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  • 1
    Signatur: AWI G3-96-0166
    In: Ecological studies, 120
    Beschreibung / Inhaltsverzeichnis: The discovery of large petroleum reserves in northern Alaska prompted the US National Research Council to recommend priorities for ecological research on disturbance effects in the Arctic. Subsequently, this led to the implementation of a field study by the Department of Energy in a small watershed on the North Slope of Alaska. This volume describes results by a research team charged with seeking answers to a number of questions related to disturbance in tundra regions: will short-term disturbances have long-term ecological consequences? Will localized effects be transferred to adjacent systems, e.g., from terrestrial to aquatic? Is it possible to extrapolate understanding of impacts from one landscape to another? The results reported in this volume are an important contribution towards the goal of implementing ecosystem-based management in arctic tundra landscapes. Landscape function and disturbance in Arctic Tundra covers a broad array of topics, from ecosystem physiology to landscape modeling. It is an important source for researchers and students interested in arctic ecology, as well as for environmental managers concerned with practical issues of disturbance.
    Materialart: Monographie ausleihbar
    Seiten: XX, 437 Seiten , Illustrationen , 24 cm
    ISBN: 3-540-59263-6
    Serie: Ecological Studies 120
    Sprache: Englisch
    Anmerkung: Contents: I INTRODUCTION. - 1 Ecosystem Response, Resistance, Resilience, and Recovery in Arctic Landscapes: Introduction / J. F. Reynolds and J. D. Tenhunen. - 1.1 Introduction. - 1.2 NRC Committee Report. - 1.3 The R4D Program. - 1.3.1 Objectives and Conceptual Framework. - 1.3.2 Program Implementation. - 1.3.3 Landscape Function. - 1.4 Summary. - References. - 2 Integrated Ecosystem Research in Northern Alaska, 1947-1994 / G. R. Shaver. - 2.1 Introduction. - 2.2 Early Days at NARL. - 2.3 The U.S. Tundra Biome Program. - 2.4 The Meade River RATE Program. - 2.5 Eagle Creek and Eagle Summit. - 2.6 The Arctic LTER Program at Toolik Lake. - 2.7 Other Studies In Alaska and Elsewhere. - 2.8 Summary and Prospects. - References. - 3 Disturbance and Recovery of Arctic Alaskan Vegetation / D. A. Walker. - 3.1 Introduction. - 3.2 Disturbance and Recovery. - 3.3Typical Disturbance and Recovery Patterns. - 3.3.1 Small Disturbed Patches. - 3.3.2 Contaminants. - 3.3.2.1 Hydrocarbon Spills. - 3.3.2.2 Seawater and Reserve-Pit Spills. - 3.3.3 Fire. - 3.3.4 Transportation Corridors. - 3.3.4.1 Bulldozed Tundra and Related Disturbances. - 3.3.4.2 Off-Road Vehicle Trails. - 3.3.4.2.1 Summer Travel. - 3.3.4.2.2 Winter Travel. - 3.3.4.3 Permanent Roads and Pads. - 3.3.4.4 Gravel Mines. - 3.3.4.5 Native Species in Revegetation of Gravel Pads and Mines. - 3.3.4.6 Road Dust. - 3.3.4.7 Roadside Impoundments. - 3.3.5 Cumulative Impacts. - 3.4 Conclusions. - References. - 4 Terrain and Vegetation of the Imnavait Creek Watershed / D. A. Walker and M. D. Walker. - 4.1 Introduction. - 4.2 Terrain. - 4.2.1 Glacial Deposits. - 4.2.2 Retransported Hillslope Deposits. - 4.2.3 Colluvial Basin Deposits. - 4.2.4 Floodplain Deposits. - 4.3 Vegetation. - 4.3.1 Flora. - 4.3.2 Vegetation Types. - 4.3.2.1 Lichen-Covered Rocks. - 4.3.2.2 Dry Heath. - 4.3.2.2.1 Exposed Sites. - 4.3.2.2.2 Snowbeds. - 4.3.2.3 Tussock Tundra. - 4.3.2.4 Riparian Areas. - 4.3.2.5 Mires. - 4.3.2.6 Beaded Ponds. - 4.4 West-Facing Toposequence. - 4.5 Terrain Sensitivity to Disturbance. - 4.6 Conclusions. - Appendix A. List of Plants for Imnavait Creek, Alaska. - References. - 5 Vegetation