The delicate balance between tourism and coastal dune pollination networks
The integrity of ecosystems and their ability to withstand future environmental changes worldwide are threatened by human-induced disturbance. Coastal dunes, including beaches, dune cordons
and interdunal wetlands, are considered among the most threatened ecosystems globally. The intense concentration of human activities and mass tourism are leading to the loss and fragmentation of coastal dunes.
In addition to this, mass tourism is also considered one of the most important factors in threatening the integrity of the last natural areas. Indeed, the effects of human disturbance have been widely recognised in local changes in species richness, with terrestrial plants and insects being the most affected groups of organisms. In order to prevent the degradation of natural areas, it is essential to understand whether, and under what conditions, tourism can be permitted.
In coastal dune ecosystems, animal-mediated pollination has a marked influence on the dynamics and diversity of plant communities. In addition, coastal dunes are a hotspot for a number of pollinator species that are highly specialised for dune habitats (particularly hymenoptera), many of which find sandy sediments a suitable substrate for nesting.
Understanding the relationship between species from two different trophic levels, which influence each other, is of great importance for the conservation of their populations and for maintaining the resilience of ecosystems over time.
Nowadays, the pollination process is increasingly threatened by human-induced extinction of plant and animal species due to the same factors that threaten the conservation of coastal dune ecosystems: land-use change, habitat loss and fragmentation, and invasions of non-native plants and animals.
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Pollination networks represent the structure of the ecological community and describe the interactions between species, offering the opportunity for a holistic assessment of ecosystem structure and functioning. .
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Dr. Edy Fantinato of the University of Venice Cà Foscari, coordinating partner of the Life Redune project, addressed the issue of assessing the impact of tourism on the structure and resilience of pollination networks in coastal ecosystems (1). The study was conducted on the North Adriatic coast, in seven sampling sites freely accessible to tourists and with different levels of tourist pressure: three at Vallevecchia, two at Laguna del Mort and two at the Cavallino Peninsula.
Pollination interactions were recorded and analysed in correlation with human disturbance descriptors along transects from sea to inland. In total, 1173 interactions between 29 plant species and 173 pollinator species were recorded and three of the most informative descriptors of human disturbance on coastal dune ecosystems were measured: path density, range connectivity of land cover types intercepted by each transect based on the detailed habitat map (produced within the Life Redune project) and the relative abundance of alien floral displays.
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The study revealed that in addition to species richness, human disturbance also affects the structure and resilience of coastal dune pollination networks.
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Focusing on pollination interactions, the study showed that intense human disturbance can significantly influence both the structure and functioning of coastal dune ecosystems, causing local extinctions of plant and pollinator species and simplifying pollination networks.
However, the results indicate that moderate human disturbance could have positive effects on coastal dune pollination networks. A moderate level of human disturbance was positively correlated with plant and pollinator species richness. This result is not surprising, as it is not the human disturbance itself that is positive, but the rejuvenating effect it could have on local communities.
rejuvenating effect it could have on local communities. Indeed, moderate disturbance could help to increase the diversity of microsites and create suitable habitats for soil-nesting pollinators.
In addition to species richness, the resilience of pollination networks was also found to be highest at moderate disturbance.
In conclusion, evidence emerges that moderate disturbance and long-term conservation of coastal dune pollination networks can coexist.
However, in order to achieve this goal, tourism should be regulated and visitor access to coastal sites managed, so as to prevent human disturbance from compromising both the structure and functionality of coastal dune ecosystems.
