Das Projekt "Nitrogen effect on molecular dynamics in forest soils (end of thesis)" wird vom Umweltbundesamt gefördert und von Universität Zürich, Geographisches Institut durchgeführt. Atmospheric nitrogen deposition affects many forests and their ecosystem functions, including organic matter cycling in soils of temperate forests. But it is not clear how, and what the underlying mechanisms are. Here we asked the question: Do compounds with high intrinsic nitrogen content (typical for microbially-derived biomass) respond differently to atmospheric nitrogen deposition than compounds with low nitrogen content (such as plant-derived biomass)? Two facts delayed the progress of the project in the first year. From May 2010 to June 2011 the PhD student Marco Griepentrog successfully completed make-up classes for the recognition of his Fachhochschule degree by the University of Zurich. His workload (30 credit points or 900 working hours) was 50Prozent of the annual workload of a full time student, and delayed the progress of the project. Furthermore the PI Dr. Alexander Heim has left research in November 2010 and started a new position in industry and the co-PI Prof. Michael Schmidt stepped in as PI. Despite the delay the project eventually progressed well thanks to the hard-working PhD student Marco Griepentrog, who worked in the lab and simultaneously compiled a detailed methodological literature review on preparative soil fractionation procedures. His review revealed striking discrepancies in the application of this frequently used method, and was submitted to a peer-reviewed journal and is still under revision. With a competitive travel grant from the European Science Foundation, Marco Griepentrog worked at the University of Ghent (Belgium) and could measure compound-specific isotope ratios of amino sugars reliable in soil density fractions for the first time, using a novel analytical technique. This was the first time that amino sugars were measured in density fractions, and we could show that especially bacterial amino sugars were associated with soil minerals. Furthermore, when combined with stable isotope labeling, it became evident that amino sugar turn over much slower when associated with soil minerals. Another unexpected result was that fungal residues turn over at the same rate as total organic carbon, while bacterial amino sugars turn over slower. The fact that fungal amino sugars turn over faster than bacterial amino sugars contradicts with previous assumptions, and our measurements are the first to show that. Results have been presented at several international conferences, and now a manuscript circulates between co-authors to be submitted to a high impact scientific journal later this year. For the final year, we plan to focus on another compound class and propose a change of the initially planned target compound lignin. Own results showed that the isotopic label might not be detectable in lignin but in fatty acids, since they have been shown to turnover faster. usw.
Das Projekt "Dendroecological Reconstruction of Climate and Stand Dynamics in the Reserach Plots" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft durchgeführt. Leading Questions: How have tree-ring growth rates (at the Long Term Forest Ecosystem Research - LTFER- sites) changes over time and what is the nature of these changes? What is the cause of any observed changes? How have the stands at the LTFER sites evolved? What effects have stand dynamics had on tree-growth in the past? Is it possible to distinguish the role of human activities from the role played by other environmental factors (e.g. climate, genetics)? What kind of climatic events and trends have influenced tree growth at the LTFER sites in the past? To what extent can climatic patterns be reconstructed from tree-ring patterns at the LTFER sites?
Das Projekt "Effects of Elevated CO2 Levels and Nitrogen Deposition on the Carbon and Nitrogen Assimilation of Fagus Sylvatica and Picea Abies and the 15/14N - resp 13/12C - Relationship" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut, Laboratorium Environmental and System Analysis durchgeführt. As a contribution to the ICAT-Project, the main goal of this investigation is to analyze the influence of elevated C02 and increased nitrogen deposition on the flux dynamics and the pools of C and N in individual plants (Fagus sylvatica and Picea abies) as well as in the ecosystem. A change in the C02 regime influences the nitrogen balance, and the alteration of the nitrogen regime greatly influences the carbon balance. The pathways ,and pools of these elements in plants and in the ecosystem will be studied and described, analyzing the stable isotope relationships (I5/l4N and 13/12C). In this study both 13C and 15N will be used as tracer elements as well. The use of these tracers will allow to study the translocation and remobilisation mechanisms of N and C under changed environmental conditions. The use of labelled nitrogen as the below ground N-source (l5N-H4+,15N- 03-) and 15NO2 for the above ground fumigation in separate chambers allows the study of the different nitrogen sources and the various pathways. Variations in physiological processes during the vegetation period will be studied by supplying and harvesting plant material from potted plants at clearly defined times. The study of the 13/l2C relationship will allow to estimate the long term water use fficiency. It is planned to use this data material for the development of mechanistic oriented models which allow the simulation of these processes. Leading Questions: 1. How does elevated CO2 influence the carbon and nitrogen balance alone or in combination with an elevated nitrogen deposition. 2. What is the influence of this situation on the C- and N-Pools a) in the individual plant, b) in the ecosystem 3. Will the turnover rates be accelerated or slowed down, or is it not influenced 4. Where and at what time will the metabolites be translocated with an elevated CO2 and nitrogen level, and how will it differ from the controls.
Das Projekt "Schutz der Waelder (besonders in den Bergen) vor uebermaessigen CO2-Konzentrationen und Stickstoffdepositionen" wird vom Umweltbundesamt gefördert und von Universität Bern, Seminar für öffentliches Recht durchgeführt. Schlussbericht: Im Rahmen des schweizerischen Beitrags zum COST-Projektes 614 wurden die Wirkungen von erhoehten C02-Konzentrationen und verstaerktem Stickstoffeintrag auf Modelloekosysteme, bestehend aus Fichten, Buchen und Unterwuchs untersucht. Mit der vorliegenden Arbeit sollte geprueft werden, wie weit im schweizerischen Gesetzeskoerper Grundlagen existieren, auf welche sich allfaellige Massnahmen zum Schutz der Waelder, besonders in den Bergen, abstuetzen lassen, wenn die Resultate aus den Modellversuchen zusammen mit anderen Untersuchungen auf eine dramatische Gefaehrdung hinweisen wuerden. Frau Dr. B.A. Heimann-Kraehenmann, welche diese Pruefung durchfuehrte, kommt zum Schluss, dass weder das WaG noch das USG als umfassende Immissionsschutzgesetze fuer den Wald betrachtet werden koennen. Das WaG enthaelt zwar verschiedene Ansatzpunkte, die einem Immissionsschutz fuer den Wald dienen, das USG enthaelt aber keine rechtlichen Instrumente, die spezifisch den Wald vor Immissionen schuetzen wollen. Deshalb spricht sich Frau Heimann bei entsprechenden Resultaten aus ICAT und anderen Untersuchungen fuer die Einfuehrung spezieller Immissionsgrenzwerte fuer das Oekosystem WALD aus. Zum Zeitpunkt des Abschlusses ihrer Arbeit lagen allerdings noch keine konkreten Forschungsresultate seitens der an ICAT beteiligten Naturwissenschaftler vor, die es erlauben wuerden, Massnahmen vorzuschlagen. Source of Information: BBW, Wissenschaftliche Kurzberichte 1998 der Schweizer Teilnehmer an Projekten von COST.