Over the last decades abandonment of farm land can be observed in several parts of Europe (Pointereau 2008, Brouwer et al 1997 and Pinto Correia 1992). Mainly due to the declining viability of small scale and / or extensive farming systems, farmers are sometimes forced to give up the land management which allows for natural succession, and eventually can lead to an increased dominance of shrubs and forest growth. This process might result in new wilderness, but it can also threaten biodiversity, especially in the so-called High Nature Value (HNV) farmlands, including ecologically valuable grasslands.