Much of man's exploitation of land and soil has had a major negative impact on life below the surface. Often it is agriculture that is being talked about, but Stella Ek has in her master's thesis at Linnaeus University, done in collaboration with Ecogain, instead looked at the impact of the construction industry on biodiversity underground.
- "There are actors who are taking action in certain areas. But the majority are calling for more knowledge and also regulation to support their work on these issues," says Stella Ek.
Biodiversity focusing on soil organisms, i.e. the life hidden below the soil surface, has received significantly less research and media attention than species living above ground. This is despite the fact that around 25-30% of the world's biodiversity is represented in the soil, and faces many of the same threats.
The European Commission report 'Caring for soil is caring for life' (2020) states that 60-70% of soil and land in Europe is in poor condition. Policy makers are now trying to reverse this trend with better knowledge and regulation. The EU Soil Directive is coming soon, and many predict that more and bigger efforts lie ahead.
The construction industry has a major impact on life below ground
In her study, Stella Ek sheds light on how human impacts threaten our soil organisms, with a particular focus on the link to the construction industry. By comparing literature and survey responses, she has identified which activities mainly affect soil biodiversity, as well as the state of knowledge of the actors in the industry and how they deal with the challenges.
THE RESULTS SHOW SEVEN AREAS OF HIGH IMPACT:
- Removal of organic matter
During construction, the ground is leveled and topsoil is removed or mixed with other soil, construction waste and rock. This damages and degrades the quality of the soil and the conditions for life because nutrients are lost, the structure changes and it becomes more difficult for roots to penetrate the soil or water to infiltrate, for example. - Soil sealing
When soils are covered with, for example, asphalt and concrete, the water and nutrient cycles are stopped, the heat balance is altered, the oxygen flow is reduced, and the carbon and nitrogen content decreases. All of this depletes the conditions for life in the soil and soil organisms risk dying. - Soil compaction
Occurs in transportation and in the use of heavy machinery or inefficient storage of soil. It forms a uniform, compacted layer of soil, where water and oxygen cannot penetrate, making it difficult for roots to grow, seeds to germinate, gases to be exchanged and burrowing creatures to move around. There is also a change in soil moisture content and an acceleration of surface runoff and soil erosion during soil compaction. - Soil contamination
Soil contamination during construction projects can result from spills, demolition and reuse of materials or when older contaminants in urban soils are exposed. For example, oil spills create a film on the soil, blocking gas exchange and thus stopping oxygen in the soil. This creates a lack of air, resulting in soil biota suffocation. - Habitat change and fragmentation
Urbanization where the remaining natural vegetation is too small or isolated means that some species do not survive. Often, green spaces are replaced with non-native ornamental species. However, exotic species may have completely different characteristics that pose risks to ecosystem processes, they may affect the soil water cycle or pH levels in a way that disrupts the natural system. - Managing invasive species
Earthworks and the transportation of soil, or the movement of soil when it is used elsewhere, can lead to the spread of invasive species. The flower lupine is an example of a well-known species that displaces other native species. This leads to changes in nutrient dynamics and affects the presence of microbial species in the soil. - Spreading of plastics
There is a risk of plastics leaking into the environment during packaging of materials and storage and waste, during transportation, and during cutting of plastic pipes, blasting and grinding on construction sites. A meta-study shows that microplastics reduce earthworm growth and reproduction, soil bacterial diversity is reduced and the microbial community structure can change.
Stakeholders call for more knowledge and support
Some 20 of the largest public sector construction actors and a handful of private actors participated in the study. A majority of them say they need more knowledge on these issues and are looking for help in implementing offsetting measures, but also for regulations, guidelines and training to better address the challenges they face in their work.
Soil contamination is the area where most stakeholders have procedures and take action to promote soil biodiversity. At the other end of the scale are habitat change and fragmentation, where most respondents say they never take action. Stella Ek believes this is due to the complexity of the issue, perhaps due to insufficient knowledge or lack of awareness. For example, not everyone in the industry knows what invasive species look like.
- These are often complex issues and the measures can differ depending on the conditions at a site or in a specific project. It is best to turn to skilled environmental consultants like Ecogain," says Stella Ek.
You can read the study in full here.
The study aimed to investigate the state of knowledge of clients and contractors of construction projects on issues related to the impact of anthropogenic activities on soil biodiversity in order to contribute to a better understanding of the current situation. As a result, no suggestions have been made regarding the most appropriate interventions to promote soil biodiversity. It is suggested that further research could focus on which interventions have long-term effects and are economically and ecologically sustainable.
