The soil’s early warning system: microbes can predict desertification before plants start to die
Researchers, including a microbial ecologist at the University of Pretoria, are studying how soil microbial communities respond to environmental stress ahead of visible plant die-off in drylands
The proposed study uses metagenomic sequencing — reading entire microbiome genomes at once — on soil samples collected across four African deserts: the Namib, Kalahari, Sahara, and the Sahel region
Samples are being compared across three ecosystem states — intact, at-risk, and degraded — to identify functional and compositional shifts that precede desertification
The goal is to establish reference microbiome data that can help pinpoint ecological "tipping points" and inform land management and conservation policy before visible degradation sets in
Desertification and the UNCCD Framework
Desertification is the process of land degradation in arid, semi-arid, and dry sub-humid areas resulting from climatic variations and human activities, distinct from the spread of existing deserts. It is governed globally by the UN Convention to Combat Desertification (UNCCD), one of the three Rio Conventions along with the UNFCCC (climate change) and CBD (biodiversity), all originating from the 1992 Rio Earth Summit.
Key Details
- UNCCD adopted: 1994; entered into force: 1996; India signed in October 1994 and ratified in December 1996
- UNCCD COP-14 was hosted by India in Greater Noida in September 2019 — the first time India hosted a UNCCD COP
- Countries have committed to Land Degradation Neutrality (LDN) as a target under SDG 15.3, aiming for neutrality by 2030
- India has pledged to restore 26 million hectares of degraded land by 2030 as part of its LDN commitment, and offered to set up a global technical support institute for LDN target-setting under the UNCCD
Early microbial indicators of desertification would feed directly into LDN monitoring frameworks, offering a faster diagnostic tool than the vegetation-cover metrics currently used to track land degradation under UNCCD reporting.
Soil Microbiome and Its Role in Carbon Cycling
The soil microbiome comprises bacterial, fungal, archaeal, and viral communities that regulate nutrient cycling, organic matter decomposition, and soil carbon storage. Because microbes respond to changes in moisture, temperature, and pH faster than plants or larger organisms, their community composition can act as a leading indicator of ecosystem stress, whereas visible vegetation loss is typically a lagging indicator.
Key Details
- Soil is one of the largest terrestrial carbon sinks; microbial activity determines whether soil organic carbon is sequestered or released as CO2 through decomposition
- Metagenomics — sequencing all genetic material in an environmental sample simultaneously, without needing to culture individual organisms — is the key S&T tool used to profile these communities
- An estimated 70-80% of clinically used antibiotics originate from soil-derived microorganisms, underscoring the biotechnological value of soil microbiome conservation
- Soil microbiome shifts have similarly been proposed as early indicators in other degradation contexts, such as permafrost thaw and coral reef stress (via analogous "microbiome sentinel" approaches)
The African dryland study applies this early-indicator logic specifically to desertification, using metagenomic comparison across intact, at-risk, and degraded sites to detect functional shifts before plant mortality becomes visible.
India's Own Desertification Monitoring — The ISRO Land Degradation Atlas
India separately monitors land degradation through remote sensing rather than microbiome analysis, using the Desertification and Land Degradation Atlas of India, prepared by the Space Applications Centre (SAC), ISRO.
Key Details
- The most recent Atlas (published June 2021, covering 2018-19 data) found that 97.85 million hectares — 29.7% of India's total geographical area (328.72 mha) — had undergone land degradation
- This marked an increase from 94.53 mha (28.76%) in 2003-05 and 96.40 mha (29.32%) in 2011-13, showing a rising degradation trend
- States with the largest degraded area include Rajasthan, Maharashtra, Gujarat, and Jammu & Kashmir; wind erosion dominates in the Thar desert region while water erosion dominates elsewhere
- India's monitoring relies on satellite-based land-cover classification rather than the soil-microbiome approach being piloted in Africa, making the two methods complementary rather than substitutable
The African microbiome research points to a potentially earlier-stage, ground-truth-based detection method that could eventually complement satellite-based degradation atlases like India's, which currently detect degradation largely after vegetation and land-cover changes are already visible from space.
- Study locations: Namib Desert, Kalahari Desert, Sahara Desert, and the Sahel region
- Method: metagenomic sequencing across three ecosystem states (intact, at-risk, degraded)
- UNCCD: adopted 1994, in force 1996; India ratified December 1996; UNCCD COP-14 hosted by India (Greater Noida, 2019)
- India's LDN pledge: restore 26 million hectares of degraded land by 2030 (SDG target 15.3)
- India land degradation (2018-19, ISRO/SAC Atlas): 97.85 million hectares, 29.7% of total geographical area — up from 28.76% in 2003-05
- An estimated 70-80% of clinically used antibiotics are derived from soil bacteria