ÖSTERLEN’S ARBORETUM is located by the Baltic sea in Kivik, neighbouring the scenic Stenshuvud Nature Reserve. The 4 hectares are owned by SLU (Swedish University of Agriculture) and managed and developed by members of the nonprofit Österlens Arboretum Association.
In the lush vegetation, over 1,000 rhododendron seedlings and seedlings of many other exotic trees and shrubs have been planted since 2007, to find out which ones are able to develop in the mild climate and eventually, hopefully contributing to new exciting plant material in southern Sweden. In springtime, the lower parts of the arboretum are covered with an endless carpet of ramson. Large oaks and beeches spread out in the area are testimony that this was once pasture - the neighbouring Kivik Esperöd arboretum includes a European Oak (Quercus robur) that is estimated to be 1000 years old.
An ongoing experiment by one of the caretakers, Leo Sjöstrand - our guide at the visit, is planting grafted walnut trees and seeding black walnuts, after thinning out birches and other vegetation. The cultivars planted downhill since 2023/24 are Buccaneer, Broadview, Franquette, Lange van Lod, Maras 12, Solize and 139.
“My idea is to let Juglans nigra fill the niche previously occupied by ash (Fraxinus excelsior) as they die from ash blight, by directly sowing large quantities of black walnut where light gaps appear in the canopy when the ash trees fall. In the long term, this could lead to very interesting hybrids between Juglans nigra and the grafted varieties of Juglans regia that we have planted here. Maybe similar to Dooley’s hybrid which produces nuts that resemble Persian/English walnuts but where the tree has a growth habit, appearance and hardiness that is similar to the black walnut”, Leo explains.
Worth a notice, the grafted walnut varieties, some quite warm-requiring as the French Franquette, had spent the winter in pots in the arboretum, well protected by the dense vegetation, and overwintered without any frost damage.
The contract with SLU is due for 40 years and ensures continuity.
The long term wish, Leo explains, is to make this public recreation spot into a seed source and a learning site, possibly with a “plant station” engaged in plant exchanges.
Interestingly enough, walnut trees seem to prefer the same conditions as ash trees, and making use of the “sun pockets” resulting from fallen ashes, is a creative way to deal with assisted migration.
Another option would be to plant walnuts next to ashes, the group contemplated, recalling a story told that many walnut trees in Scania died during the harsh war winters of 1939-42, with the exception of a few that had ash trees as neighbours.
In Nordic mythology the Tree of Life, Yggdrasil, is referred to as an ash that supports all creatures and represents the cycle of birth, growth, death and rebirth.
Is it justified to introduce walnut and sweet chestnut trees into Scania deciduous forests? If done with great care for native species and natural values, the answer is yes according to the group, arguing that the landscapes of tomorrow need to contribute to food and water security as an equal goal with biodiversity, as we will not be able to pass on the fossil energy and other finite inputs sustaining today’s food production to the next generations.
“Even
though the world has gone mad and everything seems to go in the wrong
direction, I find peace and comfort when spending my day in this
prospering greenery. The contrasts are striking; here I mow ramson while
at the grocery store next door they cost the earth”, Leo contemplated,
while we rested in the coolness of the trees on this hot day.
Kivik is known for its many apple orchards, the first established in the 19th century. With horticulture entrepreneurs, other trees were introduced as well; today, several large walnut trees and sweet chestnut trees grow in gardens and in public spaces in the area. In the future, Kivik and Southern Sweden might be known for these nut trees as well, as they have started regenerating naturally.
FUTURE FORESTS IN SOUTHERN SWEDEN
Since the 1960s, landowners have received subsidies to plant spruce monocultures on arable land and pastures, profoundly changing the landscapes and reducing biodiversity in large parts of southern Sweden. Now the Swedish Linnaeus University is exploring the future of forests in southern Sweden, (The Oak Project) studying whether and how different oak species can contribute to increased biodiversity that are better suited to meet the challenges that come with the ongoing climate change, compared to the spruce and pine stands of today. A recent study from the same University surprisingly reports that plant and insect diversity in Swedish oak forests increases toward the north.
An SLU project is since 2015 testing whether two different types of hybrid walnut (Juglans x intermedia): NG23 and NG38 can be grown on a larger scale in production forests, for timber and giving nuts while growing. So far, survival is at its peak and both grow very quickly.