Despite last-minute protests, preparations have begun in Riehen near Basel to fell trees to make way for a German road through Swiss territory.
Police started removing more than 150 protesters from the area on the Swiss-German border early on Monday morning, some of whom had climbed and chained themselves to trees.
Protection of the wooded area has been the subject of protest and debate since Germany and Switzerland agreed in 1977 on the construction of a "customs-free" highway to connect the German cities of Lörrach and Weil am Rhein.
Police distributed leaflets to protestors telling them that anyone who attempted to resist the clearing of the land, either passively or actively, could be charged.
At the end of January, the Federal Court dismissed complaints against the extension of permission to clear the land, finally allowing the work to go ahead.
The issue will be tested at the polls this weekend in Basel, in the so-called "White initiative". The indirect aim of this vote is to block the building of the road.
Local government in Basel has made it clear, however, that the vote will have no effect on the project because the agreement signed with Germany takes precedence over protection of the environment.
Parliamentarian Remo Gysin, from the centre-left Social Democratic Party, described the planned clearing of the trees as "an absurd act" which would damage nature without good reason.
Last April the town of Riehen was found to offer the highest quality of life in Switzerland in a survey compiled by Idheap, the Swiss Graduate School of Public Administration.
swissinfo with agencies
Riehen, a Basel suburb with just over 20,000 inhabitants, is known for its many recreational areas, high average income and low unemployment.
The town also boasts generous spending on education, culture, health and the environment, public transport and active participation in political decision-making.
The renowned "wrapping" artists Christo and Jeanne-Claude, who among other things wrapped the Reichstag in Berlin, visited Riehen in 1998 to wrap 178 trees with 55,000 square metres of polyester.
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