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Articles 1 - 30 of 39
Full-Text Articles in Physical Sciences and Mathematics
The Pacific Drought Knowledge Exchange: A Co-Production Approach To Deliver Climate Resources To User Groups, Ryan J. Longman, Abby G. Frazier, Christian P. Giardina, Elliott W. Parsons, Sierra Mcdaniel
The Pacific Drought Knowledge Exchange: A Co-Production Approach To Deliver Climate Resources To User Groups, Ryan J. Longman, Abby G. Frazier, Christian P. Giardina, Elliott W. Parsons, Sierra Mcdaniel
Geography
Drought is a growing threat to hydrological, ecological, agricultural, and socio-cultural systems of the tropics, especially tropical islands of the Pacific where severe droughts can compromise food and water security. Overcoming barriers to knowledge sharing between land managers and researchers is a critical cross-sector strategy for engaging and mitigating or adapting to drought. Here we describe the establishment and functioning of the Pacific Drought Knowledge Exchange (PDKE), which provides users with easier access to: (1) sector- and geography-specific climate information; (2) better and more comprehensive information; (3) improved technical assistance; and (4) a more collaborative information-transfer environment through participation in …
Climate Adaptation For Tropical Island Land Stewardship: Adapting A Workshop Planning Process To Hawai'i, Ryan J. Longman, Courtney L. Peterson, Madeline Baroli, Abby G. Frazier, Zachary Cook, Elliott W. Parsons, Maude Dinan, Katie L. Kamelamela, Caitriana Steele, Reanna Burnett, Chris Swanston, Christian P. Giardina
Climate Adaptation For Tropical Island Land Stewardship: Adapting A Workshop Planning Process To Hawai'i, Ryan J. Longman, Courtney L. Peterson, Madeline Baroli, Abby G. Frazier, Zachary Cook, Elliott W. Parsons, Maude Dinan, Katie L. Kamelamela, Caitriana Steele, Reanna Burnett, Chris Swanston, Christian P. Giardina
Geography
No abstract provided.
Sidebar: Observations Of Declining Primary Productivity In The Western Bering Strait, Karen E. Frey, Jaclyn Clement Kinney, Larry V. Stock, Robert Osinski
Sidebar: Observations Of Declining Primary Productivity In The Western Bering Strait, Karen E. Frey, Jaclyn Clement Kinney, Larry V. Stock, Robert Osinski
Geography
No abstract provided.
Phytoplankton Bloom Stages Estimated From Chlorophyll Pigment Proportions Suggest Delayed Summer Production In Low Sea Ice Years In The Northern Bering Sea, Clare B. Gaffey, Karen E. Frey, Lee W. Cooper, Jacqueline M. Grebmeier
Phytoplankton Bloom Stages Estimated From Chlorophyll Pigment Proportions Suggest Delayed Summer Production In Low Sea Ice Years In The Northern Bering Sea, Clare B. Gaffey, Karen E. Frey, Lee W. Cooper, Jacqueline M. Grebmeier
Geography
Decreased sea ice cover in the northern Bering Sea has altered annual phytoplankton phenology owing to an expansion of open water duration and its impact on ocean stratification. Limitations of satellite remote sensing such as the inability to detect bloom activity throughout the water column, under ice, and in cloudy conditions dictate the need for shipboard based measurements to provide more information on bloom dynamics. In this study, we adapted remote sensing land cover classification techniques to provide a new means to determine bloom stage from shipboard samples. Specifically, we used multiyear satellite time series of chlorophyll a to determine …
Female Pacific Walruses (Odobenus Rosmarus Divergens) Show Greater Partitioning Of Sea Ice Organic Carbon Than Males: Evidence From Ice Algae Trophic Markers, Chelsea W. Koch, Lee W. Cooper, Ryan J. Woodland, Jacqueline M. Grebmeier, Karen E. Frey, Raphaela Stimmelmayr, Cédric Magen, Thomas A. Brown
Female Pacific Walruses (Odobenus Rosmarus Divergens) Show Greater Partitioning Of Sea Ice Organic Carbon Than Males: Evidence From Ice Algae Trophic Markers, Chelsea W. Koch, Lee W. Cooper, Ryan J. Woodland, Jacqueline M. Grebmeier, Karen E. Frey, Raphaela Stimmelmayr, Cédric Magen, Thomas A. Brown