Structure and Aboveground Carbon and Nutrient Pools in the Imnavait Creek Watershed / S. C. Hahn, S. F. Oberbauer, R. Gebauer, N. E. Grulke, O. L. Lange, and J. D. Tenhunen. - 5.1 ntroduction. - 5.2 Description of Vegetation. - 5.3 Sampling Methods. - 5.3.1 Cover. - 5.3.2 Biomass and Nutrient Pools. - 5.4 Cover. - 5.5 Aboveground Biomass. - 5.5.1 Live Biomass. - 5.5.2 Photosynthetic Biomass. - 5.5.3 Lichen Biomass. - 5.5.4 Organic Litter. - 5.5.5 Watershed Patterns. - 5.6 Nutrient Pools. - 5.6.1 N and P in Heath Cryptogams. - 5.6.2 N and P in Communities. - 5.7 Discussion and Conclusions. - References. - II PHYSICAL ENVIRONMENT, HYDROLOGY, and TRANSPORT. - 6 Energy Balance and Hydrological Processes in an Arctic Watershed / L. Hinzmann, D. L. Kane, C. S. Benson, and K. R. Everett. - 6.1 Introduction. - 6.2 Radiation and Thermal Regimes. - 6.2.1 Surface Energy Balance. - 6.2.2 Snow Cover and Soil Thermal Regime. - 6.3 Hydrological Processes. - 6.3.1 Snowmelt. - 6.3.2 Plot and Basin Water Balance. - 6.3.3 Runoff and Basin Discharge. - 6.3.4 Precipitation, Evaporation, and Evapotranspiration. - 6.4 Energy Balance and Hydrology Models. - 6.4.1 Simulation of the Thermal Regime. - 6.4.2 Simulation of Snowmelt. - 6.4.3 Simulation of Catchment Runoff. - 6.5 Conclusions. - References. - 7 Shortwave Reflectance Properties of Arctic Tundra Landscapes / A. S. Hope and D. A. Stow. - 7.1 Introduction. - 7.2 Shortwave Reflectance Studies in Arctic Environments. - 7.2.1 Environmental Considerations. - 7.2.2 Radiometric Data. - 7.2.3 Image Data. - 7.3 Spectral Reflectance. - 7.3.1 Aboveground Biomass. - 7.3.2 Vegetation Composition. - 7.3.3 Landscape Patterns. - 7.3.4 Effects of Dust Deposition. - 7.4 Albedo. - 7.4.1 Undisturbed Tussock Tundra. - 7.4.2 Effects of Dust Deposition. - 7.5 Conclusions. - References. - 8 Isotopic Tracers for Investigating Hydrological Processes / L. W. Cooper, I. L. Larsen, C. Solis, J. M. Grebmeier, C. R. Olsen, D. K. Solomon, and R. B. Cook. - 8.1 Introduction. - 8.1.1 Units. - 8.1.2 Conservative vs Nonconservative Isotopes. - 8.2 Nonconservative Tracers. - 8.3 Sulfur-35. - 8.4 Oxygen-18. - 8.4.1 Oxygen-18 Content of Snowpack. - 8.4.2 Oxygen-18 Content of Imnavait Creek. - 8.4.3 Oxygen-18 Content of Soil Moisture. - 8.4.4 Covariance of Oxygen-18 and Deuterium in Watershed Compartments. - 8.4.5 Covariance of Oxygen-18 and Deuterium in Plant Water. - 8.5 Long-Lived Radioisotopes: Lead-210 and Cesium-137. - 8.5.1 Distribution of 137Cs on Tundra and in Lake Sediments. - 8.5.2 Cycling of 137Cs in Annual Berries. - 8.5.3 Distribution of 210Pb in Tundra. - 8.6 Conclusions. - References. - III NUTRIENT AND CARBON FLUXES. - 9 Surface Water Chemistry and Hydrology of a Small Arctic Drainage Basin / K. R. Everett, D. L. Kane, and L. D. Hinzman. - 9.1 Introduction. - 9.2 Watershed Instrumentation. - 9.3 Snowmelt Period. - 9.3.1 Snowmelt Hydrology. - 9.3.2 Snowmelt Chemistry . - 9.3.2.1 Overland Flow. - 9.3.2.2 Water Track Flow. - 9.3.2.3 Imnavait Creek Flow. - 9.4 Post Snowmelt Period. - 9.4.1 Atmospheric Inputs. - 9.4.1.1 Rainfall. - 9.4.1.2 Dry Deposition. - 9.4.1.3 Rime. - 9.4.2 Water Chemistry. - 9.4.2.1 Overland Flow. - 9.4.2.2 Active Layer Flow. - 9.4.2.3 Imnavait Creek Flow. - 9.5 Conclusions. - References. - 10 Nutrient Availability and Uptake by Tundra Plants / J. P. Schimel, K. Kielland, and F. S. Chapin III. - 10.1 Introduction. - 10.2 Controls on Mineralization and Nutrient Supply. - 10.2.1 Patterns of Nutrient Supply in the Soil. - 10.2.2 Patterns of Mineralization. - 10.2.3 Controls on N and P Mineralization. - 10.2.4 Controls on Decomposition and Mineralization. - 10.2.4.1 Temperature. - 10.2.4.1.1 