules have been developed as part of a regional simulation model, RSim. This study analyzes the problems of developing and calibrating the land-cover change rules in RSim. Land-cover change rules are usually derived from past trends in the landscape and also from trends in the use of land. However, some of the major issues while calibrating and developing change rules are the inconsistencies in data availability and description. Fundamental differences in the data type such as information describing land use or land cover also affect interpretations from such data. The results of this study show that human demographic variables such as urban and rural population could not be compared with high and low intensity land-cover classes directly. However urban land cover as a whole could

Frontiers in Ecology and the Environment, 2018

Risk and resilience in an uncertain world E cological disturbances are occurring with greater fre... more Risk and resilience in an uncertain world E cological disturbances are occurring with greater frequency and intensity than in the past. Under projected shifts in disturbance regimes and patterns of recovery, societal and environmental impacts are expected to be more extreme and to span larger spatial extents. Moreover, preexisting conditions will require a longer time to re-establish, if they do so at all. The word "unprecedented" is appearing more often in news reporting on droughts, fires, hurricanes, tsunamis, ice storms, and insect outbreaks. The causes and effects of these events are often exacerbated by human modifications of natural environments and influenced by technological developments. At the same time, multiple events or different types of disturbances can undermine the ability of environmental systems to recover, and interacting disturbances can cause these systems to transition to new and undesirable states. For example, the combination of an expansion of impervious surface area, changes to hydrology and drainage systems, and wetland losses can interact to amplify the frequency and severity of flooding. In addition, actions that seek to manage individual rather than combined risks may induce unintentional consequences, increase the magnitude of impacts, or decrease resilience (the ability of an ecosystem to withstand or recover quickly from a disturbance). Furthermore, re-establishment may be to a new state or to what some call an "emerging ecosystem", whose properties then influence risks of and resilience to subsequent disturbances. The need to proactively address risk and resilience is more pressing than ever. Managing complex ecosystems to maintain essential characteristics in the face of an uncertain future is challenging. Therefore, we offer a perspective on risk and resilience that encompasses interactions among ecosystems, social systems, infrastructure, and evolving technological capabilities. Management decisions need to concentrate on three topic areas: (1) risk assessment, monitoring, and mitigation; (2) natural resource use and ecosystem service management; and (3) linkages among humans, technologies, and emerging ecosystems. More effectively managing natural resources and the ecosystem services they provide requires that scientists and managers anticipate shifts in disturbance regimes and analyze risk and resilience from broader perspectives. Whether and when risks and associated losses in ecosystem services are amplified or attenuated by future disturbances depends on how the environment, society, the economy, and technology respond. We cannot assume that practices that have worked in the past will be effective in the future. Just as future disturbance regimes differ from those of the past, tools to analyze, monitor, and manage them are also changing. Ecologists have much to offer in this regard, because of their knowledge of how disturbances can affect ecosystems. Furthermore, ecologists are using new tools for detecting environmental change at different temporal, spatial, and organizational scales. For instance, the development of smartphones has led to an explosion of information sharing via apps and citizen-science initiatives. Information collected by individuals can be uploaded into mobile or web-based applications to help scientists assess change at regional and global scales. Technological advances in genomics and remote sensing have made it possible to study environments from the molecular to the ecosystem level using biomonitoring tools such as environmental DNA (eDNA) and instruments affixed to drones, submersibles, and satellites. Scientific understanding of the interactive effects of multiple disturbances is also evolving. Together, new technologies and new scientific concepts can help to address the interfaces between human and ecological systems. Combining these new tools and perspectives is essential for science, management, and planning. We urge environmental scientists to design research that analyzes the effects of shifts in disturbance regimes and identifies ways to minimize adverse impacts. The kinds of information that we believe will be useful include mechanisms or conceptual models of impact, risk maps that identify susceptible areas, means to monitor and assess current conditions, indicators of pending change, potential influences on mitigation interventions, and data on the interactions between human and ecological systems. Case studies that focus on multiple scales-including local analyses of interest to landowners and regional analyses useful to watershed, state, and federal planners-are also valuable. Because the future is uncertain and to some extent unknowable, it is imperative that ecologists become involved in the discussion and planning of future infrastructure and protection from the effects of altered disturbance regimes. Research can test and demonstrate the benefits of protecting or proactively managing important features and places, and processes that enhance provisioning of ecosystem services such as flood control and fire mitigation. It is time to demonstrate how ecological science, when applied to human-environmental systems, can reduce risks and enhance resilience in a complex, changing world.