Geography
The expected reduction of ice algae with declining sea ice may prove to be detrimental to the Pacific Arctic ecosystem. Benthic organisms that rely on sea ice organic carbon (iPOC) sustain benthic predators such as the Pacific walrus (Odobenus rosmarus divergens). The ability to track the trophic transfer of iPOC is critical to understanding its value in the food web, but prior methods have lacked the required source specificity. We analyzed the H-Print index, based on biomarkers of ice algae versus phytoplankton contributions to organic carbon in marine predators, in Pacific walrus livers collected in 2012, 2014 and 2016 from …
Assessment Of Empirical And Semi-Analytical Algorithms Using Modis-Aqua For Representing In-Situ Chromophoric Dissolved Organic Matter (Cdom) In The Bering, Chukchi, And Western Beaufort Seas Of The Pacific Arctic Region, Melishia I. Santiago, Karen E. Frey
Assessment Of Empirical And Semi-Analytical Algorithms Using Modis-Aqua For Representing In-Situ Chromophoric Dissolved Organic Matter (Cdom) In The Bering, Chukchi, And Western Beaufort Seas Of The Pacific Arctic Region, Melishia I. Santiago, Karen E. Frey
Geography
We analyzed a variety of satellite-based ocean color products derived using MODIS-Aqua to investigate the most accurate empirical and semi-analytical algorithms for representing in-situ chromophoric dissolved organic matter (CDOM) across a large latitudinal transect in the Bering, Chukchi, and western Beaufort Seas of the Pacific Arctic region. In particular, we compared the performance of empirical (CDOM index) and several semi-analytical algorithms (quasi-analytical algorithm (QAA), Carder, Garver-Siegel-Maritorena (GSM), and GSM-A) with field measurements of CDOM absorption (aCDOM) at 412 nanometers (nm) and 443 nm. These algorithms were compared with in-situ CDOM measurements collected on cruises during July 2011, 2013, 2014, 2015, …
Application Of Autoencoders For Latent Pattern Analysis In Image Time Series, Jiena He
Application Of Autoencoders For Latent Pattern Analysis In Image Time Series, Jiena He
International Development, Community and Environment (IDCE)
The Earth system is considered to possess certain modes - preferred patterns of variability that can represent the latent structure of the climate system, also known as teleconnections. There are approaches to discover these patterns, Principal Components Analysis and Empirical Orthogonal Teleconnection (EOT) analysis. However, while the latter is very effective, it is computationally intensive. An autoencoder is an unsupervised neural network that learns an efficient neural representation of input data. It is considered as a dimensionality reduction tool that is highly similar to PCA and EOT. The hidden layer of an autoencoder represents the most significant information of the …
Changes At The Edge: Trends In Sea Ice, Ocean Temperature And Ocean Color At The Northwest Atlantic/Southern Arctic Interface, Ashley V. York, Karen E. Frey, Luisa N.C. Young
Changes At The Edge: Trends In Sea Ice, Ocean Temperature And Ocean Color At The Northwest Atlantic/Southern Arctic Interface, Ashley V. York, Karen E. Frey, Luisa N.C. Young
Geography
Spatial and temporal trends of remotely sensed sea-ice cover, sea surface temperatures, chlorophyll-a concentration and primary production in the Baffin Bay, Davis Strait and Labrador Sea were analyzed for the 1998-2017 period. We found spatial variability in the trends of these cryospheric, biologic and oceanographic phenomena. For example, in the northern Baffin Bay, we observed decreases in annual sea-ice persistence, yet increases along the Labrador Sea-ice edge during winter, with the latter having significant correlations with broader atmospheric patterns. In general, we observed increases in summer sea surface temperatures across the study region, except a small area of cooling along …
