TY - JOUR A1 - Burkart, Michael A1 - Wichmann, Matthias A1 - Wattenbach, Martin A1 - Pötsch, Joachim T1 - Die Vegetation der unteren Havelaue BT - Stand der Forschung und Perspektiven JF - Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4035 SN - 1434-2375 SN - 1611-9339 VL - 13 SP - 53 EP - 71 ER - TY - THES A1 - Wattenbach, Martin T1 - The hydrological effects of changes in forest area and species composition in the federal state of Brandenburg, Germany T1 - Die hydrologischen Effekte von Veränderungen der Waldfläche und Artenzusammensetzung im Land Brandenburg, Deutschland N2 - This thesis aims to quantify the human impact on the natural resource water at the landscape scale. The drivers in the federal state of Brandenburg (Germany), the area under investigation, are land-use changes induced by policy decisions at European and federal state level. The water resources of the federal state are particularly sensitive to changes in land-use due to low precipitation rates in the summer combined with sandy soils and high evapotranspiration rates. Key elements in landscape hydrology are forests because of their unique capacity to transport water from the soil to the atmosphere. Given these circumstances, decisions made at any level of administration that may have effects on the forest sector in the state are critical in relation to the water cycle. It is therefore essential to evaluate any decision that may change forest area and structure in such a sensitive region. Thus, as a first step, it was necessary to develop and implement a model able to simulate possible interactions and feedbacks between forested surfaces and the hydrological cycle at the landscape scale. The result is a model for simulating the hydrological properties of forest stands based on a robust computation of the temporal and spatial LAI (leaf area index) dynamics. The approach allows the simulation of all relevant hydrological processes with a low parameter demand. It includes the interception of precipitation and transpiration of forest stands with and without groundwater in the rooting zone. The model also considers phenology, biomass allocation, as well as mortality and simple management practices. It has been implemented as a module in the eco-hydrological model SWIM (Soil and Water Integrated Model). This model has been tested in two pre-studies to verify the applicability of its hydrological process description for the hydrological conditions typical for the state. The newly implemented forest module has been tested for Scots Pine (Pinus sylvestris) and in parts for Common Oak (Quercus robur and Q. petraea) in Brandenburg. For Scots Pine the results demonstrate a good simulation of annual biomass increase and LAI in addition to the satisfactory simulation of litter production. A comparison of the simulated and measured data of the May sprout for Scots pine and leaf unfolding for Oak, as well as the evaluation against daily transpiration measurements for Scots Pine, does support the applicability of the approach. The interception of precipitation has also been simulated and compared with weekly observed data for a Scots Pine stand which displays satisfactory results in both the vegetation periods and annual sums. After the development and testing phase, the model is used to analyse the effects of two scenarios. The first scenario is an increase in forest area on abandoned agricultural land that is triggered by a decrease in European agricultural production support. The second one is a shift in species composition from predominant Scots Pine to Common Oak that is based on decisions of the regional forestry authority to support a more natural species composition. The scenario effects are modelled for the federal state of Brandenburg on a 50m grid utilising spatially explicit land-use patterns. The results, for the first scenario, suggest a negative impact of an increase in forest area (9.4% total state area) on the regional water balance, causing an increase in mean long-term annual evapotranspiration of 3.7% at 100% afforestation when compared to no afforestation. The relatively small annual change conceals a much more pronounced seasonal effect of a mean long-term evapotranspiration increase by 25.1% in the spring causing a pronounced reduction in groundwater recharge and runoff. The reduction causes a lag effect that aggravates the scarcity of water resources in the summer. In contrast, in the second scenario, a change in species composition in existing forests (29.2% total state area) from predominantly Scots Pine to Common Oak decreases the long-term annual mean evapotranspiration by 3.4%, accompanied by a much weaker, but apparent, seasonal pattern. Both scenarios exhibit a high spatial heterogeneity because of the distinct natural conditions in the different regions of the state. Areas with groundwater levels near the surface are particularly sensitive to changes in forest area and regions with relatively high proportion of forest respond strongly to the change in species composition. In both cases this regional response is masked by a smaller linear mean effect for the total state