Fruitful symbiosis of birch and lupin helping birch woodland restoration
18.02.2021
A view over Graystone Heath towards Húsavík town. In the foreground you see an area sowed with lupine and subsequently planted with downy birch a few years later. Together these two plant species are forming a typical birch woodland ecosystem rich in biodiversity. For instance, we see woolly willow, a species nonexistent elsewhere in the area. Screenshot from the video
An interesting symbiosis of lupine and birch can be seen on Graystone Heath, a badly eroded site just south of the town of Húsavík, North-Iceland. Where the two species are growing separately, both are struggling to survive. Where they are growing together, on the other hand, they are thriving.
Graystone Heath (Icel. Grásteinsheiði) lies at elevations of 200-300 m above sea level. Despite decades of protection from grazing, there has been no natural vegetation improvement in the area. Therefore, the erosion continues, with one exception though, former gravel areas where lupine was sown in 1993 in the effort of reclaiming healthy vegetation.
The most interesting thing are areas where birch was planted along with the lupine, as they are showing the greatest improvement. Elsewhere, lupins are even declining with little signs of other vegetation replacing them. The Icelandic forestry has released a short video-footage clearly showing this fruitful symbiosis of the two species mentioned, downy birch (Betula pubescens) and nootka lupin (Lupinus nootkatensis).
The land needs help
Through Grásteinsheiði Heath and Grjótháls Ridge, the road from Húsavík leads to Þeistareykir geothermal area. With the growing population of the town Húsavík around the mid 20th century, people moving from the countryside often brought parts of their livestock with them to secure their living. The sheep were kept grazing in areas adjacent to the town, a practise soon leading to heavy overgrazing, followed by extensive vegetation decline and soil erosion. Similar examples can be found in the vicinity of urban areas in many parts of the country. Many of those sites have been recovering with decreased grazing or protection over the last decades. But that is not the case with Graystone Heath. Due to harsh conditions in the area, it is evident that by itself, nature would need generations to regain a healthy and sustainable vegetation cover in the area. Almost no vegetation improvement has been shown during the 30 years since the area was fenced off to protect it from grazing. Water and wind continue to gnaw off the land. Eroding forces are still active. Vegetation is still declining.
Severe environmental problems
Eroded sites such as Grásteinsheiði Heath emit a lot of carbon into the atmosphere, making them a considerate part of the climate problem in Iceland. Instead of being in healthy cycle, soil organic matter is rotting away. The decomposition produces carbon dioxide (CO2), which is released into the atmosphere. Even though research is still lacking so that accurate emission figures can be produced, there is no doubt that decomposition of organic matter in declining vegetation ecosystems is one of the largest sources of greenhouse gas emissions in Iceland.
For years, Húsavík residents have worked extensively and with great success on revegetation and forestry projects, both around town and in nearby areas. Heavy dust storms used to be a frequent environmental problem in the area. Now, such events are all but history, thanks to reclaimed vegetation cover and growing forests. But that does not mean there's nothing left to be done.
The association Húsgull (meaning "House Gold") has contributed greatly to this work, as well as to comparable projects in other parts of the district. The one especially worth noting is the heavily eroded area of Hólasandur north of Lake Mývatn Nature Reserve. Over there, Húsgull has been working in collaboration with the Icelandic Soil Conservation (ISC), the Icelandic Forest Service and others. Like in Graystone Heath, lupine has proven to be very useful for speeding up land recovery.
At Graystone Heath, a few patches of gravel land were sowed with lupine by the ISC in 1993. Ever since, the lupine has been spreading slowly, mostly into barren areas, halting wind erosion by covering the soil and closing water channels where the soil was being flushed out. In recent years, however, it has been noted that lupins have been turning to decline on the first patches where it has been growing the longest. Whatever the cause, the lupine seems to be retreating from the centre of the former gravel patches without leaving much prosperity for other species to thrive. Exceptions to this are the areas where downy birch was planted in the lupine fields a few years after the sowing of the lupine. Together, both species are growing well and gaining ground for other plant species to come along.
Fruitful symbiosis
On the other hand, where the birch and lupine do not coexist, neither of them seems to be thriving, if not dying all together. In other words, coexistence clearly benefits both species and in fact many more species, because already there are willows, grasses, flowers and more sowing themselves into the area. Species such as woolly willow (Salix lanata) are nowhere to be found but in these birch-lupine areas. Elsewhere in Graystone Heath, the woolly willow has no potential. In the growing birch forest, it's thriving.
From this it is seems quite clear that the interaction or symbiosis of lupine and birch creates the means for strong vegetation development on the site. The number of species is gradually increasing, and it is evident that a typical Icelandic birch woodland ecosystem is beginning to form with its characteristic diversity of life. Over time, the birch will overshadow the lupine, which will retreat in the end. Instead, we will see the forward-march of the many typical species that characterize the Icelandic birch woodlands. At Graystone Heath and Grjótháls Ridge, about 2,000 hectares are waiting to be allowed the benefit of this effective and eco-friendly land reclamation method. The same can be said of the hundreds of thousands of hectares of degraded land throughout the country. The method of Graystone Heath described in the video can widely be applied in a sensible way resulting in resilient birch woodland ecosystems similar to those covering a large part of the country by the time of human settlement 1100 years ago.
The drone flight and filming over Grásteinsheiði Heath was carried out by Árni Sigurbjarnarson, an active land reclamation and forestry enthusiast in Húsavík. He is namely one of the promoters of the association Húsgull. We acknowledge him dearly for allowing us the use of this excellent material.