ICELAND TREE PLANTING NEWS
As you all know, Iceland is a big focus for our reforestation efforts this year. Birch woodland is the only native woodland ecotype found in Iceland and is composed with over 95% Downy Birch and a small scattering of tea-leaved willow, rowan and aspen. This means the natural composition is close to being a monoculture which has a hugely reduced capacity for supporting biodiversity. This has presented us with a conundrum of finding a balance between planting native species and increasing the biodiversity of Iceland’s forests.
I’ve been doing some research into different strategies for improving the ecological capacity of the forests. To start with, I looked back into Iceland’s geological history and fossil pollen records which show Iceland used to support tree species including Pines, Alders and Larches up until the more recent glacial periods. This pattern can be seen across much of northern Europe but due to the spatial isolation of Iceland, natural recolonisation has been incredibly slow. If we look across to Scandinavia, particularly Southern Norway, which closely matches in climate to Iceland, we can see that it supports a greater species diversity. We can use this to predict which species are suitable for Icelandic climate.
Grey Alder (Alnus incana) and Black Alder (Alnus glutinosa) are naturally found in birch woodland throughout Europe and are excellent pioneers of degraded soils because they form nitrogen fixing root nodules that increase nitrogen availability in the soils for all surrounding species. This makes it an excellent candidate for increasing Icelandic forest diversity with the added benefit of improving nutrient availability for other species. However, as it’s been around 500,000 years since Alders last naturally seeded in Iceland, they are now classed as a non-native species. As a general rule, we try to avoid using non-native species in our projects but there are a few cases, such as this one, where a non-native species can add considerable ecological value. This is recognised in the EU Taxonomy for Sustainable Activities which states the use of non-native species should be excluded unless it can be demonstrated that their use leads to favourable and appropriate ecosystem conditions.
Non-native species are already used in forestry regeneration with the Icelandic Forestry Service planting Lupins which also carry out nitrogen fixation but the Lupins are becoming invasive and outcompeting other species (see our video on “Iceland’s deserts are turning purple”). Alder poses virtually no risk of turning invasive as we can see that it forms balanced, healthy birch woodland in the similar climate of Southern Norway. Iceland already has some established Alder which will allow us to use local seed stock in our planting mix, further reducing the disease transmission risks associated with non-native species.
Cheers,
Ellie (Conservation Biologist at Mossy Earth)
If you would like to become a member and support our rewilding and reforestation efforts then be sure to check out https://mossy.earth/
Source
