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- ItemExpressing stemflow commensurate with its ecohydrological importance(Amsterdam [u.a.] : Elsevier Science, 2018) Carlyle-Moses, Darryl E.; Iida, Shin'ichi; Germer, Sonja; Llorens, Pilar; Michalzik, Beate; Nanko, Kazuki; Tischer, Alexander; Levia, Delphis F.Despite some progress, the importance of stemflow remains obscured partly due to computations emphasizing canopy interception loss. We advocate for two metrics—the stand-scale funneling ratio and the stand-scale infiltration funneling ratio—to more accurately portray stemflow inputs and increase comparability across ecosystems. These metrics yield per unit area stemflow inputs orders of magnitude greater than what would have been delivered by throughfall or precipitation alone. We recommend that future studies employ these stand-scale funnelling metrics to express stemflow commensurate with its ecohydrological importance and better conceptualize the role of stemflow in plant-soil interactions, permitting advances in critical zone science. © 2018 The Authors
- ItemEnvironmental Effects over the First 2½ Rotation Periods of a Fertilised Poplar Short Rotation Coppice(New York, NY : Springer, 2017-12-7) Kern, Jürgen; Germer, Sonja; Ammon, Christian; Balasus, Antje; Bischoff, Wolf-Anno; Schwarz, Andreas; Forstreuter, Manfred; Kaupenjohann, MartinA short rotation coppice (SRC) with poplar was established in a randomised fertilisation experiment on sandy loam soil in Potsdam (Northeast Germany). The main objective of this study was to assess if negative environmental effects as nitrogen leaching and greenhouse gas emissions are enhanced by mineral nitrogen (N) fertiliser applied to poplar at rates of 0, 50 and 75 kg N ha−1 year−1 and how these effects are influenced by tree age with increasing number of rotation periods and cycles of organic matter decomposition and tree growth after each harvesting event. Between 2008 and 2012, the leaching of nitrate (NO3 −) was monitored with self-integrating accumulators over 6-month periods and the emissions of the greenhouse gases (GHG) nitrous oxide (N2O) and carbon dioxide (CO2) were determined in closed gas chambers. During the first 4 years of the poplar SRC, most nitrogen was lost through NO3 − leaching from the main root zone; however, there was no significant relationship to the rate of N fertilisation. On average, 5.8 kg N ha−1 year−1 (13.0 kg CO2equ) was leached from the root zone. Nitrogen leaching rates decreased in the course of the 4-year study parallel to an increase of the fine root biomass and the degree of mycorrhization. In contrast to N leaching, the loss of nitrogen by N2O emissions from the soil was very low with an average of 0.61 kg N ha−1 year−1 (182 kg CO2equ) and were also not affected by N fertilisation over the whole study period. Real CO2 emissions from the poplar soil were two orders of magnitude higher ranging between 15,122 and 19,091 kg CO2 ha−1 year−1 and followed the rotation period with enhanced emission rates in the years of harvest. As key-factors for NO3 − leaching and N2O emissions, the time after planting and after harvest and the rotation period have been identified by a mixed effects model. © 2017, The Author(s).
- ItemEvaluation of a Smart System for the Optimization of Logistics Performance of a Pruning Biomass Value Chain(Basel : MDPI, 2018-10-19) Bosona, Techane; Gebresenbet, Girma; Olsson, Sven-Olof; Garcia, Daniel; Germer, SonjaThe paper presents a report on the performance evaluation of a newly developed smart logistics system (SLS). Field tests were conducted in Spain, Germany, and Sweden. The evaluation focused on the performance of a smart box tool (used to capture information during biomass transport) and a web-based information platform (used to monitor the flow of agricultural pruning from farms to end users and associated information flow). The tests were performed following a product usability testing approach, considering both qualitative and quantitative parameters. The detailed performance evaluation included the following: systematic analysis of 41 recordable parameters (stored in a spreadsheet database), analysis of feedback and problems encountered during the tests, and overall quality analysis applying the product quality model adapted from ISO/IEC FDIS 9126-1 standard. The data recording and storage and the capability to support product traceability and supply chain management were found to be very satisfactory, while assembly of smart box components (mainly the associated cables), data transferring intervals, and manageability could be improved. From the data retrieved during test activities, in more than 95% of the parameters within 41 columns, the expected values were displayed correctly. Some errors were observed, which might have been caused mainly by barriers that could hinder proper data recording and transfer from the smart box to the central database. These problems can be counteracted and the performance of the SLS can be improved so that it can be upgraded to be a marketable tool that can promote sustainable biomass-to-energy value chains. © 2018 by the authors.
