The aim of the MOSAIK-project is to test alternative management systems regarding their efficiency in maintaining the characteristic species composition of dry grasslands. We present an integrated landscape model approach to test an alternative management system for applicability in preserving dry grasslands. By rototilling, i.e. cyclic, massive disturbance in the vegetation cover, we established a controlled mosaic cycle comprising a successional series from heavily disturbed areas to grassland and shrubs. The disturbance regime affects the landscape on different temporal and spatial scales. The resulting shifting mosaics determine the habitat qualities for plant and animal species. Changes in habitat quality may reduce the survival of local or regional populations. To predict the local and regional risk of extinction of specific plant and animal functional types, we apply modelling approaches on different scales and levels of hierarchy. We achieve to integrate different modules regarding abiotic and biotic state variables, processes and complex interactions in a spatially explicit way into the MOSAIK landscape model, implementing static as well as dynamic model approaches. The parameters and data necessary for reliable modelling were determined empirically in two study sites in Germany. Subsystems of the overall model are empirically parameterized and validated by means of extensive field surveys. The MOSAIK landscape model is still in development. In this paper we give an overview on the proposed landscape model approach and show the general structure of the MOSAIK landscape model. Preliminary results are exemplified in respect to habitat modelling and economic modelling of two simple management scenarios.

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1/22 Schröder et al. – Predictive species distribution modelling in butterflies

species for fen mires which is at risk of extinction in its westernmost breeding population due to severe habitat loss. We used boosted regression trees to model habitat selection of this species and to make recommendations about effective management of the last remnant habitats. Habitat data were collected in the years 2004-06 in all remaining Aquatic Warbler breeding sites in Pomerania as well as in recently abandoned sites. In Lithuania, we examined similar Aquatic Warbler habitats for spatial validation. Probability of occurrence of Aquatic Warblers in late May/early June is high in areas with low isolation from other Aquatic Warbler sites, less eutrophic conditions, a high proportion of area mown early in the preceding year, vegetation of 60-70 cm high, high prey abundance and high habitat heterogeneity. Early summer land use is needed in the more productive sites to prevent habitat deterioration by succession to higher and denser vegetation. As this also poses a serious threat to broods, it is recommended to preserve and restore more productive Aquatic Warbler sites via management that creates a mosaic of early and late used patches. In less productive sites, winter mowing can maintain suitable habitat conditions. Aquatic Warbler-friendly land use supports a

available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/biocon A landscape model for quantifying the trade-off between conservation needs and economic constraints in the management of a semi-natural grassland community

Understanding the relationship between soil biodiversity, habitat, and function is one of the main issues of soil-ecological research. The description of spatiotemporal distributions of soil organisms at relevant scales and in relation to their activity is a prerequisite to understand and quantify the factors that control soil functions. Species distribution models can help to explain the functional relationships between organisms and their habitat by estimating occurrence probabilities from spatial-distribution data and environmental predictors for single species or species groups. Here, I present a brief overview of recent developments in species distribution models and illustrate this tool with a case study using a carabid beetle species in a small-scale highly heterogeneously structured environment. In the light of the peculiarities of soil organisms and habitat, several implications and challenges of species distribution models are discussed referencing some instructive studies on the spatial distribution of soil organisms over a range of spatiotemporal scales. The most important challenges of species distribution models for soil organisms comprise the spatiotemporal heterogeneity of soil habitat on a hierarchy of nested scales; the overwhelming diversity of soil organisms with largely unknown life histories, habitat requirements, and dispersal characteristics; taxonomic and technical limitations regarding sampling and measurements; feedbacks between soil biota and their habitat. There is a clear theoretical and practical basis for considering both environmental and geographic drivers of species distributions in soil studies, and for doing so across multiple scales. This would yield a habitat-based soil ecology by combining the spatially explicit approach proposed by Ettema and Wardle (2002) with the niche-based approach of species distribution modeling.