Ice Algae Resource Utilization By Benthic Macro- And Megafaunal Communities On The Pacific Arctic Shelf Determined Through Lipid Biomarker Analysis, Chelsea Wegner Koch, Lee W. Cooper, Jacqueline M. Grebmeier, Karen Frey, Thomas A. Brown
Ice Algae Resource Utilization By Benthic Macro- And Megafaunal Communities On The Pacific Arctic Shelf Determined Through Lipid Biomarker Analysis, Chelsea Wegner Koch, Lee W. Cooper, Jacqueline M. Grebmeier, Karen Frey, Thomas A. Brown
Geography
We studied ice algae utilization by benthic fauna from the northern Bering and Chukchi Seas using highly branched isoprenoid (HBI) biomarkers. We assessed whether various food acquisition strategies influence the observed HBI signatures. The proportion of phytoplankton to ice algae-sourced HBIs was determined through the H-Print approach that is presumed to reflect the percentage of sea ice organic carbon (iPOC) incorporated into tissues, relative to phytoplankton organic carbon. Cluster analysis separated 3 groups based on location and feeding strategy that were significantly influenced by annual sea ice persistence. Ice algae utilization was most significant in the northeast Chukchi Sea, where …
Seasonal And Latitudinal Variations In Sea Ice Algae Deposition In The Northern Bering And Chukchi Seas Determined By Algal Biomarkers, Chelsea Wegner Koch, Lee W. Cooper, Catherine Lalande, Thomas A. Brown, Karen E. Frey, Jacqueline M. Grebmeier
Seasonal And Latitudinal Variations In Sea Ice Algae Deposition In The Northern Bering And Chukchi Seas Determined By Algal Biomarkers, Chelsea Wegner Koch, Lee W. Cooper, Catherine Lalande, Thomas A. Brown, Karen E. Frey, Jacqueline M. Grebmeier
Geography
An assessment of the production, distribution and fate of highly branched isoprenoid (HBI) biomarkers produced by sea ice and pelagic diatoms is necessary to interpret their detection and proportions in the northern Bering and Chukchi Seas. HBIs measured in surface sediments collected from 2012 to 2017 were used to determine the distribution and seasonality of the biomarkers relative to sea ice patterns. A northward gradient of increasing ice algae deposition was observed with localized occurrences of elevated IP25 (sympagic HBI) concentrations from 68–70N and consistently strong sympagic signatures from 71–72.5N. A declining sympagic signature was observed from 2012 to 2017 …
Change Points Detected In Decadal And Seasonal Trends Of Outlet Glacier Terminus Positions Across West Greenland, Ashley V. York, Karen E. Frey, Sadegh Jamali, Sarah B. Das
Change Points Detected In Decadal And Seasonal Trends Of Outlet Glacier Terminus Positions Across West Greenland, Ashley V. York, Karen E. Frey, Sadegh Jamali, Sarah B. Das
Geography
We investigated the change in terminus position between 1985 and 2015 of 17 marine-terminating glaciers that drain into Disko and Uummannaq Bays, West Greenland, by manually digitizing over 5000 individual frontal positions from over 1200 Landsat images. We find that 15 of 17 glacier termini retreated over the study period, with ~80% of this retreat occurring since 2000. Increased frequency of Landsat observations since 2000 allowed for further investigation of the seasonal variability in terminus position. We identified 10 actively retreating glaciers based on a significant positive relationship between glaciers with cumulative retreat >300 m since 2000 and their average …
High-Resolution Gridded Daily Rainfall And Temperature For The Hawaiian Islands (1990-2014), Ryan J. Longman, Abby G. Frazier, Andrew J. Newman, Thomas W. Giambelluca, David Schanzenbach, Aurora Kagawa-Viviani, Heidi Needham, Jeffrey R. Arnold, Martyn P. Clark
High-Resolution Gridded Daily Rainfall And Temperature For The Hawaiian Islands (1990-2014), Ryan J. Longman, Abby G. Frazier, Andrew J. Newman, Thomas W. Giambelluca, David Schanzenbach, Aurora Kagawa-Viviani, Heidi Needham, Jeffrey R. Arnold, Martyn P. Clark
