A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth. Furthermore, grasslands are one of the largest biomes on Earth and dominate the landscape worldwide.[1] There are different types of grasslands: natural grasslands, semi-natural grasslands, and agricultural grasslands.[1] They cover 31–69% of the Earth's land area.[2][3]
"...any plant community, including harvested forages, in which grasses and/or legumes make up the dominant vegetation."
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"...terrestrial ecosystems dominated by herbaceous and shrub vegetation, and maintained by fire, grazing, drought and/or freezing temperatures." (Pilot Assessment of Global Ecosystems, 2000)
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"A region with sufficient average annual precipitation (25-75 cm) to support grass..." (Stiling, 1999)
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Included among the variety of definitions for grasslands are:
Semi-natural grasslands are a very common subcategory of the grasslands biome.[4] These can be defined as:
They can also be described as the following:
There are many different types of semi-natural grasslands, e.g. hay meadows.[8]
The graminoids are among the most versatile life forms. They became widespread toward the end of the Cretaceous period, and coprolites of fossilized dinosaur feces have been found containing phytoliths of a variety of grasses that include grasses that are related to modern rice and bamboo.
The appearance of mountains in the western United States during the Miocene and Pliocene epochs, a period of some 25 million years, created a continental climate favourable to the evolution of grasslands.[9]
Around 5 million years ago during the Late Miocene in the New World and the Pliocene in the Old World, the first true grasslands occurred. Existing forest biomes declined, and grasslands became much more widespread. It is known that grasslands have existed in Europe throughout the Pleistocene (the last 1.8 million years).[8] Following the Pleistoceneice ages (with their glacials and interglacials), grasslands expanded in the hotter, drier climates, and began to become the dominant land feature worldwide.[9] Since the grasslands have existed for over 1.8 million years, there is high variability. For example steppe-tundra dominated in Northern and Central Europe whereas a higher amount of xerothermic grasslands occurred in the Mediterranean area.[8] Within temperate Europe, the range of types is quite wide and also became unique due to the exchange of species and genetic material between different biomes.
The semi-natural grasslands first appeared when humans started farming. So for the use of agriculture, forests got cleared in Europe. Ancient meadows and pastures were the parts that were suitable for cultivation. The semi-natural grasslands were formed from these areas.[8] However, there's also evidence for the local persistence of natural grasslands in Europe, originally maintained by wild herbivores, throughout the pre-Neolithic Holocene.[10][11] The removal of the plants by the grazing animals and later the mowing farmers led to co-existence of other plant species around. In the following, the biodiversity of the plants evolve. Also, the species that already lived there adapted to the new conditions.[8]
Most of the grassland areas have been turned to arable fields and disappeared again. The grasslands permanently became arable cropping fields due to the steady decrease in organic matter.[12] Nowadays, semi-natural grasslands are rather located in areas that are unsuitable for agricultural farming.[8]
Grasslands dominated by unsown wild-plant communities ("unimproved grasslands") can be called either natural or "semi-natural" habitat. Although their plant communities are natural, their maintenance depends upon anthropogenic activities such as grazing and cutting regimes. The semi-natural grasslands contain many species of wild plants, including grasses, sedges, rushes, and herbs; 25 plant-species per 100 square centimeters can be found.[8] A European record that was found on a meadow in Estonia described 76 species of plants in one square meter.[8] Chalk downlands in England can support over 40 species per square meter.
promotion of genetic diversity
weather amelioration
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provision of wildlife habitat
prescribed fires
appropriate management of livestock and wild herbivores: in light of land use intensification caused by global food demand, grassland land use practices may need to be adjusted to better support key ecosystem services.
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tree cutting
shrub removal
invasive species control
reintroduction of native grasses and forbs via seeding or transplant: a main challenge for grassland restoration is how to overcome seed limitation.
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Despite growing recognition of the importance of grasslands, understanding of restoration options remains limited.[48] Cost of grassland restoration is highly variable and respective data is scarce.[49] Successful grassland restoration has several dimensions, including recognition in policy, standardisation of indicators of degradation, scientific innovation, knowledge transfer and data sharing.[50]
Restoration methods and measures include the following:[51]
