چشم انداز ارزیابی زیست محیطی : ابزاری برای یکپارچه سازی مسائل مربوط به تنوع زیستی در ارزیابی زیست محیطی استراتژیک و برنامه ریزی

To achieve a sustainable development, impacts on biodiversity of urbanisation, new infrastructure projects and other land use changes must be considered on landscape and regional scales. This requires that important decisions are made after a systematic evaluation of environmental impacts. Landscape ecology can provide a conceptual framework for the assessment of consequences of long-term development processes like urbanisation on biodiversity components, and for evaluating and visualising the impacts of alternative planning scenarios. The aim of this paper was to develop methods for integrating biodiversity issues in planning and strategic environmental assessment in an urbanising environment, on landscape and regional levels. In order to test developed methods, a case study was conducted in the region of Stockholm, the capital of Sweden, and the study area embraced the city centre, suburbs and peri-urban areas. Focal species were tested as indicators of habitat quality, quantity and connectivity in the landscape. Predictive modelling of habitat distribution in geographic information systems involved the modelling of focal species occurrences based on empirical data, incorporated in a landscape ecological decision support system. When habitat models were retrieved, they were applied on future planning scenarios in order to predict and assess the impacts on focal species. The scenario involving a diffuse exploitation pattern had the greatest negative impacts on the habitat networks of focal species. The scenarios with concentrated exploitation also had negative impacts, although they were possible to mitigate quite easily. The predictions of the impacts on habitats networks of focal species made it possible to quantify, integrate and visualise the effects of urbanisation scenarios on aspects of biodiversity on a landscape level.

In the footsteps of the industrialisation, agricultural societies have been transformed into urbanised landscapes. In Sweden, like in many other European countries, the urbanisation process has been going on for a long time and today around 80% of the Swedish population lives in urban areas (Nyström, 1997). In order to meet the demands for new housing areas, additional office facilities and better transportation systems, new areas are required for exploitation. This puts a high pressure on the remaining areas of nature in urban regions. Unexploited areas in and around cities accommodate a multitude of qualities, both ecological and recreational (Office of Regional Planning and Urban Transportation, 1996 and Office of Regional Planning and Urban Transportation, 2001a; Miller and Hobbs, 2002; Ricketts and Imhoff, 2003). The areas of natural and semi-natural vegetation offer living conditions for a variety of species, and are therefore essential for maintaining biodiversity. However, due to the ongoing urbanisation these areas are prone to a continuous fragmentation process and loss of habitat quality. At the political level a number of decisions have been made that emphasise nature conservation and the preservation of green areas. In Sweden, the Governmental environmental objectives require that biodiversity is preserved and dispersal possibilities are safeguarded (Government Bill, 1998). This is also in line with the Convention on Biodiversity, where an ecosystem approach is adopted and should be applied whenever appropriate (Official Journal of the European Communities (OJEU), 1993). Further, in the sixth EU Environmental Action Programme, biodiversity is one of four priority areas where action is required. An objective and priority area for action on nature and biodiversity is the conservation of species and habitats, with special concern to preventing habitat fragmentation (OJEU, 2002). In response to the political ambitions, the impacts of new developments in urban areas require careful consideration. Therefore the consequences of urban expansions need to be analysed prior to any decision that provides for the exploitation of green areas. When such a decision concerns a project, for example the construction of a motorway, the legal requirements on environmental impact assessment (EIA) state that the impacts of the project are identified before a decision is made. However, initial decisions on urban expansion and major infrastructure investments are often made at a strategic stage where the long-term development of an urban region is determined. For this type of decisions the EIA regulations can not be applied. Instead a strategic environmental assessment (SEA) can be prepared, which addresses the environmental impacts of a strategic decision (Lee and Walsh, 1992; Thérivel et al., 1992; Partidário, 1996; Glasson et al., 1999; Fischer, 2002; Balfors and Schmidtbauer, 2002). In Sweden, stricter demands on environmental assessment are raised since the Environmental Code came into force in 1999. In the