C.C. Vos

Landscape ecology of a stressed environment

The Netherlands landscape is an example of environments managed for high rates of production and other human uses. The data and emerging principles of landscape ecology as developed in this volume apply to a variety of other managed landscapes worldwide.

Genetic similarity as a measure for connectivity between fragmented populations of the moor frog (Rana arvalis).

Genetic differentiation among populations of the moor frog (Rana arvalis) was tested on a spatial scale where some dispersal between populations is expected to occur, in a landscape in The Netherlands that has become fragmented fairly recently, in the 1930s. Five microsatellite loci were used, with 2–8 alleles per locus. FIS was 0.049 across loci, and most populations were in HW equilibrium. The degree of population subdivision was low (FST=0.052). A significant positive correlation between genetic distance and geographical distance was found, indicating a limitation in dispersal among populations due to distance. To test the impact of the landscape mosaic on the connectivity between patches, distance measures were corrected for relative amounts of habitat types with known positive or negative influence on moor frog dispersal. Notably, the resistance variable for the fraction of negative linear elements (roads and railways) gave a higher explanatory value than geographical distance itself. Therefore, it is particularly the number of barriers (roads and railways) between populations that emerges as a factor that reduces exchange between populations. It is concluded that genetic techniques show promise in determining the influence of landscape connectivity on animal dispersal.

Genetic population differentiation and connectivity among fragmented Moor frog (Rana arvalis) populations in The Netherlands

We studied the effects of landscape structure, habitat loss and fragmentation on genetic differentiation of Moor frog populations in two landscapes in The Netherlands (Drenthe and Noord-Brabant). Microsatellite data of eight loci showed small to moderate genetic differentiation among populations in both landscapes (FST values 0.022 and 0.060, respectively). Both heterozygosity and population differentiation indicate a lower level of gene flow among populations in Noord-Brabant, where populations were further apart and have experienced a higher degree of fragmentation for a longer period of time as compared to populations in Drenthe. A significant isolation-by-distance pattern was found in Drenthe, indicating a limitation in dispersal among populations due to geographic distance. In Noord-Brabant a similar positive correlation was obtained only after the exclusion of a single long-time isolated population. After randomised exclusion of populations a significant additional negative effect of roads was found but not of other landscape elements. These results are discussed in view of improving methodology of assessing the effects of landscape elements on connectivity.

Population dynamics under increasing environmental variability: implications of climate change for ecological network design criteria

There is growing evidence that climate change causes an increase in variation in conditions for plant and animal populations. This increase in variation, e.g. amplified inter-annual variability in temperature and rainfall has population dynamical consequences because it raises the variation in vital demographic rates (survival, reproduction) in these populations. In turn, this amplified environmental variability enlarges population extinction risk. This paper demonstrates that currently used nature conservation policies, principles, and generic and specific design criteria have to be adapted to these new insights. A simulation shows that an increase in variation in vital demographic rates can be compensated for by increasing patch size. A small, short-lived bird species like a warbler that is highly sensitive to environmental fluctuations needs more area for compensation than a large, long-lived bird species like a Bittern. We explore the conservation problems that would arise if patches or reserve sizes would need to be increased, e.g. doubled, in order to compensate for increase in environmental variability. This issue has serious consequences for nature policy when targets are not met, and asks for new design criteria.

Corridors and species dispersal

After introducing corridor concepts, we explore how those concepts have been applied and whether the applications were effective. Based on empirical data, simulation models, and on-the-ground applications, general principles for developing effective corridors will be presented. In the last two sections, major knowledge gaps and research approaches for filling them are discussed.

Setting Biodiversity Targets in Participatory Regional Planning: Introducing Ecoprofiles

In highly developed regions, ecosystems are often severely fragmented, whereas the conservation of biodiversity is highly rated. Regional and local actor groups are often involved in the regional planning, but when making decisions they make insufficient use of scientific knowledge of the ecological system that is being changed. The ecological basis of regional landscape change would be improved if knowledge-based systems tailored to the cyclic process of planning and negotiation and to the expertise of planners, designers and local interest groups were available. If regional development is to be sustainable, goals for biodiversity must be set in relation to the actual and demanded patterns of ecosystems. We infer a set of prerequisites for the effective use of biodiversity goal-setting methods in multi-stakeholder decision making. Among these prerequisites are the requirements that ecosystem patterns are set central and that methods integrate the demands of a suite of species, are spatially explicit, and allow the aspiration level to be modified during the planning process. The decision making must also be enriched with local ecological knowledge. The current methods for setting biodiversity targets lack crucial characteristics— in particular, flexibility—and often require too high a level of ecological expertise. The ecoprofile method we designed combines an ecosystem base with spatial conditions for species metapopulations. We report experiences with this approach in two case studies, showing that the method was understood by policy makers, planners, and stakeholders, and was useful in negotiation processes. We recommend experimenting with applying this approach in a variety of circumstances, to further improve its ecological basis.

Spatial planning of a climate adaptation zone for wetland ecosystems.

