lBIS zyxwvutsrqpon 137: zyxwvutsrqpon S139-Sl46 The landscape ecological approach in bird conservation: integrating the metapopulation concept into spatial planning zyx PAUL OPDAM, RUUD FOPPEN, RIEN REIJNEN zyxw & ALEX SCHOTMAN Department of Landscape Ecology, DLO-Institute of Forestry and Nature Research, PO Box 23, 6700 AA Wageningen. The Netherlands In The Netherlands, fragmentation of (semi)natural ecosystems is regarded as a major nature conservationproblem. The current Dutch Nature ConservationPolicy Plan proposes a spatial network consisting of existing nature reserves, nature redevelopment areas and corridor zones. One of the objectives is to stop the assumed decline of biodiversity due to fragmentation.In this contribution we show that breeding birds are affected by the spatial distribution of their habitat. We also show how problems due to fragmentation can be solved by integrating landscape ecological research data into planning procedures. Frag- mented bird populations show metapopulation characteristics, dependent on the degree of fragmentation. This zyxwvut can be concluded from pattern studies, in which presence or absence patterns are correlated with spatial characteristics. Metapopulation dynamics were used, and the frequency of local extinction and of recolonization were related to size of habitat patches and spatial position in the landscape. The conclusion is that, depending on the spatial scale, landscape fragmentation is a threat to birds. On the basis of empirical data, statistical and metapopulation models are being developed to be used to evaluate spatial planning scenarios and to support decision making about which scenario is closest to the planning aims. In 1991, the Dutch government launched the National Na- ture ConservationPolicy Scheme. In this scheme, a conser- vation strategy was developed, including conservation pri- orities for particular ecosystem types and species and a proposal for a National Ecological Network. This network should consist of the actual nature areas, farmland areas in which nature is to be restored and “corridor zones’’ that are assumed to be necessary for building the network. The zyxwvu aim of this network is to stem the tide of the four major causes of the loss of biodiversity (Vos & Zonneveld 1993. Bink et al. 1994): (1) eutrophication of ground water and surface water, (2) ammonium deposition from agricultural emissions, (3) lowering of the water table and (4) habitat fragmentation. The first three factors cause a decline of habitat quality (or even a loss of habitat) that may affect the reproduction and mortality in local populations. Habitat fragmentation affects populations by altering spatial processes, such as dispersal and daily home range movements across landscapes, often in addition to the detrimentaleffects of loss of habitat quality. Habitat fragmentation includes four components, which may but do not always go together: (1) a general loss of habitat area in the landscape (habitat loss does not always go together with fragmentation, but often it does: conversely, fragmentation usually includes habitat loss): (2) a decrease in the size of habitat remnants: (3) an increasein the distance between patches: (4) an increase in the resistance to dis- persal movements of organisms between fragments (due to the disappearance of small landscape elements which facil- itate dispersal or to the introduction of barriers like roads and waterways with artificial banks). In The Netherlands, fragmentation is assumed to be a major cause of the decline of species (Bink et al. 1994),but evidence for this, other than circumstantialobservations, is scanty or extrapolated from studies on real islands or from a few empiricalstudies,mostly on forestbirds (Opdam 1991). This is particularly true of quantitative knowledge about the interrelationshipbetween the dynamics (and sustainability) of fragmented populations and the spatial configuration of the habitat sites in the landscape. Because it is felt that there is no time to lose, the national and regional authorities are actually implementingmeasures in planning schemes to re- duce habitat fragmentation. For instance, the development of corridor zones is an important issue and so is the change of agricultural landscape into areas with a primarily nature conservation function. The first challenge to ecologists is to demonstrate the ex- tent of the fragmentation problem: which species are in- volved, on which spatial scale and at what degree of frag- mentation. The next challenge is to propose solutions, and the third one is to design a method for incorporating these solutions into spatial planning. In this paper we develop a strategy leading to results that can be applied, based on a thorough knowledge of the func- tioning of fragmented populations. We discuss the following S139