News - February 18, 2010

Salt opens up verges

This winter the roads have been salted more than ever before. Does this harm nature along roadside verges? Vegetation specialist André Schaffers of the Nature Conservation and Plant Ecology Group says it could be worse.

'Salt increases the concentration of ions in the soil. This then raises the osmotic value, which you could call the absorption power, of the soil. Plants experience this as a kind of severe drought and common natural vegetation can't cope with that. Plants wither and shrivel up. Fortunately salt is a highly soluble substance and most of it is washed out of the soil again in the course of the year. We have now had very cold winters two years running and I am definitely expecting gaps in the vegetation. In the first metre especially, the vegetation will become more open.
But there are plants that do cope with it. Coastal and tidal marsh plants are slowly spreading inland. Danish scurvy grass, common saltmarsh grass and thrift seapink, for instance. This development has been noticeable since the sixties. The question is: does it matter? Roadside verges have an important function in our country. Four percent of our land surface is natural area. One and a half percent is roadside verge. That's quite a lot. Those verges aren't fertilized, although they are nearly always managed.
Potentially, they are little natural areas. We do already have the ecological main structure, this is what I always say. Some vegetations are unusual. If they disappear then that is a serious matter, but those special vegetations aren't usually found in the first few metres. So I take a cautious view. You won't hear me saying we mustn't salt the roads because it is bad for nature. The verges are not going to dry up and become barren at a blow. And the question of what is a terrible loss and what is recuperation, well, that depends on your definitions. There will always be something else to take the place of what is lost.'