is found in the Amazon basin of South America, but other forests are found in
central and west Africa, southeast Asia, Indonesia, and northern Australia. One can
find more than 200 species of trees in small areas. Leaf shapes are similar between
species of tree. The canopy is high and closed, and 70% of plant species are trees.
Most of the other plant species are also concentrated in the canopy: associated climb-
ing lianes and epiphytes such as orchids form part of the canopy. The lack of light
results in a relatively sparse understory. The roots of the large trees do not reach
far into the soil because it is permanently wet. These giant trees therefore develop
buttress roots reaching 9 m up the trunks to support them. Individual trees have
a periodicity of growth and flowering, but two individuals of the same species can
be out of phase. Periodicities of growth differ between species; they are not related
to the annual cycle and vary between 2 and 32 months.
Most of the animal species are adapted to the canopy. The greatest diversity of
primates occurs in these forests, and in South America other mammals such as sloths
(Brachydura) are also adapted to feeding in the canopy. The diversity of bird species
is high, the highest being in the Amazon forests. Feeding and breeding of many bird
and bat species are adapted to the flowering periodicities of their preferred feeding
trees.Tropical broadleaf woodlands are an extension of the tropical forests in drier sea-
sonal climates and low-nutrient soils. As an adaptation to this climate trees have large
leaves which they shed during the dry season. A few species, such as Balanitesin
Africa and Eucalyptusin Australia, have small xeromorphic leaves which are retained
throughout the year. Trees often flower at the end of the dry season before leaf
formation. The dense herb layer leads to frequent fires in the dry season so that shrubs
and trees have evolved fire resistance.
Typical of this biome are the extensive Colophospermumand Brachystegiawood-
lands of southern Africa and Isoberliniawoodlands in west Africa. The canopy varies
from 3 to 10 m and is relatively open. Soils and grasses are low in nutrients; ungu-
late species are also at low density, although some, for example roan (Hippotragus
equinus) and sable antelope (H.niger), are adapted to this habitat. Similar vegetation
occurs in Brazil, India, and southeast Asia. The Indian and Asian woodlands are the
centers of radiation for the cattle group (Bos) – gaur, banteng, kouprey, and yak.
As in the tropics, temperate woodlands occur in drier environments than the forests.
This biome covers a heterogeneous collection of small conifer and deciduous tree
habitats in the Mediterranean and Mexico, but none of them are very extensive.The best known of these types is what is called the Mediterranean vegetation – a
scrub adapted to the dry conditions of a Mediterranean climate, which consists of dry
hot summers and cool wet winters. Similar types are found in South Africa, southern
Australia, central Chile, and southern California. Shrubs are low, with sclerophyl-
lous leaves. Many are adapted to annual fires, regrowing from the root stock.
Typical trees and shrubs of the Mediterranean are various oaks (Quercus), holly
(Ilex), the evergreen pines and junipers (Juniperus), and olive (Olea); in California
Quercus, Cupressus and chaparral shrubs (Ceanothus); in Chile various cacti
(Trichocereus); in South Africa Elytropappasand the major radiation of Protea; and
in Australia the mallee scrub made up of Eucalyptusshrubs as well as “grass trees”
(Xanthorrhoea, Kingia), cycads (Macrozamia), the evergreen Casuarina, and several14 Chapter 2