Table of Contents

  • The way people are thinking about biodiversity is changing. For a long time the main arguments made for the conservation of species and habitats were based on issues such as their evolutionary uniqueness, their rarity, or on the extinction threat they may face. Today, the argument that we need to maintain biodiversity is also being made in terms of how it directly benefits people – that is how biodiversity contributes to their well-being or quality of life. One way of looking at the relationships between biodiversity and the benefits that people gain from ecological systems is in terms of what is known as ecosystem services. These are services which fundamentally depend on the properties of living systems, ranging from individual species to habitats. Thus biodiversity loss does not only mean the loss of species, but also the loss of ecosystem services through changes in ecosystem functions.

  • Changes in the spatial structure of habitats, such as declining habitat areas and the spatial fragmentation of habitats are, together with a decreasing habitat quality, a major pressure on biological diversity. Spatial indicators can function as a suitable tool for the assessment of habitat structure and its effects on biological diversity.

  • Changes in landscape structure, including both the loss and fragmentation of habitats, are widely recognised as major causes of the loss of biodiversity. Habitat fragmentation can be described as the spatial splitting of a habitat as a consequence of changes in land-use and land-cover. Humaninduced changes in landscape structure generally involve direct habitat destruction through e.g. urbanisation, infrastructure development and intensification of agricultural land use. In addition to the obvious loss of habitat, these processes also fragment and isolate remaining habitat patches. Based on the theories of island biogeography (McArthur and Wilson 1967) and metapopulations (Levins 1969), research has shown that landscape structure significantly affects biodiversity (Bogaert 2003; Fisher and Lindenmayer 2007; Jaeger and Holderegger 2005; Seiler and Folkeson 2006). The negative impacts of reduced habitat area can be exacerbated by the fact that remaining habitats become separated by distances exceeding the natural dispersal distance for key species and/or endangered species. Furthermore, reduced patch sizes and changed patch structures may lead to increased edge-effects and thus increased disturbance from surrounding land-use. Whilst direct loss of habitat has to be taken into account when planning landscape changes, the wider effects of habitat fragmentation may be neglected because their impacts are less obvious and less easily measured.

  • The scientific and political recognition of the importance of habitat fragmentation shows that fragmentation, its effects on habitat structure and its consequences for biodiversity should be integrated in monitoring programmes. Over recent years many methods to measure habitat fragmentation have been developed. However, approaches to integrate such measures within monitoring programmes are scarce. One reason is that state and development of biodiversity depend on a variety of parameters, which affect habitat quality and thus biodiversity. Habitat structure is but one parameter of a larger number, and it can therefore be difficult to determine relationships between habitat structure and biodiversity isolated from other parameters and pressures. Furthermore, relationships between habitat structure and biodiversity highly depend on species’ specific characteristics. E.g. dispersal distances and consequently responses to changes in habitat structure differ substantially between different species. Finally, map data for habitat structure have often not been adequate to reasonably assess fragmentation.

  • The theory of island biogeography by McArthur and Wilson (1967) has had essential influence on approaches to link spatial characteristics of habitats to conditions for biological diversity. The theory holds that the number of species found on an island (the equilibrium number) is determined by the island size and the distance from the mainland. As the chance of extinction is larger on small islands than on large ones, larger islands can hold more species. Furthermore, islands closer to the mainland are more likely to receive immigrants from the mainland than islands further away from the mainland. Consequently, island size and distance to the mainland affect rates of extinction and immigration. The interplay between species extinction and immigration can thus be used to establish how many species an island can hold at equilibrium (see Figure 1).

  • This chapter presents abstracts provided by the authors, with illustrations selected by the editors from the presentations. There were many recurring themes throughout the presentations. Virtually everybody touched on issues of data availability, quality and scale, agreeing that the lack of data at species and habitat levels limits the degree to which indicators can be meaningful and appropriate. This is perhaps most obvious for international approaches, where the development of methods and tools is far ahead of the provision of standardised data at a sufficient level of resolution. Yet the same challenges are seen at the national level. To overcome this we see various forms of sampling in use, both in national and international projects, aiming to provide relevant data of sufficient quality to elucidate links between biodiversity and landscape structure.

  • The table in Appendix C presents the outcome of a first attempt to produce an overview of data, available for the assessment of habitat structure in Norway, Sweden, Finland and Denmark. Seemingly there is quite a lot of available data in the four Nordic countries. However, there is also considerable variation in spatial resolution, thematic resolution and geographical coverage and therefore also large differences in suitability for indicator calculation, both within and between countries.

  • As highlighted in the preface, biodiversity and its supporting landscapes are highly dynamic, driven by pressures occurring from human as well as physio-geographical and ecological forces. Presentations given throughout the workshop as well as lots of references to scientific publications clearly indicate the relevance of habitat fragmentation as a main pressure on biodiversity, species survival and adaptation. Consequently, a main issue in the workshop discussions was whether and how spatial indicators in a Nordic context can be applied in a way, making them meaningful descriptors of impacts on biodiversity. This discussion led to following main conclusions

  • The central aim of the workshop was to gather experts in order to clarify opportunities and limitations to integrate assessments of the spatial structure of habitats in nature monitoring in a Nordic context. Considering the presentations, discussions and conclusions of the workshop, a number of specific recommendations and guidelines for further actions and research in the Nordic countries can be given.