Geography
Spatially continuous data products are essential for a number of applications including climate and hydrologic modeling, weather prediction, and water resource management. In this work, a distance-weighted interpolation method used to map daily rainfall and temperature in Hawaii is described and assessed. New high-resolution (250 m) maps were developed for daily rainfall and daily maximum (Tmax) and Minimum (Tmin) near-surface air temperature for the period 1990-2014. Maps were produced using climatologically aided interpolation, in which station anomalies were interpolated using an optimized inverse distance weighting approach and then combined with long-term means to produce daily gridded estimates. Leave-one-out cross validation …
Patterns And Drivers Of Recent Disturbances Across The Temperate Forest Biome, Andreas Sommerfeld, Cornelius Senf, Brian Buma, Anthony W. D’Amato, Tiphaine Després, Ignacio Díaz-Hormazábal, Shawn Fraver, Lee E. Frelich, Álvaro G. Gutiérrez, Sarah J. Hart, Brian J. Harvey, Hong S. He, Tomáš Hlásny, Andrés Holz, Thomas Kitzberger, Dominik Kulakowski, David Lindenmayer, Akira S. Mori, Jörg Müller, Juan Paritsis, George L.W. Perry, Scott L. Stephens, Miroslav Svoboda, Monica G. Turner, Thomas T. Veblen, Rupert Seidl
Patterns And Drivers Of Recent Disturbances Across The Temperate Forest Biome, Andreas Sommerfeld, Cornelius Senf, Brian Buma, Anthony W. D’Amato, Tiphaine Després, Ignacio Díaz-Hormazábal, Shawn Fraver, Lee E. Frelich, Álvaro G. Gutiérrez, Sarah J. Hart, Brian J. Harvey, Hong S. He, Tomáš Hlásny, Andrés Holz, Thomas Kitzberger, Dominik Kulakowski, David Lindenmayer, Akira S. Mori, Jörg Müller, Juan Paritsis, George L.W. Perry, Scott L. Stephens, Miroslav Svoboda, Monica G. Turner, Thomas T. Veblen, Rupert Seidl
Geography
Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001–2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and …
Resource Extraction And Infrastructure Threaten Forest Cover And Community Rights, Anthony J. Bebbington, Denise Humphreys Bebbington, Laura Aileen Sauls, John Rogan, Sumali Agrawal, César Gamboa, Aviva Imhof, Kimberly Johnson, Herman Rosa, Antoinette Royo, Tessa Toumbourou, Ricardo Verdum
Resource Extraction And Infrastructure Threaten Forest Cover And Community Rights, Anthony J. Bebbington, Denise Humphreys Bebbington, Laura Aileen Sauls, John Rogan, Sumali Agrawal, César Gamboa, Aviva Imhof, Kimberly Johnson, Herman Rosa, Antoinette Royo, Tessa Toumbourou, Ricardo Verdum
Geography
Mineral and hydrocarbon extraction and infrastructure are increasingly significant drivers of forest loss, greenhouse gas emissions, and threats to the rights of forest communities in forested areas of Amazonia, Indonesia, and Mesoamerica. Projected investments in these sectors suggest that future threats to forests and rights are substantial, particularly because resource extraction and infrastructure reinforce each other and enable population movements and agricultural expansion further into the forest. In each region, governments have made framework policy commitments to national and cross-border infrastructure integration, increased energy production, and growth strategies based on further exploitation of natural resources. This reflects political settlements among …
Trends In Benthic Macrofaunal Populations, Seasonal Sea Ice Persistence, And Bottom Water Temperatures In The Bering Strait Region, Jacqueline M. Grebmeier, Karen E. Frey, Lee W. Cooper, Monika Kędra
Trends In Benthic Macrofaunal Populations, Seasonal Sea Ice Persistence, And Bottom Water Temperatures In The Bering Strait Region, Jacqueline M. Grebmeier, Karen E. Frey, Lee W. Cooper, Monika Kędra
Geography