Frontiers in Ecology and the Environment, 2018

S cientific breakthroughs at Federally Funded Research and Development Centers (FFRDCs) can lead ... more S cientific breakthroughs at Federally Funded Research and Development Centers (FFRDCs) can lead to changes in policy and affect funding priorities for ecological research. For example, while the scientific hypothesis underlying the relationship between land-use change (LUC) and climate change had been long established (Revelle and Suess 1957), for decades there was great uncertainty about how current deforestation influenced atmospheric CO 2 and thus climate change. It took a dedicated team of ecologists, historians, foresters, geographers, and economists to document how current effects of LUC alter atmospheric CO 2 concentration by about 10% rather than the high estimate of 50% (Post et al. 1990; Dale et al. 1991). This team, led by an FFRDC, showed that since the early 1900s fossil-fuel combustion has been the major contributor to the annual flux of carbon to the atmosphere. The good news is that this work influenced policy makers to focus on the burning of fossil fuels as the main contributor to climate change. The bad news is that it also decreased funding for research on LUC since its effect on climate change was found to be relatively small. Testing such complex scientific hypotheses is a key emphasis of FFRDCs. These institutions provide an engaging career opportunity for scientists interested in a career spanning both basic and applied ecology and that involves investigating subject matter with environmental policy implications. If you want to apply your expertise in a group setting to address the most challenging scientific issues of the day, FFRDCs are the place for you. FFRDC research is often interdisciplinary and involves large teams, going back to its roots in the Manhattan Project, which engaged more than 130,000 people in atomic research during World War II and laid the groundwork for having many scientists tackle a single problem. In 1960, two FFRDCs, Oak Ridge National Laboratory (ORNL) and Savannah River National Laboratory, initiated research in radioecology, as lands contaminated with radioactive waste provided an "opportunity" for tracing nutrients through ecosystems. Subsequently, systems ecologists at these and other FFRDCs and universities established the foundations for ecological modeling and ecosystem studies under the International Biological Program (IBP), which ran from 1964 to 1974. Today, FFRDC researchers explore safe and environmentally appropriate energy options and address other national challenges. Throughout the US, ten FFRDCs currently perform ecological research under contracts with the US Department of Energy (DOE) and the National Science Foundation (NSF)

Madera y Bosques, 2016

Statistical analysis between three weighted additive biomass equations are presented for planted ... more Statistical analysis between three weighted additive biomass equations are presented for planted pine species typical of the coniferous forests of the Western Sierra Madre mountain range of Durango, Mexico. Statistical and graphical analyses were used to select the best single and multiple individual biomass component equation. Linear equations better fitted the biomass components. Therefore, three linear additive procedures were tested: (i) the conventional, (ii) a harmonization, and ( iii) the seemingly-unrelated regression in two types of equations of component biomass estimation using both simple regression and multiple regression techniques. These tests were performed at two scales: (a) each of three pine species and (b) all three species. For both the simple linear and best multiple regression equation, the seemingly-unrelated equations provided more precise biomass component estimates, with tendencies consistent with the conventional non-additive non-linear regression procedu...

Potential climate impacts on the hydrology of two seasonally snow-covered catchments is evaluated... more Potential climate impacts on the hydrology of two seasonally snow-covered catchments is evaluated using 24 years of data from Niwot Ridge Long Term Ecological Research Site, CO. At the larger (220 ha), higher elevation (3,570 m) GL4 catchment, annual discharge did not change significantly based on nonparametric trend testing. However, October streamflow volumes and groundwater storage did increase, despite drought conditions near the end of the record in 2000-2004. In contrast, at the smaller (8 ha), lower elevation (3,400 m) MART catchment, annual discharge decreased significantly over the study period with the most substantial changes in July-September. The study period was separated into "wet," "normal," and "dry" years based on the 75 th and 25 th quartiles of annual precipitation. Results indicate that MART is particularly sensitive to changes in precipitation with dry years exhibiting decreased snowmelt peak flows, earlier snowmelt timing, decreased annual discharge, and reduced late-season flows. GL4 was less susceptible to changes in precipitation, and surprisingly late-season flow volumes (Sept.-Oct.) were not significantly different among wet, normal, and dry conditions. Glacial melt from the Arikaree glacier may account for up to 43 percent of the increase in late-season flows based on ablation measurements. We downscaled a regional permafrost model based on topoclimatic variables to assess whether subsurface ice within permafrost and rock glaciers could account for the remaining deficiency. Results suggest that with only 1°C of warming over one-third of permafrost area would be lost. Over the study period mean annual minimum temperatures increased by 0.6° decade-1 , with some of the most prominent increases occurring in July (1.5°C decade-1). Additionally, limited ground temperature measurements at an active rock glacier indicate a 1°C increase over the past decade. This suggests that the source of late-season streamflow at GL4 has shifted towards permafrost meltwater in recent warm, dry years. This study shows that seasonally snow-covered catchments are particularly sensitive to changes in climate, but the hydrologic response may depend on landscape characteristics.

