Delhi’s Forest Department (FD) has started to ‘restore’ the Central Ridge to ‘its pristine purity’. That’s what their plans say.
In March of this year, the FD issued a Tender for creating a new ‘Van’ on the Ridge which tasked the contractor with carrying out ‘anti-termite treatment’ before planting any trees. The treatment involved the use of an organophosphate called Chlorpyrifos and a banned chemical called Lindane, which together would have destroyed not just termites but all the microbes and insects that live in the soil. The collateral damage to other forms of life would have been catastrophic.
This was a tragedy in the making and there was an outcry in the media, including an article in Down To Earth. Anti-termite treatment makes ‘dead’ soil. You can then kiss goodbye to any thoughts of restoring the natural ecology of any tract of land.
To the credit of the FD, it responded by rescinding its tender and canceling the order to use the two toxic chemicals. But we came very, very close to a situation where the greatest asset that the Ridge possesses — its living soil — would have been destroyed.
Still, it raises worrying thoughts — has the FD been using these chemicals on the Ridge routinely in the past? Civil society found out fortuitously this one time and raised an alarm. What about all the planting that has happened on the Ridge especially since 2021?
How important is it to protect the soil? Avoiding the use of toxins seems self-evident, but are there other considerations?
Plenty, as it turns out.
If you peer carefully at dry soil on the Ridge, you might notice patches of dark soil topped with a short, golden grass in the hot months (like now). This is called Oropetium thomaeum — or ‘rock grass’ — which grows in little tufts along with liverworts fanning out at its base.
Oropetium is a tiny wonder-grass on its own. Scientists call it a ‘resurrection grass’ because of its amazing ability to recover from extreme desiccation even after losing 95 per cent of its cellular water. ‘Drying without dying’ — drought tolerance — is closely studied in cutting-edge biolabs because it is key to understanding how life survives with no — or very little — water.
In arid places on the Ridge, Oropetium makes sporadic ground cover and manages to escape intense grazing pressure because it is so short. It stabilises soils which would otherwise be bare and conserves moisture wherever it grows. Most people just walk past these little tufts with no idea of the useful role they play in keeping this ecosystem ticking.
But you need to ‘look under the hood’, because there is something even more vital that lurks underneath.
Oropetium and its liverwort companions are only the top dressing of teeming communities of micro-organisms that form living ‘crusts’ in arid and semi-arid soils like the soils we have on the Ridge.
Biocrusts are created by cyanobacteria (previously called ‘blue-green algae’) which are the first pioneering, single-celled organisms to do the work of ‘starting’ a biocrust. Under a microscope you can see them creating sticky fibres (microbial mucilage) which bind soil particles together, making a sponge-like structure that absorbs water when it rains. This becomes a congenial microhabitat for mosses, green algae, microfungi and lichens to move into. None of this happens quickly — it can take decades for a biocrust to acquire a firm, well-populated knobby crust that Oropetium can grow on. Biocrust communities vary with soils. Lichens may be completely absent; microfungi may predominate. But wherever biocrusts have enjoyed enough time and freedom from disturbance to grow in, they can make up an astonishing 70 per cent or more of living ground cover. Scientists estimate that the biodiversity of biocrusts far exceeds that of the plant community they grow in — they can contain hundreds to thousands of species, compared with plant communities which normally contain fewer than a hundred.
Biocrusts are most common in arid and semiarid landscapes worldwide. They occupy sites where light reaches the surface of the soil and thrive best where vascular plants are not already dominant. In arid sandy
tracts they may be concentrated only in the top 3 or 4mm of soil, though they can grow fatter than that. Much of the time, however, biocrusts are dormant and are ‘awakened’ only when the surface of the soil is wetted; they remain active only for a day or so before the soil dries again.
Biocrusts have a long, detailed CV that is available for anyone to explore online. In essence, they are vital for the formation and stabilisation of soil. Without biocrusts, the quartzite rocks on the Ridge would all be completely bare, swept clean by wind and rain. It is biocrust that enables rock surfaces to be colonised first by a layer of soil, then by Oropetium and liverworts, and finally by other plants.
That’s not all. Biocrusts hold in soil moisture and potentiate the infiltration of water into the ground. Being photosynthetic organisms, they contribute carbon to soil. They also fix atmospheric nitrogen and are an important food source for organisms that live below the surface of the soil.
Much like the discovery of trillions of bacteria in the human gut, the discovery of biocrusts has revolutionised our understanding of dryland soils. We are still exploring their multitudinous lives and processes, but we already know one thing for certain — without biocrusts much less life would exist in arid places. That’s why scientists call them the ‘living skin’ of arid soils.
Biocrusts, however, are delicate. The hooves of a deer or human boots can damage biocrust and break underlying soil connections. It takes very long to repair. One scientist has estimated that “Under good conditions, a thin veneer of cyanobacteria may return in 5 years. Recovery may take up to 20 years in places of higher rainfall and up to 250 years in places of lower rainfall, assuming an area is not again disturbed.”
Once we recognise the vital roles of biocrust, we need to do everything we can to protect it. Earth-moving machines that churn up the soil to remove invasive plants have no place in such a scheme.
We need to convince the FD of this, because so far, those prehistoric earth movers are rushing around to uproot vilaiti keekar trees (Neltuma juliflora) and destroying biocrust everywhere. The Department’s manuals call for ‘deep tilling’ of the soil up to a depth of 1 metre!
It’s only in the last 10 or 12 years that scientists have started studying biocrusts closely.
Government plans don’t mention biocrust because it hasn’t yet appeared in a forester’s lens. Even more surprising is that fungi are not mentioned either, when — together with the microbes found in biocrust — fungi are the chemical engineers responsible for most (up to 90 per cent) of the energy flow in the soil system. For the FD and the Forest Research Institute that created the management plan for the Ridge, the chemical engineers are not important enough to deserve a mention. They don’t seem to matter.
Destroying biocrust, fungi and termite mounds needs to stop NOW. The FD has put its chemicals away. It needs to shackle its earth movers too.
Pradip Krishen is an ecological restoration practitioner and a writer about trees
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth