Towards the identification and assessment of HNV Dehesas: a meso-scale approach

Iberian dehesa and montado are paradigmatic high nature value (HNV) agroforestry systems in Europe. Nevertheless their conservation status is uncertain as a consequence of their typological variety, different intensity of management practices on the ground, and other ongoing processes challenging their long-term sustainability. The existing broad gradients of dehesa and montado types impose difficulties in estimating not only their distribution and extent, but also their condition, since probably not all these agroforestry systems should readily be considered as HNV. Tackling with these difficulties, we explore a methodology based on GIS-analyses of land cover cartographies to estimate the extent and condition of dehesa farmland in an area covering ten municipalities in northern Andalusia region (Spain) based on: (1) integration of available thematic maps to obtain an improved land-use cartography; (2) application of GIS map generalization techniques to delimit potential HNV farmland types; (3) definition and calculation of several indices of 'structural diversity' and 'impact' within patches of dehesa farmland; (4) automatized weighted integration of indices to obtain a cartography assessing dehesa's HNV in an ordinal scale from very low to very high. Estimated natural value was significantly worse for cultivated dehesas, with dehesas of pastures showing higher structural diversity and lower impact indices. Weaknesses and strengths of the proposed methodology are discussed.