Like aquatic and terrestrial organisms, soil organisms are threatened by a series of environmental issues. The major threat that they face is habitat loss, which results from land conversion, pollution, climate change and invasive species. Agricultural activities such as “tillage” alter composition of bacterial communities and reduce diversity of soil fungi and larger animals. Construction of roads, buildings and street pavement damage the soil structure and destroy soil organism’s habitat.
Habitat degradation occurs when the soil is polluted. Pollutants such as heavy metal and excess nutrients change the soil environment chemically, usually in an abrupt and profuse manner. This makes the soil condition unfavourable for many existing soil microorganisms. As a result, only a few pollution-tolerant species survive and dominate the community. The overall microbial diversity and activity decrease.
The alteration of environmental parameters as a result of climate change also affects soil organisms. Increased concentration of atmospheric CO2 triggers responses of soil fungal communities. Such responses are reflected in the amount of living plants in the area. Quantity and frequency of rainfall and changes of temperature also impact underground animals such as insects. However, the impacts vary by taxon (unit used by scientists to classify organisms) and ecosystem as some are more resistant to environmental changes while some are more vulnerable.
The intrusion of invasive species such as exotic plants brings changes to the soil environment as well as underground microbial communities.
Their roots release a new combination of chemicals e.g. sugars and enzymes into the soil. The type and amount of chemicals are different from the ones released by original plant communities. This affects the activity and population size of microbial community at the rhizosphere i.e. portion of soil surrounding roots of living plant as its biological and chemical properties are influenced by the roots. The invasive plants also impact the soil organisms by interfering with nutrient cycling e.g. the legume plants, or changing the amount of litter and root inputs.
Conservation measures to support soil biodiversity include managing natural areas, restoring degraded ecosystems, adopting sustainable farming practices and adapting urban areas for both nature and people. Identifying undisturbed land and protecting it are important to sustain soil biodiversity as the habitat quality of soil organisms is maintained. Other than that, both artificial and natural revegetation of disturbed land help soil microbes and fauna to re-establish.
Sustainable farming practices are also important in conserving soil biodiversity. Reduced tillage, crop rotation, planting of cover crop and retention of litter are some useful measures to improve soil quality as well as support soil biodiversity. Allocating spaces for greenery and wildlife in urban planning, establishing green roofs and rain gardens, reduced soil compaction and using mulch as groundcover are some of the ways that encourage soil biodiversity in urban areas.
References:
Alizabeth M. Bach, K. S. (2020). Soil Biodiversity Integrates Solutions for a Sustainable Future. Sustainability, 2662.
Nihorimbere, V., Ongena, M., Smargiassi, M., & Thonart, P. (2011). Beneficial Effect of the Rhizosphere Microbial Community for Plant Growth and Health. BASE, 327-337. Retrieved from https://popups.uliege.be/1780-4507/index.php?id=7578
Urban Biodiversity Initiative (UBI) 