- ItemCommentary: What We Know About Stemflow's Infiltration Area(Lausanne : Frontiers Media, 2020) Carlyle-Moses, Darryl E.; Iida, Shin'ichi; Germer, Sonja; Llorens, Pilar; Michalzik, Beate; Nanko, Kazuki; Tanaka, Tadashi; Tischer, Alexander; Levia, Delphis F.[No abstract available]
- ItemHave wind turbines in Germany generated electricity as would be expected from the prevailing wind conditions in 2000-2014?(San Francisco, Ca. : PLOS, 2019) Germer, Sonja; Kleidon, AxelThe planning of the energy transition from fossil fuels to renewables requires estimates for how much electricity wind turbines can generate from the prevailing atmospheric conditions. Here, we estimate monthly ideal wind energy generation from datasets of wind speeds, air density and installed wind turbines in Germany and compare these to reported actual yields. Both yields were used in a statistical model to identify and quantify factors that reduced actual compared to ideal yields. The installed capacity within the region had no significant influence. Turbine age and park size resulted in significant yield reductions. Predicted yields increased from 9.1 TWh/a in 2000 to 58.9 TWh/a in 2014 resulting from an increase in installed capacity from 5.7 GW to 37.6 GW, which agrees very well with reported estimates for Germany. The age effect, which includes turbine aging and possibly other external effects, lowered yields from 3.6 to 6.7% from 2000 to 2014. The effect of park size decreased annual yields by 1.9% throughout this period. However, actual monthly yields represent on average only 73.7% of the ideal yields, with unknown causes. We conclude that the combination of ideal yields predicted from wind conditions with observed yields is suitable to derive realistic estimates of wind energy generation as well as realistic resource potentials. © 2019 Germer, Kleidon. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
- ItemA review of stemflow generation dynamics and stemflow-environment interactions in forests and shrublands(Hoboken, NJ : Wiley, 2015) Levia, Delphis F.; Germer, SonjaMany geoscientists now recognize stemflow as an important phenomenon which can exert considerable effects on the hydrology, biogeochemistry, and ecology of wooded ecosystems and shrublands. Despite the explosive growth of stemflow research, until this review there has been no comprehensive attempt to summarize and synthesize this literature since 2003. Topical areas of substantive new knowledge in stemflow research include the following: (1) the interrelationships among stemflow and meteorological conditions, especially within individual rain events; (2) the dynamic interplay between stemflow and canopy structure; (3) stemflow and the cycling of solutes and transport of particulate matter; (4) stemflow and its interactions with canopy fungi and corticolous lichens; and (5) stemflow-soil interactions. Each of these five topical areas of substantive new stemflow research is summarized and synthesized, with areas of future research opportunities discussed. In addition, we have reviewed the parameters which can be used to describe stemflow and critically evaluate their utility for different purposes. This review makes a call for scientists studying stemflow to utilize common metrics in an effort to increase the cross-site comparability of stemflow studies. Capitalizing on the insights of prior research, exciting research opportunities await hydrologists, biogeoscientists, and forest ecologists who will conduct studies to deepen our knowledge of stemflow which will enable a better and more accurate framing of stemflow in the larger context of watershed hydrology and biogeochemistry.