Enzyme Activities. - 10.2.4.1.2 Microbial Activity at Low Temperatures. - 10.2.4.1.3 Freeze-Thaw Events. - 10.2.4.2 Effects of Low Oxygen on Microbial Activity and Mineralization. - 10.2.4.3 Substrate Quality. - 10.3 Fate of Available Nutrients. - 10.3.1 Microbial Nutrient Uptake and Competition with Plants. - 10.3.2 Plant Uptake. - 10.3.2.1 Soil Factors Controlling Nutrient Absorption. - 10.3.2.2 Rooting Strategies. - 10.3.2.3 Uptake Characteristics of Tundra Plants. - 10.3.2.4 Retranslocation vs Current Uptake. - 10.4 Disturbances. - 10.4.1 Vehicle Tracks. - 10.4.2 Road Dust. - 10.4.3 Gray Water. - 10.4.4 Climate Change. - References. - 11 Landscape Patterns of Carbon Dioxide Exchange in Tundra Ecosytems / S. F. Oberbauer, W. Cheng, C. T. Gillespie, B. Ostendorf, A. Sala, R. Gebauer, R. A. Virginia, and J. D. Tenhunen. - 11.1 Introduction. - 11.2 Methods. - 11.2.1 Community Types. - 11.2.2 Leaf Photosynthesis. - 11.2.3 Ecosystem Efflux. - 11.2.4 Ecosystem Net CO2 Exchange. - 11.3 CO2 Uptake. - 11.3.1 Factors Affecting CO2 Uptake. - 11.3.1.1 Light. - 11.3.1.2 Temperature. - 11.3.1.3 Phenology. - 11.3.1.4 Water Availability. - 11.3.1.5 Nutrition. - 11.3.2 Landscape Patterns in Leaf Photosynthesis. - 11.4 CO2 Efflux. - 11.4.1 Factors Affecting CO2 Efflux. - 11.4.1.1 Live Plant Biomass. - 11.4.1.2 Soil Quality. - 11.4.1.3 Thaw Depth and Depth to Water Table. - 11.4.1.4 Soil Moisture. - 11.4.1.5 Soil Temperature. - 11.4.2 Landscape Patterns of CO2 Efflux. - 11.4.3 Daily and Seasonal Patterns of CO2 Efflux. - 11.4.4 Dust Deposition Effects on CO2 Efflux. - 11.5 Landscape Patterns in Net CO2 Exchange. - 11.6 Conclusions. - References. - 12 Control of Tundra Methane Emission by Microbial Oxidation / S. C. Whalen, W. S. Reeburgh, and C. E. Reimers. - 12.1 Introduction. - 12.2 Sampling Procedure. - 12.3 Results and Discussion. - 12.3.1 Methane Flux and Environmental Variables in Tundra and Taiga. - 12.3.2 Physiology, Controls, and Potential for Microbial CH4 Oxidation. - 12.3.3 Methane Oxidation by Tundra Soils in a Warmer Climate. - 12.4 Conclusions. - References. - 13 Dynamics of Dissolved and Particulate Car
    Standort: AWI Lesesaal
    Zweigbibliothek: AWI Bibliothek
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  • 2
    Schlagwort(e): environmental research ; environmental degradation ; research policy and organisation ; environment policy and protection of the environment ; adaptation to climate change ; arid zone ; atlas ; degradation of the environment ; demography ; desertification ; environmental policy ; environmental protection ; environmental research ; erosion ; natural disaster ; research report ; soil pollution ; soil protection ; soil science ; sustainable agriculture
    Beschreibung / Inhaltsverzeichnis: The third edition of the World Atlas of Desertification (WAD3) takes a fresh look at land degradation – a phenomenon triggered by human land use that is likely to threaten our ability to make productive use of the Earth while still maintaining the critical global environmental goods and services in the future. Human activity is a main driver of global environmental changes. Where issues that signal global change coincide, they may lead to land transformations that can cause degradation of the land resource. Global telecoupled and dynamic human consumption patterns precipitate interaction of these issues and their impact at the local level. Accommodating this complexity, WAD3 offers an information framework from which to identify the nature of potential problems and pursue solutions that conform to local conditions. The two decades since publication of WAD2 saw a tremendous growth in our understanding of coupled-human and natural systems, and an overwhelming increase in global environmental datasets and analytical tools. Building on these advances, WAD3 portrays the dynamic human footprint on Earth and its consequences for the land resources. WAD3 identifies areas of concern where multiple lines of evidence converge that suggest potential problems so that they might be confirmed and suggest actions to reverse, arrest, or adapt to them.
