1,721,121 research outputs found
Jahresbericht 2010-11 zum Förderprojekt 01879 Untersuchung der Veränderung der Konzentration von Luftbeimengungen und Treibhausgasen im hohen Fichtelgebirge 2007 – 2014
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160 Jahre Bayreuther Klimazeitreihe - Homogenisierung der Bayreuther Lufttemperatur- und Niederschlagsdaten
No full textPartitioning NEE for absolute C input into various ecosystem pools by combining results from eddy-covariance, atmospheric flux partitioning and (CO2)-C-13 pulse labeling
No full textThe complexity of ecosystem processes, especially under continuously changing environmental conditions, requires high-resolution insight into ecosystem carbon (C) fluxes. It is essential to gain not only information about relative C balance and fluxes (common for partitioning studies), but also to obtain these in absolute mass units. To evaluate absolute fluxes in belowground C pools, the results of 21-day eddy-covariance and stable isotope labeling experiment in summer 2010, were combined. Eddy-covariance based net ecosystem exchange was measured on extensively managed grassland and separated into underlying assimilation and ecosystem respiration through the use of a C flux partitioning model. Resultant CO2 assimilation served as absolute C input into the ecosystem and was further partitioned by applying the relative C distribution in subsidiary pools, gained by C-13 pulse labeling and tracing. The results form eddy-covariance measurements showed that the extensively managed grassland was a significant net C sink of -91 g C m(-2) a(-1) in 2010. The mean daily assimilation of -7.1 g C m(-2) d(-1) was partitioned into fluxes of 2.5, 0.8, 0.5, 2.3 and 1.0 g C m(-2) d(-1) into shoots, roots, soil, shoot respiration and CO2 efflux from soil, respectively. We conclude that the combination of EC measurements with isotope labeling techniques allowed determining the absolute C input into several ecosystem pools. Hence, the study demonstrates an approach to expand atmospheric flux measurements and to gain insight into the importance of individual ecosystem pools for soil C cycling.Bavarian State Ministry of Sciences, Research and Art
Carbon dioxide fluxes measured at eddy-covariance station EC-P
No full textThe Tibetan highlands host the largest alpine grassland ecosystems worldwide, bearing soils that store substantial stocks of carbon (C) that are very sensitive to land use changes. This study focuses on the cycling of photoassimilated C within a Kobresia pygmaea pasture, the dominating ecosystems on the Tibetan highlands. We investigated short-term effects of grazing cessation and the role of the characteristic Kobresia root turf on C fluxes and belowground C turnover. By combining eddy-covariance measurements with 13CO2 pulse labeling we applied a powerful new approach to measure absolute fluxes of assimilates within and between various pools of the plant-soil-atmosphere system. The roots and soil each store roughly 50% of the overall C in the system (76 Mg C ha−1), with only a minor contribution from shoots, which is also expressed in the root:shoot ratio of 90. During June and July the pasture acted as a weak C sink with a strong uptake of approximately 2 g C m−2 d−1 in the first half of July. The root turf was the main compartment for the turnover of photoassimilates, with a subset of highly dynamic roots (mean residence time 20 days), and plays a key role for the C cycling and C storage in this ecosystem. The short-termgrazing cessation only affected aboveground biomass but not ecosystem scale C exchange or assimilate allocation into roots and soil
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Application of a multi-step error filter for postprocessing of atmospheric flux and meteorological basic data
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