Earth Science: Origins and Geology – Types Of Forests
Forests cover about one-third of the Earth’s land area. Acting as a sort of green lung, they produce oxygen and store large amounts of atmospheric carbon dioxide, so counteracting global warming.
Three prominent types of forest make up the green belt of our Earth. The central green zone along the Equator is formed by tropical rain forests, including the adjacent marginal tropic and monsoon forests. Trees, bushes, ferns, palms, orchids, and herbaceous plants grow in several levels over and on top of each other, as well as side-by-side.
They form the most species-rich and complex ecosystem on Earth, and are home to approximately 90 percent of all animal and plant species. Rain forests used to cover about 14 percent of the Earth’s land area; now, this has halved. Toward the North Pole, the evergreen boreal coniferous forests-the Russian taiga-are the northernmost trees.
Severe cold and an abundance of snow, combined with a short summer, mean that the vegetation period lasts only about 150 days of the year. Only a limited number of trees can grow in the meager and often infertile soils, and the undergrowth is also sparse. Boreal coniferous forests cover approximately 10 percent of the landmass of the Earth.
Within the wide band of temperate latitudes there are deciduous and mixed forests. Year-round rainfall facilitates the plant world, with a growth period of more than six months. In the cool temperate latitudes, deciduous forests with many tree varieties, as well as lush undergrowth, are found.
The leaves they shed in autumn protect them from being killed off by frost during winter. Along the subtropical west coasts of the continents, original hard-leaf forests protect themselves against evaporation during hot summers with small, tough leaves, such as those of the holly leaf oak in the Mediterranean and the eucalyptus in Australia.
Leatherlike leaves characterize laurel forests, which are scattered worldwide in perpetually damp, subtropical climates. Such moist forests are likely to be found along east coasts, such as eastern China, southern Japan, and Florida.
BASICS
FOLIAGE LEAVES adjust their position relative to the sun for maximum photosynthesis. Shorter days and declining temperatures initiate leaf shedding in autumn. Nutrient material previously embedded in stems serves to initiate new leaf growth in spring
NEEDLE LEAVES reduce the exposed surface area and protect against moisture evaporation and snow fracture. Almost all conifers retain their leaves in winter.