Let’s talk grass: Why do we need grasslands?
At first glance, the prairies, savannahs, and pampas of the United States, Africa, and Argentina might look like sparse, unpopulated grassy deserts. But these overlooked habitats are some of the biggest and most important ecosystems on Earth. Despite how important they are, grassland biodiversity is degrading faster than ever before in human history(1).
Grasslands can be found under many names such as savannahs, shrublands, steppes, rangelands, drylands, prairies, veld, llano, pampas, and meadows. Each has their own unique geology, climate, ecological traits, uses, and cultural distinctions. They account for between 20 and 40 percent of the world's land area, depending on how they are defined—an estimated 52.5 million square kilometers. To put this in perspective, the African continent is 30.3 million square kilometers.
Facts about grass
- There approx. 1,400 species of grass in the United States
- Antarctic hairgrass (Deschampsia Antarctica) is the only species of grass that grows in Antarctica
- The largest variety of grass is bamboo which can grow 150 ft tall!
- Grass is used to make sake, beer, chicha, and whiskey
- 800 million people depend on grasslands for agriculture and livelihood
What is grass, exactly?
Grass looked very different 70 million years ago. The plant evolved towards the end of the Cretaceous period and was only found on the forest floor. Over time, extensive grasslands spread across huge areas as it adapted to more open, arid environments.
Poaceae (the scientific name for the grass family) is one of the largest plant families on Earth, with over 11,000 unique species. Grasses are monocotyledonous—which means that a single leaf sprouts from one seed. Grasses are flowering plants, but their flowers are often so small that they need special names. Grass flowers are called florets, and one or more florets make up a spikelet. Sometimes it can be very hard to tell grasses apart, even among the experts!
Grass grows a lot like human hair, from the base, rather than the tip like most other plants. Grasses defend themselves using tiny silica* crystals called phytoliths, which provide some resistance to overgrazing. These phytoliths prevent herbivores from eating too much as it wears down their teeth.
Grass does more than just exist. It draws massive amounts of carbon from the atmosphere, provides food and shelter for countless species, and keeps soil in place with their roots which prevents erosion. Despite its importance to the planet, grasslands are one of our most overlooked ecosystems. We will talk more about this later.
Types of grassland
A 2019 ESA journal entry outlined three major kinds of grasslands: natural, semi-natural, and improved grasslands.
- Natural grasslands are wild areas that were created by natural processes like climate, fire, and wildlife grazing. They are also sometimes used for livestock grazing.
- Semi-natural grasslands are managed by humans and require livestock grazing or cutting for maintenance.
- Improved grasslands are pastures and farmland created through plowing and sowing, made with non-native, highly fertilized monocultures with high yield potential.
Natural and semi-natural grasslands are usually made up of many different kinds of grass. For example, the tallgrass prairies in the wetter eastern US support big bluestem, Indian grass, and switch grass which can grow up to eight feet. Travel further inland to the arid mid-grass prairies and you’ll see a region dominated by side-oats grama and wheatgrass.(2) In Africa, the most common grasses are bluestem, thatching grass, and kangaroo grass.
The variety and individuality of the grasses in the grasslands are what makes them such a biodiversity hotspot. Grasslands around the world have been heavily influenced by the evolution of grazing herbivores such as horses and cattle. These grazers have evolved specialized teeth and stomachs to digest the grass and withstand wear and tear. Known as ecosystem engineers, these herbivores are the architects of the grasslands, and alongside fire, help shape the landscape.
Why is grass so important?
Grasslands are often undervalued and overlooked ecosystems because they may not be as exciting as coral reefs or rainforests—but they are fundamental to the planet and its future.
Cultural significance
Grasslands have played a central role in human development and human history. Some people have thought that without the grasslands of modern-day Mongolia and Ukraine—which allowed easier movement of large armies and enough food for their horses—the conquests of Ghengis Khan and Caesar would not have been possible(3).
Over centuries, indigenous communities have used grasslands to build nomadic* and pastoral* lifestyles in this natural environment. Nomads in Mongolia, Kenya’s Massai, Gran Chaco Herders in Mexico, and the Sicangu Oyate in the US are all examples of communities who rely on the open grasslands for herding and growing their crops.
