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Freiburger Geographische Hefte, Heft 66

Manuel Weis (2010): Methode zur Entwicklung von Landschaftsleitbildern mithilfe einer dynamischen Landschaftsmodellierung - erarbeitet am Fallbeispiel Hinterzarten im Hochschwarzwald.

Dynamic change is an inherent characteristic of cultural landscapes. The interplay of socioeconomic and natural factors and processes determines the spatial and temporal pattern of land use change. Due to an accelerating societal change Middle European rural areas have considerably altered since the last five decades. For these reasons combined with a growing diversification of usage interests it will be a considerable task preserving the ecological and cultural diversity, beauty and character of a landscape (as laid down in § 1 of the German Federal Nature Conservation Act) and at the same time harmonizing ecological with social and economic interests (in line with the concept of sustainability).

As the ideas of the future development of landscapes differ from one stakeholder to the other, a consensual Leitbild of a landscape has to be developed, that balances and coordinates ecological, economic and social interests (a Leitbild represents a summarized depiction of an aspired future state, which is supposed to be achieved in a certain area in a certain period of time, cf. BASTIAN 1999e: 410). Most of the existing approaches on Leitbild-development do neither considerate diverse interests nor the relationship between the dynamics of landscape and society.

This thesis presents an approach on how to develop a Leitbild on a local scale, based on a complex consideration of landscape dynamics, land use change and societal change. The central idea is to merge a retrospective and prospective view on landscape development. By dynamic landscape modeling socioeconomic and ecocological aspects are integrated in order to meet a landscape’s functional complexity. The presented method allows depicting the consequences that have resulted from changing conditions for land use in the past or will result from changing conditions in the future, and – by application of appropriate approaches – analysing the impacts on the (earlier and potential future) capacity of the landscape to perform its essential functions. The resulting knowledge serves as a basis for a societal reflection process that leads to a decision for a Leitbild. Thus, the thesis contributes to answer the question on how to achieve a better stakeholder involvement in landscape planning.

The different steps of the approach, that build the prerequisite of the societal reflection process, have been developed and tested in the case of Hinterzarten (Black Forest).

As it is not possible to predict future landscape change the approach integrates the scenario technique, in order to allow a prospective view on landscape development. In order to develop scenarios, intrinsic and extrinsic factors that induce landscape change are distinguished. For the analysis of extrinsic factors the concept of driving forces is enhanced by a separation between determined and highly uncertain external driving forces of landscape change (givens and drivers). The investigation of intrinsic factors which affect the local land use system focuses on strategies that local stakeholders develop under the changing conditions. Following the objective to model area-wide landscape scenarios, the approach demonstrates how to derive precise scenario and model assumptions from the developed scenarios which provide the general conditions for land use. This step especially serves as an interface between socioeconomic, cultural, historical and landscape ecological aspects of land use. Spatial modelling of the landscape scenarios is carried out by applying a rule-based modelling approach which explicitly includes exceptions and single-assumptions in order to approach the reality of the local land use system. In order to generate realistic land use patterns, area-related information on natural and cultural attributes as well as proximity relations and the landscape structure are considered for land use allocation. The thesis demonstrates how to integrate scenario development in a Leitbild approach and reasonably use the potential of the scenario technique. Thus, it contributes to meet research needs.

Aside from a prospective view on landscape development the presented Leitbild approach allows to integrate a retrospective consideration of landscape change. Historical landscape patterns of different time-slices are reconstructed and the causes of landscape change are investigated.

Spatially explicit landscape modelling faces the challenge to detect the impacts of socioeconomically induced landscape change on the capacity of the landscape to perform its essential functions. Therefore, the thesis focuses as well on applicating and enhancing existing, and on developing new methodological approaches to analyse the impacts of past land use change and to predict the consequences of potential future developments. Based on the specific problems and necessities of the research area, methods for the analysis of selected landscape functions and potentials are presented.

In order to analyse the scenarios out of a nature conservation perspective a GIS-based assessment model for openland habitats is developed which goes beyond a single-patch survey by integrating spatial criteria of habitat suitability. The model allows to assess the indirect impacts on habitats (i.e. isolation, fringe-effect) being induced by land use change in the proximity of a biotope. For that purpose, amongst other aspects, the interplay of spatial distances of habitats and their matrix is investigated. Furthermore a GIS-based method for an area-wide hemeroby assessment of forest ecosystems (stand-level) is presented which gives an overview of the actual state of the forests.

Assessing the aesthetic potential of the landscape a GIS-based method is applied, that is based on a cognitive approach coming from environmental psychology. The model was developed by AUGENSTEIN (2002) and was modified and enhanced to be applicable on a local scale. In addition, the visual sensitivity of a landscape’s scenery is integrated into the assessment model. Furthermore, a survey is carried out on the change of the characteristic of a landscape over time. Concerning the assessment of potential future landscapes the results show that spatially explicit land use scenarios serve as an adequate basis for the integration of the landscape’s character in the development of a Leitbild. As characteristic visibilities and views are important for the experience of landscape, model simulations based on surface models are carried out which enable to incorporate the complex constellations of different driving parameters as landform, spatial configurations of landscape elements, height of vegetation and buildings by the use of visibility algorithms. Thus, it is possible to quantify the impact of past and potential future landscape changes on this factor of landscape experience.

The analysis of the local water balance and the impact of landuse change is carried out by using the quantitative hydrological modeling system ArcEGMO as well as a qualitative assessment of the capacity of the landscape to retain surface water und thus to reduce direct discharge. The model is run for different time-slices in the past and for the scenarios, using land use as a variable and keeping climatic conditions constant. That way, it is possible to quantify and assess characteristic long-term impacts of land use change on the local water balance. The high temporal and spatial resolution modeling proves to be of special advantage analysing historical and potential future land use patterns as it is possible to identify the specific impacts of land use change on the water balance components.

This thesis forms part of the DFG research training group ”Formation and Development of Present-Day Landscapes”, which aims at investigating the mutual dependences and interactions in the man-nature-relationship focused on the TriRhena region (the plain of the Upper Rhine and the surrounding uplands). The second phase of the research programme concentrates on change in proportion of woodland and openland. Due to increasing agricultural abandonment in peripheral and disfavoured regions like the Black Forest this question is of particular importance. The thesis contributes to this research topic by investigating driving forces and impacts of land use change, especially in terms of the proportion of woodland and openland, in the case of Hinterzarten (Black Forest) in a period of time ranging from the past (late 18th century) to the future (scenarios) using a wide range of methods.

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