habitat

habitat

[hab-i-tat]

Place where an organism or a community of organisms lives, including all living and nonliving factors or conditions of the surrounding environment. A host organism inhabited by parasites is as much a habitat as a place on land such as a grove of trees or an aquatic locality such as a small pond. “Microhabitat” refers to the conditions and organisms in the immediate vicinity of a plant or animal.

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Heaths are shrubland habitats characterised by open, low growing woody vegetation, found on mainly infertile acidic soils. They are similar to moorland, but they differ in terms of climate and vegetation. Heathland is generally warmer and drier than moorland.

Heaths are widespread worldwide. Heaths form extensive and highly diverse communities across Australia in humid and sub-humid areas. Fire regimes with recurring burning are required for the maintenance of the heathlands. Even more diverse though less widespread heath communities occur in Southern Africa. Extensive heath communities can also be found in California, New Caledonia, central Chile and along the shores of the Mediterranean Sea. In addition to these extensive heath areas the vegetation type is also found in more scattered locations across all continents, except Antarctica.

Characteristics

Heathland is favoured where climatic conditions are typically warm and dry, particularly in summer, and soils acidic, of low fertility, and often sandy and very free-draining; bogs do occur where drainage is poor, but are usually only small in extent. Heaths are dominated by low shrubs, 0.2–2 m tall.

Heath vegetation is extremely plant species rich, and heathlands of Australia are home to some 3,700 endemic or typical species in addition to numerous less restricted species. The fynbos heathlands of South Africa are second only to tropical rainforests in plant biodiversity with over 7,000 species . In marked contrast the tiny pockets of heathland in Europe are extremley depauperate with a flora comprised primarily of heather (Calluna vulgaris), heath (Erica species) and gorse (Ulex species).

The bird fauna of heathlands are usually cosmopolitan species of the region . In the depauperate heathlands of Europe bird species tend to be more characteristic of the community and include Montagu's Harrier, and the Tree Pipit. In Australia the heathland avian fauna is dominated by nectar feeding birds such as Honey-eaters and lorikeets although numerous other birds from emus to eagles are also common Australian heathlands. Australian heathlands are also home to the world's only nectar feeding terrestrial mammal: the Honey Possum. The bird fauna of the South African fynbos includes sunbirds warblers and siskins. Heathlands are also an excellent habitat for insects including ants, moths, butterflies and wasps with many species being restricted entirely to it.

Anthropogenic heaths

Anthropogenic heaths habitats are a cultural landscape that can be found worldwide in locations as diverse as northern and western Europe, the Americas, Australia, New Zealand, Madagascar and New Guinea where they have been created or expanded by centuries of human clearance of natural forest and woodland vegetation by grazing and burning. In some cases this clearance could go as far that parts of the heathland gave way to open spots of pure sand and sanddunes with a very local desert climate that, even in Europe can run up to local temperatures of 50 degrees Celsius in summer, drying the sand spot bordering heathland and further rising its vulnerability for wildfires. In recent years the conservation value of even these man-made heaths has become much more appreciated and consequently, most Heathlands are protected. However they are also threatened by tree incursion as a result of the discontinuation of traditional management techniques such as grazing and burning that mediated the landscapes. Some are also threatened by urban sprawl. Anthropogenic heathlands are maintained artificially by a combination of grazing and periodic burning (known as Swailing ), or (rarely) mowing; if not so maintained, it is rapidly re-colonised by forest or woodland. Any re-colonising tree species will depend on the local seed source, and may not reflect the natural vegetation before the Heathland became established.

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