Plants on calcareous grassland are typically short and
hardy, and include
grasses and herbs such as
clover. Calcareous grassland is an important habitat for insects, particularly
butterflies and ants, and is kept at a
plagioclimax by
grazing animals, usually sheep and sometimes cattle.
Rabbits used to play a part but due to the onset of
myxomatosis their numbers decreased so dramatically that they no longer have much of a grazing effect. The
lichen flora of chalk grasslands represents an often overlooked component of calcareous grassland biodiversity. A comprehensive survey of English chalk grasslands in the 1990s identified two main
lichen communities: the widespread
Lecideetum watsomiae association found on chalk pebbles and flints, and the more restricted
Fulgensietum fulgentis community. These lichen communities require specific conditions to grow, including areas of open ground created through natural or human disturbance, such as rabbit
grazing,
trampling, or historical agricultural practices. The richest lichen sites are often found where soil has been disturbed within the past century or where natural factors like
landslips create suitable habitats. Key factors promoting lichen diversity include the presence of stable
flints, areas of nutrient-poor soil, and the presence of a small
loess (windblown silt) fraction in the soil. Characteristic species include
Gyalolechia fulgens and various
Cladonia species. Many calcareous grassland lichen communities have shown significant decline since the mid-20th century, attributed to factors such as reduced grazing, nitrogen deposition, and habitat loss. ==See also==