Abstract
ContextRoad infrastructure construction is integral to economic development, but negatively affects biodiversity. To mitigate the negative impacts of infrastructure, various types of wildlife crossings are realized worldwide, but little is known about their effectiveness, and cost-effectiveness.ObjectiveThe paper contributes to the methodological and empirical discussion on the effectiveness of wildlife crossings for enhancing the quality of surrounding nature and its cost-effectiveness by analyzing a large-scale wildlife-crossings program in the Netherlands.MethodA multi-criteria cost–benefit analysis is applied, comprised of monetary and non-monetary measures, and a mixed-method approach is used to determine ecological effects. Ecological effects are expressed in the standardized weighted hectare measurement of threat-weighted ecological quality area (1 T-EQA = 1 ha of 100% ecological quality, averagely threatened). Cost-effectiveness is calculated comparing the monetary costs of intervention with ecological benefits (Euro costs/T-EQA), for different types of wildlife crossings and for two other nature policies.ResultsThe Dutch habitat defragmentation program has induced an increase in nature value of 1734 T-EQA at a cost of Euro 283 million. Ecological gains per hierarchically ordered groups of measures differ strongly: The most effective are ecoducts (wildlife crossing bridges) followed by shared-use viaducts and large fauna tunnels. Ecoducts generated the largest gain in nature value, but were also the most costly measures. In terms of cost-effectiveness, both large fauna tunnels and shared-use viaducts for traffic and animals outperformed ecoducts.ConclusionsEcoducts deliver ecologically, but their cost-effectiveness appears modest. Purchasing agricultural land for restoration of nature appears more cost-effective than building wildlife crossings. Yet, reducing environmental pressures or their effects on existing nature areas is likely to be most cost-effective.
Highlights
As economic development continues and human impacts on landscapes increase, biodiversity nearly always declines (Young et al 2005; Li et al 2010; Dirzo et al 2014; Fraser et al 2019)
The Dutch habitat defragmentation program has induced an increase in nature value of 1734 T-EQA at a cost of Euro 283 million
Part 1 of the table provides the estimate of the economic costs of the Meerjarenprogramma Ontsnippering’ (MJPO); part 2 summarizes results of the three methods; and part 3 shows the costeffectiveness analysis
Summary
As economic development continues and human impacts on landscapes increase, biodiversity nearly always declines (Young et al 2005; Li et al 2010; Dirzo et al 2014; Fraser et al 2019). Infrastructure construction is part of economic development and may affect biodiversity and the ecological quality of landscape in different ways (Coffin 2007): direct habitat destruction, increased environmental pressure (e.g. exhaust or noise), and lower connectivity due to habitat fragmentation (van der Grift et al 2009; Wilson et al 2016; Torres et al 2016; Sawaya et al 2019). Several authors argued that it is imperative, given the large financial resources used to construct wildlife crossings, to conduct well-performed evaluations of the effects of these structures on long-term viability of adjacent wildlife populations (Corlatti et al 2009; van der Ree et al 2009; van der Grift et al 2013). Earlier studies showed clearest effects when corridors connect the same habitat type (Eycott et al 2010; Hodgson et al 2011). Roedenbeck et al (2007) and van der Grift et al (2013) called for research designs with greater inferential strength and especially argue for either a manipulative or non-manipulative Before-After-Control-Impact (BACI) approach for most relevant road ecology questions as the preferred research designs
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