The Sea Holly was first found, in Norway, at Lista in 1826 and Norway’s main population has always been situated here. Today, more than 90% of the Norwegian Sea Holly population grows at Lista. In 2010, the botanist Oddvar Pedersen started collecting seeds from a lonely, old individual, and brought them to the Botanical Garden in Oslo. Here they grew before he took them back to Lista, but they didn’t survive. In connection with the preservation strategy, The County Governor of Agder took the initiative to plant new Sea Hollies. In 2020 Oddvar made another attempt to increase the population at Lista and brought new seeds to the botanical garden that over a two year period had grown into 154 individuals. Compared to previous plantings this one resembled a combination of a military operation and a seminar. In total, we were around 20 people that took part in this operation. Even a Facebook-group was started for organizing people to take further care of them, hoping for a higher survival rate this time. Sadly, it was not as successful as hoped.
This intervention is therefore a greenhouse to increase the likelihood of survival for newly planted Sea Hollies. The growth of the Sea Holly each year starts with the development of one or more basal leaves. It has a well-developed taproot, that can reach a length of 3-5 m. The roots have access to the water-table, which in dunes is frequently about 3–4 m below the surface, although this varies with site and season. The thick taproot enables the species to hold water reserves, and it is able to survive dry periods. It receives nutrients from sea spray, and material blown from the drift line.
This part of my diploma is therefore a greenhouse to increase the likelihood of survival for newly planted Sea Hollies.The greenhouse consists of five timber frames fixed to a foundation of rammed earth lined with geo-textile. The facade, roof, and gutter is made of natural polymer composites. Water buckets at either end are placed to collect rain water to water the plants inside.Both greenhouse and water buckets are fixed in the sanddunes using spears. The house has three levels, corresponding to the three stages of Sea Holly planting. First the seeds ripen on the top shelf. Once ready to sprout, they are planted in pots and placed on the second shelf. And after growing for two years, they are ready to be planted directly in the sand. After five years, the Sea Hollies have outgrown the need for the greenhouse, and the timber frames, facades, roof, and gutters are demounted and moved to a new location where the cycle is repeated. By this time, the roots have anchored the Sea Hollies, while the foundations of the house start to decompose. Slowly the remains of the house disappear, and the Sea Hollies take over.
Supervisors Matthew Anderson and Lisbeth Funck