@misc{KoechyBrakenhielm2008,
  author    = {K{\"o}chy, Martin and Br{\aa}kenhielm, Sven},
  title     = {Separation of effects of moderate N deposition from natural change in ground vegetation of forests and bogs},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16621},
  year      = {2008},
  abstract  = {The effect of moderate rates of nitrogen deposition on ground floor vegetation is poorly predicted by uncontrolled surveys or fertilization experiments using high rates of nitrogen (N) addition. We compared the temporal trends of ground floor vegetation in permanent plots with moderate (7-13 kg ha-1 year-1) and lower bulk N deposition (4-6 kg ha-1 year-1) in southern Sweden during 1982-1998. We examined whether trends differed between growth forms (vascular plants and bryophytes) and vegetation types (three types of coniferous forest, deciduous forest, and bog). Trends of site-standardized cover and richness varied among growth forms, vegetation types, and deposition regions. Cover in spruce forests decreased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs cover decreased faster with low deposition. Cover of bryophytes in spruce forests increased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs and deciduous forests there was a strong non-linear increase with moderate deposition. The trend of number of vascular plants was constant with moderate and decreased with low deposition. We found no trend in the number of bryophyte species. We propose that the decrease of cover and number with low deposition was related to normal ecosystem development (increased shading), suggesting that N deposition maintained or increased the competitiveness of some species in the moderate-deposition region. Deposition had no consistent negative effect on vegetation suggesting that it is less important than normal successional processes.},
  language  = {en}
}
@misc{KoechyMathajJeltschetal.2008,
  author    = {K{\"o}chy, Martin and Mathaj, Martin and Jeltsch, Florian and Malkinson, Dan},
  title     = {Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18720},
  year      = {2008},
  abstract  = {Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future.},
  language  = {en}
}
@inproceedings{PoppBlaumDomptailetal.2006,
  author    = {Popp, Alexander and Blaum, Niels and Domptail, Stephanie and Herpel, Nicole and Gr{\"o}ngr{\"o}ft, Alexander and Hoffman, T. T. and J{\"u}rgens, Norbert and Milton, Sue and Nuppenau, Ernst-August and Rossmanith, Eva and Schmidt, Michael and Vogel, Melanie and Vohland, Katrin and Jeltsch, Florian},
  title     = {From satellite imagery to soil-plant interactions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7302},
  year      = {2006},
  abstract  = {Decisions for the conservation of biodiversity and sustainable management of natural resources are typically related to large scales, i.e. the landscape level. However, understanding and predicting the effects of land use and climate change on scales relevant for decision-making requires to include both, large scale vegetation dynamics and small scale processes, such as soil-plant interactions. Integrating the results of multiple BIOTA subprojects enabled us to include necessary data of soil science, botany, socio-economics and remote sensing into a high resolution, process-based and spatially-explicit model. Using an example from a sustainably-used research farm and a communally used and degraded farming area in semiarid southern Namibia we show the power of simulation models as a tool to integrate processes across disciplines and scales.},
  language  = {en}
}
@inproceedings{RossmanithBlaumKeiletal.2006,
  author    = {Rossmanith, Eva and Blaum, Niels and Keil, Manfred and Langerwisch, F. and Meyer, Jork and Popp, Alexander and Schmidt, Michael and Schultz, Christoph and Schwager, Monika and Vogel, Melanie and Wasiolka, Bernd and Jeltsch, Florian},
  title     = {Scaling up local population dynamics to regional scales},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7320},
  year      = {2006},
  abstract  = {In semi-arid savannas, unsustainable land use can lead to degradation of entire landscapes, e.g. in the form of shrub encroachment. This leads to habitat loss and is assumed to reduce species diversity. In BIOTA phase 1, we investigated the effects of land use on population dynamics on farm scale. In phase 2 we scale up to consider the whole regional landscape consisting of a diverse mosaic of farms with different historic and present land use intensities. This mosaic creates a heterogeneous, dynamic pattern of structural diversity at a large spatial scale. Understanding how the region-wide dynamic land use pattern affects the abundance of animal and plant species requires the integration of processes on large as well as on small spatial scales. In our multidisciplinary approach, we integrate information from remote sensing, genetic and ecological field studies as well as small scale process models in a dynamic region-wide simulation tool. <hr> Interdisziplin{\"a}res Zentrum f{\"u}r Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006.},