Recent declines in sea ice extent and warming seawater temperatures in the Arctic have the potential to impact regional and pan-Arctic marine ecosystems. To investigate marine biological response to these key drivers and other environmental factors, we undertook a robust trend analysis of benthic macrofaunal populations and environmental drivers in the Bering Strait region. Our focus was on the waters of the northern Bering and southern Chukchi Seas, which are shallow (m) and seasonally productive, with strong pelagic-benthic coupling between water-column-derived organic matter and the seafloor. Studies indicate that both in situ production and advection of upstream phytodetritus support persistent …
Unraveling Phytoplankton Community Dynamics In The Northern Chukchi Sea Under Sea-Ice-Covered And Sea-Ice-Free Conditions, A. R. Neeley, L. A. Harris, K. E. Frey
Unraveling Phytoplankton Community Dynamics In The Northern Chukchi Sea Under Sea-Ice-Covered And Sea-Ice-Free Conditions, A. R. Neeley, L. A. Harris, K. E. Frey
Geography
The timing of sea ice retreat, light availability, and sea surface stratification largely control the phytoplankton community composition in the Chukchi Sea. This region is experiencing a significant warming trend, an overall decrease in sea ice cover, and a documented decline in annual sea ice persistence and thickness over the past several decades. The consequences of earlier seasonal sea ice retreat and a longer sea-ice-free season on phytoplankton community composition warrant investigation. We applied multivariate statistical techniques to elucidate the mechanisms that relate environmental variables to phytoplankton community composition in the Chukchi Sea using data collected during a single field …
Data Descriptor: Compilation Of Climate Data From Heterogeneous Networks Across The Hawaiian Islands, Ryan J. Longman, Thomas W. Giambelluca, Michael A. Nullet, Abby G. Frazier, Kevin Kodama, Shelley D. Crausbay, Paul D. Krushelnycky, Susan Cordell, Martyn P. Clark, Andy J. Newman, Jeffrey R. Arnold
Data Descriptor: Compilation Of Climate Data From Heterogeneous Networks Across The Hawaiian Islands, Ryan J. Longman, Thomas W. Giambelluca, Michael A. Nullet, Abby G. Frazier, Kevin Kodama, Shelley D. Crausbay, Paul D. Krushelnycky, Susan Cordell, Martyn P. Clark, Andy J. Newman, Jeffrey R. Arnold
Geography
Long-term, accurate observations of atmospheric phenomena are essential for a myriad of applications, including historic and future climate assessments, resource management, and infrastructure planning. In Hawai'i, climate data are available from individual researchers, local, State, and Federal agencies, and from large electronic repositories such as the National Centers for Environmental Information (NCEI). Researchers attempting to make use of available data are faced with a series of challenges that include: (1) identifying potential data sources; (2) acquiring data; (3) establishing data quality assurance and quality control (QA/QC) protocols; and (4) implementing robust gap filling techniques. This paper addresses these challenges by …
(Un)Frozen Spaces: Exploring The Role Of Sea Ice In The Marine Socio-Legal Spaces Of The Bering And Beaufort Seas, Kristen L. Shake, Karen E. Frey, Deborah G. Martin, Philip E. Steinberg
(Un)Frozen Spaces: Exploring The Role Of Sea Ice In The Marine Socio-Legal Spaces Of The Bering And Beaufort Seas, Kristen L. Shake, Karen E. Frey, Deborah G. Martin, Philip E. Steinberg
Geography
Sea ice is a dynamic physical element of the greater Arctic marine system, one that has myriad connections to human systems on a variety of spatial and temporal scales. Changes to the spatial extent of sea ice simultaneously permits and endangers maritime operations, as well as impacts current debates over maritime boundaries, presenting an interesting challenge for international law. Sea ice is not a stationary object; it moves through time and space in response to the physical forces of wind, ocean currents, and heating. It has a tangible, material and substantive role in contestations over territory, resources and marine boundaries …
A Walk On The Wild Side: Disturbance Dynamics And The Conservation And Management Of European Mountain Forest Ecosystems, Dominik Kulakowski, Rupert Seidl, Jan Holeksa, Timo Kuuluvainen, Thomas A. Nagel, Momchil Panayotov, Miroslav Svoboda, Simon Thorn, Giorgio Vacchiano, Cathy Whitlock, Thomas Wohlgemuth, Peter Bebi
A Walk On The Wild Side: Disturbance Dynamics And The Conservation And Management Of European Mountain Forest Ecosystems, Dominik Kulakowski, Rupert Seidl, Jan Holeksa, Timo Kuuluvainen, Thomas A. Nagel, Momchil Panayotov, Miroslav Svoboda, Simon Thorn, Giorgio Vacchiano, Cathy Whitlock, Thomas Wohlgemuth, Peter Bebi
Geography
Mountain forests are among the most important ecosystems in Europe as they support numerous ecological, hydrological, climatic, social, and economic functions. They are unique relatively natural ecosystems consisting of long-lived species in an otherwise densely populated human landscape. Despite this, centuries of intensive forest management in many of these forests have eclipsed evidence of natural processes, especially the role of disturbances in long-term forest dynamics. Recent trends of land abandonment and establishment of protected forests have coincided with a growing interest in managing forests in more natural states. At the same time, the importance of past disturbances highlighted in an …
Is Initial Post-Disturbance Regeneration Indicative Of Longer-Term Trajectories?, Nathan S. Gill, Daniel Jarvis, Thomas T. Veblen, Steward T.A. Pickett, Dominik Kulakowski
Is Initial Post-Disturbance Regeneration Indicative Of Longer-Term Trajectories?, Nathan S. Gill, Daniel Jarvis, Thomas T. Veblen, Steward T.A. Pickett, Dominik Kulakowski
Geography
The ability to estimate and model future vegetation dynamics is a central focus of contemporary ecology and is essential for understanding future ecological trajectories. It is therefore critical to understand when the influence of initial post-disturbance regeneration versus stochastic processes dominates long-term post-disturbance ecological processes. Often, conclusions about post-disturbance dynamics are based upon initial regeneration in the years immediately after disturbances. However, the degree to which initial post-disturbance regeneration indicates longer-term trends is likely to be contingent on the types, intensities, and combinations of disturbances, as well as pre-disturbance ecosystem structure and composition. Our relatively limited understanding of why initial …
Estimation Of The Instantaneous Downward Surface Shortwave Radiation Using Modis Data In Lhasa For All-Sky Conditions, Xu Lu
International Development, Community and Environment (IDCE)
Measuring the solar irradiance with high accuracy is the basis of PV power forecasting. Although the downward surface shortwave radiation (DSSR) data derived from satellite images are widely used in the PV industry, the instantaneity and accuracy of these data are not suitable for PV power forecasting in a short-time period. In this study, an algorithm to calculate instantaneous DSSR for all-sky conditions was developed by combining clear-sky radiative transfer model and 3D radiative transfer model using MODIS products (MOD03-07, 09). The algorithm was evaluated by ground measurements from a station in Lhasa and a reference dataset from FLASHFlux. The …
Summer 2015 Internship: Enterprise Gis Support For The National Audubon Society, Monica Noon
Summer 2015 Internship: Enterprise Gis Support For The National Audubon Society, Monica Noon
International Development, Community and Environment (IDCE)
From May to August 2015, I worked with the National Audubon Society as an Enterprise GIS Support Intern, under the supervision of Doreen Whitley Rogers. I assisted the department with the GIS help desk requests and supported ArcGIS users with project assistance and training. This report summarizes the structure of the organization, my role as an Enterprise GIS Support Intern and my assessment and reflection of my experience.