Recent declines in North American breeding bird populations have sparked great concern over the e... more Recent declines in North American breeding bird populations have sparked great concern over the effects of habitat fragmentation. Neotropical migrant birds use and are influenced by two biomes during a single life span. Yet assessment of the relative importance of changes in tropical wintering areas versus temperate breeding areas is complicated by regional variation in rates and extent of habitat change. Landscape-level measurements of forest fragmentation derived from remotely-sensed data provide a means to compare the patterns of habitat modification on the wintering and breeding grounds of migrant birds. This study quantifies patterns of forest fragmentation in the Southern Appalachian Mountains and tropical Amazon and relates these patterns to the resource needs of neotropical migrant birds. Study sites were selected from remotely-sensed images to represent a range of forest fragmentation (highly fragmented landscape to continuous forest).

A simulation model for the development of timber stands in the Pacific Northwest is described. Th... more A simulation model for the development of timber stands in the Pacific Northwest is described. The model grows individual trees of 21 species in a 0.20-hectare (0.08-acre) forest gap. The model provides a means of assimilating existing information, indicates where knowledge is deficient, suggests where the forest system is most sensitive, and provides a first testing ground for hypotheses. Model verification simulations are included for up to 500 years on various sites. Fire, wind, or clearcutting can occur at intervals and intensities specified by users. The model was developed by modifying an existing forest succession simulator of eastern deciduous forests. Birth, growth, and death of individual trees are functions of existing light and temperature conditions, competition and species characteristics. Modifications of the existing simulator include tree height growth being related to temperature and moisture conditions, the foliage biomass to diameter relationship being more realistic, and five mortality classes and shade tolerance classes being defined.

Ecological Modeling for Resource Management

Environmental Management, 2014

be translated or copied in whole or in part without the written permission of the publisher (Spri... more be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely byanyone. Production coordinated by Chernow Editorial Services, Inc., and managed by Tim Taylor; manufacturing supervised by Jeffrey Taub.

Springer Series on Environmental Management, 2009

This book responds to questions in three general areas: characterization of hypoxia; characteriza... more This book responds to questions in three general areas: characterization of hypoxia; characterization of nutrient fate, transport and sources; and the scientific basis for goals and management options. In the sections below, these questions (shown in italics below) are addressed very briefly with references to those sections of this book where more detailed science on that particular question may be

Springer Series on Environmental Management, 2009

This report is the first in a series of six reports developed as the scientific basis for an inte... more This report is the first in a series of six reports developed as the scientific basis for an integrated assessment of the causes and consequences of hypoxia in the Gulf of Mexico, as requested by the White House Office of Science and Technology Policy and as required by Section 604a of P.L. 105-383. For more information on the assessment and the assessment process, please contact the National Centers for Coastal Ocean Science at (301) 713-3060. DECISION ANALYSIS SERIES The Decision Analysis Series has been established by NOAA's Coastal Ocean Program (COP) to present documents for coastal decision makers which contain analytical treatments of major issues or topics. The issues, topics, and principal investigators have been selected through an extensive peer review process. To learn more about the COP or the Decision Analysis Series, please write to:

Ambiente & Sociedade, 1999

Este artigo analisa o processo de criação e proteção de unidades de conservação no Estado de Rond... more Este artigo analisa o processo de criação e proteção de unidades de conservação no Estado de Rondônia. Este processo tem tido o apoio financeiro e orientação programática do Banco Mundial através de diferentes programas de desenvolvimento regional desde o início dos anos 80. A partir da discussão sobre o papel fundamental das unidades de conservação na preservação dos ecossistemas Amazônicos, o artigo realiza uma análise histórica do processo de criação destas unidades no Estado de Rondônia. A partir desta análise é feita uma revisão das principais limitações, principalmente as institucionais e de capital social, que acabam comprometendo os esforços de conservação ambiental como os desenvolvidos em Rondônia. Uma discussão específica é feita sobre o persistente papel da construção de estradas como ferramenta de desenvolvimento regional, e de seu impacto sobre a integridade das unidades de conservação e reservas extrativas e indígenas. O artigo conclui que grandes investimentos na ree...

Proceedings of the National Academy of Sciences, 2013

Landscape Ecology, 1988

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantif... more Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.

Landscape Ecology, 1989

Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. ... more Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. The ability to make predictions at more than one level of resolution requires identification of the processes of interest and parameters that affect this process at different scales, the development of rules to translate information across scales, and the ability to test these predictions at the relevant spatial and temporal scales. This paper synthesizes discussions from a workshop on 'Predicting Across Scales: Theory Development and Testing' that was held to discuss current research on scaling and to identify key research issues.

Agronomy for Sustainable Development, Jan 8, 2019

Environmental Management, Jun 1, 2010

Efroymson brings extensive expertise in risk assessment and environmental toxicology. Her work ha... more Efroymson brings extensive expertise in risk assessment and environmental toxicology. Her work has focused on land management, natural resources, water quality, and rare species, with recent work on benefits and risks of energy alternatives. ENVIRONMENTAL MANAGEMENT has been publishing research on the management and conservation of natural resources and habitats since 1976. Articles discuss implications for an international audience and examine a scientific or management hypothesis. As a premier scientific journal in applied and cross-cutting areas, articles come from a variety of disciplines including biology, botany, climatology, earth sciences, ecology, ecological economics, environmental engineering, fisheries, forest sciences, geography, information science, law, management science, politics, public affairs, social sciences, and zoology, most often in combinations determined by the interdisciplinary topic of the study. The journal strives to improve cross-disciplinary communication by making ideas and results available to environmental practitioners from other backgrounds. The goal of ENVIRONMENTAL MANAGEMENT is to present a wide spectrum of viewpoints and approaches, and to this end the journal consists of four main sections. Forum contains addresses, editorials, comments, and opinions about environmental matters. Articles in the

I DISCLAIMER Portions of this document may be illegible in electronic image products. Images are ... more I DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

The changes that accompany growth and development over a region are reflected in many ways. Chang... more The changes that accompany growth and development over a region are reflected in many ways. Changes to the land can be observed using data derived from remote sensing to create land-cover maps. Land-cover data provide a snapshot of the land status at a specific period of time. Hence any major growth or development in a region should reflect associated changes in the land cover. To explore causes and implications of land-cover changes, land-cover change rules have been developed as part of a regional simulation model, RSim. This study analyzes the problems of developing and calibrating the land-cover change rules in RSim. Land-cover change rules are usually derived from past trends in the landscape and also from trends in the use of land. However, some of the major issues while calibrating and developing change rules are the inconsistencies in data availability and description. Fundamental differences in the data type such as information describing land use or land cover also affect interpretations from such data. The results of this study show that human demographic variables such as urban and rural population could not be compared with high and low intensity land-cover classes directly. However urban land cover as a whole could

