ترکیب ارزش شبکه های اکولوژیکی به تجزیه و تحلیل هزینه - منفعت برای بهبود صریح برنامه ریزی استفاده از زمین فضایی

Our research is based on the assumption that cost–benefit analysis facilitates efficient and effective decision-making in spatially explicit land-use planning where there are competing land uses. Land-use planning can be improved if the value of the spatial relationships between land uses can be computed sufficiently easily. In this paper, we developed an economically sound way to incorporate the spatial dimensions (size and connectedness) of ecological networks within cost–benefit analysis. The methodology computes the value of ecological networks by accounting for the essential spatial characteristics (size and configuration) of areas of natural land. This methodology can be generalised to other land uses, which we illustrate using a hypothetical case study that contains all the relevant elements. The optimal configuration of different land uses, which accounts for the value of the ecosystem network, will generate a land-use plan with the highest net benefit.

Increasing pressure on land demands a careful assessment of competing activities in land-use planning. Cost–benefit analysis (CBA) is increasingly used in planning processes to select the land-use plan that delivers the highest net social benefits. Accurate assessment of the value of the competing land uses is necessary for the credible use of CBA in planning processes. Aggregate measures of non-market values, though useful, can obscure the heterogeneous nature of the underlying resources that provide those services (Troy and Wilson, 2006). The adoption of a spatially explicit approach to economic valuation when non-market values are important is desirable because this can lead to more accurate economic valuation figures (Eade and Moran, 1996). The concept of ecological networks is of growing importance in land-use planning. Spatial modelling of values and the valuation of ecosystem networks will be a valuable tool for planning processes in which different spatial configurations (i.e., ecological networks) must be chosen from among a group of competing land uses. Land-use planning can be improved if the value of spatial relationships between land uses can be computed (or can be computed easily enough that this computation can be included in the cost–benefit analysis). In this paper, we focus on an approach that will permit efficient and effective decision-making when ecological networks exist amidst other land uses. We develop a methodology to assess the economic value of these ecological networks based on the ecological value that depends on the size and configuration of the natural areas. This value of ecological networks is based on species. We then extend this methodology to compute the economic value of different spatial configurations of land uses (given a few regularity assumptions) so as to enable the selection of a more economically efficient layout based on CBA. Three areas of research that support spatial planning for natural areas can be distinguished. First, there are methodologies designed to assess the ecological value of a region within a planning procedure based on specific targets and restrictions. Examples include the work of Opdam et al., 2003, Opdam et al., 2006 and Termorshuizen and Opdam, 2009. This first area of research explicitly incorporates size and configuration effects, but often concentrates on a single land-use function, preventing the analysis from seeking an overall balance among several competing land-use functions. Perfecto and Vandermeer, 2002 and Vandermeer and Perfecto, 2007 expanded this analysis beyond a single function by analysing the spatial interaction between agriculture and forests. Termorshuizen and Opdam (2009) addressed two prerequisites that landscape ecological science must meet for this field to effectively produce appropriate knowledge capable of supporting bottom-up landscape-development processes: the analysis must include a valuation component, and it must be suitable for use in collaborative decision-making at a local scale. In the present study, we address both criteria, but focus on the valuation criterion. The second group of studies developed methods to compute the balance between costs and benefits for various alternative layouts of a region that includes natural areas (e.g., van der Heide et al., 2008 and van der Horst, 2006). In these studies, the value of a specific land use (e.g., nature conservation) is expressed per unit area, and therefore fails to capture the influence of the shape and size of the patches within the surrounding landscape. A particular value per unit area of natural land is generally used (based on benefit transfers or specific surveys) for the entire mosaic of land uses, irrespective of the sizes and shapes of the patches of each land use within the wider landscape. This line of research concentrates on quantification of the (monetary) value of land functions, but generally ignores the dependence of these values on the size and configuration of the patches. Incorporating size and configuration effects in CBA is essential to obtain a realistic economic valuation that accounts for the value of ecological networks in a region (Hanink, 1995 and Heidkamp, 2008). This observation is not a peculiarity of ecological values; it holds, in principle, for all activities with strong interaction or scale effects, such as housing and the establishment of industrial sites and nature conservation areas. Interactions can refer to scale effects on a single activity or to values that arise from the adjacency of distinct functions, such as the increase in value of houses established near natural areas or bodies of water (Cheshire and Sheppard, 1995, Fik et al., 2003 and Geoghegan et al., 1997). Finally, the third group of studies is concerned with modelling at a detailed grid level using (for example) simulation experiments and automata theory (e.g., Drechsler and Wätzold, 2009 and Parkhurst and Shogren, 2007). This domain of research introduces interesting concepts that relate to order that arises from local interactions and spatial correlations. However, the fragmentation thresholds used in landscape ecology to characterise ecological networks do not play a dominant role in this approach. In the work of Polasky et al., 2005, Polasky et al., 2010, Groeneveld et al., 2005, Groeneveld and Weikard, 2006 and Lewis et al., 2011, the effect of fragmentation on the biodiversity score of a landscape was accounted for explicitly, as was the economic value of other land uses. The biodiversity quality in these studies, however, was not converted into monetary values and empirical information on anthropogenic valuation of species and habitats is not fully exploited. Instead, the ecological and economic values were expressed in their own units, resulting in trade-offs during boundary analysis. The contribution of this paper to the literature is the consistent and transparent way in which the economic value of ecological networks is computed in a CBA context to support communication in land-use planning processes. First, we consider ecological networks and how to capture the essential spatial characteristics of these networks that must be introduced into the economic analysis. We formulate the valuation of ecological networks, as described by Termorshuizen et al., 2007, Opdam et al., 2008 and Pouwels et al., 2008, in such a way that this valuation can be easily integrated within economic analysis. In fact, the evaluation of ecological networks within this framework becomes a specific example of a more general methodology for the valuation of land-use changes. Second, we add the spatial aspects of ecological networks into their economic valuation by means of CBA. We extend this framework to other land uses and show its applicability for land-use planning using a hypothetical example. Last, we draw conclusions about the approach and the need for future research to elaborate on this framework. Particularly in our hypothetical analysis, we ground the analysis in the reality that any landscape comprises a matrix of existing land uses, and that changing land use to a more optimal pattern has costs that must be included in the analysis.

