Grasslands exist in many parts of the world and are often influenced by
humans. At southern latitudes, arid conditions may limit grass growth,
sometimes resulting in
competition among grasses for water.
Grasslands are often grazed by domestic animals or mown
by farmers and this may influence the distribution and abundance of
plants in the sward. However, natural herbivores, for example, mammals,
birds and insects, may also feed on grasslands.
At northern latitudes, local disturbance patterns as
well as larger scale land management may influence
species interactions in the grasslands. In Iceland and elsewhere in
northern Europe, grasslands are much influenced by lifestock grazing.
Grasslands are often semi-natural, for example, cultivated grasses and
legumes are frequently sown into grasslands to increase their
production.
Over a thousand years ago, the early settlers of Iceland
burned woodlands to open new pastures. Here, the fertility of the soil
is important for grass growth. Tufted Hair-grass (Deschampsia
caespitosa) is the dominant on infertile land whereas Common
Bent-grass (Agrostis capillaris) thrives on fertile land.
