For decades, the spotlight has been on the issue of overgrazing, where expanding herds of cattle and other livestock degrade grasslands, steppes, and desert plains. However, a groundbreaking global study has unveiled a contrasting trend: in many regions, livestock numbers are significantly declining, a phenomenon researchers have termed “destocking.”
According to the study co-authored by Osvaldo Sala, an ecologist and professor at Arizona State University, “We often assume that rangelands are being degraded because we overgraze them, but the data show that it’s not the whole story: nearly half of livestock production occurs in areas that have experienced destocking over the past 25 years.”
Understanding Destocking: More Than Just the Reverse of Overgrazing
The findings highlight that destocking isn’t merely the opposite of overgrazing; it introduces new ecological and land management challenges. “We need to manage both processes,” Sala emphasized. “It’s not that destocking is automatically positive and that we should just leave it alone.”
For instance, when livestock numbers dwindle, unchecked plant growth may elevate wildfire risks. While biodiversity might recover in certain areas, it could decline in others, contingent on ecosystem responses. The study, published in the Proceedings of the National Academy of Sciences, underscores these complexities.
By the Numbers: Global Livestock Trends
Livestock populations have shrunk by about 12% over the past 25 years in regions that held 42% of the world’s cattle, buffalo, sheep, and goats in 1999.
Destocking is notably prevalent in Europe, North America, Australia, and parts of Africa and Asia, with Eastern Europe experiencing the steepest declines at 37%. Conversely, livestock numbers are burgeoning in Middle Africa, Central Asia, and South America, with overall numbers soaring by 40% since 1999.
Exploring the Drivers Behind Diverging Trends
To decipher the factors behind these diverging trends, Sala and co-author José Anadón from the Instituto Pirenaico de Ecología explored links to social, economic, and environmental variables. Surprisingly, changes in international trade and climate change did not account for the shifts in stocking rates.
“Climate change exists, but it doesn’t explain these particular spatial patterns of destocking and increasing stocking rates,” Sala remarked.
Instead, regional economic output and human population growth emerged as pivotal factors. In affluent regions where livestock numbers are waning, reliance on feed-based and industrial farming, coupled with advanced technology, results in meat production per animal being 72% higher than in less wealthy regions where rangeland herds are expanding.
“Stopping grazing doesn’t always mean more water to downstream users; effects are location-specific and need to be studied,” Sala said.
Implications for Planetary Health and Future Strategies
Livestock grazing occupies roughly a quarter of Earth’s land surface, rendering it humanity’s most extensive land use. The large-scale reduction in grazing livestock has significant implications for planetary health, which have been largely overlooked by conservation scientists and land managers.
Destocking and the ensuing decrease in grazing can not only heighten wildfire risk but also lead to the elimination of vulnerable plant species by allowing a few species to dominate. Conversely, reduced grazing could enhance ecosystems’ ability to capture atmospheric carbon dioxide, benefiting the global climate.
“This is not just doom and gloom — it’s a more realistic, complex picture that suggests both risks and opportunities,” Sala noted.
Charting a Path Forward
By concentrating heavily on overgrazing, researchers and policymakers have missed opportunities to manage destocking to achieve conservation, carbon storage, and rural livelihood goals. Sala emphasizes the need for better data, more experiments, and thoughtful policies that acknowledge regional differences.
“These are important issues for land managers, policymakers, and the public,” he concluded. “We need better science to decide what works where.”
