Climate regulation: and Ibiza, Biodiversity and Culture (Spain)

An important feedback loop exists between ecosystems and climate. While ecosystems regulate climate by influencing the mechanisms of water, energy and greenhouse gases (GHGs) exchange between land and the atmosphere, climate variation itself impacts the dynamics of ecosystem processes, determining the maintenance of their integrity and capacity to provide goods and services for people (Bonan, 2008; Foley et al., 2003; Heimann & Reichstein, 2008; Millennium Ecosystem Assessment, 2005; World Bank, 2010). As such, climate regulation is important to ensure the normal functioning of the biosphere, which in turn will maintain the delivery of regulation services. The latest IPCC report states that "continued emissions of GHGs will cause further warming and changes in all components of the climate system" (IPCC, 2013). Under current climate change scenarios, protected areas are key to ensuring the provision of regulation services that can act both in terms of mitigation, by sequestering carbon and reducing deforestation; and in terms of adaptation to climate change, by ensuring the resilience of the ecosystems to extreme events is maintained and services such as climate regulation continue to be provided (World Bank, 2010).The two case studies –the Canadian Rocky Mountain Parks and Ibiza - have been selected to highlight the benefits ecosystems deliver through climate regulation in terrestrial and marine environments.

Key messages

- World Heritage Sites that contain large tracts of forest can significantly contribute to the delivery of climate regulating services by ensuring that carbon stocks remain undisturbed.

- Coastal and aquatic ecosystems also play an important role in carbon sequestration by capturing significant amounts of ‘blue carbon'

- Regulation effects occur not only on a local scale, but taken together these sites can also impact the global climate system; therefore, World Heritage sites can be of particular importance for mitigating further impacts of climate change

- Since the effects of climate change already occurring are likely to not be reduced even under best-case scenarios, it is important for areas that provide regulation services to be managed and have a protection status, given that they too are likely to suffer indirect consequences from a changing climate.




Ibiza, Biodiversity and Culture (Spain)

Christine Pergent Martini

Location and World Heritage designation

The World Heritage site "Ibiza, Biodiversity and Culture" is located in the Balearic Islands, Western Mediterranean. This site was inscribed on the World Heritage List in 1999 as a mixed site for both its cultural and natural values. The site provides an excellent example of the interaction between the marine and coastal ecosystems (UNEP-WCMC, 2011) and includes areas of salt marshes and seagrass meadows. The natural component of the World Heritage site is included in the Salinas de Ibiza y Formentera Nature Reserve. The site has also been declared a Special Protection Area (SPA) and is included in the EU Natura 2000 Network, and is a Zone of Special Protection of Birds.

The marine component of the site, with an area of 13 776 ha, includes the open sea between these islands up to limit of the 40 m depth. The main part of the underwater area in the Salinas de Ibiza y Formentera Nature Reserve is a vast underwater platform with sandy substrate, spreading between Ibiza and Formentera Islands. The area is characterized by dense and very well preserved coral reefs, dominated by Cladocora caespitosa, and P. oceanica meadows. P. oceanica is considered as an endangered species of the Mediterranean (e.g. Barcelona Convention – Annex II of the SPA/BD Protocol) (UNEP-MAP-RAC/SPA 1995).

Climate regulation

The literature provides sufficient evidence on the capacity of submerged aquatic vegetation to physically and chemically engineer their environment and to supply coastal protection services, a term applied to describe the benefits that human populations obtain from ecosystem functions (Millenium Ecosystem Assessment, 2005). Seagrasses are one such ecosystem and are known as ecological engineer species (Wright and Jones 2006). They provide important ecological services (Costanza et al. 1997) such as organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions (Orth et al. 2006).

The Posidonia meadows play an important role in the dynamic and evolution of the coastal zone of the islands and the interaction between the marine and coastal ecosystems. The plant material produced in the meadows, supplies significant quantities of sediment and nutrients to the beach and associated dune system, particularly in regions where sediment production is of biogenic origin, as in the Balearic Islands (Marbà 2009).

Posidonia oceanica seagrass meadows can absorb and bury a significant portion of atmospheric CO2, helping to reduce greenhouse gases and regulate the planet's climate. This meadow acts as a long-term carbon sink which stores five times as much carbon for each kilometer of coastline as the average recorded for the Mediterranean.

Posidonia meadows produce an excess of organic carbon which can be stored in a specific structure, called "matte". Due to the slow decomposition, the organic fraction of the matte can be preserved for a long time, forming structures several meters thick (Mateo et al. 1997). Therefore the matte acts as a long-term carbon sink with the sequestration of carbon for several centuries or even thousands of years (Boudouresque et al. 1980; Mateo et al. 1997). Although several studies have highlighted the major role played by coastal vegetation (salt marshes, mangroves and seagrasses) in carbon sequestration, with more than 70 % of the  ‘blue carbon' stored (Nellemann et al. 2009), P. oceanica has the largest documented organic among seagrass species (Fourqurean et al. 2012; Serrano et al. 2012).

P. oceanica meadows of the Balearic Islands are particularly abundant (Diaz & Marbá, 2009). The P. oceanica meadows within the Ibiza World Heritage site constitute more than 70 % of the meadows of Ibiza and Formentera islands, and in comparison to the whole Balearic Islands, they have the highest ratio between surface of seagrasses and length of coastline. This area shows an exceptionally high carbon fixation rates (0.23 106 tC a-1 or 0.84 106 tCO2 a-1). The Balearic Islands' contribution to total national emissions of the greenhouse gases is 2.4 %. However, emissions per capita in the Balearic Islands are slightly higher than the national average and, since 1990, the population of the islands has increased by 45.3 % and has been accompanied by an increase in emissions per capita (Mac Cord and Mateo 2010). So it can be estimated that P. oceanica meadows surrounding the Islands offset 8.7 % of these emissions. The total stock accumulated equals 105 years of the Balearic Islands' CO2 emissions. The store of carbon sequestered beneath the meadows (matte) corresponds, for each kilometre of coastline, to an accumulation five times higher than the average recorded for the Mediterranean. On the global carbon market, this stock is valued at 4 billion euros, i.e. around 6 € m-2. These estimates confirm the outstanding role of Posidonia oceanica in the Balearic Islands as a carbon sink (Pergent et al. 2012).