Bengaluru, Oct 19 (IANS) Experimental elimination of grazing by herbivores in grazing ecosystems in the Spiti region of the Himalayas has been found to increase fluctuations in soil carbon level, which can lead to unintended negative consequences for the global carbon cycle.
The study, spanning 16 years, was carried out by researchers from the Ecological Science Center (CES) and the Divecha Center for Climate Change (DCCC), Indian Institute of Science (IISc).
According to the study, large herbivorous mammals like yak and ibex play a crucial role in stabilizing the soil carbon pool in grazing ecosystems such as the Spiti region of the Himalayas.
Since soil contains more carbon than all plants and the atmosphere combined, it is important to ensure its persistence. When plants and animals die, dead organic matter remains in the soil for a long time before microbes break it down and release carbon into the atmosphere as carbon dioxide. aceThe soil basin is a reliable sink for sequestering carbon,” says Sumanta Bagchi, associate professor at CES and lead author of the study published in the Proceedings of the National Academy of Sciences.
Maintaining stable soil carbon levels is therefore essential to offset the effects of climate change, the IISc statement said.
Bagchi began studying the impact of grazing animals on Himalayan ecosystems during his PhD in 2005. With the support of the state government of Himachal Pradesh, local authorities and residents of Kibber village in Spiti, he and his team established fenced plots (where animals were excluded) as well as plots where animals like yak and ibex grazed. Over the next decade, he and his students collected soil samples from the area and analyzed their chemical composition, tracking and comparing carbon and nitrogen levels in each plot year after year.
From year to year, soil carbon fluctuated 30-40% more in fenced plots where animals were absent, compared to grazed plots where it remained more stable each year. One of the main factors underlying these fluctuations was nitrogen. Depending on soil conditions, nitrogen can either stabilize or destabilize the carbon pool. Grazing by herbivores, however, alters their interactions in a way that tips the balance in favor of the former, the researchers found.
Many previous studies have focused on measuring carbon and nitrogen levels over long time intervals, assuming that carbon buildup or loss is a slow process, says Dilip GT Naidu, a DCCC PhD student and first author of the study. But the year-to-year fluctuations they noticed in their data paint a very different picture, he adds. These fluctuations can have consequences for the climate because they are linked to how large herbivorous mammals influence the soil, the IISc press release states.
Given that grazing ecosystems make up about 40% of Earth’s land surface, protecting herbivores that keep soil carbon stable should remain a key priority for mitigating climate change, the researchers suggest.
“Domestic and wild herbivores influence climate through their effects on soil carbon,” says Shamik Roy, a former CES doctoral student and another author of the study. As part of ongoing research, Bagchi and his team are also assessing why domesticated herbivores such as goats and sheep differ from their wild relatives in their impact on ecosystems. “Domestic and wild herbivores are very similar in many ways, but they differ in how they influence plants and soil. Understanding why they don’t look alike can lead us toward more effective soil carbon management,” adds Roy.
–IANS
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