    Seiten: Online-Ressource (248 Seiten) , Illustrationen, Diagramme, Karten
    Ausgabe: 3rd edition
    ISBN: 9789279753497
    Sprache: Englisch
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  • 3
    Publikationsdatum: 2017-06-16
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
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  • 4
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Ecology Letters 12 (2009): E15-E18, doi:10.1111/j.1461-0248.2009.01332.x.
    Beschreibung: Hartley et al. question whether reduction in Rmass, under experimental warming, arises because of the biomass method. We show the method they treat as independent yields the same result. We describe why the substrate-depletion hypothesis cannot alone explain observed responses, and urge caution in the interpretation of the seasonal data.
    Beschreibung: This research was supported by the Office of Science (BER), U.S. Department of Energy, the Andrew W. Mellon Foundation and U.S. National Science Foundation grants to the Coweeta LTER program.
    Schlagwort(e): Acclimation ; Adaptation ; Soil respiration ; Thermal biology ; Temperature ; Carbon cycling ; Climate change ; Climate warming ; Microbial community ; CO2
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
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  • 5
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Ecology Letters 11 (2008): 1316-1327, doi:10.1111/j.1461-0248.2008.01251.x.
    Beschreibung: In the short-term heterotrophic soil respiration is strongly and positively related to temperature. In the long-term its response to temperature is uncertain. One reason for this is because in field experiments increases in respiration due to warming are relatively short-lived. The explanations proposed for this ephemeral response include depletion of fast-cycling, soil carbon pools and thermal adaptation of microbial respiration. Using a 〉15 year soil warming experiment in a mid-latitude forest, we show that the apparent ‘acclimation’ of soil respiration at the ecosystem scale results from combined effects of reductions in soil carbon pools and microbial biomass, and thermal adaptation of microbial respiration. Mass specific respiration rates were lower when seasonal temperatures were higher, suggesting that rate reductions under experimental warming likely occurred through temperature-induced changes in the microbial community. Our results imply that stimulatory effects of global temperature rise on soil respiration rates may be lower than currently predicted.
    Beschreibung: This research was supported by the Office of Science (BER), U.S. Department of Energy and the Andrew W. Mellon Foundation.
    Schlagwort(e): Acclimation ; Adaptation ; Soil respiration ; Thermal biology ; Temperature ; Carbon cycling ; Climate change ; Climate warming ; Microbial community ; CO2
    Repository-Name: Woods Hole Open Access Server
    Materialart: Preprint
    Format: application/pdf
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  • 6
    Publikationsdatum: 2022-05-26
    Beschreibung: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Environmental Research Letters 11 (2016): 034014, doi:10.1088/1748-9326/11/3/034014.
    Beschreibung: As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
    Beschreibung: This work was supported by the National Science Foundation ARCSS program and Vulnerability of Permafrost Carbon Research Coordination Network (grants OPP-0806465, OPP-0806394, and 955713) with additional funding from SITES (Swedish Science Foundation), Future Forest (Mistra), and a Marie Curie International Reintegration Grant (TOMCAR-Permafrost #277059) within the 7th European Community Framework Programme.
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 7
    ISSN: 1365-2486
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Energietechnik , Geographie
    Notizen: We use a spatially explicit landscape model to investigate the potential role of rainfall on shrub–grass transitions in the Jornada Basin of southern New Mexico during the past century. In long-term simulations (1915–1998) along a 2700 m transect running from a dry lake bed to the foothills of a small mountain, we test two hypotheses: (i) that wetter winters and drier summers may have facilitated shrub encroachment in grasslands, and (ii) that increases in large precipitation events may have increased soil water recharge at deeper layers, thus favoring shrub establishment and growth. Our model simulations generally support the hypothesis that wetter winters and drier summers may have played a key role, but we are unable to reproduce the major shifts from grass- to shrub-domination that occurred in this landscape during the early part of the 1900s; furthermore, the positive shrub response to wetter winters and drier summers was only realized subsequent to the drought of 1951–1956, which was a relatively short ‘window of opportunity’ for increased shrub establishment and growth. Our simulations also generally support the hypothesis that an increase in the number of large precipitation events may also have favored shrub establishment and growth, although these results are equivocal, depending upon what constitutes a ‘large’ event and the timing of such events. We found complex interactions among (i) the amount/seasonality of rainfall, (ii) its redistribution in the landscape via run-on and runoff, (iii) the depth of the soil water recharge, and (iv) subsequent water availability for the growth and reproduction of shrubs vs. herbaceous plants at various landscape positions. Our results suggest that only a mechanistic understanding of these interactions, plus the role of domestic cattle grazing, will enable us to elucidate fully the relative importance of biotic vs. abiotic factors in vegetation dynamics in this semiarid landscape.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In previous papers we have described and verified a primary production model of the desert shrub Larrea tridentata. Here we address the validation phase of the evaluation of this model. Two versions of the model which differ in the priority scheme used for allocating carbon to reproductive or vegetative organs were compared on the basis of their usefulness and reliability over a range of soil-moisture conditions. Over an entire growing season when soil-moisture conditions were near “normal” both versions of the model were adequate predictors of total above-ground vegetative growth and one was an adequate predictor of reproductive growth as well. A more detailed analysis revealed that the versions varied in the range of soil-moisture conditions over which they were adequate and that neither was adequate when soil-moisture had remained high for extended periods. The validation process has revealed some likely areas for model improvement to increase adequacy.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Landscape ecology 8 (1993), S. 155-162 
    ISSN: 1572-9761
    Schlagwort(e): Contagion index ; spatial pattern ; probability ; information index ; landscape ecology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A contagion index was proposed by O'Neill et al. (1988) to quantify spatial patterns of landscapes. However, this index is insensitive to changes in spatial pattern. We present a new contagion index that corrects an error in the mathematical formulation of the original contagion index. The error is identified mathematically. The contagion indices (both original and new) are then evaluated against simulated landscapes.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Landscape ecology 13 (1998), S. 187-201 
    ISSN: 1572-9761
    Schlagwort(e): vegetation pattern ; tussock tundra ; landscapes ; topography ; water drainage ; scaling up
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We present a topographically-derived vegetation model (TVM) that predicts the landscape patterns of arctic vegetation types in the foothills of the Brooks Range in northern Alaska. In the Arctic there is a strong relationship between water and plant structure and function and TVM is based on the relationships between vegetation types and slope (tan β) and discharge (δ), two independent variables that can be easily derived from digital terrain data. Both slope and discharge relate to hydrological similarity within a landscape: slope determines the gravitational hydrological gradient and hence influences flow velocity, whereas discharge patterns are computed based on upslope area and quantify lateral flow amount. TVM was developed and parameterized based on vegetation data from a small 2.2 km2 watershed and its application was tested in a larger 22km2 region. For the watershed, TVM performed quite well, having a high spatial resolution and a goodness-of-fit ranging from 71–78%, depending on the functions used. For the larger region, the strength of the vegetation types predictions drops somewhat to between 56–59%. We discuss the various sources of error and limitations of the model for purposes of extrapolation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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