Study advocates strategies to halt rapid degradation of grasslands

Grasslands are endangered everywhere on Earth, warns a group of researchers from several countries in Nature Reviews Earth & Environment. The solution involves restoration and the pursuit of sustainable economic development alternatives.

By José Tadeu Arantes  |  Agência FAPESP – Researchers in several countries worked for five years to produce a comprehensive analysis of the current threats to global grasslands from ongoing degradation. Local studies were complemented by two in-person workshops and an intense exchange of emails among the scientists involved.

The outcome was the article “Combating global grassland degradation”, published in Nature Reviews Earth & Environment and signed by researchers based in Brazil, China, France, Germany, India, Switzerland and the United Kingdom.

The authors define grasslands as open grassland, grassy shrubland and savanna covering about 40% of Earth’s surface and 69% of its agricultural area.

“Grasslands are threatened everywhere on Earth, but the degradation process is different from region to region. The main problem is conversion of these biomes into arable land. In Brazil, for example, the original vegetation of the Cerrado [a savanna-like biome], which is extremely rich in biodiversity, is being replaced with large plantations of soybeans, sugarcane, eucalyptus, and so on,” Brazilian researcher Giselda Durigan told Agência FAPESP.

Durigan is a member of the Scientific Council of the São Paulo State Institute of Environmental Research and a professor of forest science and ecology at São Paulo State University (UNESP) and the State University of Campinas (UNICAMP), also in São Paulo. She has been researching the Cerrado for a long time, with several grants from FAPESP. When the study in question began, she was principal investigator for two projects (14/50710-7 and 13/24760-4) funded by FAPESP.

“Another form of degradation is exhaustive economic development of grasslands, as seen in much of Africa. Overdevelopment robs the original biome of its capacity to produce, its biodiversity, and its ecosystem services,” Durigan said.

Worse still, according to Durigan, is that few people care about the degradation or loss of these biomes, which can be considered “invisible”. Many people associate the idea of natural ecosystems with the presence of trees.

“The ignorance is so great that we Brazilians lack even a proper equivalent for the term grasslands in our language,” she said. “If you search for the word in Google Translate or English-Portuguese dictionaries, in print or on the internet, the result is pastagem [pasture]. That makes sense to some extent because roughly speaking grasslands can be thought of as any ecosystem on the planet with grasses that grazing animals can eat. Nevertheless, the term pasture isn’t at all the same as grassland.”

Brazil’s grassland-like biomes include the Pampa in the South region, campos de altitude [mountain-top shrublands] in the Southeast, and much of the Pantanal and practically all of the Cerrado in the Central region – except the “Cerradão”, which is more properly described as scrubby woodland. In sum, the term applies to the natural meadows, grasslands and savannas that predominate in some of its main biomes (Pampa, Cerrado and Pantanal). It can also apply to “islands” of grassy vegetation in the Amazon, Caatinga and Atlantic Rainforest.

“The point of our study and the published article was to show the global importance of grasslands in terms of biodiversity and ecosystem services, and to suggest ways of stopping the degradation and promoting their conservation and sustainable use,” Durigan said. “Project lead Richard Bardgett, Professor of Ecology at the University of Manchester in the UK, took pains to assemble researchers from different countries. Representativity was important so that we could develop an approach that made sense on a global scale.”

Solutions

The strategies advocated by the authors of the article for all this to result in genuinely effective public policies include adopting standardized indicators of degradation that are easily understood and applied globally, developing and disseminating ecologically effective and economically viable restoration techniques that meet the different interests of society, and finding economic development alternatives for these ecosystems that are sustainable and avoid their degradation.

“Grasslands are essential not only for the ecosystem services that protect water, soil and biodiversity, but also for the provision of food and other products essential to people’s lives in different parts of the world,” Durigan said. “Conservation of grasslands shouldn’t entail excluding people. There are people whose existence and culture depend entirely on these ecosystems. Their needs and views must be taken into consideration.”

Different “levels” of restoration should be determined, she added, and in such a way that they can be accepted, developed and put into practice by the various actors involved. They should range from mere restoration of the productivity of natural pasturage degraded by overuse to complete restoration of complex ecosystems, each in its own place. Successful initiatives are very rare but must be widely shared so that they can be replicated.

This set of initiatives is especially urgent in Brazil, where degradation and devastation are proceeding apace. Large swathes of the Pampas are becoming eucalyptus plantations for the production of paper pulp. The drying-up of the Pantanal due to the climate crisis tends to convert vast previously floodable areas into soybean fields. Large-scale agriculture has already swallowed up half of the Cerrado, the most biodiverse savanna on Earth.

“The Cerrado has suffered irreversible losses. One thing is restoring a biome degraded by overgrazing. Another is restoring an area that’s been changed by agriculture so much that it’s lost its original characteristics,” Durigan said. “When native grass was replaced by brachiaria grass, which is native to Africa, the impact was significant but plant and animal biodiversity remained high even so. However, traditional livestock farming is now being replaced by vast croplands with machines that cut roots deep down, and powerful herbicides that leave the soil completely without plant cover, so that nothing is left of the Cerrado that existed before.”

As reported previously by Agência FAPESP, besides biodiversity loss and destruction of the landscape, if the Cerrado collapses the consequences could be incalculable in terms of the impact on the rainfall regime. Some of Brazil’s most important rivers – the Xingu, Tocantins, Araguaia, São Francisco, Parnaíba, Gurupi, Jequitinhonha, Paraná and Paraguay, among others – rise in the Cerrado.

“Conservation and properly managed use of what’s left, with at least partial restoration of what’s been lost, is an enormous scientific, technological and political challenge, but fundamental for the survival of these rivers, which are major sources of both fresh water and hydropower,” Durigan said.

The article “Combating global grassland degradation” is at: www.nature.com/articles/s43017-021-00207-2.