Sclerophyll
Sclerophyllous plants occur in many parts of the world,[1] but are most typical of areas with low rainfall or seasonal droughts, such as Australia, Africa, and western North and South America.
Plant species with this type of adaptation tend to be evergreen with great longevity, slow growth and with no loss of leaves during the unfavorable season.
As a result, the thickets that make up these ecosystems are of the persistent evergreen type, in addition to the predominance of plants, even herbaceous ones, with "hard" leaves, which are covered by a thick leathery layer called the cuticle, that prevents water loss during the dry season.
Most of the plant species in the sclerophyll zone are not only insensitive to summer drought, they have also used various strategies to adapt to frequent wildfires, heavy rainfall and nutrient deficiencies.
[3] The type of sclerophyllic trees in the Palearctic flora region include the holm oak (Quercus ilex), myrtle (Myrtus communis), strawberry tree (Arbutus unedo), wild olive (Olea europaea), laurel (Laurus nobilis), mock privet (Phillyrea latifolia), the Italian buckthorn (Rhamnus alaternus), etc.
These lower transpiration rates may reduce the uptake of toxic ions and better provide for C-carboxylation under nutrient-poor conditions, particularly low availability of mineral nitrogen and phosphate.
Sclerophyllous plants are found in tropical heath forests, which grown on nutrient-poor sandy soils in humid regions in the Orinoco and the Rio Negro basins of northern South America on quartz sand, in the kerangas forests of Borneo and on the Malay Peninsula, in coastal sandy areas along the Gulf of Guinea in Gabon, Cameroon, and Côte d'Ivoire, and in eastern Australia.
Through overexploitation (logging, grazing, agricultural use) and frequent fires caused by people, the original forest vegetation is converted.
Some sclerophyll areas are closer to the equator than the Mediterranean zone—for example, the interior of Madagascar, the dry half of New Caledonia, the lower edge areas of the Madrean pine-oak woodlands of the Mexican highlands between 800 and 1,800 metres (2,600 and 5,900 ft) or around 2,000 m (6,600 ft) high plateaus of the Asir Mountains on the western edge of the Arabian Peninsula.
In the sclerophyll regions near the coast, permanent crops such as olive and wine cultivation established themselves; However, the landscape forms that characterize the degenerate shrubbery and shrub heaths maquis and garrigue are predominantly a result of grazing (especially with goats).
[15] Most areas of the Australian continent able to support woody plants are occupied by sclerophyll communities as forests, savannas, or heathlands.
Most of the wooded parts of present-day Australia have become sclerophyll dominated as a result of the extreme age of the continent combined with Aboriginal fire use.
Deep weathering of the crust over many millions of years leached chemicals out of the rock, leaving Australian soils deficient in nutrients, particularly phosphorus.
However such deficient soils cannot support the nutrient losses associated with frequent fires and are rapidly replaced with sclerophyllous species under traditional Aboriginal burning regimens.
[22] All the Australian sclerophyllous communities are liable to be burnt with varying frequencies and many of the woody plants of these woodlands have developed adaptations to survive and minimise the effects of fire.