area. Two critical sources of uncertainty in the model results have been investigated. The first one originates from the model calibration parameters estimated in the pre-study for lowland regions, such as the federal state. The combined effect of the parameters, when changed within their physical meaningful limits, unveils an overestimation of the mean water balance by 1.6%. However, the distribution has a wide spread with 14.7% for the 90th percentile and -9.9% for the 10th percentile. The second source of uncertainty emerges from the parameterisation of the forest module. The analysis exhibits a standard deviation of 0.6 % over a ten year period in the mean of the simulated evapotranspiration as a result of variance in the key forest parameters. The analysis suggests that the combined uncertainty in the model results is dominated by the uncertainties of calibration parameters. Therefore, the effect of the first scenario might be underestimated because the calculated increase in evapotranspiration is too small. This may lead to an overestimation of the water balance towards runoff and groundwater recharge. The opposite can be assumed for the second scenario in which the decrease in evapotranspiration might be overestimated. N2 - Das übergreifende Ziel der vorliegenden Arbeit ist es, die Interaktion zwischen Landnutzungsänderung und dem Landschaftswasserhaushalt zu quantifizieren. Das Untersuchungsgebiet für die Analyse ist das Land Brandenburg. Bedingt durch seine Kombination geringer Sommerniederschläge mit der Dominanz sandiger Böden und hoher Verdunstungsraten, insbesondere von den großflächigen Wäldern und Forsten, ist es besonders empfindlich gegenüber Landnutzungsänderung. Waldflächen sind Schlüsselelemente im Landschaftswasserhaushalt, da sie den Bodenwasserspeicher effizienter mit der Atmosphäre koppeln als die meisten anderen Vegetationsformen. Im ersten Teil der Arbeit war es daher notwendig, ein geeignetes Modellkonzept zu finden. Der Ansatz sollte in der Lage sein, die hydrologischen Effekte auf Landschaftsebene zu modellieren, ohne dabei die Datenverfügbarkeit in diesem Anwendungsbereich zu überschreiten. Das entwickelte Modellkonzept wurde in das ökohydrologische Einzugsgebietsmodell SWIM (Soil Water Integrated Model) integriert. Nach einer Test- und Entwicklungsphase konnte das Modell für die integrierte Analyse der Wirkung von zwei Szenarien auf den Landeswasserhaushalt verwendet werden. Das erste Szenario beschäftigt sich mit der möglichen Zunahme der Waldfläche als Folge der Neuausrichtung der Agrarsubventionspolitik der Europäischen Union. Die Waldflächenzunahme führt zu einer Steigerung der Evapotranspiration im langjährigen Mittel. Das zweite Szenario behandelt die Auswirkung des Brandenburger Waldumbauprogramms und hat eine vergleichsweise geringe Abnahme der langjährigen mittleren Verdunstung zur Folge. Der lineare mittlere Verlauf überdeckt ein ausgeprägtes räumliches und saisonales Muster der Veränderung. Die Zonen starker Effekte der beider Szenarien überlappen sich nur in einigen Fällen, so ist es möglich, dass die positiven Wirkungen des Waldumbauprogramms in einigen Regionen durch eine mögliche Ausweitung der Waldfläche aufgehoben werden. Die vorgestellten Ergebnisse zeigen deutlich, dass Landnutzungsänderungen, die durch politische oder administrative Entscheidungen ausgelöst werden, Auswirkungen auf elementare Landschaftsfunktionen wie den Wasserhaushalt haben. Es wird deutlich, dass ein integrativer Modellierungsansatz, der die wahrscheinlichen Wirkungen administrativer Entscheidungen in Betracht zieht, Grundlagen für eine nachhaltige Entwicklung liefern kann. Diese Ergebnisse werden umso relevanter, je stärker die betroffene Ressource bereits eingeschränkt ist. In Bezug auf die Wasserressourcen im Land Brandenburg ist das der Fall und aktuelle Studien zum Globalen Wandel in der Region prognostizieren eine Verschärfung dieser Situation. KW - Pinus sylvestris KW - Quercus KW - SWIM KW - Grundwasser KW - Globaler Wandel KW - global change KW - CAP KW - water balance KW - ground water KW - forestry Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-27394 ER - TY - JOUR A1 - Reichstein, Markus A1 - Bahn, Michael A1 - Ciais, Philippe A1 - Frank, Dorothea A1 - Mahecha, Miguel D. A1 - Seneviratne, Sonia I. A1 - Zscheischler, Jakob A1 - Beer, Christian A1 - Buchmann, Nina A1 - Frank, David C. A1 - Papale, Dario A1 - Rammig, Anja A1 - Smith, Pete A1 - Thonicke, Kirsten A1 - van der Velde, Marijn A1 - Vicca, Sara A1 - Walz, Ariane A1 - Wattenbach, Martin T1 - Climate extremes and the carbon cycle JF - Nature : the international weekly journal of science N2 - The terrestrial biosphere is a key component of the global carbon cycle and its carbon balance is strongly influenced by climate. Continuing environmental changes are thought to increase global terrestrial carbon uptake. But evidence is mounting that climate extremes such as droughts or storms can lead to a decrease in regional ecosystem carbon stocks and therefore have the potential to negate an expected increase in terrestrial carbon uptake. Here we explore the mechanisms and impacts of