Decadal Bering Sea Seascape Change: Consequences For Pacific Walruses And Indigenous Hunters, G. Carleton Ray, Gary L. Hufford, James E. Overland, Igor Krupnik, Jerry Mccormick-Ray, Karen Frey, Elizabeth Labunski
Decadal Bering Sea Seascape Change: Consequences For Pacific Walruses And Indigenous Hunters, G. Carleton Ray, Gary L. Hufford, James E. Overland, Igor Krupnik, Jerry Mccormick-Ray, Karen Frey, Elizabeth Labunski
Geography
The most signifi cant factors currently affecting the Pacifi c walrus (Odobenus rosmarus divergens) population are climate change and consequent changes in sea-ice morphology and dynamics. This paper integrates recent physical sea-ice change in the Bering Sea with biological and ecological conditions of walruses in their winter-spring reproductive habitat. Historically, walrus in winter-spring depended on a critical mass of sea-ice habitat to optimize social networking, reproductive fi tness, feeding behavior, migration, and energetic effi ciency. During 2003-2013, our cross-disciplinary, multiscale analysis from shipboard observations, satellite imagery, and ice-fl oe tracking, reinforced by information from indigenous subsistence hunters, documented change of …
Optical Properties And Bioavailability Of Dissolved Organic Matter Along A Flow-Path Continuum From Soil Pore Waters To The Kolyma River Mainstem, East Siberia, Karen E. Frey, William V. Sobczak, Paul J. Mann, Robert M. Holmes
Optical Properties And Bioavailability Of Dissolved Organic Matter Along A Flow-Path Continuum From Soil Pore Waters To The Kolyma River Mainstem, East Siberia, Karen E. Frey, William V. Sobczak, Paul J. Mann, Robert M. Holmes
Geography
The Kolyma River in northeast Siberia is among the six largest Arctic rivers and drains a region underlain by vast deposits of Holocene-aged peat and Pleistocene-aged loess known as yedoma, most of which is currently stored in ice-rich permafrost throughout the region. These peat and yedoma deposits are important sources of dissolved organic matter (DOM) to inland waters that in turn play a significant role in the transport and ultimate remineralization of organic carbon to CO2 and CH4 along the terrestrial flow-path continuum. The turnover and fate of terrigenous DOM during offshore transport largely depends upon the composition and amount …
Not Only Climate: Interacting Drivers Of Treeline Change In Europe, Dominik Kulakowski, Ignacio Barbeito, Alejandro Casteller, Ryszard J. Kaczka, Peter Bebi
Not Only Climate: Interacting Drivers Of Treeline Change In Europe, Dominik Kulakowski, Ignacio Barbeito, Alejandro Casteller, Ryszard J. Kaczka, Peter Bebi
Geography
Treelines have long been recognized as important ecotones and likely harbingers of climate change. However, over the last century many treelines have been affected not only by global warming, but also by the interactions of climate, forest disturbance and the consequences of abrupt demographic and economic changes. Recent research has increasingly stressed how multiple ecological, biophysical, and human factors interact to shape ecological dynamics. Here we highlight the need to consider interactions among multiple drivers to more completely understand and predict treeline dynamics in Europe.
Interactions Among Spruce Beetle Disturbance, Climate Change And Forest Dynamics Captured By A Forest Landscape Model, Christian Temperli, Thomas T. Veblen, Sarah J. Hart, Dominik Kulakowski, Alan J. Tepley
Interactions Among Spruce Beetle Disturbance, Climate Change And Forest Dynamics Captured By A Forest Landscape Model, Christian Temperli, Thomas T. Veblen, Sarah J. Hart, Dominik Kulakowski, Alan J. Tepley
Geography
The risk of bark beetle outbreaks is widely predicted to increase because of a warming climate that accelerates temperature-driven beetle population growth and drought stress that impairs host tree defenses. However, few if any studies have explicitly evaluated climatically enhanced beetle population dynamics in relation to climate-driven changes in forest composition and structure that may alter forest suitability for beetle infestation. We synthesized current understanding of the interactions among climate, spruce beetles (Dendroctonus rufipennis) and forest dynamics to parameterize and further advance the bark beetle module of a dynamic forest landscape model (LandClim) that also integrates fire and wind disturbance …
Negative Feedbacks On Bark Beetle Outbreaks: Widespread And Severe Spruce Beetle Infestation Restricts Subsequent Infestation, Sarah J. Hart, Thomas T. Veblen, Nathan Mietkiewicz, Dominik Kulakowski
