Presentation on theme: "World Biomes Subtropical evergreen forest. Introduction In the middle latitudes, the prevailing winds carry moisture-laden air masses over the west coasts."— Presentation transcript:
Introduction In the middle latitudes, the prevailing winds carry moisture-laden air masses over the west coasts of the continents, which receive substantial rainfall in consequence. In much the same manner, the subtropical east coasts of the continents are kept wet by the trade winds. In these regions, the combination of ample precipitation and comparatively mild temperatures produces dense forests in which evergreen species, both broadleaf and coniferous, preponderate.
Climate Is created by warm, moist air flowing out of the subtropical high pressure cells onto the eastern sides of the continents. Has abundant summer rainfall, mainly convectional with an occasional tropical cyclone (monsoons). Receives winter precipitation from wave cyclones. Annual precipitation shows a significant variation between 1,000 mm and 3,000 mm Temperature ranges from 0°C in winter to 20°C In summer.
Distribution of biome The most extensive region of subtropical evergreen forests is in East Asia, where rain falls throughout the year and summers are hot. These forests occupy a large transitional zone between the deciduous forests of northern China and Japan and the tropical evergreen forests of Southeast Asia. The corresponding forests in North America are confined to the Atlantic coastal plain of the south- eastern United States, where evergreen oaks and magnolias flourish in the maritime climate. Far to the south of the Equator, significant subtropical evergreen forests grow in south-eastern Australia, New Zealand, and the coast and highlands of southern Brazil.
Soil Soils are depleted by high rainfall as nutrients are washed out of the soil. Soils have a subsurface horizon in which clays have accumulated, often with strong yellowish or reddish colours resulting from the presence of Fe oxides. Because of their acidity and relatively low quantities of plant-available Ca, Mg, and K, soils are poorly suited for continuous agriculture without the use of fertilizer and lime. With these inputs, however, these soils can be very productive.
Plants I Some of subtropical forests are sufficiently wet to be called rainforests. As in the more familiar rainforests of the tropics, many of the trees reach enormous size, and epiphytes are common. Because more light penetrates the canopy, however, the vegetation of the understorey and forest floor is better developed than in the tropics.
People Urbanisation, industrialisation, logging, agricultural expansion, and associated road building threaten this globally important region of biological diversity. Habitat loss, hunting, and the wildlife trade threaten many species.