  language  = {en}
}
@misc{WackervonElert2001,
  author    = {Wacker, Alexander and von Elert, Eric},
  title     = {Polyunsaturated fatty acids : evidence for non-substitutable biochemical resources in Daphnia galeata},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17587},
  year      = {2001},
  abstract  = {The factors that determine the efficiency of energy transfer in aquatic food webs have been investigated for many decades. The plant-animal interface is the most variable and least predictable of all levels in the food web. In order to study determinants of food quality in a large lake and to test the recently proposed central importance of the long-chained eicosapentaenoic acid (EPA) at the pelagic producer-grazer interface, we tested the importance of polyunsaturated fatty acids (PUFAs) at the pelagic producerconsumer interface by correlating sestonic food parameters with somatic growth rates of a clone of Daphnia galeata. Daphnia growth rates were obtained from standardized laboratory experiments spanning one season with Daphnia feeding on natural seston from Lake Constance, a large pre-alpine lake. Somatic growth rates were fitted to sestonic parameters by using a saturation function. A moderate amount of variation was explained when the model included the elemental parameters carbon (r2 = 0.6) and nitrogen (r2 = 0.71). A tighter fit was obtained when sestonic phosphorus was incorporated (r2 = 0.86). The nonlinear regression with EPA was relatively weak (r2 = 0.77), whereas the highest degree of variance was explained by three C18-PUFAs. The best (r2 = 0.95), and only significant, correlation of Daphnia's growth was found with the C18-PUFA α-linolenic acid (α-LA; C18:3n-3). This correlation was weakest in late August when C:P values increased to 300, suggesting that mineral and PUFA-limitation of Daphnia's growth changed seasonally. Sestonic phosphorus and some PUFAs showed not only tight correlations with growth, but also with sestonic α-LA content. We computed Monte Carlo simulations to test whether the observed effects of α-LA on growth could be accounted for by EPA, phosphorus, or one of the two C18-PUFAs, stearidonic acid (C18:4n-3) and linoleic acid (C18:2n-6). With >99 \% probability, the correlation of growth with α-LA could not be explained by any of these parameters. In order to test for EPA limitation of Daphnia's growth, in parallel with experiments on pure seston, growth was determined on seston supplemented with chemostat-grown, P-limited Stephanodiscus hantzschii, which is rich in EPA. Although supplementation increased the EPA content 80-800x, no significant changes in the nonlinear regression of the growth rates with α-LA were found, indicating that growth of Daphnia on pure seston was not EPA limited. This indicates that the two fatty acids, EPA and α-LA, were not mutually substitutable biochemical resources and points to different physiological functions of these two PUFAs. These results support the PUFA-limitation hypothesis for sestonic C:P < 300 but are contrary to the hypothesis of a general importance of EPA, since no evidence for EPA limitation was found. It is suggested that the resource ratios of EPA and α-LA rather than the absolute concentrations determine which of the two resources is limiting growth.},
  language  = {en}
}
@misc{WackervonElert2002,
  author    = {Wacker, Alexander and von Elert, Eric},
  title     = {Strong influences of larval diet history on subsequent post-settlement growth in the freshwater mollusc Dreissena polymorpha},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17627},
  year      = {2002},
  abstract  = {Significant seasonal variation in size at settlement has been observed in newly settled larvae of Dreissena polymorpha in Lake Constance. Diet quality, which varies temporally and spatially in freshwater habitats, has been suggested as a significant factor influencing life history and development of freshwater invertebrates. Accordingly, experiments were conducted with field-collected larvae to test the hypothesis that diet quality can determine planktonic larval growth rates, size at settlement and subsequent post-metamorphic growth rates. Larvae were fed one of two diets or starved. One diet was composed of cyanobacterial cells which are deficient in polyunsaturated fatty acids (PUFAs), and the other was a mixed diet rich in PUFAs. Freshly metamorphosed animals from the starvation treatment had a carbon content per individual 70\% lower than that of larvae fed the mixed diet. This apparent exhaustion of larval internal reserves resulted in a 50\% reduction of the postmetamorphic growth rates. Growth was also reduced in animals previously fed the cyanobacterial diet. Hence, low food quantity or low food quality during the larval stage of D. polymorpha lead to irreversible effects for postmetamorphic animals, and is related to inferior competitive abilities.},
  language  = {en}
}