Biodiversity in the Netherlands is declining rapidly, partly due to the fragmentation of nature reserves. David Kleijn and Philippine Vergeer, professor and associate professor of Plant Ecology and Nature Management at Wageningen University & Research, are therefore working on a solution in the province of South Limburg: together with local stakeholders, these WUR researchers are restoring connecting zones between nature areas in the valley of the river Geul with minor interventions in the landscape. The University Fund Wageningen has started a crowdfunding campaign to help the researchers finance these measures.
'Nature areas are fragmented, sometimes fenced and delineated by a ditch. On the other side of the ditch, there is intensive agriculture. That is how we humans have designed the landscape: wild animals and plants here, farmland and cows there. But that is not how it works. The fragmentation prevents animals from roaming freely, and plants from growing where they naturally would, while this is precisely what is needed for cross-pollination and genetic variation', says David Kleijn. "If you just look at the plants, about 17 percent of all species have disappeared in South Limburg since the 1950s, and at the moment another quarter is on the verge of collapse," Philippine Vergeer adds.
Minor interventions
This has to change, the researchers thought, and they started to look for ways to interlink nature and other uses of space. They sat down with various stakeholders (farmers' organisations, municipalities, nature protection organisations, the water authorities, waterworks and the province) four years ago for the first time to discuss how the landscape might be designed differently through minor interventions rather than drastic, costly changes.
Restoring natural gradients, the transition between areas of nature and cultivation, is an example of this. The parties agreed that field margins, hedges and verges in agricultural areas were to be ecologically managed, so that they could function as a link between the fragmented plots of nature. The hilly countryside of Southern Limburg is exceptionally suited for this type of intervention, as it historically contains lynchets, earth terraces with permanent vegetation that result from erosion or have been constructed by farmers wishing to level their fields.
Bee-friendly management
The bee-friendly management of water buffers and natural meadows is another such example. This means the fields are mowed in stages, so that there are always some flowers throughout the season. David Kleijn: 'This may appear a small intervention, but once you start to discuss it, you discover how complicated everything is in the Netherlands. There are always multiple parties that are involved-for example, not just the farmer but also the lessor and the water authority.
A project such as this reveals how complicated things are in the Netherlands
However, most parties are very affable. The fact that measures to counter the loss of biodiversity are necessary is widely accepted. Nature has already proven to be very resilient. The shrill carder bee, for example, returned to Limburg, and the bee population has demonstrably increased in recent years.
Unique and complex ecosystem
The ecosystem within which the study is set - the Geuldal, between Valkenburg and Gulpen - is, like many ecosystems, unique and complex. Plants that depend on the specific local circumstances, such as calcium in the soil and calcium-rich expelled groundwater, grow here and almost nowhere else in the Netherlands. The researchers want to reintroduce larger populations of these species into the landscape. 'However,' says Philippine Vergeer, 'this requires detailed knowledge of the ecosystem. If these so-called abiotic factors (calcium, seep) are lacking, these plant species will not occur, so there is no point in simply planting them somewhere by the roadside.'
The project will not be finished for a while. 'The project will only be completed once the population of wild bees has permanently increased in size and diversity', says David. 'You need to be able to prove that the increased biodiversity is the result of your intervention to show that certain measures are necessary to increase biodiversity sustainably. And, above all, you want the idea of biodiversity to become firmly entrenched within the area's inhabitants' way of thinking. Only when biodiversity becomes everyone's concern can we prevent the most cost-effective management methods from being selected time and again. A wealth of flora is an excellent indicator of the state of nature. If the area is suitable for bees, it is also suitable for many other species.'
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Taking all these measures costs money. David: "At the moment, it is almost impossible to get government subsidies for nature areas outside Natura2000 areas, while we think that we can make up for a lot of loss in these areas. The money from this campaign can make a difference by very strategically restoring those landscape elements in certain places and thus improving biodiversity. This is how we turn fragments of nature into a large nature reserve again."
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