Landscape rehabilitation
The world is facing a natural crisis, and Norway has joined the UN Convention on Nature. An important solution to contribute to land neutrality is to reuse already developed areas and restore damaged nature, for example old mines. We want to restore wounds in the terrain with suitable treated masses.
As of today, the company has extensive experience with this from the rehabilitation of two craters from limestone extraction on Langøya. When these are fully filled and top-sealed, the plan is to continue rehabilitating the Vallnes Quarry in our quarry in Sokndal municipality. The vision here is to return the area to good commercial and industrial sites, as requested by the municipality. Read more in the link to the right.
Langøya
After 100 years of mining was Langøya in 1980 characterized by deep craters. Now the old limestone quarries are being rehabilitated and the areas are being returned to open air areas and natural landscapes with growing grounds for rare species. In the north, large parts are open with free access for the general public. In a few years, the southern part of the island will also be returned to an open air area.
The terrain is shaped close to the island's original topography, while ensuring good water drainage and functionality. The island's shape is built with treated and stabilized waste. Above the filling with stable waste gypsum, the island is sealed with a dense membrane of clay and a layer of native limestone. On top of the limestone is a thin layer of native soil. In total, 618 acres are returned as an open recreational area. The nature in the open recreational area is established as open shallow limestone; a species-rich and highly endangered habitat type that naturally belongs to Langøyas limestone soil.
The northern tip and the coastal strip on the eastern side of the island have been established as a nature reserve to protect rich fossil deposits in the Oslo field. The nature reserve comprises 212 acres. The fossils are from animals in clay layers on the seabed from 420 million years ago. The nature is characterized by lime pine forest and open, low-lying limestone ground.
The outdoor areas facilitate access and activity. Simple infrastructure such as paths and places for accommodation are established, while the need for maintenance is limited. Pressure on the nature reserve must also be limited.
Landscape rehabilitation
Since the early 1990s, NOAH has rehabilitated damaged nature from limestone mining on the island. Read more about backfilling and capping here..
The craters have been filled with treated waste materials, sealed and then re-vegetated back to the original habitat type, so-called open basal limestone. The habitat type is highly threatened in Norway and constitutes an important habitat for over 100 red-listed species, i.e. species that are in danger of disappearing from Norwegian nature.
Open shallow limestone fields are naturally treeless, open areas on calcareous bedrock, and are found along the coast in southern Norway where the climate is favorable. Although the habitat usually covers smaller areas, it is rich in species that depend on lime and bright, warm climates and are drought tolerant. Langøya is one of the few areas with both limestone soil and a warm climate, and is therefore a rare opportunity to establish a robust ecosystem for this endangered nature type.
The threats to open limestone soils include settlement, overgrowth and the spread of alien species. Overgrowth of trees and dense grass leads to shade and more organic matter, which threatens the specialized species that thrive in this barren environment.
Restoration of the natural type on Langøya is based on the use of local limestone and soil. The terrain is formed by a layer of limestone that protects a dense clay membrane over the stabilized plaster from Langøyas processing plant. A thin layer of soil is placed over the limestone, and becomes nature's growth layer. The soil is taken from Dambukt on the east side of the island, where it was laid aside during the period of mining. It contains older seed material, and contributes to the spread of naturally occurring species Langøya. Read more about the rare species that grow on Langøya here.. The aim is a natural re-establishment of the ecosystem. We have nevertheless chosen to plant some selected species, while at the same time carrying out systematic care to prevent alien species from establishing themselves.
The project on Langøya is in line with the UN Decade for Ecosystem Restoration. In December 2022, Norway signed the Nature Convention, which aims to stop and reverse the loss of nature and ecosystems. In 2020, the nature type open shallow limestone was already designated as a 'selected nature type' in Norway, with an action plan to improve the condition and take care of species diversity.
Other restoration work for open ground limestone is taking place on the islands in the Inner Oslofjord, especially within the conservation areas of Bleikøya, Nakholmen and Skilpadda in Oslo. This work is carried out by Oslo municipality on behalf of the state administrator in Oslo and Viken.
Sources:
The Nature Agreement: The global Kunming-Montreal framework for biodiversity (The Nature Agreement) - regjeringen.no
The Norwegian Environment Agency: Action plan for open limestone soil in the boreonemoral zone - Norwegian Environment Agency (miljodirektoratet.no)
Norwegian Institute for Natural Research (NINA): Open shallow limestone field (nina.no)
The state administrator in Oslo and Viken: Tablecloth for open, shallow calcareous soil.
UN: About the UN Decade | UN Decade on Restoration