Serie, vierteilig. "In the series 'Birken', 2005, (...) Mansen takes up the idea of continual cutting. (...) In 'Birken', the trees trees remain where they are, but the spectator is moving towards them. (...) Basically, Mansen is exploring the degree to which a combination of white line cutting and black line cutting can be combined to achieve new effets. The use of coloured papers is a further innovation and enhances Mansen's possibilities."
Christian Rümelin, in Print Quarterly, December 2007, Vol XXIV, no. 4, p. 418f.