From the prairies of North America and the steppes of Central Asia to African savannahs and European pastures: grasslands dominate the landscape in many regions of the world. It has, depending on the climate, many faces and just as many names. Habitats known as grasslands cover 52 million square kilometres on all continents except Antarctica. Thus, they cover 40 percent of the land mass and are home to a large part of the biodiversity of this planet. Some animal species even cross entire continents to benefit from lush greenery at any time of the year: white storks hunt in European meadows in summer and in the African savannahs in winter.
Despite its omnipresence on almost all parts of the ground, grassland plays a rather subordinate role in the nature conservation debate compared to other habitat types. While the protection of the forests - which even cover a smaller area on earth with around 30 percent - has had great priority in the fight against climate change for several years, the ecological importance of grassy open land for nature, man and climate has so far rarely been prominent.
Experts on grassland ecosystems and the editors of the renowned scientific journal »Science« want to change this. In four major review articles entitled »The Unrecognized Value of Grasses« in a special issue of the magazine, they summarize the current state of research on these diverse ecosystems, which play a vital role for many life forms all over the world – in the form of seagrass meadows even in the oceans. » Grasslands create and stabilize fertile soil, store carbon, produce oxygen, and provide habitat for animals, building materials, and food," write Science editor Bianca Lopez and her colleagues in the editorial.
In fact, grass landscapes are very similar to forests. They are hotspots of biodiversity, existential suppliers of food, formative places for many cultures and - last but not least - significant allies in the fight against climate change. "Grassland stores about a third of the global terrestrial carbon supplies and can serve as important carbon sinks in the soil," Yongfei Bai and Francesca Cotrufo write in a contribution to the role of this habitat for climate protection.
The enormous storage capacity illustrates how important it is to preserve grassland agriculture as a form of land use in order to permanently bind carbon. Because meadows and pastures are still being converted into arable land or cultivated on a large scale. According to the two researchers from the Chinese Academy of Sciences and Colorado State University, the "ecosystem service" provided by such areas because they store organic carbon could even be significantly expanded through renaturation. European countries could also make much greater use of and exploit this potential for additional natural climate protection, they write.
The scientists see the preservation of grassland as a win-win situation for climate and nature conservation: in order to be able to make better use of natural climate protection capabilities, the biodiversity in the grasslands must be strengthened. "Recent studies show that plant diversity increases the storage of organic carbon in the soil by increasing the carbon input into the underground biomass," they explain. Simple, practical measures such as reducing livestock density on pastures could increase biodiversity and thus "offer inexpensive and carbon-rich options for natural solutions to combat climate change in global grassland," according to the researchers.
From the cradle of mankind to the ecological crisis region
The US scientists Caroline Strömberg and Carla Staver make it clear in their work on the history of the origin and the current problems of grassland habitats that the global grasslands are far away from an appreciation of this "ecological capital", despite their outstanding importance for humans. The biologists remind that our history is also closely connected with grassy habitats. After all, it was the savannahs in which modern man was able to develop two million years ago. And it was only the domestication of some of the more than 10,000 species of grasses such as wheat and barley that made the emergence of agricultural societies and thus modern civilization possible about 10,000 years ago. Today, there are half a dozen cultivated grass species that, in addition to corn and rice as the most important staple foods on Earth, ensure the survival of mankind. Cattle breeding is also inconceivable without grassland, Strömberg and Staver emphasize the importance of this habitat type.
Particularly endangered and little protected
The authors also take a look at the threats to the different grass landscapes worldwide. As Strömberg and Staver find, these ecosystems are particularly affected by overuse, climate change and direct destruction due to a changed land use. At the same time, they were among the least protected habitats almost everywhere.
As a result, 90 percent of the original grasslands in temperate climate regions have already been converted into agricultural land or human settlement areas. According to the authors, only one percent of the remaining land is currently protected from development. "While the rainforests in the Amazon have attracted the attention of the media, the ongoing threat to the savannas, especially in Africa, South America and Asia, through reforestation, slash-and-burn and land conversion has gone unnoticed," they complain. The effects of further destruction on the biodiversity of savannas, prairies, meadows and pastures are devastating. Strömberg and Staver expect that 40 percent of all vertebrate species adapted to grasslands will be lost in the next decades. "This puts the fate of the evolutionarily ancient grassland biomes at stake, with fatal consequences for their different communities," is the less optimistic conclusion.
In a contribution to the chances of renaturalizing destroyed grassland habitats, Elise Buisson and colleagues illuminate the importance of preservation of the few still existing regions. The latest research results indicated that grassland only slowly and sometimes do not recover from disorders, they write. At the same time, there are large gaps in knowledge in research on this area. "At the beginning of the decades of restoration of ecosystems just called by the United Nations, progress in science and practice of green countries is of crucial importance if we want to combat the decline in biological diversity," the scientists believe.
Germany is not a model pupil when it comes to grassland protection
Grass habitats are also under great pressure in Europe and Germany. In the report on the state of nature in Europe published by the EU Commission every six years, grassland is one of the worst performers. In the national German report, the situation is even more devastating: only the melting glaciers are even worse off as a habitat here on land. Because Germany cares too little about this habitat, which is particularly protected under the European Fauna-Flora-Habitat Nature Conservation Directive (FFH), the EU Commission has filed a lawsuit against the Federal Republic of Germany before the European Court of Justice. According to EU law, the condition of the protected species and habitats in these areas must not deteriorate. However, according to calculations by the EU Commission, around 18,000 hectares of meadows have been destroyed in the German FFH areas in recent years. This is due to the conversion of grassland into arable land, overfertilization and an excessive use of pesticides.
More scientific research and a higher appreciation for a habitat that surrounds and affects us all directly, the authors of the »Science« special edition see the key to preserving steppes, meadows and savannas-and thus a central part of biological diversity the earth. "Grasses could offer solutions for many of our current social challenges if we only fully recognize their diversity and value," is the conclusion of the "Science" editors.
