Kochi: Over three years, more than five million large trees have ‘vanished’ from India’s farmlands, as per a study published on May 15 in the journal Nature Sustainability. The hotspots of such vanishing include parts of central India, particularly Maharashtra and Telangana.
An unlikely culprit could be potentially driving this huge loss in biodiversity, the study suggests: the expansion of paddy fields, facilitated by better water availability. But while the potential causes of this loss would require more analysis, the study suggests a particularly worrying trend: while people are cutting large trees in crop fields, “trees are now being cultivated within separate block plantations typically with lower ecological value,” per the study.
Large trees and farmlands
Large trees are a common sight in farmlands in India: from lush neem trees that don green even during dry summers, to old, huge jamun (Syzygium cumini) trees whose luscious purple fruits attract not just local wildlife — such as fruit-eating birds — but is a favourite among people too.
Across most of India, agroforestry — the practice of retaining large trees in and along croplands — is the norm. Such trees (which can also include forest species such as mahua Madhuca longifolia) play several vital roles, including serving as important food resources for local biodiversity and people, preventing soil erosion and providing shade. Studies such as this one have also documented the crucial role of farmland trees in carbon sequestration globally.
While forests cover only around 20% of India’s area, farmlands are spread across more than half of India (56 per cent). As per one estimate, the area under agroforestry in India is 13.75 million hectares. The highest concentration is in the states of Uttar Pradesh (1.86 million ha), followed by Maharashtra (1.61 million ha), Rajasthan (1.55 million ha) and Andhra Pradesh (1.17 million ha). An official estimate, however, pegs the total area under agroforestry in India at around 28.42 million hectares, covering about 8.65% of India’s total geographical area.
Large trees within fields and croplands in India are “clearly visible” in satellite images and examining historical Google Earth images showed him how “clear the decline of large trees was”, said Martin Brandt, associate professor at the Department of Geosciences and Natural Resource Management, University of Copenhagen. This was why Brandt and his colleagues decided to focus specifically on India and study this, Brandt said in a reply to a question on X, formerly Twitter:
the large trees within fields are clearly visible in the images, and I when looking around with Google Earth historic images I was surprised how clear the decline of large trees was.
— Martin Brandt (@matin_brandt) May 16, 2024
The team mapped individual large trees (that have a canopy diameter or tree crown centre of more than 10 square meters) across farmlands all over India. These included trees in fallow fields, hedgerows and those along rural roads and rivers as well.
To do this, the scientists turned to high-quality satellite images. They used RapidEye satellite data for the years 2010 and 2011, and data from PlanetScope imagery between 2018 and 2022. The team trained deep-learning models to detect individual non-forest trees between 2011 and 2022. And then they studied the changes across years by tracking individual tree crown centres.
The disappearing act
What they found is highly disconcerting: around 11% of large trees that had a crown size of around 96 square metres (around 1,000 square feet, an area slightly bigger than a badminton court) that could be mapped with a high confidence in 2010 or 2011 could not be detected in the 2018-2022 images.
There were several hotspots of tree loss: some regions lost more than 50 trees per square kilometre, per the study. The maps generated by the study suggest that hotspots where trees have “vanished” include parts of northwestern India, and central India including Maharashtra and Telangana. Per the study, these areas in central India have lost up to 50 per cent of their large farmland trees (with up to 22 trees per square kilometre disappearing). The team also observed “smaller hotspot areas of loss”, such as in eastern Madhya Pradesh, around Indore.
The team also found that between 2018 and 2022 alone, 5.6 million large farmland trees (with a crown size of about 67 square metres) had simply “vanished”.
“This number of disappeared trees, considered a conservative estimate due to the method applied, was still high considering that a majority of the losses must have occurred between 2018 and 2020,” the study noted.
The authors write in the study that they “observed similar situations all over Indian croplands, reflecting a considerable national-scale thinning of India’s large farmland trees over such a short period”.
