Water and ion movement through a minicatchment at Risdalsheia, Norway (RAIN project)

At Risdalsheia (Southernmost Norway) the relation between flow paths and streamwater chemistry through a small headwater catchment was investigated. The importance of these pathways for the interaction between soil solution and runoff chemistry was investigated by a tracer experiment with LiBr. The experiment was designed using all available information about ion transport at EGIL-catchment in a simple model that predicted the breakthrough curve for a given tracer input. The unique facility of a roofed catchment allowed attainment and maintainace of a hydrological steady-state under highflow conditions during this tracer experiment. The chemical changes of the moving soil water due to soil/soil solution interaction mainly occured during vertical (unsaturated) infiltration. Most ions reached their runoff concentration levels after these few cm of vertical infiltration. Only the ions SO4, NO3, and H increased along the saturated lateral flow path. Subsurface, translatory flow and equilibrum reactions along vertical infiltration flow paths are the key process that explain the behavior of stormflow chemistry at the EGIL-catchment.Norsk Hydrologisk komite (NHK

Berechnung der Sickerwassermenge unter Wald

This report describes the soil water budget of two beech forests and two clearings in the forest distict of Essen (West Germany). A physical model of water movement in soil was used to calculate monthly sums of the seepage water that leaves the root zone. This information is essential for the evaluation of the ion budgets at these sites. The simple model of water flow through a forest ecosystem is calibrated against measurements of soil water potential over depht and time. The report exemplifies how such models can help to reduce the experimental effort within studies that aim at the water and ion budget of forests.SILVA Økologische Gutachten und Umweltanalytik Gmbh, am Pappelberg 10. D-3401 Ebergøtze

Reversibility of acidification: Soils and surface waters

Recent declining levels of acid deposition in both North America and Europe have initiated reversal of acidification and recovery of impacted ecosystems. The reversibility of acidification has also been investigated by means of large-scale experiments with whole ecosystems. Predictive models can account for much of this empirical and experimental data, at least at coarse spatial and temporal scales. Discrepancies between observed and predicted effects are due in part to the increasingly important role of nitrogen in soil and water acidification. "Nitrogen saturation" threatens to offset the incipient recovery due to reductions in SO2 emissions. Possible ecosystem impacts of future climate change add further uncertainty to predictions of long-term acidifications trends

Recurrence analysis of Eddy covariance fluxes

Measuring energy and matter fluxes between the atmosphere and vegetation using the Eddy Covariance (EC) technique is the state-of-the-art method to quantify carbon exchange between terrestrial ecosystems and their surrounding. The EC equipment is usually mounted onto a flux tower reaching higher than the local canopy. Today, more than 600 flux towers are in operation worldwide. The methodological requirements lead to high sampling frequency (20 Hz) and thus to the production of very long time series. These are related to temperature, wind components, water vapour, heat and gas exchange, and others. In this chapter, the potential of Recurrence Analysis (RA) to investigate the dynamics of this atmosphere-vegetation boundary system is elucidated. In particular, the effect of temporal resolution, the identification of periods particular suitable for reliable EC flux calculations, and the detection of transitions between dynamical regimes will be highlighted

Ordinal pattern and statistical complexity analysis of daily stream flow time series

When calculating the Bandt and Pompe ordinal pattern distribution from given time series at depth D, some of the D! patterns might not appear. This could be a pure finite size effect (missing patterns) or due to dynamical properties of the observed system (forbidden patterns). For pure noise, no forbidden patterns occur, contrary to deterministic chaotic maps. We investigate long time series of river runoff for missing patterns and calculate two global properties of their pattern distributions: the Permutation Entropy and the Permutation Statistical Complexity. This is compared to purely stochastic but long-range correlated processes, the k-noise (noise with power spectrum f−k), where k is a parameter determining the strength of the correlations. Although these processes closely resemble runoff series in their correlation behavior, the ordinal pattern statistics reveals qualitative differences, which can be phrased in terms of missing patterns behavior or the temporal asymmetry of the observed series. For the latter, an index is developed in the paper, which may be used to quantify the asymmetry of natural processes as opposed to artificially generated data.Fil: Lange, H.. Norwegian Forest and Landscape Institute; NoruegaFil: Rosso, Osvaldo Aníbal. Universidade Federal de Alagoas; Brasil. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Computación. Laboratorio de Sistemas Complejos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hauhs, M.. University of Bayreuth; Alemani

