Surveillance of habitats and plant diversity indicators across a regional gradient in the Iberian Peninsula

Located in the west of the Mediterranean and with high environmental heterogeneity, the Iberian Peninsula represents a challenging region for designing and implementing observation systems for landscape, habitat and species diversity indicators. Within the framework of a project designed to set up a European Biodiversity Observation Network (EBONE), a standardized protocol for field survey was used in pilot sites located across a major gradient in Portugal and Spain. Results are presented and compared to assess the efficiency of the method in detecting patterns along this gradient. These sites represent different types of Iberian landscapes selected using a stratified random procedure implemented in the Madrid province (Spain) and in the north of Portugal. Species and habitat richness and diversity (as well as their components) are compared in their relation to environmental gradients and survey area. Results from spatial analyses of landscape heterogeneity are also presented and discussed in relation to appropriate indicators. The implications for setting up cost-efficient observation schemes that capture the key indicators effectively are discussed. Perspectives for integration with complementary monitoring schemes targeted at key species, habitat and landscape indicators are also discussed in order to optimize the power and efficiency of these observation networks. © 2012 Elsevier Ltd. All rights reserved.