Tag: soil

Biodiversity restated: > 99.9% of global species in Soil Biota

Soil’s vast biodiversity is under severe threat from topsoil erosion and poisoning, potentially leading to widespread extinctions.

More than 99.9% of global species diversity is found within soils, according to a new review paper published in ZooKeys.

Comparing different studies on soil biota, author Robert J. Blakemore challenges previous estimates, which suggested a much lower proportion of life in soils. “Most life is found in Soil and most is microbial, affected by the current mass extinction event having profound effects influencing all evolution on Earth,” he says.

From the review paper: “Micro monde” progressions with microbial proportions greatly increased from Blakemore after Larsen et al.

“Soil filters and stores freshwater stocks (being subject to Earth tides!) and, as well as ~ 99% of human food, it provides most building materials plus many of our essential medicines/antibiotics. Thus, an important metric must be the scope and snapshot status of living or dormant Soil biota.”

One of the most recent estimates suggests that the soil realm is home to approximately 2.1 x 10²⁴ taxa, which is thought to be more than 99.9% of global species biodiversity, mainly comprised of bacteria and other microbes.

The more you look, the more you find (lhs, pin-head after SCIENCE 2002; rhs, Bacteria on a pin tip courtesy Dr Kateryna Kon of Kharkiv National Medical University).

“Soil also supplies >99.7% of calorific food (just 0.3% from ocean plus 0.3% from aquaculture mostly fed with farmed stockfeed); with just about 6% total global protein from all fish; soil filters and stores most freshwater and is thus responsible for hydrological-recycle rainfall on land,” Blakemore says.

“My other paper last year on Biomass shows Soil houses >99% of organic carbon and it is the loss of this vital resources that is the greatest contributor to atmospheric carbon increase, despite the ‘greening’ effect on land.”

Blakemore, R. J. (2024). Biomass Refined: 99% of Organic Carbon in Soils. Biomass, 4(4), 1257-1300. https://doi.org/10.3390/biomass4040070.

However, this immense biodiversity is under threat. “Soil erosion is one of our greatest global issues of concern, and one of the most ignored. Droughts, floods, deserts, poisoning, capping and so on are affecting all soils and, due to this massive soil loss, plants are incapable of thriving. At the same time deforestation continues, mainly clearing for cattle pastures or soy fields to feed CAFO cows (or other stock),” the author says.

The loss of soil biodiversity has far-reaching consequences, leading to ecosystem degradation, reduced food production, and loss of potentially valuable resources, such as sources of medicines and antibiotics. Furthermore, soil loss inevitably results in silent species loss, mostly of microbes that are most dominant in soils, but also of more obvious soil macrobes, and specifically of earthworms, which are vital for soil health.

Around 7,000 ‘true’ earthworm species have been described, but estimates suggest the total number of earthworm species may be closer to 30,000-35,000 globally. “Due to their high endemicity and Soil’s heterogeneity, their unknowns are legion,” the author notes in his paper.

From the review paper: Global Soil Biodiversity Atlas (GBIF 2016) reporting ~ 667,000 soil biota or just about one third of known 2 million). Note that earthworms have 7,000 known and > 30,000 estimated species. Bacteria had 15,000 known species but estimated over one million (< 1.5% described). However, when microbes (excluding viruses) are properly considered and counted, as herein, soil unknowns are much higher (likely just < 0.0001% known at best). Vascular plants add ~ 400,000 species (cf. Anthony et al. 2023 with 466,000 angiosperm “Plantae”).

Earthworms enhance microbial activity, improve soil structure, and promote plant growth, which is why Blakemore suggests that “a simple solution to soil degradation is to attempt, in any way and at all times, to preserve and enhance earthworm populations.”

“Healthy soils are carbon-rich, hugely biodiverse and are a massive sponge for water – neither flooding nor drying during climatic extremes,” the author says, a reminder that healthy soils are not only vital for maintaining biodiversity, but also indispensable in supporting essential functions of planet and human survival.

“Due to the most pressing problem of topsoil erosion and irreversible extinction losses, a major shift should be realizing the overwhelming importance and fragility of our precious Soil,” Robert Blakemore writes in his paper.

Calling for a change in attitudes and funding to recognise the true scope of soil biodiversity, he encourages the formation of a dedicated Soil Ecology Institute that would catalogue, research and reverse the mass degradation of our planet’s most crucial, yet most neglected ecosystem – that of the Soil Realm.

References:

Blakemore RJ (2025) Biodiversity restated: > 99.9% of global species in Soil Biota. ZooKeys 1224: 283-316. https://doi.org/10.3897/zookeys.1224.131153

Blakemore, R. J. (2024). Biomass Refined: 99% of Organic Carbon in Soils. Biomass, 4(4), 1257-1300. https://doi.org/10.3390/biomass4040070.

Blog post on the topic by Robert J. Blakemore: https://vermecology.wordpress.com/2025/02/10/tandc

Soil carried on sea freight loaded with dangerous pests and diseases

Soil collected from the external surfaces of sea freight was found to support live microorganisms, worms, seeds and insects, including various regulated biosecurity organisms.

Often introduced unintentionally by human activities, invasive alien species can outcompete and overwhelm native flora and fauna, driving species to the brink of extinction and disrupting the balance of ecosystems. Understanding why exactly they establish in new locations and how they got there in the first place is crucial if we are to mitigate their destructive effects. Unfortunately, there isn’t enough research on this, and the answers might not always be straightforward.

A research team from AgResearch and Better Border Biosecurity (B3) investigated the biological risk posed by soil on the external surfaces of sea freight such as shipping containers or used machinery at sea ports in New Zealand. With their work, the researchers hope to facilitate the assessment of relative biosecurity risks between different introduction pathways and contribute to the development of more efficient measures against them.

The team found soil on most types of sea freight, irrespective of origin, with all soil likely to vector microbes, including plant pathogens. The amount of soil recovered from a single sea container was 5.3 kg, while the overall mean weight collected from sea freight was 417g, with most of the soil found on the underside of sea freight.

“While the presence of soil is perhaps not surprising, the presence of live bacteria, fungi, worms, seeds and insects associated with the soil was of greater concern. Various regulated biosecurity organisms were recovered from the samples, including plant-parasitic worms, seeds, insects and spiders that were not recorded as being present in New Zealand,” says Mark McNeill of AgResearch, who led the study.

Seeds of *Euphorbia prostrata*, a new record to New Zealand, were found on sea freight. Photo by Stefan.lefnaer under a CC BY-SA 4.0

“Not only does the spread of exotic species through these networks represent significant environmental, economic and social costs to natural and agricultural environments if invasive alien species were to establish, a loss of biodiversity is also an expected consequence of invasive alien species establishment. For islands, the implications can be significant, as they have high levels of endemism and invasive alien species establishment can lead to extinction of species as well as biodiversity declines,” the researchers write in their paper, which was published in the open-access journal NeoBiota.

Compared to a previous study on contaminated footwear carried in luggage by international airline passengers, the number and diversity in soil on sea freight was smaller than soil transported in more protected environments (e.g., footwear in luggage). This showed that biosecurity risk can vary with pathway. However, prioritising one soil pathway over another according to the risks they present, and differentially allocating resources is problematic, because the relative risk is dynamic, dictated by factors such as new pests or diseases entering the respective pathways.

Unwelcome guests: International tourism and travel can be a pathway for introducing invasive species

Even so, the researchers suggest that contaminated sea freight is an important introduction pathway for exotic species. The establishment of such species can be prevented by cleaning containers prior to departure, inspection at the border, and further cleaning where required.

Research article:

McNeill MR, Phillips CB, Richards NK, Aalders LT, van Koten C, James TK, Young SD, Bell NL, Laugraud A (2023) Defining the biosecurity risk posed by soil found on sea freight. NeoBiota 88: 103-133. https://doi.org/10.3897/neobiota.88.98440

Follow NeoBiota on Facebook and X.

Lifting the veil over mysterious desert truffles: Terfezia’s ecology and diversity towards cultivation

Developing below the soil surface, desert truffles are hard to find. Recently, researchers of the University of Évora updated the number of known species of the desert truffle genus Terfezia occurring in Portugal from three to ten species. They thoroughly characterized their ecological preferences, adding new knowledge on Terfezia’s cryptic lifestyle. These findings are of major importance, as desert truffles have a high economic value. The study was published in the open-access journal MycoKeys.

In a caring, symbiotic relationship, mycorrhizal fungi live and feed in the roots of specific plants, while providing water and nutrients to their ‘companion’. In arid and semi-arid environments, mycorrhization processes are essential to the survival of both plants and fungi. Moreover, the fungus’ hyphal network, which spreads within the soil connecting several plant individuals, is of utmost importance to enhancing soil quality and fertility.

Researchers of the University of Évora in Portugal, led by biologist Celeste Santos e Silva, worked on Terfezia fungi, the most diverse and species-rich genus among desert truffles. Their study, published in the open-access journal MycoKeys, might prove particularly valuable to rural populations in the Mediterranean basin, where desert truffles, highly valued in local markets, are an important food source. Increasingly turning into an exquisite component of the Mediterranean diet, Terfezia products can also be very profitable. Furthermore, these fungi are essential for soil conservation, preventing erosion and desertification.

