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Are we overlooking the role of grasslands in mitigating climate change?

There is growing recognition for the need for the right, context-specific nature-based solutions.

June 29, 2021 / 04:09 PM IST
Mongabay

Mongabay


-- Forest restoration is more well-known than grassland restoration, even though grasslands, just like forests, are important carbon sinks and crucial for carbon sequestration.

-- Nature-based solutions include restoration activities and these are considered the cheapest and quickest nature-based measures to implement to tackle climate change.

-- However, developing the right solutions is important, and attention should be paid to systems that are not just forests, caution studies.

-- Though dialogue on the need to conserve and restore grasslands has begun, we could still be a long way from changing the “forest-centric” view, say researchers.

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In 2019, black wattle trees stood tall in around 50 hectares of land in Pazhathottam in Kerala’s Pambadum Shola National Park. Black wattle, in India, is an exotic, invasive tree and here, in Pazhathottam, it had invaded the open montane grasslands that occur naturally in these higher reaches of the Western Ghats.

When an unexpected fire gutted the stand, forest officials were presented with a unique opportunity: they could now restore the land to its original habitat. They could grow back a grassland. And they did just that. Officials roped in local communities to plant native grass species such as Chrysopogon nodulibarbis and finger grasses (Digitaria species). Today, two years later, a lush grassland stands strong where invasive trees once stood. Arun K. Nair, assistant wildlife warden of the Shola National Park, where this restoration project was undertaken, says the changes are apparent.

“Streams have now rejuvenated on these slopes,” he said.

Direct sightings of wildlife and pictures caught on camera traps suggest that wildlife presence has increased, he said: large herbivores including Indian gaur and sambhar deer are now regulars here. Even human-wildlife conflict may have decreased over the last two years, claimed Nair (if you go by the indirect and not-so-ideal metric of the total monetary compensation that the Munnar Forest Division has to offer people for wildlife-caused losses in the area).

This story of growing back a grassland, however, is not a common one. Forest restoration, or the glamorous but tough job of growing back trees, is more well-known: tree- and forest-growing techniques such as the Miyawaki method are very popular. Moreover, the benefits of restoring forests are sung loud and clear, detailing not just their role in maintaining biodiversity but also their ability to fix large amounts of carbon from the atmosphere and thereby mitigate climate change.

Grasslands, in comparison, barely make it to the climate change mitigation or restoration narrative in India. Most nature-based solutions advocated to tackle land degradation and climate change are tree-centric. Are we overlooking grasslands, including their role in carbon sequestration?

Grasslands as habitats

The world’s natural grasslands are ancient. Fossil records and soil analyses tell us that natural temperate and tropical grasslands were born during the Late Cretaceous and Early Paleogene periods (around 56 to 66 million years ago) and evolved across multiple stages over the millennia that followed. There are different types of grasslands – ranging from open, vast grassland expanses to woody savannas (where small trees or other scrubs occur along with grasses). Like forests, these systems are an integral part of the carbon cycle too: they fix carbon from the atmosphere into organic material or biomass. But unlike forests, most of this carbon doesn’t dwell above ground in trunks or branches; it hides mostly in the dense network of roots underground, and in other organic soil matter (known as ‘soil organic carbon’).

Studies show that changes in land use and management – such as grazing, species composition and availability of mineral nutrients – can impact such soil carbon stocks. Soils are also the largest terrestrial carbon reservoir in the world. According to estimates, grasslands cover approximately 25 percent of the earth’s land surface and contain roughly 12 percent of the terrestrial carbon stocks.

“There is increasing evidence to show that grasslands are extremely important for carbon sequestration,” said Vasanth Bosco, founder of Upstream Ecology, who has been studying high-altitude grasslands in the Nilgiris in Tamil Nadu and working to conserve and restore them for the past nine years.

India’s diverse grasslands, however, just like the carbon they store, have remained hidden in the conservation discourse despite being a crucial source of livelihood for many local communities, and home to very unique biodiversity.

One of the many challenges is that savanna grasslands in India are not even considered habitats, said Abi Tamim Vanak, associate professor at the Ashoka Trust for Research in Ecology and the Environment (ATREE) who studies these semi-arid systems in peninsular India. In a first, Vanak and his colleagues are currently mapping India’s open natural systems, including grasslands, savanna woodlands, deserts and rocky outcrops.

Across the country, many of these open habitats are slowly disappearing. Some are being converted to agricultural land. Studies show that such conversions to cropland can affect the carbon sequestration potential of the system. Scientists have noted how rapid land-use change including construction in southern Tamil Nadu has caused traditional mullai and paalai habitats, or grass and scrub jungles, to disappear. India reportedly has lost 31 percent, or 5.65 million hectares, of grassland area between 2005 and 2015, as per data presented by the Union government to the United Nations Convention to Combat Desertification during the 14th Conference of Parties hosted in India in 2019.

Nature-based solutions and grasslands

An integral means to mitigate such losses and degradation are nature-based solutions: solutions to protect, sustainably manage and restore natural resources from both environmental and social perspectives. Restoring habitats is one of the most recommended among them.

A recently released report from the first-ever collaboration between the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and Intergovernmental Panel on Climate Change (IPCC)-selected scientists, points to this too: that restoring carbon- and species-rich ecosystems is one of the cheapest and quickest nature-based measures to implement to tackle climate change. China’s restored grasslands, for instance, fared better over degraded ones when it came to planting biomass and soil organic carbon levels, showing the potential for carbon sequestration with restoration. Another study found that restoring grassland biodiversity accelerated soil carbon sequestration.

And yet, restoring grasslands is not as common in India as planting trees or growing forests to mitigate climate change is. Using restoration to tackle degradation and deforestation is one of the main aims of the Bonn Challenge, an international effort by more than 60 countries to restore 350 million hectares of deforested and degraded land by 2030. India has pledged to restore 21 million hectares of land.

However, a lot of such compensatory afforestation projects occur on grassland tracts, pointed out Bosco. Most of the areas that the World Resources Institute’s restoration atlas recommended as having “high restoration potential” in India were savanna grasslands, said Vanak. “This is a common problem,” he said. Carbon sequestration is an important currency for valuating grasslands. But there are also a host of other benefits they provide, including the ecosystem services such as the livestock they support, he added.

“Grasslands are certainly ignored and worse, mismanaged, in India’s tree-centric carbon storage and climate change mitigation narratives,” commented scientist Mahesh Sankaran of Bengaluru’s National Centre for Biological Sciences, who studies various aspects of grassland and forest systems in India.

In large part this stems from a lack of recognition and appreciation of the uniqueness and antiquity of these biomes, the biodiversity they support and the ecosystem services they provide, he said. “We do know that they store significant amounts of carbon below ground. While increasing tree cover can lead to increased aboveground carbon stocks in the short term, it can potentially also lead to a loss of below ground and overall ecosystem carbon stocks in the longer term…thus defeating the purpose.”

Aboveground carbon stocks are also susceptible to losses due to fires and herbivory (which are integral components of these systems), he added. A recent study, for instance, shows that grasslands are likely to be more reliable carbon sinks in the face of future climatic changes such as drought. Moreover, increasing woody cover in grasslands can also alter hydrological cycles (reduce stream flow), decrease albedo (a measure of solar radiation reflected from the earth’s surface) which can contribute to warming, and lead to loss of unique biodiversity, said Sankaran.

Developing the right solutions

Interestingly, the IPBES-IPCC report calls out this ‘mitigation’ measure, by identifying some of such “focused” measures that are harmful to biodiversity. For instance, planting trees in ecosystems that have not historically been forests and reforesting the area with monocultures, especially of exotic tree species, “can contribute to climate change mitigation but is often damaging to biodiversity, food production and other nature’s contributions to people has no clear benefits for climate adaptation, and may displace local people through competition for land,” a press release on the report said.

“Any measures that focus too narrowly on climate change mitigation should be evaluated in terms of their overall benefits and risks,” it adds. Indeed, rather than the indiscriminate tree planting measures we are currently witnessing, we should only be planting trees, and the right mix of trees, in the right places (areas that were previously forested but are now degraded), said Sankaran. “In the case of open areas such as grasslands, we should be concentrating our efforts on restoring the grasses and herbaceous layer.”

There is growing recognition for the need for the right, context-specific nature-based solutions. Only by following strict guidelines – including remembering that nature-based solutions involve a wide range of ecosystems on land and in the sea and not just forests and that they have to be implemented with the full consent of local communities – can such solutions provide sustainable benefits to society commented a review on nature-based solutions to climate change.

A new study that compared above-ground versus below-ground biomass across different vegetation types across the world including India found that grasslands stored the highest levels of plant biomass below the ground (67 percent) when compared to forests and shrublands (22 and 47 per cent respectively). “These results make a compelling case to move away from simplistic (above-ground) carbon-based tree plantation policies,” says Ashish Nerlekar.

But even restoration of grasslands needs to be mindful. Scientists including Nerlekar (currently with Texas A&M University) found that manually removing exotic Prosopis julifora trees that have invaded the native Banni grassland of Gujarat helped restore native plant diversity. And yet, large-scale removal of this tree from this grassland is no solution, they say. For removal comes with several trade-offs: local communities now depend on the invasive tree as a source of charcoal, firewood, and construction material. Removing the tree manually is a costly affair too. So until these trade-offs are understood well, the landscape needs to be managed as a matrix of native grassland and invasive trees, the scientists say.

India’s grassland perspectives

So is India slowly waking up to the need to conserve grasslands and restore them? A recent study by scientists including Robin V.V. (Indian Institute for Science Education and Research Tirupati) identified around 250 square kilometers of montane grasslands that can be restored in the southern Western Ghats. Using satellite imagery, the team also prioritised specific grassland conservation and restoration sites in Kerala and Tamil Nadu.

But we are still a long way from changing the ‘forest-centric’ view, said Robin. “Perhaps some officers get the idea after engaging with new literature and findings. However, this has not seeped down to the ground-level staff. And ultimately, implementation on the ground depends on how well the ground-staff know these details,” he added. There is indeed a “widespread lack of awareness of the importance of grasslands among policymakers, managers and people implementing such tree-planting initiatives on the ground,” said Sankaran.

Robin and his colleagues, who presented their data to Kerala’s Chief Wildlife Warden and a panel of wardens, were told that the data would go into the state’s management plan. Tamil Nadu, meanwhile, already has a high court committee overseeing restoration activities in the state, and several trial restoration plots are already in place, he added. But while government lands have the largest extent of grasslands that can be restored, there is tremendous potential for grassland restoration in private lands too, said Robin.

“There are large estates and holdings of private individuals, trusts etc, and if sufficient motivation exists these people could create small patches of grasslands,” he wrote in an email to Mongabay India. “Although such areas will be small, it will aid connectivity and potentially help species like the endemic Nilgiri pipit that is at the brink of local extinction.”

Meanwhile, the Kerala Forest Department’s success at reviving a native grassland in Pazhathottam is spurring them to try out restoration in smaller one to two-hectare patches nearby. “This is possibly the first time the local community has been roped in through an Eco-Development Committee for eco-restoration activities and we hope to continue this,” said Nair, assistant wildlife warden of the Shola National Park.

This story was first published on Mongabay, click here to access it…

 
first published: Jun 29, 2021 04:05 pm
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