- Planting soil microbiome like fungi together with trees as a part of ecosystem restoration could lead to an average 64% increase in plant growth, a new study has found.
- The research suggests that managed landscapes like farmland and forestry plantations have the greatest potential for restoration using soil organisms as they cover half of Earth’s habitable land area.
- Southeast Asia, in particular, presents an interesting case study for incorporating microbial communities in forest restoration, as it has vast swaths of degraded land that could be restored.
JAKARTA — How do you supercharge vegetation growth for a reforestation project? Bring in the microorganisms.
That’s the finding from a new study, which shows that incorporating a microbial community of fungi, bacteria, algae and archaea into ecosystem restoration can accelerate plant biomass production by 64% on average.
Researchers say this application holds plenty of promise for restoration work in Southeast Asia, where large swaths of once-forested landscapes have been degraded for large-scale agriculture.
Soil microbiome like fungi carry out a critical task known as soil transplant, moving soil and associated microbial communities from one location to another. But they’re often overlooked in conservation and restoration efforts, said study lead author Colin Averill, a senior microbial and ecosystem scientist at the Swiss Federal Institute of Technology, or ETH Zürich.
“When we think to plant a tree, we never think to ‘plant’ the microbiome, right? But what if we did?” Averill told Mongabay.
To find out how big a role the microbiome plays in ecosystem restoration, Averill and colleagues from ETH Zürich, the Czech Academy of Sciences in Prague and Vrije Universiteit in the Netherlands pored over the date from 27 restoration projects that incorporated microbial restoration.
Their study, published in the journal Nature Microbiology, found that across all the restoration works, there was an average of 64% increase of plant growth. In one case, plant growth was stimulated by 700%.
The study shows that incorporating the microbiome in managed landscapes like farmland and forestry concessions has the greatest potential. This is because managed landscapes account for the majority of human land use, covering half of the global habitable land surface.
“Belowground communities represent an incredible opportunity for us to enhance biodiversity at the same time as promoting aboveground plant health in both natural and managed landscapes,” Thomas Crowther, senior author of the paper and head of ETH Zürich’s Crowther Lab, said in a statement.
The pressure to grow ever more food for the world’s ballooning population, which recently hit the 8 billion milestone, has resulted in large-scale monoculture plantations. These require massive amounts of synthetic fertilizers and pesticides, as well as selective breeding, cloning and genetic modification to increase productivity and efficiency.
But while this has been good for yields, it has been disastrous for biodiversity, both above ground and below ground. Consequently, these monoculture ecosystems have become more susceptible to extreme climate events, pathogens and pests.
But by introducing microbial communities, these agricultural and forestry plantations that are currently devoid of biodiversity could become reservoirs of it, Averill said.
“[The] huge opportunity there is actually below ground, the microbiome,” he said. “We spend so much time optimizing the things we see above ground, we haven’t touched below ground.”
There’s a caveat, though.
To increase biodiversity and enrich these managed landscapes, it’s important to avoid using single species or very low-diversity, non-native soil organisms at a large scale, Averill said.
The study notes an increasing number of microbial inoculant companies advocating for just this on the argument that it could improve crop yields. But the mass application of a single species could lead to a loss of genetic and ecological diversity, and is unlikely to account for ecosystem-specific requirements, the study says.
It instead recommends using locally sourced, native and biodiverse communities of soil organisms as these can promote biodiversity in managed landscapes without limiting crop yields.
“[But] we’re seeing people go precisely the opposite way,” Averill said. “They’re repeating the mistakes of aboveground agriculture below ground, selling microbial inoculants that are like one or a handful [of] species and apply them everywhere. It’s insane.”
Southeast Asian forest restoration
Soil microbes present a particularly promising opportunity for ecosystem restoration in Southeast Asia. The region is home to vast rainforests, accounting for nearly 15% of the world’s tropical forests.
“I think Southeast Asia is so important. The biodiversity of those forests are so incredible,” Averill said. “Dipterocarp forests [in Southeast Asia] are like [a] completely novel type of ecosystem.”
The dipterocarp forests of Southeast Asia are unique as they form a symbiosis with ectomycorrhizal fungi, similar to the trees in the boreal forests of Canada and Russia and many temperate forests.
“As a result, there is a lot of truly novel fungal and other soil microbial biodiversity present in these forests,” Averill said.
But these unique rainforests are disappearing at an alarming rate for agriculture and logging. Southeast Asia has one of the highest rates of deforestation among major tropical regions, with 1.2% of forest lost every year, behind only Latin America. This deforestation rate is also the most severe in terms of biodiversity loss.
By 2100, up to three-quarters of Southeast Asia’s forests and 42% of its biodiversity could disappear should current deforestation rates persist. This could be a disaster for the climate, as tropical forests are an important natural carbon sink.
Governments in Thailand, Indonesia and the Philippines have attempted to rehabilitate degraded forests through a number of policies. Indonesia, for instance, home to the third-largest extent of tropical forest in the world (behind only Brazil and the Democratic Republic of Congo), started implementing land rehabilitation in the 1950s and has a goal of rehabilitating 12 million hectares (30 million acres) of degraded land by 2030.
It’s estimated that Southeast Asia has 121 million hectares (299 million acres) of degraded land — an area one-tenth the size of the U.S. — that’s biophysically suitable for reforestation.
But with the region’s rainforests continuing to be cut down, it’s crucial for all stakeholders to move fast in restoring the region’s ecosystems, and this is where soil microbes can play a huge role, Averill said.
“We know that intense amounts of land conversion is happening there [in Southeast Asia], with palm oil and many other things,” he said. “So there’s real reason to move fast there” to protect and restore forests.
Promoting the use of the microbiome in restoration work could also contribute to the protection of soil biodiversity, which is crucial in light of the ongoing global biodiversity crisis. As microbial species decline, ecosystem stability and human food sources will suffer, in part because systems with low ecological and genetic diversity are more susceptible to extreme climate events.
“Protecting and restoring the belowground microbiome is essential to protecting all of Earth’s biodiversity,” Averill said.
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Sodhi, N. S., Posa, M. R., Lee, T. M., Bickford, D., Koh, L. P., & Brook, B. W. (2009). The state and conservation of Southeast Asian biodiversity. Biodiversity and Conservation, 19(2), 317-328. doi:10.1007/s10531-009-9607-5
Sodhi, N. S., Koh, L. P., Brook, B. W., & Ng, P. K. (2004). Southeast Asian biodiversity: An impending disaster. Trends in Ecology & Evolution, 19(12), 654-660. doi:10.1016/j.tree.2004.09.006
Sharma, S., & Yonariza. (2021). Chapter 7 — Evaluating forest reforestation policies in Southeast Asia: A case study from Indonesia, Philippines, and Thailand. In Natural Resource Governance in Asia (pp. 79-97). doi:10.1016/B978-0-323-85729-1.00004-9
Zeng, Y., Sarira, T. V., Carrasco, L. R., Chong, K. Y., Friess, D. A., Lee, J. S., … Koh, L. P. (2020). Economic and social constraints on reforestation for climate mitigation in Southeast Asia. Nature Climate Change, 10(9), 842-844. doi:10.1038/s41558-020-0856-3
Banner image: Fungi in the forests of Sabah. Image by John C. Cannon/Mongabay.
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