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  • 1
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    Permafrost longterm monitoring sites (Arctic and Antarctic) (2014)
    PANGAEA
    In:  Supplement to: Bartsch, Annett; Allard, Michel; Biskaborn, Boris K; Burba, George; Christiansen, Hanne Hvidtfeldt; Duguay, Claude R; Grosse, Guido; Günther, Frank; Heim, Birgit; Högström, Elin; Kääb, Andreas; Keuper, Frida; Lanckman, Jean-Pierre; Lantuit, Hugues; Lauknes, Tom Rune; Leibman, Marina O; Liu, Lin; Morgenstern, Anne; Necsoiu, Marius; Overduin, Pier Paul; Pope, Allen; Sachs, Torsten; Séjourné, Antoine; Streletskiy, Dmitry A; Strozzi, Tazio; Ullmann, Tobias; Ullrich, Matthias S; Vieira, Gonçalo; Widhalm, Barbara (2014): Requirements for monitoring of permafrost in polar regions - A community white paper in response to the WMO Polar Space Task Group (PSTG), Version 4, 2014-10-09. Austrian Polar Research Institute, Vienna, Austria, 20 pp, hdl:10013/epic.45648.d001
    Details
    Publication Date: 2023-11-16
    Description: About 50 locations ('cold spots') where permafrost (Arctic and Antarctic) in situ monitoring has been taking place for many years or where field stations are currently established (through, for example the Canadian ADAPT program) have been identified. These sites have been proposed to WMO Polar Space Task Group as focus areas for future monitoring by satellite data. Seven monitoring transects spanning different permafrost types have been proposed in addition.
    Keywords: Changing Permafrost in the Arctic and its Global Effects in the 21st Century; Country; Elevation, maximum; Elevation, mean; Elevation, minimum; File name; Identification; LATITUDE; Latitude 2; LONGITUDE; Longitude 2; PAGE21; Permafrost; Persistent Identifier; Site
    Type: Dataset
    Format: text/tab-separated-values, 572 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Earlier snowmelt may lead to late season declines in plant productivity and carbon sequestration in Arctic tundra ecosystems (2022)
    In:  EPIC3Scientific Reports, 12(1), ISSN: 2045-2322
    Details
    Publication Date: 2024-04-19
    Description: Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties through a novel record of 119 site-years of summer data from eddy covariance towers representing dominant tundra vegetation types located on continuous permafrost in the Arctic. Here we found that earlier snowmelt was associated with more tundra net CO2 sequestration and higher gross primary productivity (GPP) only in June and July, but with lower net carbon sequestration and lower GPP in August. Although higher evapotranspiration (ET) can result in soil drying with the progression of the summer, we did not find significantly lower soil moisture with earlier snowmelt, nor evidence that water stress affected GPP in the late growing season. Our results suggest that the expected increased CO2 sequestration arising from Arctic warming and the associated increase in growing season length may not materialize if tundra ecosystems are not able to continue sequestering CO2 later in the season.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
  • 3
    Electronic Resource
    Electronic Resource
    Interannual variability in net CO2 exchange of a native tallgrass prairie (2003)
    Oxford, UK : Blackwell Science, Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Year-round eddy covariance flux measurements were made in a native tallgrass prairie in north-central Oklahoma, USA during 1997–2000 to quantify carbon exchange and its interannual variability. This prairie is dominated by warm season C4 grasses. The soil is a relatively shallow silty clay loam underlined with a heavy clay layer and a limestone bedrock. During the study period, the prairie was burned in the spring of each year, and was not grazed. In 1997 there was adequate soil moisture through the growing season, but 1998 had two extended periods of substantially low soil moisture (with concurrent high air temperatures and vapor pressure deficits), one early and one later in the growing season. There was also moisture stress in 1999, but it was less severe and occurred later in the season. The annual net ecosystem CO2 exchange, NEE (before including carbon loss during the burn) was 274, 46 and 124 g C m−2 yr−1 in 1997, 1998, and 1999, respectively (flux toward the surface is positive), and the associated variation seemed to mirror the severity of moisture stress. We also examined integrated values of NEE during different periods (e.g. day/night; growing season/senescence). Annually integrated carbon dioxide uptake during the daytime showed the greatest variability from year to year, and was primarily linked to the severity of moisture stress. Carbon loss during nighttime was a significant part of the annual daytime NEE, and was fairly stable from year to year. When carbon loss during the burn (estimated from pre- and post-burn biomass samples) was incorporated in the annual NEE, the prairie was found to be approximately carbon neutral (i.e. net carbon uptake/release was near zero) in years with no moisture stress (1997) or with some stress late in the season (1999). During a year with severe moisture stress early in the season (1998), the prairie was a net source of carbon. It appears that moisture stress (severity as well as timing of occurrence) was a dominating factor regulating the annual carbon exchange of the prairie.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00567.x
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Inversion of net ecosystem CO2 flux measurements for estimation of canopy PAR absorption (2002)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 8 (2002), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The fractional absorption of photosynthetically active radiation (fPAR) is frequently a key variable in models describing terrestrial ecosystem–atmosphere interactions, carbon uptake, growth and biogeochemistry. We present a novel approach to the estimation of the fraction of incident photosynthetically active radiation absorbed by the photosynthetic components of a plant canopy (fChl). The method uses micrometeorological measurements of CO2 flux and incident radiation to estimate light response parameters from which canopy structure is deduced. Data from two Ameriflux sites in Oklahoma, a tallgrass prairie site and a wheat site, are used to derive 7-day moving average estimates of fChl during three years (1997–1999). The inverse estimates are compared to long-term field measurements of PAR absorption. Good correlations are obtained when the field-measured fPAR is scaled by an estimate of the green fraction of total leaf area, although the inverse technique tends to be lower in value than the field measurements.The inverse estimates of fChl using CO2 flux measurements are different from measurements of fPAR that might be made by other, more direct, techniques. However, because the inverse estimates are based on observed canopy CO2 uptake, they might be considered more biologically relevant than direct measurements that are affected by non-physiologically active components of the canopy. With the increasing number of eddy covariance sites around the world the technique provides the opportunity to examine seasonal and inter-annual variation in canopy structure and light harvesting capacity at individual sites. Furthermore, the inverse fChl provide a new source of data for development and testing of fPAR retrieval using remote sensing. New remote sensing algorithms, or adjustments to existing algorithms, might thus become better conditioned to ‘biologically significant’ light absorption than currently possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2002.00488.x
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Names on the maps of Venus: A pre-MAGELLAN review (1990)
    Springer
    Earth, moon and planets 50-51 (1990), S. 541-558 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The topographic features on Venus are named with female names: craters and paterae have names of famous women as well as female first names, non-crater features have names of mythological characters. The first 80 names appeared on the maps after the Pioneer Venus mission; about 300 more names after the Venera 15 and 16 missions. 376 features of 17 types are now named. All the names are listed with their coordinates and attribute data. A large number of new names will be necessary after the MAGELLAN mission when detailed maps will be produced for nearly the whole surface of Venus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00142406
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    Paper (German National Licenses)
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