Nitrogen deposition in tropical areas is projected to increase rapidly in the next decades due to increase in N fertilizer use, fossil fuel consumption and biomass burning. As tropical forest ecosystems cover about 17 percent of the land surface and are responsible for about 40 percent of net primary production, even small changes in N (and consequently C) cycling can have global consequences. Until now studies an consequences of enhanced N input in tropical forest ecosystems have been very limited and even very rarely addressed its deleterious effects to the environment. There is undoubtedly a huge discrepancy between the expected increase in N deposition in the tropics and the present knowledge an how tropical forest ecosystems will react to this extra input of reactive N. Our research aims at quantifying the changes in processes of N retention (plant growth, biotic and abiotic N immobilization in the soil) and losses (gaseous N losses, nitrification, denitrification, leaching of different forms of dissolved N). Implementation of policy and management tools, like the international trading of carbon credits under the Kyoto Protocol, need researches that allow us to better understand the consequences of environmental change (N deposition) an forest productivity. Our research will have important implications for predicting future responses of forest C cycle to changes in N deposition, and for the role of N deposition in tropical forests to affect potential feedback mechanisms of CO2 fertilization and climate change.
Biotische Störungen in Wäldern sind klima-sensitiv. In diesem Projekt werden die Auswirkungen von klimatisch begünstigten Insektenkalamitäten auf die C-Dynamiken und die C-Speicherung im Boden analysiert und die resultierenden Rückkopplungseffekte zwischen Waldvegetation, Boden und Atmosphäre quantifiziert. Das Projekt konzentriert sich auf die wichtigsten Prozesse des terrestrischen Kohlenstoffkreislaufs, in enger Koppelung mit den Stickstoffumsätzen. Durch kombinierte Feldexperimente werden die C- und N-Vorräte und deren Umsatzrate in Böden mittels Chronosequenzen befallener und nicht befallener Laub- und Nadelwälder erfasst und die C-Sequestierung bewertet. Mit räumlichen Modellen werden aktuell (und zukünftig) vulnerable Bestände simuliert und bilanziert, Risikogebiete identifiziert sowie deren relativer Beitrag zum Treibhauseffekt durch Emissionen von CO2, N2O und VOCs abgeschätzt ('global warming potential').
Glendonites are pseudomorphs after the mineral ikaite (CaCO3 x 6H2O) and composed of calcite (CaCO3). In the past, they have been used as a paleo-thermometer because the primary mineral ikaite, according to observations and experiments, seems to be formed at temperatures near freezing, high alkalinity and high phosphate concentrations in marine sediments. An enigmatic occurrence of the largest glendonites known world-wide, in the Early Eocene Fur Formation of northwestern Denmark offers the unique possibility to shed more light on the actual mechanism and controlling parameters of ikaite formation. Right in the aftermath of the Paleocene-Eocene thermal maximum, a time known for its global pertubation in the global carbon cycle, the formation of authigenic calcium carbonate concretions start in the Fur Formation. In a specific stratigraphic interval inbetween these concretions, the glendonites can be found. We will investigate if termperature changes or changes in geochemical parameters of the Danish Basin caused the sudden formation of ikaite during a time interval that was based on known paleoclimatic reconstructions (semi tropic) not favorable for ikaite formation.
The majority of the worlds forests has undergone some form of management, such as clear-cut or thinning. This management has direct relevance for global climate: Studies estimate that forest management emissions add a third to those from deforestation, while enhanced productivity in managed forests increases the capacity of the terrestrial biosphere to act as a sink for carbon dioxide emissions. However, uncertainties in the assessment of these fluxes are large. Moreover, forests influence climate also by altering the energy and water balance of the land surface. In many regions of historical deforestation, such biogeophysical effects have substantially counteracted warming due to carbon dioxide emissions. However, the effect of management on biogeophysical effects is largely unknown beyond local case studies. While the effects of climate on forest productivity is well established in forestry models, the effects of forest management on climate is less understood. Closing this feedback cycle is crucial to understand the driving forces behind past climate changes to be able to predict future climate responses and thus the required effort to adapt to it or avert it. To investigate the role of forest management in the climate system I propose to integrate a forest management module into a comprehensive Earth system model. The resulting model will be able to simultaneously address both directions of the interactions between climate and the managed land surface. My proposed work includes model development and implementation for key forest management processes, determining the growth and stock of living biomass, soil carbon cycle, and biophysical land surface properties. With this unique tool I will be able to improve estimates of terrestrial carbon source and sink terms and to assess the susceptibility of past and future climate to combined carbon cycle and biophysical effects of forest management. Furthermore, representing feedbacks between forest management and climate in a global climate model could advance efforts to combat climate change. Changes in forest management are inevitable to adapt to future climate change. In this process, is it possible to identify win-win strategies for which local management changes do not only help adaptation, but at the same time mitigate global warming by presenting favorable effects on climate? The proposed work opens a range of long-term research paths, with the aim of strengthening the climate perspective in the economic considerations of forest management and helping to improve local decisionmaking with respect to adaptation and mitigation.
Confronting Climate Change is one of the paramount societal challenges of our time. The main cause for global warming is the increase of anthropogenic greenhouse gases in the Earth's atmosphere. Together, carbon dioxide and methane, being the two most important greenhouse gases, globally contribute to about 81% of the anthropogenic radiative forcing. However, there are still significant deficits in the knowledge about the budgets of these two major greenhouse gases such that the ability to accurately predict our future climate remains substantially compromised. Different feedback mechanisms which are insufficiently understood have significant impact on the quality of climate projections. In order to accurately predict future climate of our planet and support observing emission targets in the framework of international agreements, the investigation of sources and sinks of the greenhouse gases and their feedback mechanisms is indispensable. In the past years, inverse modelling has emerged as a key method for obtaining quantitative information on the sources and sinks of the greenhouse gases. However, this technique requires the availability of sufficient amounts of precise and independent data on various spatial scales. Therefore, observing the atmospheric concentrations of the greenhouse gases is of significant importance for this purpose. In contrast to point measurements, airborne instruments are able to provide regional-scale data of greenhouse gases which are urgently required, though currently lacking. Providing such data from remote sensing instruments supported by the best currently available in-situ sensors, and additionally comparing the results of the greenhouse gas columns retrieved from aircraft to the network of ground-based stations is the mission goal of the HALO CoMet campaign. The overarching objective of HALO CoMet is to improve our understanding and to better quantify the carbon dioxide and methane cycles. Through analysing the CoMet data, scientists will accumulate new knowledge on the global distribution and temporal variation of the greenhouse gases. These findings will help to better understand the global carbon cycle and its influence on climate. These new findings will be utilized for predicting future climate change and assessing its impact. Within the frame of CoMet and due to the operational possibilities we will concentrate on small to sub-continental scales. This does not only allow to identify local emission sources of greenhouse gases, but also opens up the opportunity to use important remote sensing and in-situ data information for the inverse modelling approach for regional budgeting. The project also aims at developing new methodologies for greenhouse gas measurements, and promotes technological developments necessary for future Earth-observing satellites.
Die Groesse der Quellen und Senken fuer atmosphaerisches CO2 sind bislang noch unzureichend bekannt, um zukuenftige CO2-Gehalte der Atmosphaere vorhersagen zu koennen. Neben direkten Messungen des derzeitigen CO2-Anstiegs erlauben Isotopenuntersuchungen wichtige Rueckschluesse der CO2-Fluesse zwischen den einzelnen Reservoiren (Atmosphaere, Biosphaere, Hydrosphaere); Vorgaenge in der Vergangenheit lassen sich einzig und allein nur durch Isotopenuntersuchungen von fixiertem atmosphaerischen CO2 erkennen. Die Untersuchungen im Institut fuer Chemie befassen sich mit der Ermittlung des CO2-Inputs in die Atmosphaere aufgrund von C-13-Messungen an datierten Holzproben, um biosphaerische CO2-Senken oder Quellen der Vergangenheit erkennen zu koennen. Bisher vorliegende Messungen an Baeumen der noerdlichen Hemisphaere und des industriellen Zeitraumes sind statistisch genuegend abgesichert. Die Messungen sollen an Baeumen der suedlichen Hemisphaere und des vorindustriellen Zeitraumes weitergefuehrt werden. Daneben werden C-13 Messungen an derzeitigen atmosphaerischen CO2 Proben durchgefuehrt. Zur Modellauswertung der Ergebnisse sind ferner Isotopenuntersuchungen zum CO2-Austausch zwischen Atmosphaere und Meer erforderlich.
| Origin | Count |
|---|---|
| Bund | 686 |
| Kommune | 1 |
| Land | 9 |
| Wissenschaft | 18 |
| Type | Count |
|---|---|
| Daten und Messstellen | 17 |
| Ereignis | 2 |
| Förderprogramm | 672 |
| Text | 12 |
| unbekannt | 9 |
| License | Count |
|---|---|
| geschlossen | 18 |
| offen | 694 |
| Language | Count |
|---|---|
| Deutsch | 509 |
| Englisch | 323 |
| Resource type | Count |
|---|---|
| Archiv | 1 |
| Bild | 2 |
| Datei | 19 |
| Dokument | 10 |
| Keine | 427 |
| Unbekannt | 1 |
| Webdienst | 1 |
| Webseite | 263 |
| Topic | Count |
|---|---|
| Boden | 641 |
| Lebewesen und Lebensräume | 663 |
| Luft | 580 |
| Mensch und Umwelt | 712 |
| Wasser | 608 |
| Weitere | 712 |