Ecological influence of land protection status on landscape dynamics.

Protected areas (PAs) represent cornerstones of biodiversity conservation at all governance levels, from local to international. Traditionally their establishment has been based on the protection of threatened species and habitats or of singular landscapes to ensure their maintenance into the future [1]. In the last two decades, European countries have made large efforts in the establishment of protected areas with the aim of maintaining or improving the conservation status of the biodiversity associated to their natural and cultural landscapes, even in the face of changing environmental conditions. However, up to date, the effectiveness of PAs has rarely been assessed formally [2].

In this study we assessed landscape stability in PAs, as a measurement of the effects of the protection status of the territory at a regional scale, using as a case study 28 municipalities on the southern slope of the Cantabrian Mountains (NW Spain). More than 50% of this area has been protected under different schemes since the beginning of the 1990s (e.g. National Parks, Natura 2000 sites, Biosphere reserves). Using land cover maps derived from supervised classification of LANDSAT images [3], we assessed whether the extent and spatial configuration of forest and shrublands (including heathlands) differed among PAs and non-PAs at the regional scale from 1991 (when PAs began to be declared) to 2004. In particular, we calculated several patch-base metrics – shape index, mean area and number of patches [4] – and the area occupied by core and isolated patches and corridors [5] in each time period. We used general linear mixed models to evaluate the influence of land protection on the observed dynamics.

Protection has generally been effective in maintaining and increasing forested areas (+5% in the entire period) and their connectedness (increase in the extent of corridors), although the recovery of forested areas was also detected in non-PAs undergoing land abandonment (+0.47%). These favourable results for forested areas came at the expense of core shrubland patches, which were mechanically removed or fragmented (-10% in PAs) to increase the availability of foraging resources for extensive grazing and reduce fuel connectedness and therefore, the risk and extent of wild forest fires.

Our results indicate there is ample potential for improvement in the management of PAs in the Cantabrian Mountains. In particular, landscape management strategies to date have tended to favour the protection of forest stands. Management objectives should be expanded to ensure a better balance of land cover representation, increasing the efforts devoted to those shrublands/heathlands of high conservation value [6]. Landscape-scale analyses can then be used effectively for monitoring and assessing the effectiveness of PAs in achieving their multiple objectives.