Negative Feedbacks On Bark Beetle Outbreaks: Widespread And Severe Spruce Beetle Infestation Restricts Subsequent Infestation, Sarah J. Hart, Thomas T. Veblen, Nathan Mietkiewicz, Dominik Kulakowski
Geography
Understanding disturbance interactions and their ecological consequences remains a major challenge for research on the response of forests to a changing climate. When, where, and how one disturbance may alter the severity, extent, or occurrence probability of a subsequent disturbance is encapsulated by the concept of linked disturbances. Here, we evaluated 1) how climate and forest habitat variables, including disturbance history, interact to drive 2000s spruce beetle (Dendroctonus rufipennis) infestation of Engelmann spruce (Picea engelmannii) across the Southern Rocky Mountains; and 2) how previous spruce beetle infestation affects subsequent infestation across the Flat Tops Wilderness in northwestern Colorado, which experienced …
Sea-Air Co2 Exchange In The Western Arctic Coastal Ocean, Wiley Evans, Jeremy T. Mathis, Jessica N. Cross, Nicholas R. Bates, Karen E. Frey, Brent G.T. Else, Tim N. Papkyriakou, Mike D. Degrandpre, Fakhrul Islam, Wei Jun Cai, Baoshan Chen, Michiyo Yamamoto-Kawai, Eddy Carmack, William J. Williams, Taro Takahashi
Sea-Air Co2 Exchange In The Western Arctic Coastal Ocean, Wiley Evans, Jeremy T. Mathis, Jessica N. Cross, Nicholas R. Bates, Karen E. Frey, Brent G.T. Else, Tim N. Papkyriakou, Mike D. Degrandpre, Fakhrul Islam, Wei Jun Cai, Baoshan Chen, Michiyo Yamamoto-Kawai, Eddy Carmack, William J. Williams, Taro Takahashi
Geography
The biogeochemical seascape of the western Arctic coastal ocean is in rapid transition. Changes in sea ice cover will be accompanied by alterations in sea-air carbon dioxide (CO2) exchange, of which the latter has been difficult to constrain owing to sparse temporal and spatial data sets. Previous assessments of sea-air CO2 flux have targeted specific subregional areas of the western Arctic coastal ocean. Here a holistic approach is taken to determine the net sea-air CO2 flux over this broad region. We compiled and analyzed an extensive data set of nearly 600,000 surface seawater CO2 partial pressure (pCO2) measurements spanning 2003 …
Mining, Risk And Climate Resilience In The 'Other' Pacific: Latin American Lessons For The South Pacific, Anthony J. Bebbington, Jeffrey Bury, Nicholas Cuba, John Rogan
Mining, Risk And Climate Resilience In The 'Other' Pacific: Latin American Lessons For The South Pacific, Anthony J. Bebbington, Jeffrey Bury, Nicholas Cuba, John Rogan
Geography
We suggest the value of considering Pacific Latin America and the South Pacific in relationship to each other in contexts of climate change and investment in extractive industry. The paper explores the interactions between extractive industry, climate change and environmental governance through the lenses of double exposure, double movements, resilience and risk. The first part of the paper addresses the nature and scope of investments in extractive industries in this 'other Pacific'. The geography of these investments is changing the actual and perceived distribution of exposure and risk in the region. The nature of this risk is also being affected …
Assessing The Potential Impacts Of Declining Arctic Sea Ice Cover On The Photochemical Degradation Of Dissolved Organic Matter In The Chukchi And Beaufort Seas, Christie L. Logvinova, Karen E. Frey, Paul J. Mann, Aron Stubbins, Robert G.M. Spencer
Assessing The Potential Impacts Of Declining Arctic Sea Ice Cover On The Photochemical Degradation Of Dissolved Organic Matter In The Chukchi And Beaufort Seas, Christie L. Logvinova, Karen E. Frey, Paul J. Mann, Aron Stubbins, Robert G.M. Spencer
Geography
A warming and shifting climate in the Arctic has led to significant declines in sea ice over the last several decades. Although these changes in sea ice cover are well documented, large uncertainties remain in how associated increases in solar radiation transmitted to the underlying ocean water column will impact heating, biological, and biogeochemical processes in the Arctic Ocean. In this study, six under-ice marine, two ice-free marine, and two ice-free terrestrially influenced water samples were irradiated using a solar simulator for 72 h (representing ~10 days of ambient sunlight) to investigate dissolved organic matter (DOM) dynamics from the Chukchi …