In this paper, we expanded the CBA methodology to include the concept of ecosystem networks, as proposed by Opdam et al., 2006 and Opdam et al., 2008, so that these networks could be assigned their proper value in spatial planning. To make well-informed decisions about the trade-offs between different layouts, all costs and benefits must be taken into account (de Groot et al., 2010). To do so, we transformed the ecological value of species in the context of ecological networks into an economic value, corresponding to other land-use functions in the planning process. The virtue of our methodology and the contribution to literature is the consistent and transparent way in which the economic value of ecological networks is computed using empirical valuation information (from literature) to be used in CBA. This transparent methodology facilitates communication and support in the planning process in which the CBA will be used. An advantage of our proposed methodology is that it can be elaborated both in ecological as well as in economic research. In that case, quantitative information of biodiversity (based on species) can be used to communicate with the general public to obtain better information on the anthropogenic value of biodiversity to be included in the CBA. Since most respondents are not familiar with the term ‘biodiversity’, the number of species is the approach prevalent in the literature to describe changes in biodiversity. The quantitative representation of the viability of population as described above, added with relevant aspects of these species (e.g. Christie et al., 2006 and Czajkowski et al., 2009) seems to be a better indicator to capture the economic value of ecological networks. We also showed that the economic value of natural areas configured into an ecological network exceeds the value of the same areas when they are present as fragmented patches. Our hypothetical example demonstrated that maximizing the ecological value will not automatically generate the highest economic value in a land-use plan. Creating ecological networks produces a net benefit until a certain threshold is reached. An optimal configuration of different land uses that accounts for the value of the ecosystem network will generate the highest net benefit. The issue of the ecologic and economic value of multiple species is recognized in the literature as an important though extremely difficult issue. In our hypothetical example, thresholds defined for ecological networks are species-specific. Therefore, the marginal value of natural areas is zero above the threshold μ1, but in practice, another, higher threshold would be applicable for species that need bigger patches. Conflicting spatial configurations for different species are not dealt with in our methodology (which implicitly assumes that bigger patches are better). The methodology to compute the ecological value based on multiple species is not yet (fully) developed. Also the economic valuation of biodiversity based on the human values placed on (multiple) species needs more quantitative foundation. Future improvements in the valuation of multiple species can be included in our methodology. If ecological research were more able to translate the quality of ecological networks into a quantitative value, this ecological value could be implemented in stated-preference experiments (Christie et al., 2006). The results would provide useful information on the value of ecological networks that could be readily applied in land-use planning. Furthermore, the results could be used to quantitatively verify the assumptions made in Section 4 of this paper, or to find evidence to replace the assumption of linearity with an empirically derived functional relationship. To extend our framework to other land-use functions, we must establish the relationship between the economic value and the spatial characteristics of these functions. The first step will be to determine this relationship qualitatively (as we did in Fig. 4 for agriculture). Thereafter, a quantitative foundation for this relationship can be developed. For some land uses (e.g., housing), the relationship between the value and the distance to other land uses is already known. Finally, the concept of CBA should be integrated better within land-use planning to incorporate the current state of the art in our knowledge of different sectors, as in the interactive planning approach proposed by Woud et al. (2004).