Einfluss der Deposition von Luftschadstoffen auf Oberflaechen- und Grundwasser in einem ausgesuchten Waldoekosystem der Langen Bramke/Oberharz (Zustand und Prognose)

SIGLEAvailable from TIB Hannover: RN 8908(91-045) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Bayreuter Institut fuer Terrestrische Oekosystemforschung (BITOeK). Forschungsbericht 1994 Vorhersage und Erklaerung des Verhaltens und der Belastbarkeit von Oekosystemen unter veraenderten Umweltbedingungen

Understanding the function and critical thresholds of ecosystems is a supposition for their appropriate management. Thus the aim of BITOEK is to understand and predict the impact of changing environmental conditions on forest ecosystems. Focus is given to the effects of decreasing S inputs, chronically high N inputs and to the regulation of transpiration. Investigations are conducted on various temporal and spatial scales reaching from short term laboratory to several year field studies. Generalization of the results is the aim of modelling and ecosystem-theroy. BITOe?'K has shown, - that the N load of forest ecosystems is higher than assumed, - that N-deposition causes several destabilizing changes in forest ecosystems, - that N deposition influences water quality from forested catchments, - that the N emissions needs a drastic decrease in order to match critical loads, - that decreasing S deposition does not immediately result in recovery of soils and groundwater, - that soil and water acidification will continue to be high - that the ground vegetation adds significantly to the total transpiration of forests, - that the transpiration can be quantitatively modelled on various scales. The results demonstrate the strong implication of atmospheric pollutants on the functioning of forest ecosystems and will find their application in forest- and water management, nature conservation, and air pollution strategies. (orig.)Der oekologisch vertraegliche Umgang mit Oekosystemen setzt die Kenntnis ihrer Funktionsweise und Belastbarkeit vorraus. Ziel der Arbeiten von BITOeK ist daher die Erklaerung und Vorhersage der Effekte von Umweltveraenderungen in Waldoekosystemen. Im Mittelpunkt stehen dabei die Auswirkungen verminderter S-Eintraege, chronisch ueberhoehter N-Eintraege und die Regulation der Verdunstung durch Umweltfaktoren. Die Untersuchungen finden auf verschiedenen Ebenen der raeumlichen und zeitlichen Aufloesung statt und reichen von relativ kurzfristigen Laborversuchen bis hin zu mehrjaehrigen Messungen im Freiland. Die Verallgemeinerung und Uebertragbarkeit der Ergebnisse auf andere Oekosysteme wird durch Modellierung und theoretische Analysen ueberprueft. Es wurde gezeigt, - dass die N-Belastung der Waldoekosysteme hoeher ist als bisher angenommen, -dass die N-Eintraege vielfaeltige und destabilisierende Wirkungen auf die Waelder haben, - dass nur eine drastische Reduktion der N-Emissionen langfristig tolerable Belastungsraten fuer Waldoekosysteme ermoeglicht, - dass die N-Eintraege die Gewaesserqualitaet aus Waldgebieten beeinflussen, - dass die Abnahme der atmogenen S-Belastung nicht zu einer unmittelbaren Erholung der Oekosysteme und Gewaesser fuehrt, - dass Boden- und Gewaesserversauerung weiter in hohen Raten verlaufen, - dass die Verdunstung von Waldbestaenden auch massiv ueber die Bodenvegetation erfolgt, - dass die Regulation der Verdunstung auf verschiedenen Skalen quantitativ beschreibbar ist. Die Ergebnisse zeigen die starke Beeinflussung von Waldoekosystemen durch Luftschadstoffe und haben Anwendungen im Bereich der Forst- und Wasserwirtschaft, des Naturschutzes und der Umweltpolitik, insb. der Luftreinhaltung. (orig.)SIGLEAvailable from TIB Hannover: RR 6937(15) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman