A forest is a significant area overgrown with trees, which is a single ecosystem that plays an important role in maintaining the atmospheric balance. Forests cover about a third of the Earth's land surface.
A forest is not just a collection of trees, shrubs and other plants. It is a separate ecosystem - a complex community of closely interconnected elements, which includes living organisms (plants, animals, microorganisms) and non-living components (water, air, soil). Streams of substances, such as oxygen and water, circulate in the ecosystem, forming a cycle. Thus, the elements of animate and inanimate nature are linked into one whole.
The most important function of the forest as a natural zone is the production of oxygen. It is thanks to green plants that release oxygen in the process of photosynthesis that our planet has acquired its modern form in the course of many millions of years of evolutionary development. In addition, green plants are, directly or indirectly, a food source for almost all other living things.
The classification of forests by natural zones, as a rule, is tied to climatic zones. It is customary to distinguish tropical, subtropical and temperate forests. However, trees can grow outside the specified climatic areas. Thus, a kind of transitional zones are formed: forest-steppe, forest-tundra, logged and high-mountain forests.
Tropical forests grow in the equatorial, subequatorial and tropical zones. This natural area is characterized by high humidity and warm or hot air temperatures throughout the year. Favorable natural conditions serve as a habitat for many species of plants and animals. More than two-thirds of the entire species diversity of the planet Earth is concentrated in tropical rainforests.
The natural zone of subtropical forests is located in the subtropics of the Northern and Southern Hemispheres. Natural green areas in this area have been significantly affected by massive logging. Most of what was once a subtropical forest is now occupied by agricultural crops. The surviving forests of this zone include the hemigilia in the south of the Brazilian Highlands and southeast Africa, monsoon mixed forests in the coastal areas of Asia, Australia, North and South America, and the hard-leaved forests of the Mediterranean and the California coast.
Temperate forests are located mainly in the Northern Hemisphere. They occupy a significant part of Europe, Russia, Canada and the north of the United States. This natural zone is characterized by a pronounced seasonality of the life cycles of plants and animals. The species composition is much poorer here than in tropical and subtropical forests.