Soil Biodiversity Threat Assessment Tools

Understanding Underground Biodiversity

Underground biodiversity refers to the variety of life forms that exist beneath the soil's surface. This includes everything from bacteria and fungi to insects, worms and mammals. These organisms are essential for nutrient cycling, soil formation, and plant growth.

Mycorrhizal Fungi: The Unsung Heroes

Among the underground dwellers, mycorrhizal fungi are especially important. These fungi form symbiotic relationships with the roots of ~90% of all plant species, helping them absorb water and nutrients. In return, plants supply the fungi with sugars and fats. These trade partnerships are crucial for plant health and productivity, but also for the Earth’s nutrient cycle.

Mycorrhizal fungi however, like many other underground organisms, face threats from soil degradation, climate change, pollution, habitat loss, and agricultural practices. Understanding these threats is the first step in mitigating them.

Threats to Belowground Biodiversity

Several factors threaten belowground biodiversity, ranging from human activities to natural phenomena. Let's explore some of these threats:

Soil Degradation

Soil degradation is a significant threat to underground biodiversity. This occurs when soil loses its fertility and structure due to overuse, physical disruption, chemical contamination (e.g., from pesticides), or erosion. Roughly 80% of Earth’s agricultural lands are impacted by moderate to severe erosion. Degraded soils provide a less hospitable environment for underground organisms, reducing biodiversity.

Climate change

The effects of climate change on soil biodiversity differ among ecosystems and soil organisms. For instance, warming in Mediterranean forests might decrease total soil biodiversity, while warming in Tundra ecosystems could increase soil biodiversity. Similarly, certain soil taxa may thrive under the new climates, while others will not be able to cope and face extinction.

Pollution

Chemical pollutants, such as pesticides or toxic heavy metals from industrial waste, can have devastating effects on soil biodiversity. These substances can alter the chemical balance of the soil or disrupt critical biological pathways, making it inhospitable for many soil species. Approximately 2 million tonnes of pesticides are applied annually in crop systems.

Habitat loss

For mycorrhizal fungi, habitat loss occurs when their aboveground host plant dies or is replaced by a novel plant species. As a result, events like crop harvesting, forest clear-cutting, or the arrival of dominant invasive species represent habitat loss events for underground mycorrhizal fungi. From 2000 to 2020, the Earth underwent a net loss of more than 100 million hectares of forest cover, primarily from deforestation.

Agricultural Practices

Modern agricultural practices, such as monoculture and the excessive use of fertilizers, can disrupt underground biodiversity. These practices often lead to nutrient imbalances and soil compaction, which can harm the organisms living in the soil.

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Assessing Threats to Soil Biodiversity

Protecting species against extinction requires an understanding of threats that shrink their habitat or harm their ability to grow and reproduce. To protect belowground biodiversity, it is crucial to accurately assess the threats it faces. Several tools and methods can help in this assessment.

Soil Sampling and Chemical Analyses

Soil sampling is a fundamental method for assessing soil biodiversity and soil quality. Performing soil quality tests is not new — ancient romans used a variety of soil measurements to establish “solum bonum” or “good earth” as part of land valuations, including tasting for bitterness of viticulture soil and squeezing wet soil clumps to test for cohesion. By collecting soil samples and analyzing them in a laboratory, modern scientists can identify levels of nutrients, pollution, and organic matter to assess the health of the soil ecosystem and compare to the abundance and diversity of soil organisms.

DNA Sequencing

DNA sequencing is a powerful tool for studying underground biodiversity. By extracting DNA from soil samples, researchers can identify the different species present in the soil. This method provides detailed insights into the diversity and abundance of soil organisms, especially microbes such as bacteria, fungi, and viruses that are hard to distinguish even with microscopes. These genetic sequencing tools have unlocked our ability to study millions of different soil microbes that are the engines driving how soils work. See this article on how we use environmental DNA (eDNA) in our own research. 

Bioindicators

Soils contain an overwhelming number of species, which can make it difficult to focus on threat impacts across highly diverse communities. Bioindicators are specific species or groups of species that have large impacts on the diversity and functioning of entire systems, thereby providing information about an ecosystem’s overall health. Certain soil organisms, such as earthworms and specific fungi, can serve as bioindicators of soil health. Monitoring these organisms can help rapidly assess the impact of environmental changes on soil biodiversity.

GIS and Remote Sensing Technology

Advancements in GIS databases and remote sensing technology have made it possible to assess ecosystem conditions from a distance. There is a growing catalog of spatial data which can be used to predict general threats to ecosystems like climate change or urban expansion. New satellite monitoring systems are being built to track the location and causes of specific habitat disturbances like tree removal, which can severely degrade soil biodiversity and the vital forest ecosystem benefits that flow through soils. By using satellite imagery and other remote sensing tools, researchers can monitor changes in landcover, soil properties, and other habitat details to detect potential threats to biodiversity.

Protecting Underground Biodiversity

While assessing threats to soil biodiversity is crucial, it is equally important to take steps to protect it. Here are some strategies for conserving belowground biodiversity:

Sustainable Agricultural Practices

Adopting sustainable agricultural practices can significantly reduce the impact on soil biodiversity. Practices such as crop rotation, reduced tillage, and organic farming can help maintain soil health and support diverse underground life.

Pollution Control

Reducing pollution is essential for protecting soil biodiversity. This can be achieved by minimizing the use of chemical fertilizers and pesticides, as well as properly managing industrial waste.

Soil Restoration

Restoring degraded soils can help revive underground biodiversity. Techniques such as adding organic matter, planting cover crops, and reforesting areas with native species can improve soil structure and create a more hospitable environment for soil organisms.

Public Awareness and Education

Raising public awareness about the importance of soil biodiversity is crucial for its conservation. Education programs can help individuals understand the role of soil organisms and the threats they face, encouraging more sustainable practices.

Conclusion

Soil biodiversity is vital for the health and productivity of our ecosystems. However, it faces numerous threats from human activities and environmental changes. By using assessment tools like soil sampling, DNA sequencing, and remote sensing, we can better understand these threats and take action to protect underground biodiversity. Through sustainable practices, pollution control, and soil restoration, we can ensure that the rich diversity of life beneath our feet continues to thrive.

Protecting underground biodiversity is not just about preserving the environment; it's about securing the future of our planet. By valuing and safeguarding the life hidden beneath the soil, we contribute to a healthier, more sustainable world for future generations.