Grazing by mammalian herbivores can be a climate mitigation strategy
The soil carbon fluctuated by 30 to 40 per cent in the areas devoid of grazing. Photo: iStock Grazing by herbivores can stabilise soil carbon pool and can be used as a climate mitigation strategy, according to a new study.
Inadequate grazing management can lead to rapid soil carbon loss, which cannot be easily recovered by improved management, stated the study published in the journal Proceedings of the National Academy of Sciences.
“Overgrazing depletes soil carbon stocks. Under moderate grazing intensities, these direct and indirect effects of herbivores can result in net soil carbon gains,” the study stated.
The 16-year-long study was conducted by researchers from the Centre for Ecological Sciences (CES) and the Divecha Centre for Climate Change, Indian Institute of Science (IISC).
Sumanta Bagchi, associate professor at CES and senior author of the study, started studying the impacts of grazing on soil carbon in 2005 in Kibber village in Spiti.
He and his team used a replicated long-term field experiment in the Trans-Himalayan grazing ecosystem to arrive at the results.
The researchers established fenced plots — where animals were excluded — as well as plots in which animals like yak and ibex grazed for analysing soil carbon levels.
Over the following decade, the researchers collected soil samples from the region. They analysed their chemical composition and compared each plot’s carbon and nitrogen levels year after year, according to the IISc press release.
“Grazing by mammalian herbivores can be a climate mitigation strategy as it influences the size and stability of a large soil carbon pool,” stated the study.
The soil carbon fluctuated by 30 to 40 per cent in the areas devoid of grazing. But it remained more stable in the places where the large mammals continued to graze.
“As soil contains more carbon than all plants and the atmosphere put together, conserving large mammalian herbivores in grazing ecosystems remains a priority to ensure the persistence of soil carbon,” the findings of the study highlighted.
It added that grazing ecosystems play a major role in these land-atmosphere feedbacks because they cover about 40 per cent of the world’s terrestrial ice-free surface — nearly 50 million square kilometres).
They span across grasslands, savannas and shrub steppes and contain about a third of all soil carbon. These ecosystems have a high potential to provide carbon sinks via soil carbon storage.
Soil carbon stocks can help decarbonise the atmosphere. Rewilding and conservation of large mammalian herbivores can be an essential climate mitigation strategy, it added.
Bagchi and his team are also assessing why domestic herbivores such as goats and sheep differ from their wild relatives in how they impact ecosystems.
“Understanding why they are not alike can lead us toward more effective stewardship of soil carbon,” said Shamik Roy, a former PhD student at CES.
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