Das Projekt "Ecological Effects of Energy Nurse Crops - Forest Restoration and Biomass Production" wird vom Umweltbundesamt gefördert und von Universität Freiburg, Waldbau-Institut durchgeführt. Storms, droughts, and pest insect outbreaks regularily disturb forests, in particular those that are characterized by tree species that are not in accordance with site conditions. Ordinary restoration methods establishing juvenile target trees in open areas often face problems in terms of seedling survival owing to stress from frost, drought, sun, or pests. From an ecological point of view, delayed restoration success can result in increased nutrient elution and reduction of carbon stored in soils. To address this problem nurse crops comprising robust and fast growing tree species such as birch (Betula ssp.) or poplar (Populus ssp.) have been used to establish an overstory sheltering sensitive target tree species against weather extremes. This project aims to utilize forest biomass provided by nurse crops to support the production of renewable energy (Energy Nurse Crops, ENCs). However, exporting additional forest biomass affects the nutrient cycles and thus may undermine the principle of sustainability. Therefore, this project will investigate and evaluate the concept of ENCs and its consequences relative to ordinary restoration methods especially for forest ecosystems sensitve to windblow such as pure black spruce stands (Picea abies) stocking on periodically wet soils. Tree species such as birch or poplar are known to develop extensive root systems. Because ENCs reliably establish in open areas and because their roots can quickly penetrate soils, they may be able to retain much more nutrients on site than any target tree species could ever do when established under unfavourable growth conditions. Eventually the positive effects of nutrient retention and soil carbon fixation may outweigh the negative effects of nutrient export with biomass. To explore this question, field experiments quantifying nutrient elution, nutrient pools, carbon pools, biomass production, and root growth will be conducted in ENC stands of different age, site, and tree species. Introducing additional tree species such as birch or poplar may also affect forest ground vegetation composition and species abundance. A research approach addressing species diversity of forest ground vegetation will be considered in the future.
Das Projekt "Teilvorhaben 2: Charakterisierung von Kandidatengenen der N-Effizienz und massenspektrometrische Analyse" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung durchgeführt. Die Gefahr des Stickstoffaustrags in das Grundwasser und der sparsame Umgang mit der knappen Ressource Wasser werden in den nächsten Jahren durch die Intensivierung des Anbaus nachwachsender Rohstoffe an Bedeutung gewinnen. Für Mitteleuropa werden ausgeprägte Trockenperioden speziell im Frühjahr und Frühsommer prognostiziert, wenn gleichzeitig die Phasen des stärksten vegetativen Wachstums und der höchsten Stickstoffaufnahme bei Stärkekartoffeln zu verzeichnen sind. Im Rahmen des vorangegangenen Forschungsvorhabens 'PROKAR' konnten Proteine identifiziert werden, welche bei eingeschränkter Wasserverfügbarkeit bzw. Stickstoffmangel in vitro bei unterschiedlich toleranten Genotypen differentiell abundant sind. Gegenstand des gegenwärtigen Forschungsvorhabens ist die Validierung der Proteine an bereits konserviertem Material aus Rain-Out-Shelter-Versuchen bzw. aus Material aus durchzuführenden Topfversuchen. Zudem soll die Übertragbarkeit auf weitere Genotypen geprüft werden. Die Entwicklung neuer Methoden zur Quantifizierung der Kandidatenproteine und eines Schnelltests für ihren Nachweis sind weitere Projektinhalte.
Das Projekt "Wind Tunnel study of sheltering effect by vegetation in the atmospheric boundary layer: implication for soil erosion and snow transport" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft, Eidgenössisches Institut für Schnee- und Lawinenforschung durchgeführt. Soil erosion and desertification, blowing and drifting snow, transport of pollen and seeds, dust entrainment and transport of (particulate) pollutants are some among a large number of processes governed by wind blowing on an erodible surface. The impact of these processes on the environment and both directly and indirectly on the human societies is huge, having implications for land surface geomorphology, human health, water resources, soil fertility and ecosystem biogeochemistry. In order to have full understanding of the physical mechanisms responsible for soil/snow entrainment, it is thus of crucial importance to investigate the very inner layer of the atmosphere, as close as possible to the ground. The interaction between the wind and the earth surface gives rise to a turbulent boundary layer which can lead to erosion of particles, often ranging from micron sized dust to millimeter sand grains. The action of the turbulent boundary layer essentially lead to a stress acting on the surface and ultimately a force acting on each single particle. In fluid mechanics the latter is referred to as the shear stress. In all surface transport models (from dust in deserts, to gravel in rivers, to PM10 particles in an industrial area) the shear stress is the key parameter. The amount of particles transported has almost always been described as a function of the difference between the shear stress and a threshold. Therefore, the prediction of the shear stress acting on the surface is a crucial pre-requisite to estimate mass transport rates. Very often, erodible soil or snow surfaces are covered by vegetation. It has long been known that vegetated surfaces prevent soil erosion by means of mainly three mechanisms. Firstly vegetation shelters the soil by simply reducing the surface exposed to the wind. Secondly, vegetation can trap particles in motion hence acting like a sink for sediments. Finally, vegetation decreases the shear stress acting on the erodible ground by absorbing the momentum flux from the airflow above, therefore weakening the erosive power of the wind. In this project we are concerned with quantifying this last effect for a selected variety of plants species and plant cover densities. The long term application of such study will be to develop a model which, for a given wind velocity and vegetation cover is able to predict the shear stress acting on the bottom surface. Such information can then be used as an input for sediment/snow transport models.
Das Projekt "Functional morphology and productivity of a tussock grassland in the Bolivian Altiplano" wird vom Umweltbundesamt gefördert und von Universität Basel, Philosophisch-Naturwissenschaftliche Fakultät durchgeführt. Tropical and subtropical high elevation grasslands are generally dominated by tall tussock grasses, a life form that seems to dominante in year round cold climates but otherwise quite different soil moisture regimes, from very wet (New Guinea, New Zealand, Ecuador) to rather dry, even semi-arid, as is the case in the NW-Argentinan and Bolivian Altiplano. The biomass production of these vast areas is largely unknown, since the classical harvesting technique cannot be applied in perennial vegetation without affecting growth. Given the steady increase in land use intensity, such information is needed to estimate the carrying capacity of these vast rangelands. In this thesis, I developed the needed non-destructive tools and applied them for a 30-month productivity analysis in the Bolivian Altiplano. The work was conducted in Sajama National Park at 4250 m elevation. The study plant, Festuca orthophylla, is a tall (up to 1 m, mostly around 60 cm) tussock forming grass that represents more than 90Prozent of all biomass in many parts of the Altiplano, including the study area. Forming clones of initially compact, but later fragmented shape, persisting many decades, this species is characteristic for the appearance of the semi-arid, Andean landscape over thousands of square kilometers at elevations between 3600 and 4600 m a.s.l. As a first step, I analysed the clonal structure, the morphology and biomass allocation in representative tussocks. The core of the theses is related to the tussock biomass production using a demographic approach and land cover data (Chapter 3), followed by an assessment of seasonal leaf dynamics (Chapter 4). In conclusion, our data provide a quantitative characterisation of the architecture and dry matter investment of this dominant Altiplano species, the first year-round productivity estimation for a high-elevation tropical, grassland, and a detailed assessment of leaf dynamics for the rainy and the dry season. In a number of ways the traits exhibited, contrast Festuca orthophylla from other, non-woody, high elevation taxa. In particular, the foliage of these tussocks operates at temperature close to that of the free atmosphere, while at the same time, providing shelter to below-ground shoot meristems. The large amount of dead plant material constrains photosynthetic light interception, and reflects slow rates of decomposition, a likely trade-off of generally poor nutrional quality (Patty et al., 2010), which, in turn, relates to the heavy herbivory pressure. The rates of biomass accumulation per unit of tussock area are quite high, much higher than one would expect in such a semi-arid rangeland. The most plausible explanation is that these tussocks are utilizing a far greater land area for water and nutrient acquisition than represented by their projected canopy area. The space in-between tussocks is, thus, a most likely mechanism explaining these high rates of productivity.