Here we present a spatial planning approach for the implementation of adaptation measures to climate change in conservation planning for ecological networks. We analyse the wetland ecosystems of the Dutch National Ecological Network for locations where the effectiveness of the network might be weakened because of climate change. We first identify potential dispersal bottlenecks where connectivity might be insufficient to facilitate range expansions. We then identify habitat patches that might have a too low carrying capacity for populations to cope with additional population fluctuations caused by weather extremes. Finally, we describe the spatial planning steps that were followed to determine the best locations for adaptation measures. An essential part of our adaptation strategy is to concentrate adaptation measures in a ‘climate adaptation zone’. Concentrating adaptation measures is a cost-effective planning strategy, rendering the largest benefit per area unit. Measures are taken where abiotic conditions are optimal and measures to enhance the spatial cohesion of the network are taken close to existing areas, thus creating the highest possible connectivity with the lowest area demands. Another benefit of a climate adaptation zone is that it provides a spatial protection zone where activities that will have a negative impact on ecosystem functioning might be avoided or mitigated. The following adaptation measures are proposed within the climate adaptation zone: (1) link habitat networks to enable species to disperse from present to future suitable climate zones, (2) enlarge the carrying capacity by either enlarging the size of natural areas or by improving habitat quality to shorten population recovery after disturbances, (3) increase the heterogeneity of natural areas, preferably by stimulating natural landscape-forming processes, to avoid large synchronised extinctions after extreme weather events. The presented approach can be generalised to develop climate adaptation zones for other ecosystem types inside or outside Europe, where habitat fragmentation is a limiting factor in biodiversity responses to climate change.

The role and evolution of boundary concepts in transdisciplinary landscape planning

In this paper we address two challenges that are faced by scientists who engage in transdisciplinary landscape planning. In building a common understanding and application of the knowledge they bring in, they face the need to integrate knowledge from a range of scientific disciplines to create comprehensive solutions, while aligning the diverging values and perspectives on the future of involved actors. Boundary management has been proposed as a strategy to support the decision-making of actors by reconfiguring the boundaries between different forms of academic and non-academic expertise and between facts and opinions, interests and values. In this paper we investigate how landscape concepts can play a role as a boundary concept in transdisciplinary landscape planning. By analysing three Dutch case studies, we conclude that collective views and coordinated actions within the local planning groups grew during the planning process. We argue that the characteristics of the landscape concepts contributed to this emerging collaboration by creating a discursive space for actors with different values and knowledge bases. We find that this role evolved during the planning process, from conceptually binding, via broadening the planning focus and the coalition, towards facilitating the implementation of collective action to adapt the landscape. Thus, whereas in the early phases of the planning process the concept linked landscape value to landscape functioning, later on it connected landscape functioning to landscape structure.

Landscape diversity enhances the resilience of populations, ecosystems and local economy in rural areas

ContextIn today’s world, rapid environmental and economic developments and changes pose major threats to ecosystems and economic systems.ObjectiveIn this context we explore if resilience can be increased by the spatial configuration of the rural landscape in an integrated ecological-genetic-economic way.MethodsWe study the concept of landscape diversity from genetic, ecological and economic perspectives.ResultsWe show that small-scale landscapes are potentially more resilient than large-scale landscapes, provided that ecosystem patch sizes are sufficiently large to support genetic diversity and ecosystem and economic functions. The basic premise underlying this finding is that more variation in a landscape generally leads to greater genetic and species diversity. This, in turn, stabilizes populations and strengthens the different ecosystem elements in the landscape. Greater variation in ecosystem elements provides for more varied ecosystem services, which may enhance the resilience of the local economy.ConclusionWe conclude that a resilient landscape is shaped within the context of economic and ecological possibilities and constraints, and is determined by landscape diversity and spatial organisation.

Synthesis of ecosystem vulnerability to climate change in the Netherlands shows the need to consider environmental fluctuations in adaptation measures

Climate change impacts on individual species are various and range from shifts in phenology and functional properties to changes in productivity and dispersal. The combination of impacts determines future biodiversity and species composition, but is difficult to evaluate with a single method. Instead, a comparison of mutually independent approaches provides information and confidence in patterns observed beyond what may be achieved in individual approaches. Here, we carried out such comparison to assess which ecosystem types in the Netherlands appear most vulnerable to climate change impacts, as arising from changes in hydrology, nutrient conditions and dispersal limitations. We thus combined meta-analyses of species range shifts with species distribution modelling and ecohydrological modelling with expert knowledge in two respective impact studies. Both impact studies showed that nutrient-poor ecosystems and ecosystem types with fluctuating water tables—like hay meadows, moist heathlands and moorlands—seem to be most at risk upon climate change. A subsequent meta-analysis of species–environmental stress relations indicated that particularly endangered species are adversely affected by the combination of drought and oxygen stress, caused by fluctuating moisture conditions. This implies that adaptation measures should not only aim to optimise mean environmental conditions but should also buffer environmental extremes. Major uncertainties in the assessment included the quantitative impacts of vegetation-hydrology feedbacks, vegetation adaptation and interactions between dispersal capacity and traits linked to environmental selection. Once such quantifications become feasible, adaptation measures may be tailor-made and optimised to conserve vulnerable ecosystem types.