Biodiversity
Grassland ecosystems are full of life, and rely on a delicate balance of predators and prey to function efficiently. Foxes, prairie dogs, wildebeest, bison, and countless other species rely on grasslands for food and shelter.
A closer look between the blades reveals a tiny world of insects and invertebrates, all of which help the grasslands thrive through pollination, seed dispersal, and nutrient cycling. Reptiles, amphibians, and small mammals actively shape vegetation. Below the surface, interactions among roots, microbes and fungi supports decomposition and the release of essential nutrients, maintaining soil fertility and grassland productivity.
Carbon Mitigation
Grasslands play a vital and undervalued role in mitigating climate change. Their large surface area absorbs sunlight and prevents the ground from heating up too much. It is estimated that grasslands store approximately 34 percent of the global stock of carbon in terrestrial ecosystems, which is only slightly less than forests which store approximately 39 percent. Protected grasslands have the potential to be more stable carbon stores than forests, because they can withstand environmental changes such as fire and drought.
Water Regulation
The deep, dense roots of grass systems allow rainwater to penetrate deep into the ground. This creates reliable sources of groundwater, prevents flooding, and maintains valuable water sources necessary to maintain vegetation during dry spells. Grass also acts as a water purifier, trapping pollutants and excess nutrients from rainwater as it runs down the leaves, through the roots and into the soil.(4)
Threats to grasslands
It’s hard to talk about grasslands without acknowledging how much has been lost. In Germany, around 40 percent of endangered ferns and flowering plants are found in grassland, which has been steadily declining since 1991(5). In America, 1.6 million acres of the Great Plains was destroyed in 2021 alone, and 32 million total acres of grassland habitat have been plowed up since 2012.(6) Globally, around half of all major grasslands and savannahs have been lost.(7) The reason? Agriculture.
Our need to feed the planet has impacted natural grasslands in a big way. The nutrient rich soil and vast open spaces have made these spaces ideal for raising livestock and cultivating crops. This in itself isn’t an issue, but it’s the unsustainable nature of modern agricultural production that’s the main driver. What’s more, only 8 percent of grassland biomes* are protected worldwide. Additionally, the balance between human needs and environmental conservation can (and do) lead to conflicts over resources. A lack of awareness about the value of grasslands has contributed to their vulnerability. This has led to a slower pace of action on the global conservation stage.(8)
The future of the grasslands also hinges on its animals. The American bison once dominated the prairies of North America, but were exploited to the point of near extinction by European settlers during the 19th century. 40-50 million plains bison were slaughtered by the end of the century, and the result of their disappearance was profound and far reaching. Many indigenous tribes faced food shortages as they lost their primary source of sustenance, leading to famine.
Bison are a keystone species, and many species directly rely on them for survival. They are ecosystem engineers who prune and shape the grasslands as they forage. Bison love to roll around in the dirt, creating wallows that help the grasslands catch and retain rainwater. Once the bison move on, these wallows are inhabited by insects which are food for birds and small mammals(9). This is an example of how the bison’s presence keeps the food chain strong and contributes to the ecosystem.
In our latest mission, Planet Wild went to Montana to work with a group of conservationists who are working with local ranchers to bring the bison and other wildlife back to the Great Plains. They are doing this by rewilding old cattle ranches and farms, letting nature return to the American grasslands.
From the savannahs of southern Africa to the Great Plains of the United States, grasslands are a vital and important ecosystem, but they are facing some of the fastest and highest rates of conversion and degradation of any biome. Despite their resilience from fire, flooding, and drought, they are sensitive to human interference. Even though grasslands are a major carbon sink, grasslands are often under-represented in nature-based investments and climate mitigation strategies. A big part of challenging this idea is to learn more about why grass is so important, and to make sure grasslands can be valued and protected.
Glossary of terms
Biome - a large, naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or ocean.
Silica - Silicon dioxide, also known as silica, is an oxide of silicon, commonly found in nature as quartz.
Nomadic - Nomads are people who live by traveling from place to place. They live a nomadic lifestyle, meaning they move around a lot.
Pastoral - People who herd or shepherd animals as part of their lifestyle. Raising sheep or cattle for food and work.