Integrating field survey on geo-environmental factors and orthophoto information to monitor coastal dune habitats – A pilot study to evaluate coastal dune vulnerability

Plants play a crucial role in coastal sand dune development, because they interact directly with wind action, preventing sand movement. Vegetation works like an obstacle, in fact it deforms air flow and prevents sediment transport causing the decrease of the energy transfer. The interaction between vegetation, sand and wind shapes the coastal landscape, which is characterised by a sequence of different plant communities in accordance to a sea-inland ecological gradient mainly determined by salt spray, substrate incoherence, nutrient scarcity, water deficit, and high irradiance. Coastal ecosystems can be difficult to monitor effectively in the field because of the heterogeneity and discontinuity of these habitats. Integrating field analysis on several environmental variables with vegetation coverage obtained by orthophotos can be a challenging method to monitor coastal dune habitats. In particular, the aim of the present research is to integrate abiotic and biotic information to develop a vulnerability index in order to determine the conservation status of coastal dunes. This study has been planned in two pilot sites: Migliarino - San Rossore - Massaciuccoli Regional Park in Italy (Mediterranean Sea), and Acarai National Park in Brazil (Atlantic Ocean). In both sites, the following data will be collected: a) distribution and coverage of the different plant communities classified in three natural cover types (pioneer annual vegetation, herbaceous vegetation growing on embryonic and mobile dunes, shrub and woody vegetation of fixed dunes); b) geomorphological and sedimentological information (such as topography and sediment transport rate); c) acquisition of a set of environmental parameters (wind speed and direction, ground temperature and humidity) by means of wireless sensor technology. Relationships between plant communities coverage, geomorphological and sedimentological data, and environmental variables are investigated through Canonical Correspondence Analysis (CCA). An index of coastal dune vulnerability will be built integrating vegetation condition, geomorphological and sedimentological information, wind influence, and soil parameters. Results from the two pilot studies can be used for management and conservation planning.