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Potsdam, Germany

Frick A.,LUP GmbH | Steffenhagen P.,Free University of Bozen Bolzano | Zerbe S.,University of Greifswald | Timmermann T.,Free University of Bozen Bolzano | Schulz K.,Free University of Bozen Bolzano
Photogrammetrie, Fernerkundung, Geoinformation | Year: 2011

Peatland was subject to heavy drainage and degradation throughout the world and thus is now the focus of large scale restoration attempts. The monitoring of both vegetation development and balance of matter after restoration has started is indispensable, since an important objective of peat-lands rewetting is the rehabilitation of their sink function. Against this background, we investigated rewetted fens in NE Germany in order to qualitatively and quantitatively evaluate the vegetation development after restoration measures. The aim of this study was to analyse the vegetation composition with multispectral and very high spatial resolution satellite imagery. We investigated two sites with different rewetting dates and also took biomass and carbon content samples for the main plant species in order to estimate nutrient storage. We tested the applicability of various satellite sensors (QuickBird, WorldView I and SPOT) and an iterative classifcation scheme based on decision trees for mapping several wetland plant species (e. g. Phragmites australis, Typha spp. and Carex spp.) and vegetation types. We chose three different widely used decision tree classifers for this study: AdaBoost, See5 and RandomForest. Evaluation criteria were overall accuracy and mean class accuracy. Multispectral and very high spatial resolution satellite data and the developed method allow for the identifcation of the most important vegetation types in rewetted fens. All applied sensors yielded good results with overall accuracies of 85% and 92%. Some classes reached lower accuracies due to different reasons (capture date, size of training set or spatial resolution of the sensor). We found remote sensing a very valuable tool not only for the observation of the restoration success in rewetted peatland but also for the analysis of the peat accumulation potential as well as biomass and nutrient storage. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung. Source

Tegetmeyer C.,University of Greifswald | Frick A.,LUP GmbH | Seifert N.,University of Greifswald
Ostrich | Year: 2014

The only well-studied wintering ground of the globally threatened Aquatic Warbler Acrocephalus paludicola is the 'Djoudj area' in Senegal. This study identifies potential Aquatic Warbler habitats within that area and gives an estimate of the size of the local wintering population. A land-cover map was generated by classifying high-resolution satellite images. Overlaying it with presence-absence data from field surveys and using logistic regression models (GLMM), we derived the presence probability of the Aquatic Warbler in the study area. Using presence probability as a proxy of habitat suitability we identified 4 729 ha of potential habitat. We calculated the population density of the Aquatic Warbler by applying a Poisson mixed model to our land-cover raster data and estimate a total population size of 776 individuals (range 260-4 057), i.e. 0.37-19.8% of the world population. However, this estimate is complicated by uncertainties including the unknown efficiency of the bird-catching method, clumped presence of individuals, the variability of water levels and other seasonal changes. An effective management of Aquatic Warbler habitats in the Djoudj area should include extensive grazing, the control of litter accumulation and shrub growth, and the removal of plant material from the channels to improve water circulation. © 2014 © NISC (Pty) Ltd. Source

Holzhauer S.I.J.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | Holzhauer S.I.J.,Senckenberg Institute | Franke S.,Leibniz Institute for Plasma Science and Technology | Kyba C.C.M.,Leibniz Institute of Freshwater Ecology and Inland Fisheries | And 17 more authors.
Sustainability (Switzerland) | Year: 2015

Artificial light at night (ALAN) is one of the most obvious hallmarks of human presence in an ecosystem. The rapidly increasing use of artificial light has fundamentally transformed nightscapes throughout most of the globe, although little is known about how ALAN impacts the biodiversity and food webs of illuminated ecosystems. We developed a large-scale experimental infrastructure to study the effects of ALAN on a light-naïve, natural riparian (i.e., terrestrial-aquatic) ecosystem. Twelve street lights (20 m apart) arranged in three rows parallel to an agricultural drainage ditch were installed on each of two sites located in a grassland ecosystem in northern Germany. A range of biotic, abiotic, and photometric data are collected regularly to study the short- and long-term effects of ALAN on behavior, species interactions, physiology, and species composition of communities. Here we describe the infrastructure setup and data collection methods, and characterize the study area including photometric measurements. None of the measured parameters differed significantly between sites in the period before illumination. Results of one short-term experiment, carried out with one site illuminated and the other acting as a control, demonstrate the attraction of ALAN by the immense and immediate increase of insect catches at the lit street lights. The experimental setup provides a unique platform for carrying out interdisciplinary research on sustainable lighting. © 2015 by the authors. Source

Steffenhagen P.,University of Greifswald | Zerbe S.,Free University of Bozen Bolzano | Frick A.,LUP GmbH | Schulz K.,University of Greifswald | Timmermann T.,University of Greifswald
Naturschutz und Landschaftsplanung | Year: 2010

In the German federal state of Mecklenburg-Western Pomerania lowland fens having been rewetted within the 'Mire Conservation Program' were investigated in order to qualitatively and quantitatively assess ecosystem services. A particular focus was laid on vegetation development after rewetting, aboveground biomass production, and nutrient standing stock by helophytes and water plants and an assessment of peat forming potential on the landscape level. In particular, reed (Phragmites australis) plays a major role regarding biomass production and nutrient storage. In conclusion, after 10 years of rewetting the 'Mire Conservation Program' in Mecklenburg-Western Pomerania has to be considered a success with regard to the restoration of ecosystem services: (1) A diverse mosaic of different vegetation types has developed providing a valuable habitat for wetland species, (2) considerable amounts of nutrients (C, N, P) are retained which positively contribute to the landscape nutrient balance in an eutrophicated landscape by natural peat accumulation or artificial removal through mowing, and (3) a considerable potential of peat accumulation as one of the main objectives of sustainable mire conservation. Source

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