climate extremes on the terrestrial carbon cycle, and propose a pathway to improve our understanding of present and future impacts of climate extremes on the terrestrial carbon budget. Y1 - 2013 U6 - https://doi.org/10.1038/nature12350 SN - 0028-0836 VL - 500 IS - 7462 SP - 287 EP - 295 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Frank, Dorothe A. A1 - Reichstein, Markus A1 - Bahn, Michael A1 - Thonicke, Kirsten A1 - Frank, David A1 - Mahecha, Miguel D. A1 - Smith, Pete A1 - Van der Velde, Marijn A1 - Vicca, Sara A1 - Babst, Flurin A1 - Beer, Christian A1 - Buchmann, Nina A1 - Canadell, Josep G. A1 - Ciais, Philippe A1 - Cramer, Wolfgang A1 - Ibrom, Andreas A1 - Miglietta, Franco A1 - Poulter, Ben A1 - Rammig, Anja A1 - Seneviratne, Sonia I. A1 - Walz, Ariane A1 - Wattenbach, Martin A1 - Zavala, Miguel A. A1 - Zscheischler, Jakob T1 - Effects of climate extremes on the terrestrial carbon cycle: concepts, processes and potential future impacts JF - Global change biology N2 - Extreme droughts, heat waves, frosts, precipitation, wind storms and other climate extremes may impact the structure, composition and functioning of terrestrial ecosystems, and thus carbon cycling and its feedbacks to the climate system. Yet, the interconnected avenues through which climate extremes drive ecological and physiological processes and alter the carbon balance are poorly understood. Here, we review the literature on carbon cycle relevant responses of ecosystems to extreme climatic events. Given that impacts of climate extremes are considered disturbances, we assume the respective general disturbance-induced mechanisms and processes to also operate in an extreme context. The paucity of well-defined studies currently renders a quantitative meta-analysis impossible, but permits us to develop a deductive framework for identifying the main mechanisms (and coupling thereof) through which climate extremes may act on the carbon cycle. We find that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle. The expected regional impacts of future climate extremes will depend on changes in the probability and severity of their occurrence, on the compound effects and timing of different climate extremes, and on the vulnerability of each land-cover type modulated by management. Although processes and sensitivities differ among biomes, based on expert opinion, we expect forests to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks. At the global scale, we presume that droughts have the strongest and most widespread effects on terrestrial carbon cycling. Comparing impacts of climate extremes identified via remote sensing vs. ground-based observational case studies reveals that many regions in the (sub-)tropics are understudied. Hence, regional investigations are needed to allow a global upscaling of the impacts of climate extremes on global carbon-climate feedbacks. KW - carbon cycle KW - climate change KW - climate extremes KW - climate variability KW - disturbance KW - terrestrial ecosystems Y1 - 2015 U6 - https://doi.org/10.1111/gcb.12916 SN - 1354-1013 SN - 1365-2486 VL - 21 IS - 8 SP - 2861 EP - 2880 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Kayatz, Benjamin A1 - Baroni, Gabriele A1 - Hillier, Jon A1 - Lüdtke, Stefan A1 - Heathcote, Richard A1 - Malin, Daniella A1 - van Tonder, Carl A1 - Kuster, Benjamin A1 - Freese, Dirk A1 - Hüttl, Reinhard A1 - Wattenbach, Martin T1 - Cool farm tool water BT - A global on-line tool to assess water use in crop production JF - Journal of cleaner production N2 - The agricultural sector accounts for 70% of all water consumption and poses great pressure on ground water resources. Therefore, evaluating agricultural water consumption is highly important as it allows supply chain actors to identify practices which are associated with unsustainable water use, which risk depleting current water resources and impacting future production. However, these assessments are often not feasible for crop producers as data, models and experiments are required in order to conduct them. This work introduces a new on-line agricultural water use assessment tool that provides the water footprint and irrigation requirements at field scale based on an enhanced FAO56 approach combined with a global climate, crop and soil databases. This has been included in the Cool Farm Tool - an online tool which already provides metrics for greenhouse gas emissions and biodiversity impacts and therefore allows for a more holistic assessment of environmental sustainability in farming and agricultural supply chains. The model is tested against field scale and state level water footprint data providing good results. The tool provides a practical, reliable way to assess agricultural water use, and offers a means to engage growers and stakeholders in identifying efficient water management practices. (C) 2018 The Authors. Published by Elsevier Ltd. KW - Water footprint KW - FAO56 KW - Crop water use KW - Stakeholder involvement KW - Water resource management KW - Irrigation requirements Y1 - 2018 SN - 0959-6526 SN - 1879-1786 VL - 207 SP - 1163 EP - 1179 PB - Elsevier CY - Oxford ER -