Rewilding Iceland

Before the arrival of humans, between 25% and 40% of Iceland was covered by forests. Link

Human occupation (agriculture, cutting wood for construction and fuel) reduced forest cover to 2% of the land area. There are groups who are attempting to reforest Iceland as well as other traditionally-forested places like Romania.

One group involved in this activity is doing something that I particularly like. Due to several extenuating circumstances they are reforesting with species that purists claim are "not native".

The group's reasoning is that there is evidence that the "non-native" species they are planting were part of Iceland's forests in the last 20,000 years but have since become extinct in Iceland.

Furthermore, Iceland is an island and if glaciation happens the species cannot retreat southward like they could in North America or China or to a lesser extent in Europe. They were expatriated from Iceland but survived in North America and Europe and returned to their former latitudes on those continents.

Perhaps a few species survived in tiny pocket valleys in Iceland or perhaps their seeds are particularly mobile and arrived on the feet or in the guts of wayward birds. So those few species are now the ones that made up Iceland's forests.

Green shaded area denotes native range of P. angustifolia. The ancestoral home is Kansas, Oklahoma and Texas. All of the other regions and all of the isolated patches are attributed to native-Americans moving them.

Another consideration is that there is evidence that many plants in the Eastern United States benefited from "human assisted migration" before Columbus took credit for finding the Western Hemisphere. Given Iceland's isolation, there have been very limited opportunities for human-assisted migration.

Iceland circled in red. Alder is one of the types of wood that was identified. Alnus incana exists in both North American (blue shaded area) and European populations (green shaded). Proximity favors the European population while the Gulf Stream (yellow arrow) favors Nova Scotia and Newfoundland populations

Undoubtedly, given another ten or twenty thousands of years these species would once again colonize Iceland. But why forego the benefits in the meanwhile by waiting for Mother Nature and random chance to act?

Alnus glutinosa is another type of Alder. A. incana is a shrub while A. glutinosa is a slender tree.

If you are not a "plant guy" you might be wondering about my making a big deal about a couple of obscure tree/shrub species.

There are two reasons. One is that adding one more woody species to the Icelandic portfolio increases it by a whopping 25%. More species means greater resilience in the event of environmental shocks. The second reason is that Alder species are capable of fixing nitrogen when their roots are colonized by the proper microbes. That is, they can pull nitrogen out of the air and turn it into fertilizer. A very cool trick on nutrient poor soil. The alder benefits and the surrounding plants benefit when alder drops its leaves in the fall.

As a person who lives in a region that was recently covered by glaciers (maybe 8000 years ago) I appreciate the ideological flexibility shown by those people who added Alders into the mix.