Globally, coastal ecosystems like Mangrove forests, sea grass meadows and salt marshes are well known for their ability to capture and store atmospheric carbon effectively. In Sweden, there is still limited knowledge about local coastal ecosystems with similar functions, with alder swamp forests being an interesting example. Therefore, this study aimed to increase knowledge of the factors that can contribute to the potential carbon sequestering ability of alder swamps. Vegetation data and sediment samples were collected from a total of 37 sampling plots across four alder swamps in Bohusl?n on the Swedish west coast.

In coastal wetlands carbon/organic matter can be stored for long periods of time thanks to, among other things, the presence of water which slows down the decomposition. Because of this, restauration and management of such habitats have the potential to decrease the emission of greenhouse gasses and help mitigate climate. Internationally these environments are called ?blue carbon? ecosystems. In Sweden, alder (Alnus glutinosa and Alnus incanata) covered wetlands along the coast is a nature type that potentially could function as a ?blue carbon? habitat.

Research suggests that society's vulnerability to natural disasters along coasts could increase as a result of climate change, which is likely to lead to elevated sea levels and possibly an increase in the occurance of meteorological phenomena such as storms and tropical cyclones. Following the Indian Ocean tsunami disaster in 2004 and Hurricane Katrina in 2005, both of which received considerable media attention, empirical data has indicated that coastal vegetation might be able to protect and reduce damages to coastal communities during tsunami events and tropical cyclones.The aim of the essay has been to study the function of coastal ecosystems as protection against tsunami waves and storms from a risk management perspective, meaning that I have, through an overview of scientific articles, compiled current research on how coastal ecosystems can attenuate storm surges and tsunami waves, and analysed how this knowledge can be put into practice in coastal communities from a risk management perspective, i.e. if coastal ecosystems are a viable risk reduction measure, are practically applicable, and if so, how they could be applied.There is empirical evidence suggesting that coastal ecosystems, particularly Mangroves, can reduce the strength of a tsunami wave, but full scientific consensus on this issue has not yet been reached. With regard to protection against storm surges, there is extensive scientific evidence that coastal vegetation can mitigate damages and reduce the height of a storm surge, although the wave has to traverse several kilometres inland through thick vegetation for the protection to be effective. A synthesis in the form of a figure regarding the many physical factors that influence wave development through coastal ecosystems has been created in an attempt to simplify and explain the phenomenon.The conservation and restoration of coastal ecosystems can be justified from a risk management perspective, but planting new forest belts for the purpose of disaster mitigation is quite unrealistic and can rarely be sustainable, since, for protection to be effective, the forest belt must extend several kilometres inland from the coast, and would thus likely prove difficult to implement along coastal societies..