Sheep and horses may help grasslands lock more carbon underground

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🗞️ Driving the news: A study of Icelandic grasslands suggests that removing livestock does not necessarily increase soil-carbon storage
• Researchers compared 34 pairs of fenced and grazed plots, where livestock had been excluded for 20–83 years, and found that grazed land generally retained more carbon in its topsoil

🔭 The context: The difference was concentrated in the top 10 cm of soil: ungrazed plots held about 8% less carbon, while their roots contained 29% less carbon
• Grazing may stimulate root growth and return nutrients through dung, helping move plant carbon underground
• However, the researchers stress that grazing intensity, species, climate and soil conditions matter, and some ungrazed sites showed no decline in soil carbon

🌍 Why it matters for the planet: The findings challenge the assumption that removing livestock is always beneficial for carbon storage in grasslands
• They also highlight the importance of protecting below-ground carbon, particularly in northern ecosystems where tree planting may not deliver the expected climate benefits

⏭️ What’s next: Because the fences were not established as a controlled experiment, researchers cannot determine the rate of carbon accumulation or prove that reintroducing livestock would restore lost carbon
• More studies are needed across different climates and grazing regimes

💬 One quote: “Grazing is not the same as grazing,” said Anna Gudrun Thorhallsdottir, highlighting the importance of local conditions and management

📈 One stat: Grazed grassland stored about 43 tonnes of carbon per acre in its top foot, compared with 35 tonnes under heath and 25 tonnes under mature birch woodland

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