Frontiers in Ecology and the Environment, 2018

Risk and resilience in an uncertain world E cological disturbances are occurring with greater fre... more Risk and resilience in an uncertain world E cological disturbances are occurring with greater frequency and intensity than in the past. Under projected shifts in disturbance regimes and patterns of recovery, societal and environmental impacts are expected to be more extreme and to span larger spatial extents. Moreover, preexisting conditions will require a longer time to re-establish, if they do so at all. The word "unprecedented" is appearing more often in news reporting on droughts, fires, hurricanes, tsunamis, ice storms, and insect outbreaks. The causes and effects of these events are often exacerbated by human modifications of natural environments and influenced by technological developments. At the same time, multiple events or different types of disturbances can undermine the ability of environmental systems to recover, and interacting disturbances can cause these systems to transition to new and undesirable states. For example, the combination of an expansion of impervious surface area, changes to hydrology and drainage systems, and wetland losses can interact to amplify the frequency and severity of flooding. In addition, actions that seek to manage individual rather than combined risks may induce unintentional consequences, increase the magnitude of impacts, or decrease resilience (the ability of an ecosystem to withstand or recover quickly from a disturbance). Furthermore, re-establishment may be to a new state or to what some call an "emerging ecosystem", whose properties then influence risks of and resilience to subsequent disturbances. The need to proactively address risk and resilience is more pressing than ever. Managing complex ecosystems to maintain essential characteristics in the face of an uncertain future is challenging. Therefore, we offer a perspective on risk and resilience that encompasses interactions among ecosystems, social systems, infrastructure, and evolving technological capabilities. Management decisions need to concentrate on three topic areas: (1) risk assessment, monitoring, and mitigation; (2) natural resource use and ecosystem service management; and (3) linkages among humans, technologies, and emerging ecosystems. More effectively managing natural resources and the ecosystem services they provide requires that scientists and managers anticipate shifts in disturbance regimes and analyze risk and resilience from broader perspectives. Whether and when risks and associated losses in ecosystem services are amplified or attenuated by future disturbances depends on how the environment, society, the economy, and technology respond. We cannot assume that practices that have worked in the past will be effective in the future. Just as future disturbance regimes differ from those of the past, tools to analyze, monitor, and manage them are also changing. Ecologists have much to offer in this regard, because of their knowledge of how disturbances can affect ecosystems. Furthermore, ecologists are using new tools for detecting environmental change at different temporal, spatial, and organizational scales. For instance, the development of smartphones has led to an explosion of information sharing via apps and citizen-science initiatives. Information collected by individuals can be uploaded into mobile or web-based applications to help scientists assess change at regional and global scales. Technological advances in genomics and remote sensing have made it possible to study environments from the molecular to the ecosystem level using biomonitoring tools such as environmental DNA (eDNA) and instruments affixed to drones, submersibles, and satellites. Scientific understanding of the interactive effects of multiple disturbances is also evolving. Together, new technologies and new scientific concepts can help to address the interfaces between human and ecological systems. Combining these new tools and perspectives is essential for science, management, and planning. We urge environmental scientists to design research that analyzes the effects of shifts in disturbance regimes and identifies ways to minimize adverse impacts. The kinds of information that we believe will be useful include mechanisms or conceptual models of impact, risk maps that identify susceptible areas, means to monitor and assess current conditions, indicators of pending change, potential influences on mitigation interventions, and data on the interactions between human and ecological systems. Case studies that focus on multiple scales-including local analyses of interest to landowners and regional analyses useful to watershed, state, and federal planners-are also valuable. Because the future is uncertain and to some extent unknowable, it is imperative that ecologists become involved in the discussion and planning of future infrastructure and protection from the effects of altered disturbance regimes. Research can test and demonstrate the benefits of protecting or proactively managing important features and places, and processes that enhance provisioning of ecosystem services such as flood control and fire mitigation. It is time to demonstrate how ecological science, when applied to human-environmental systems, can reduce risks and enhance resilience in a complex, changing world.

Frontiers in Ecology and the Environment, 2018

S cientific breakthroughs at Federally Funded Research and Development Centers (FFRDCs) can lead ... more S cientific breakthroughs at Federally Funded Research and Development Centers (FFRDCs) can lead to changes in policy and affect funding priorities for ecological research. For example, while the scientific hypothesis underlying the relationship between land-use change (LUC) and climate change had been long established (Revelle and Suess 1957), for decades there was great uncertainty about how current deforestation influenced atmospheric CO 2 and thus climate change. It took a dedicated team of ecologists, historians, foresters, geographers, and economists to document how current effects of LUC alter atmospheric CO 2 concentration by about 10% rather than the high estimate of 50% (Post et al. 1990; Dale et al. 1991). This team, led by an FFRDC, showed that since the early 1900s fossil-fuel combustion has been the major contributor to the annual flux of carbon to the atmosphere. The good news is that this work influenced policy makers to focus on the burning of fossil fuels as the main contributor to climate change. The bad news is that it also decreased funding for research on LUC since its effect on climate change was found to be relatively small. Testing such complex scientific hypotheses is a key emphasis of FFRDCs. These institutions provide an engaging career opportunity for scientists interested in a career spanning both basic and applied ecology and that involves investigating subject matter with environmental policy implications. If you want to apply your expertise in a group setting to address the most challenging scientific issues of the day, FFRDCs are the place for you. FFRDC research is often interdisciplinary and involves large teams, going back to its roots in the Manhattan Project, which engaged more than 130,000 people in atomic research during World War II and laid the groundwork for having many scientists tackle a single problem. In 1960, two FFRDCs, Oak Ridge National Laboratory (ORNL) and Savannah River National Laboratory, initiated research in radioecology, as lands contaminated with radioactive waste provided an "opportunity" for tracing nutrients through ecosystems. Subsequently, systems ecologists at these and other FFRDCs and universities established the foundations for ecological modeling and ecosystem studies under the International Biological Program (IBP), which ran from 1964 to 1974. Today, FFRDC researchers explore safe and environmentally appropriate energy options and address other national challenges. Throughout the US, ten FFRDCs currently perform ecological research under contracts with the US Department of Energy (DOE) and the National Science Foundation (NSF)

Madera y Bosques, 2016

Statistical analysis between three weighted additive biomass equations are presented for planted ... more Statistical analysis between three weighted additive biomass equations are presented for planted pine species typical of the coniferous forests of the Western Sierra Madre mountain range of Durango, Mexico. Statistical and graphical analyses were used to select the best single and multiple individual biomass component equation. Linear equations better fitted the biomass components. Therefore, three linear additive procedures were tested: (i) the conventional, (ii) a harmonization, and ( iii) the seemingly-unrelated regression in two types of equations of component biomass estimation using both simple regression and multiple regression techniques. These tests were performed at two scales: (a) each of three pine species and (b) all three species. For both the simple linear and best multiple regression equation, the seemingly-unrelated equations provided more precise biomass component estimates, with tendencies consistent with the conventional non-additive non-linear regression procedu...

Potential climate impacts on the hydrology of two seasonally snow-covered catchments is evaluated... more Potential climate impacts on the hydrology of two seasonally snow-covered catchments is evaluated using 24 years of data from Niwot Ridge Long Term Ecological Research Site, CO. At the larger (220 ha), higher elevation (3,570 m) GL4 catchment, annual discharge did not change significantly based on nonparametric trend testing. However, October streamflow volumes and groundwater storage did increase, despite drought conditions near the end of the record in 2000-2004. In contrast, at the smaller (8 ha), lower elevation (3,400 m) MART catchment, annual discharge decreased significantly over the study period with the most substantial changes in July-September. The study period was separated into "wet," "normal," and "dry" years based on the 75 th and 25 th quartiles of annual precipitation. Results indicate that MART is particularly sensitive to changes in precipitation with dry years exhibiting decreased snowmelt peak flows, earlier snowmelt timing, decreased annual discharge, and reduced late-season flows. GL4 was less susceptible to changes in precipitation, and surprisingly late-season flow volumes (Sept.-Oct.) were not significantly different among wet, normal, and dry conditions. Glacial melt from the Arikaree glacier may account for up to 43 percent of the increase in late-season flows based on ablation measurements. We downscaled a regional permafrost model based on topoclimatic variables to assess whether subsurface ice within permafrost and rock glaciers could account for the remaining deficiency. Results suggest that with only 1°C of warming over one-third of permafrost area would be lost. Over the study period mean annual minimum temperatures increased by 0.6° decade-1 , with some of the most prominent increases occurring in July (1.5°C decade-1). Additionally, limited ground temperature measurements at an active rock glacier indicate a 1°C increase over the past decade. This suggests that the source of late-season streamflow at GL4 has shifted towards permafrost meltwater in recent warm, dry years. This study shows that seasonally snow-covered catchments are particularly sensitive to changes in climate, but the hydrologic response may depend on landscape characteristics.

Recent declines in North American breeding bird populations have sparked great concern over the e... more Recent declines in North American breeding bird populations have sparked great concern over the effects of habitat fragmentation. Neotropical migrant birds use and are influenced by two biomes during a single life span. Yet assessment of the relative importance of changes in tropical wintering areas versus temperate breeding areas is complicated by regional variation in rates and extent of habitat change. Landscape-level measurements of forest fragmentation derived from remotely-sensed data provide a means to compare the patterns of habitat modification on the wintering and breeding grounds of migrant birds. This study quantifies patterns of forest fragmentation in the Southern Appalachian Mountains and tropical Amazon and relates these patterns to the resource needs of neotropical migrant birds. Study sites were selected from remotely-sensed images to represent a range of forest fragmentation (highly fragmented landscape to continuous forest).

