Rangelands matter — for food, but for biodiversity and climate change?

Having our cake and eating it, too: Can we grow more food on the world’s range lands while at the same time conserving the wealth of biodiversity those range land support?

Rangelands cover one-quarter of earth’s land mass and they are storehouses of biodiversity. The scrublands of the Southern African Karoo, for example, are estimated to support some 6,000 species while Africa’s savannahs are renowned for their numbers and diversity of big mammals.

Rangelands may also be crucial to increasing livestock production in sustainable ways. Consider the Brachiaria grasses native to the rangelands of Central and Eastern Africa but now planted widely in the pastures of South America. These grasses not only allow for greater yields of milk by the ruminants who graze on them but also capture significant amounts of nitrous oxide, a potent greenhouse gas.

So rangelands matter—to biodiversity, to producing food while mitigating climate change, and of course to the livelihoods of the pastoral and agro-pastoral people who make their living largely through extensive livestock keeping.

But many of the world’s rangelands are under stress and in decline. Grasslands are increasingly being converted to croplands and/or are under pressure from expanding livestock production. Other threats include drying and more erratic climate do to global warming and the fragmentation of once open rangeland habitats due to infrastructure development. Any declines in rangeland biodiversity undermine the ecosystem benefits provided by these landscapes, which include their ability to purify and store water and to capture carbon  as well as to support food production.

Today, one-tenth of the global meat supply comes from rangelands, which support an estimated 200 million pastoralists and their herds of nearly 1 billion livestock—mainly camels, cattle, goats and sheep as well as yaks, horses and reindeer.

With the world’s population expected to top 9.3 billion by the year 2050 and demand for meat and milk products rising rapidly across the developing world, smarter approaches to rangeland management—including maintenance of rangeland biodiversity—are now seen as critical to creating sustainable food production systems that can feed the growing world.

A study published in the Proceedings of the National Academy of Sciences (PNAS) considered how to boost agriculture production in ways that are compatible with rangeland biodiversity conservation. The study found that it is possible to increase rangeland agricultural productivity while at the same time reducing biodiversity losses by incorporating high levels of agricultural knowledge, science and technology.

The study’s authors, including an ecologist from the International Livestock Research Institute (ILRI), examined two likely ways rangeland development would unfold in future.

If our food production practices don’t change, they said, but take a ‘business as usual’ approach, livestock grazing on rangelands is likely to continue to increase at a moderate pace in many regions while also growing more dependent on livestock feed produced on croplands, which would further increase the amount of rangelands displaced by crop agriculture and lead to dramatic losses of biodiversity.

On the other hand, if livestock production expanded under the guidance of high levels of agricultural knowledge, science and technology promoting widespread adoption of resource-efficient production technologies, rangeland biodiversity losses would be modest rather than severe through the year 2050.

In addition, the authors found that bringing more knowledge and technology to bear on livestock production could actually decrease the overall amount of rangeland used for grazing, particularly in Africa, where areas used for grazing could be halved by 2050 due to partial replacement of traditional livestock production systems with more resource-efficient farms mixing crop with livestock production. Despite these changes, however, the researchers found that even under this more optimistic scenario, milk and meat production per hectare  would still remain depressed in sub-Saharan Africa—with an output in 2050 less than 40% of the average of the European Union in 2000.

This paper’s sobering assessment also acknowledges the significant challenges faced by farmers in adopting more efficient livestock production practices, particularly in Africa, where poverty is still widespread and human and institutional resources thin on the ground. And the PNAS paper acknowledges the huge variations in productivity inherent in the different livestock production systems (pastoral, agro-pastoral, mixed farming, industrial) practiced around the world, variations which obviate any ‘one-size fits all’ solutions.

Agricultural intensification of range as on other lands must become ‘eco-efficient’, the researchers say. Neither our rangelands nor their biodiversity will be conserved by implementing ‘high-yielding agricultural practices’ alone, they argue. But the reverse is also true, they warn: Policies aiming to preserve rangeland biodiversity in developing countries are doomed to fail if they don’t help people find ways to make a decent living off those rangelands.

Read the paper in the Proceedings of the National Academy of Sciences (PNAS): Assessing the impacts of livestock production on biodiversity in rangeland ecosystems, by Rob Alkemade, Maurits van den Berg and Michel Jeuken, all of the PBL Netherlands Environmental Assessment Agency; Robin Reid, of the Center for Collaborative Conservation (Colorado State University) and formerly of ILRI; and Jan de Leeuw, then of ILRI and now at the World Agroforestry Centre (both based in Kenya), 24 Dec 2013.