Habitat monitoring in coastal landscapes: the use of vegetation pattern information for habitat discrimination in satellite images classification

Coastal environments are among the most threatened worldwide, undergoing numerous human-induced and natural pressures resulting in habitat loss, alteration and fragmentation. Conservation of coastal environments is one of the major concerns of the European Union Biodiversity Strategy to 2020, and periodic monitoring of biodiversity changes at different scales constitutes a key issue to adopt adequate conservation policies. Structure, composition and spatial pattern of coastal plant communities may be extensively surveyed by means of in situ methodologies. The integration of in situ data (vegetation) with earth observation (EO) data offer a significant enhancement, through direct or indirect mapping of habitats at different spatial and temporal scales. In the framework of the BIO_SOS project, funded within the European Union FP7-SPACE third call (www.biosos.eu), a pre-operational system for periodic monitoring of changes in land cover and habitats within Natura 2000 sites was developed. The FAO - Land Cover Classification System (LCCS) was considered as the most appropriate Land Cover/Use (LC/LU) taxonomy for habitat mapping, since in situ expert knowledge can be easily embedded in such a framework (Tomaselli et al., 2013). Besides a wide and in depth documentation on omposition, structure and ecology of plant communities, the effectiveness of information related to the vegetation pattern (zonation) has been also explored to enhance the habitat discrimination process. As case study, two coastal Natura 2000 sites located on the Adriatic side of the Puglia region were selected: "Le Cesine" and "Zone umide della Capitanata e Paludi presso il Golfo di Manfredonia". LC/LU maps were produced directly in LCCS taxonomy (scale 1:5000) on the basis of pre-existing information. In order to investigate the application of topological rules based on vegetation pattern for LC/LU to habitats translation, available literature data on ecological gradients and vegetation pattern relationships in Mediterranean coastal environments were examined. Then, in order to validate the feasibility of the rules in the study sites, eight vegetation transects (with regular vegetation plots) were carried out and vegetation composition and structure were surveyed in each plot. Data were analyzed and grouped in plant communities using multivariate analysis. Plant communities were related to syntaxa and then to habitat types according to Annex I (92/43/EEC Directive) and EUNIS taxonomies. The spatial patterns observed are in accordance with the existing literature for Central-Southern Italian peninsula and Puglia region (Biondi,Casavecchia, 2010; Biondi et al., 2006; Sciandrello, Tomaselli, 2014). Adjacency rules based on vegetation pattern turned out to be effective in habitat discrimination, and the products of the habitat mapping process were validated with high rates of overall accuracy. Nevertheless, the whole expected zonation is present only where pressures have none or low relevance. Human activities determining habitat loss, alteration and fragmentation cause deep changes in the vegetation spatial pattern. In cases of intense disturbance, regression effects may also occur (Acosta et al., 2007; Doing, 1985). Therefore, in defining and applying such rules, local expert information is required. Acosta A., Ercole S., Stanisci A., De Patta Pillar V., Blasi C., 2007. Coastal vegetation zonation and dune morphology in some Mediterranean ecosystems. Journal of Coastal Research, 23: 1518-1524. Biondi E., Casavecchia S., 2010. The halophilous retro-dune grasslands of the italian adriatic coastline. Braun-Blanquetia, 46: 11-127. Biondi E., Casavecchia S., Guerra V., 2006. Analysis of vegetation diversity in relation to the geomorphogical characteristics in the Salento coasts (Apulia-Italy). Fitosociologia, 43(1): 25-38. Doing H., 1985. Coastal fore-dune zonation and succession in various parts of the world. Vegetatio, 61: 65-75. Sciandrello S, Tomaselli V., 2014. Coastal salt marshes plant communities of the Salicornietea fruticosae class in Apulia (Italy). Biologia, 69(1): 53-69. Tomaselli V., Dimopoulos P., Marangi C., Kallimanis A.S., Adamo M., Tarantino C., Panitsa M., Terzi M., Veronico G., Lovergine F., Nagendra H., Lucas R., Mairota P., Mücher C.A., Blonda P., 2013. Translating land cover/land use classifications to habitat taxonomies for landscape monitoring: a Mediterranean assessment. Landscape Ecology, 28(5): 905-930