A simulation model for the development of timber stands in the Pacific Northwest is described. Th... more A simulation model for the development of timber stands in the Pacific Northwest is described. The model grows individual trees of 21 species in a 0.20-hectare (0.08-acre) forest gap. The model provides a means of assimilating existing information, indicates where knowledge is deficient, suggests where the forest system is most sensitive, and provides a first testing ground for hypotheses. Model verification simulations are included for up to 500 years on various sites. Fire, wind, or clearcutting can occur at intervals and intensities specified by users. The model was developed by modifying an existing forest succession simulator of eastern deciduous forests. Birth, growth, and death of individual trees are functions of existing light and temperature conditions, competition and species characteristics. Modifications of the existing simulator include tree height growth being related to temperature and moisture conditions, the foliage biomass to diameter relationship being more realistic, and five mortality classes and shade tolerance classes being defined.

Ecological Modeling for Resource Management

Environmental Management, 2014

be translated or copied in whole or in part without the written permission of the publisher (Spri... more be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely byanyone. Production coordinated by Chernow Editorial Services, Inc., and managed by Tim Taylor; manufacturing supervised by Jeffrey Taub.

Springer Series on Environmental Management, 2009

This book responds to questions in three general areas: characterization of hypoxia; characteriza... more This book responds to questions in three general areas: characterization of hypoxia; characterization of nutrient fate, transport and sources; and the scientific basis for goals and management options. In the sections below, these questions (shown in italics below) are addressed very briefly with references to those sections of this book where more detailed science on that particular question may be

Springer Series on Environmental Management, 2009

This report is the first in a series of six reports developed as the scientific basis for an inte... more This report is the first in a series of six reports developed as the scientific basis for an integrated assessment of the causes and consequences of hypoxia in the Gulf of Mexico, as requested by the White House Office of Science and Technology Policy and as required by Section 604a of P.L. 105-383. For more information on the assessment and the assessment process, please contact the National Centers for Coastal Ocean Science at (301) 713-3060. DECISION ANALYSIS SERIES The Decision Analysis Series has been established by NOAA's Coastal Ocean Program (COP) to present documents for coastal decision makers which contain analytical treatments of major issues or topics. The issues, topics, and principal investigators have been selected through an extensive peer review process. To learn more about the COP or the Decision Analysis Series, please write to:

Ambiente & Sociedade, 1999

Este artigo analisa o processo de criação e proteção de unidades de conservação no Estado de Rond... more Este artigo analisa o processo de criação e proteção de unidades de conservação no Estado de Rondônia. Este processo tem tido o apoio financeiro e orientação programática do Banco Mundial através de diferentes programas de desenvolvimento regional desde o início dos anos 80. A partir da discussão sobre o papel fundamental das unidades de conservação na preservação dos ecossistemas Amazônicos, o artigo realiza uma análise histórica do processo de criação destas unidades no Estado de Rondônia. A partir desta análise é feita uma revisão das principais limitações, principalmente as institucionais e de capital social, que acabam comprometendo os esforços de conservação ambiental como os desenvolvidos em Rondônia. Uma discussão específica é feita sobre o persistente papel da construção de estradas como ferramenta de desenvolvimento regional, e de seu impacto sobre a integridade das unidades de conservação e reservas extrativas e indígenas. O artigo conclui que grandes investimentos na ree...

Proceedings of the National Academy of Sciences, 2013

Landscape Ecology, 1988

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantif... more Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.

Landscape Ecology, 1989

Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. ... more Landscape ecologists deal with processes that occur at a variety of temporal and spatial scales. The ability to make predictions at more than one level of resolution requires identification of the processes of interest and parameters that affect this process at different scales, the development of rules to translate information across scales, and the ability to test these predictions at the relevant spatial and temporal scales. This paper synthesizes discussions from a workshop on 'Predicting Across Scales: Theory Development and Testing' that was held to discuss current research on scaling and to identify key research issues.