After 8 years of exhaustive field exploration in search of desert truffles and many hours in the molecular biology lab, the researchers noted some previously unknown trends in the ecology of Terfezia species. They recorded seven species that were new to Portugal, including two that are new to science – Terfezia lusitanica and Terfezia solaris-libera. This brings the number of Terfezia species known to be growing in the country to ten. Particularly important was the discovery of a broader ecological range for many of the studied species (e.g. Terfezia grisea). Adding valuable information about their possible hosts, symbionts and ecological constraints, these findings help open new opportunities for truffle cultivation.

“It is very difficult to identify all specimens given that the Terfezia species look so much alike, and molecular biology was absolutely fundamental here”, explains the researcher. “The technique was essential to update and solve problems about their taxonomy and the relationship between the species in the genus.”

Furthermore, the discoveries are also expected to positively impact the local communities by stimulating agriculture produce, business and even employment.

Desert truffle production explained. Video by University of Évora

Knowledge gained in this research about the conditions in which different Terfezia species grow is an important step to desert truffle cultivation: the fungi are hard to find in the wild, which is why it would make a big difference – including financially – for local communities if they figure out a way to grow truffles themselves.

Within the project “Mycorrhization of Cistus spp with Terfezia arenaria (Moris) Trappe and its application in the production of desert truffles” (ALT20-03-0145-FEDER-000006), the researchers took a step forward towards achieving mycorrhizal association of desert truffles with perennial plants (rock roses), which would allow their mass production for various sectors such as food, medicine and soil recovery. This new form of production, assures the MED researcher and leader of the project, “will make it possible to create more jobs, reversing the current trend towards desertification in rural areas, while being a great tool for ecosystem recovery and restoration”.

Research article:

Santos-Silva C, Louro R, Natário B, Nobre T (2021) Lack of knowledge on ecological determinants and cryptic lifestyles hinder our understanding of Terfezia diversity. MycoKeys 84: 1-14. https://doi.org/10.3897/mycokeys.84.71372

Long-distance survival: Effects of storage time and environmental exposure on soil bugs

Contaminated soil frequently arrives at the borders through transported items, and is widely recognised as a vector for non-native species, potentially threatening the local agriculture, horticulture and natural ecosystems. However, although soil is the target of management practices that aim to minimise the spread of invasive alien species, crucial knowledge of the biosecurity hazards that can accompany transported soil is currently lacking. While not much is known about the relative survival rates of the transported soil organisms, nor about their establishment probabilities, this information is essential to support optimal policy and management decisions.

A recent study, led by Mark McNeill from AgResearch’s Biosecurity and Biocontrol team at Lincoln, New Zealand, and published in the open access journal NeoBiota, shows that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes. The scientists sought the answer of a simple question – are soil organisms still risky after a year in the sun?

To find out, Mark and his team collected soil from both a native forest and an orchard and stored it on, in and under sea containers, as well as in cupboards. They tested it after three, six and twelve months for bacteria, fungi, nematodes and seeds.

“Soil can carry unwanted microbes, insects and plants, and this study showed that some died faster when exposed, than when protected in a cupboard. This work shows some of the risks presented by soil contamination,” Mark says.

“The results showed that viability of certain bacteria, nematodes and plants declined over 12 months, irrespective of soil source and where the soil was stored. But mortality of most organisms was higher when exposed to sunlight, moisture and desiccation than when protected,” he explains. “However, bacterial and fungal numbers were higher in exposed environments, possibly due to ongoing colonisation of exposed soil by airborne propagules.”

“The results were consistent with previous observations that organisms in soil intercepted from seaports tend to carry less bugs than soil found on footwear,” McNeill notes.

“The research also raised wider questions, because some results were unexpected, including trying to understand why the microbe numbers went up and down like they did in the soil sitting on the sea containers when everything else died off. Was it the circle of life or just new microbe migrants creating new populations?

“We hope that the work will be useful for plant quarantine authorities to assess the risk presented by transported soil based partly on where the soil is found and the age of the soil. This would help authorities to optimally allocate management resources according to pathway-specific risks. Importantly, the study will assist in the development of recommendations for increasing management efficiency and efficacy at national borders.”

###

Original source:

McNeill MR, Phillips CB, Robinson AP, Aalders L, Richards N, Young S, Dowsett C, James T, Bell N (2017) Defining the biosecurity risk posed by transported soil: Effects of storage time and environmental exposure on survival of soil biota. NeoBiota 32: 65-88. https://doi.org/10.3897/neobiota.32.9784