Kurzbeschreibung
(Englisch)
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Silvopastoral systems are traditional but vulnerable components of the landscape in the Swiss Jura Mountains. The present project is devoted to the simulation of alternative scenarios of climate change and land use, using a novel spatially explicit model of pasture-woodland dynamics. Different observed time series of key state variables will be used for calibration and validation. To investigate the qualitative behavior of the model and to test its ability to generate spatio-temporal patterns, simulations will be performed using simplified artificial landscapes with various spatial grains (cell sizes). Alternative realistic scenarios of climate change and land use will be compared through model simulations starting from the current configurations in several selected real landscapes in the Jura Mountains and Valais (Switzerland). Scenarios will in-clude various degrees of segregation vs. integration of ecosystem land use under a changing climate, in either externally controlled (trial-and-error human decisions) or internally self-organized landscapes (active adaptive management).
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Partner und Internationale Organisationen
(Englisch)
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AT, BE, BG, CH, CZ, DE, DK, EE, ES, FI, FR, GR, HR, IE, IT, LT, LV, NL, NO, PT, RS, SI, SK, UK
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Abstract
(Englisch)
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Silvopastoral systems are traditional components of the landscape in the Swiss Jura Mountains, and are among the most promising approaches for a sustainable management of mountain areas worldwide. Due to the manifold interactions driving the dynamics of the grassland-forest mosaic, wood-pastures are vulnerable to the currently occurring coincidence of land-use and climate change. Diachronic analyses of land-cover statistics and aerial photographs evidenced a segregation between grassland and woodland over the last century. Therefore, integrative long-term predictions of successional trends are required to support management decisions. The interactions between vegetation patterns, cattle activity, grassland dynamics and tree regeneration have been thoroughly expressed in the spatially explicit, dynamic model WoodPaM. Climatic and management forcing variables have been implemented to allow scenarios of both land-use and climate change. We innovatively combined retrospective simulations of past landscape dynamics starting in the Middle Ages with prospective simulations following two IPCC scenarios of climate change. Retrospective simulations showed the strong dependence of the landscape mosaic on both climate and management. At high elevation, climate cooling hindered tree regeneration and reduced forage production, both leading to an increase in open grassland and to a simplification of the landscape. In turn, climate warming showed the opposite effect. At lower elevations, high cattle stocking rates have generally led plant successions toward a slow development of simplified patterns hardly affected by historical climate variability. Comparisons of simulated patterns with aerial photographs suggested that logging and windstorms were critical in shaping landscape structure. Climate-change scenarios predicted delayed but inevitable structural changes of the landscape mosaic and a drastic breakdown of ecosystem services, depending on the degree of climate warming. Although our simulations showed hardly any landscape structural changes until 2050, rapid shifts occurred afterwards. Currently dominating Norway spruce was predicted to collapse and to be slowly replaced either by beech under moderate warming or by Scots pine under extreme warming. Heavy summer droughts following extreme warming would drastically reduce forage production. In order to maintain the mosaic structure of pasture-woodlands and to prevent the loss of species-rich open grasslands and wood-pastures, we recommend a future increase in stocking densities of mountain pastures and the use of mixed herds. Forests will gain importance if socio-economic constraints do not favor enhanced stocking under future climate change. Logging strategies should be adapted to maintain ecosystem mosaics. Additionally, beech regeneration should be promoted from now on in order to smoothen tree species replacement with warming and to ensure the continuous provision of forest ecosystem services.
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