We mapped a half billion individual farmland trees in India, and tracked their fate over a decade. Many large trees have disappeared. The paper in Nature Sus.: https://t.co/GcDVfuKtKA, Viewer: https://t.co/rdY5tQB5BF. It’s a new framework for temporal monitoring of single trees..
— Martin Brandt (@matin_brandt) May 15, 2024
Indian scientist Jagdish Krishnaswamy, dean of the School of Environment and Sustainability at Bengaluru’s Indian Institute for Human Settlements, called the results of the study “worrying” on X:
This is so worrying. I wonder whether the huge and lovely Mahua trees amidst the farm fields of Jhabua District in Madhya Pradesh in Central India that I saw over twenty years ago are also disappearing.
— Jagdish Krishnaswamy (@JagdishKrishna8) May 16, 2024
An unlikely culprit?
Brandt’s team also interviewed villagers from parts of Telangana, Haryana, Kerala, Maharashtra, Andhra Pradesh, Uttar Pradesh and Jammu and Kashmir: all areas where they had noticed the disappearance of trees as their maps showed. All villagers who took part in the interviews (though a small number, 12) confirmed that there has indeed been a huge decrease in the numbers of mature trees within and along fields.
The interviews suggest that new agricultural practices may have brought about this change. Farmers dug new borewells, and the additional water supply meant that many of these croplands that support paddy or rice fields could be expanded to boost crop yields. Large trees in such areas had to go because people thought that the shade that these large-crowned trees provide could affect their crop yields.
But while the potential causes of this loss would require more analysis, what is particularly worrying is that while people are cutting large trees in crop fields, “trees are now being cultivated within separate block plantations typically with lower ecological value,” per the study. According to the study, their findings are “particularly unsettling given the current emphasis on agroforestry as an essential natural climate solution playing a crucial role in both climate change adaptation and mitigation strategies, as well as for livelihoods and biodiversity”.
Indeed, this has direct implications for India’s climate change adaptation and mitigation measures. That’s because the Indian government has been promoting agroforestry very actively, and especially so over the last few years. The union environment ministry even passed a hugely controversial amendment to the Forest Conservation Act of 1980 recently that also proposes to remove private land holdings from the ambit of the Act to “encourage plantations” so that this would improve green cover and carbon sequestration.
Large trees, carbon capture and tree cover changes
However, experts have pointed out that this would not bode well for India’s biodiversity or carbon capture because the amendment would essentially remove protection for forest or tree cover – which also includes large trees and forest trees – within private-owned lands such as crop lands. So instead of protecting existing old trees that already play an important role in carbon sequestration, this could place more focus on developing more plantations and monocultures, which are less valuable in terms of the ecological functions they serve.
Another question that arises from the results of the study is whether the loss of a whopping five million+ trees from its farmlands means that India’s official claims of increasing tree cover hold.
As per the latest 2021 ‘State of Forest’ report compiled by the Forest Survey of India (FSI) – a government organization under the Ministry of Environment, Forest and Climate Change – and released in January 2022, the country’s forest and tree cover has increased by 2,261 sq km since the last assessment in 2019. Experts have pointed out several issues with the report to The Wire Science. One of them is that the FSI’s definitions of forest and tree cover mean that its analyses also include plantations and monocultures which do not perform the same functions that a forest does, and in numerous ways. Scientists have told The Wire Science that this is essentially “greenwashing” (conveying a false impression of environmental benefits or sustainability).
But despite experts highlighting the gaping flaws of the report and expressing doubts about whether India’s forest cover has really increased, the report’s claimed increase in forest and tree cover is something that the Indian government could use to further its international climate change commitments, as The Wire Science has reported.
The authors of the latest study, however, specify that their results “do not contradict reports concluding that there has been a net increase in planted trees outside forests as a result of tree planting being encouraged and actively carried out in India”. They put this down to the fact that their study reports “only gross losses and did not consider tree gains as a separate class” – unlike the State of Forest report does. The team also did not include plantations in their analyses – which again, the State of Forest report does (by including plantations and monocultures as forest and tree cover).
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