European context, regulations on environmental impact assessment have been tightened in the amended EU Directive for project EIA from 1997 (OJEU, 1997). The recent enactment of a new EU Directive concerning the assessment of the effects of certain plans and programmes on the environment (OJEU, 2001) strengthens the need for environmental consideration in physical planning. Both directives emphasise the importance of identifying impacts at an early stage of the planning process. The Directives require a general incorporation of SEA in European planning systems, but still there exists a high degree of uncertainty on how a SEA should be carried out. In for example, Sadler and Verheem (1996) and Verheem and Tonk (2000), a number of methodological and procedural complications related to SEA are identified and discussed. A main issue in this discussion is that each SEA requires an approach that is adapted to the particular qualities of the plan, programme or policy. Hildén et al. (1998) stated that the high level of abstraction of plans, programmes and policies involves a major methodological problem for the prediction of impacts. The integration of biodiversity issues in the assessment requires prediction tools that employ relevant knowledge on the impact of land use changes on the fauna and flora inhabiting the area. Loss and fragmentation of natural habitats are major causes of decline of biodiversity (Fahrig, 1997), but the magnitude and significance of the impacts on biodiversity are not easy to determine, as this depends on various aspects such as the landscape context of the claimed area, the scope of the proposed development and the vulnerability of a species to external influences. Effects of habitat loss and fragmentation and relations between landscape pattern and ecological processes are studied in landscape ecology, where the landscape level is considered as more inclusive than the ecosystem level, as it is a collection of ecosystems (Forman and Godron, 1986; Farina, 2000; Wiens, 2002). For the protection of biodiversity, considerations are needed at genetic, species and ecosystem scales, and the quality, quantity and connectivity of natural habitats are essential. A site-based conservation approach is not sufficient, but rather a look at persistence requirements of species and communities in the entire landscape. Suitable and accessible habitat can be planned in habitat networks, consisting of core areas sufficient for species’ persistence in the landscape, linked together through corridors, which enable dispersal (Opdam et al., 2002). In this way, landscape ecology can provide knowledge and a conceptual framework for the assessment of ecological consequences of long-term development on wildlife potential (Fernandes, 2000; Aspinall and Pearson, 2000; Botequilha Leitão and Ahern, 2002). Habitat loss and fragmentation are consequences of the urbanisation process, which also causes disturbances on remaining nature areas. Thus, biodiversity is gradually affected, but the level of change is varying in different parts of an urbanising landscape. Consequences of urbanisation like habitat fragmentation and disturbance effects have been explored by for example Bolger et al. (1997), Sauvajot et al. (1998) and Mörtberg, 1996, Mörtberg, 1998 and Mörtberg, 2001 and were reviewed in Fernandez-Juricic and Jokimaki (2001). Ecological effects of infrastructure like habitat fragmentation and associated barrier effects on the movements of sensitive species have been studied by for instance Forman (2000), and reviewed in Trocmé et al. (2002). As a result of urbanisation and infrastructure development, apparently small impacts on individual sites can result in considerable cumulative effects on the availability of natural habitat in a region, which calls for a landscape perspective in impact assessment. Within the research of conservation biology and landscape ecology, simulations and predictions of species’ occurrences are growing fields (e.g. Akçakaya and Raphael, 1998; Dettmers and Bart, 1999; Guisan and Zimmermann, 2000; Scott et al., 2002). Such predictions are based on an established relation between the occurrence of a species and environmental variables, describing its suitable habitat. These environmental variables are used to predict potential sites for the species. Predictive habitat models, using GIS, can be applied over large areas and are useful in the conservation and management of ecosystems (Guisan and Zimmermann, 2000; Scott et al., 2002; Geneletti, 2002). In several studies (e.g. Natuhara and Imai, 1999; Watson et al., 2001; Coops and Catling, 2002), predictive models are used to assess the ecological effects of alternative management plans that could alter or remove habitat for studied species or groups. Thus, the ecological and environmental advantages of a certain policy, plan or project can be demonstrated. The transformation of the ecological models into a spatial format makes knowledge about species distributions suitable for scenario-testing and accessible to the planning process (Harms et al., 1993 and Harms et al., 2000; Swetnam et al., 1998; Botequilha Leitão and Ahern, 2002). In order to predict and assess consequences of fragmentation caused by urbanisation and infrastructure, biodiversity needs to be quantified, which requires biodiversity indicators that are sensitive to these processes (Noss, 1990; Lambeck, 1997). Useful indicators can be the habitat networks of focal species that are specialised to a certain habitat type, have large area requirements, and/or have low dispersal capacity (Vos et al., 2001; Hansson, 2001). The requirements for persistence of a suite of such focal species, sensitive to the threatening processes, can collectively represent a variety of landscape characteristics that will encompass the needs of many other species. It is assumed that an essential part of biodiversity in a landscape will benefit from the preservation of these (Lambeck, 1997). Focal species have been used in the development of large-scale habitat models in order to select conservation areas and to guide management plans (Lambeck, 1997; Watson et al., 2001; Bani et al., 2002; Hess and King, 2002; Sanderson et al., 2002). There are different examples of integration of biodiversity issues and landscape ecological knowledge in planning and impact assessments, such as the Ecological Main Structure of the Netherlands (Ministerie LNV, 1990) and Fernandes (2000). In Germany and the Netherlands several projects have been carried out that aimed to integrate land use and natural resources (Petry and Krönert, 1998; Knol and Verweij, 1999; Harms et al., 2000). In these projects, nature conservation and development were combined with functions like urbanisation and recreation. Still, there is a gap between knowledge development and knowledge application in landscape ecology, and a lack of tools for integration in multidisciplinary landscape studies (Opdam et al., 2002). Within environmental impact assessment this lack of tools is also manifest. According to Treweek et al. (1998) and Geneletti (2002), environmental impact statements often fail to provide quantitative predictions concerning nature conservation and biodiversity. Instead, these issues are usually treated as restrictions for the proposed development. Therefore tools need to be developed that allow an effective integration of biodiversity issues in planning and impact assessments. The aim of this paper was to develop methods for integrating biodiversity issues in planning and strategic environmental assessment in an urbanising environment, on landscape and regional levels. The research questions that were addressed concerned (1) what effects could be predicted of urbanisation scenarios on habitat networks of focal species, and (2) how predictive modelling of biodiversity components could be integrated in the strategic environmental assessment process. In order to support this integration, a landscape ecological assessment (LEA) was developed and designed to accommodate prevalent planning structures. As a part of the research project a case study was carried out to demonstrate the application of a LEA in an urbanising region.

The prediction of biodiversity impacts is essential in the long-term planning of urbanised regions. In the context of strategic environmental assessment, LEA provides a tool to assess the potential impacts of planning and design options, to select those which minimise ecological risk and to plan measures for the mitigation of potential adverse impacts. In order to be able to make reliable predictions it is important to identify relevant biodiversity indicators, which are representative on landscape and/or regional scales. Within LEA specific landscape targets are defined, which take into consideration habitat networks of given sets of taxa related to these landscape targets, in a relatively transparent and exploratory framework. LEA provides a systematic procedure that encourages the exploration of data and priority settings that aims to quantitatively address landscape and ecosystem levels of biodiversity issues in an area. As in the case study, not all elements of biodiversity present in and around the city may benefit from considerations and protection of habitat networks of focal species. But the crucial environmental parameters involved—quality, quantity and connectivity of habitat types like mature and old coniferous forest, forest on rich soils, wet forest and mires—should favour a substantial part of the biodiversity in need of consideration and protection. When the habitat networks of a suite of focal species are taken into consideration and provided for, a landscape designed and managed to meet their needs will protect habitat for other species with similar requirements. The link to targets for landscape types and the explicit link to threatening processes make LEA useful in EIA and SEA, and thus has the potential to improve the quality of SEA's and ultimately contribute to sustainable planning and decision-making.