Tropical forests are characterised by the greatest diversity of species. They occur near the equator. One of the major characteristics is their distinct seasonality: winter is absent, and only 2 seasons are present (rainy and dry). Temperature is on average 20-25* C and varies little. Precipitation is evenly distributed throughout the year (~2000mm). Soil is nutrient poor and acidic. Canopy is multilayered and continuous.
Temperate forests occur in eastern North America, north- eastern Asia and western and central Europe. Well-defined seasons with distinct weather characterise this forest biome. Moderate climate and a growing season of 140-200 days during 4-6 frost-free moths distinguish temperate forest. Temperature varies from –30 to 30* C. Precipitation is distributed evenly throughout the year (75-150 cm). Soil is fertile, enriched with decaying litter. Canopy is moderate dense and allows light to penetrate resulting in rich biodiversity.
Boreal forests, or taiga, represent the largest terrestrial biome. They can be found in the broad belt of Eurasia and North America. Seasons are divided into short, moist and moderately warm summers and long winters. Temperatures are very low. Precipitation is mainly in the form of snow, (40-100cm). Soil is thin, nutrient poor and acidic, canopy permits low light penetration and as a result, vegetation is limited.
Although temperate forests are not significantly decreasing, tropical forests are declining at a rate that will decrease their 1950 extent to 300 million hectares of forest. (15% to 7 %). (2)
Worldwide there are between 5 to 80 million species of plants and animals, which make up the biodiversity of our planet. Tropical rain forest- covering only 7 % of the total dry surface of the earth hold over half of all these species. Probably the most serious and most shortsighted consequence of deforestation is the loss of biodiversity. Many of the rain forest plants and animals can only be found in small areas, because they require a special habitat to live. This makes them very vulnerable to deforestation. If their habitat is cut down, they may go extinct. Every year 50,000 species disappear from the tropical rain forests as they are cut.
The loss of species has a great impact on the planet. (3)
The cause of deforestation is a very complex subject. A competitive global economy, forces the need for money in poorer tropical countries. At the national level, the government sell logging concessions to raise money for projects, to pay international debt, or to develop industry. Brazil had an international debt of $ 159 billion in 1995 on which it must make payments each year. The logging companies seek to harvest the forest and make profit from the sales of valuable hardwoods and pulp.
Deforestation by a peasant farmer is often done to raise crops for self-subsistence, and is driven by the basic human need for food. Most tropical countries are very poor by U. S. standards and farming is a basic way of life for a large part of the population. (4)
To limit the impact of mans activities on forests, sustainable forestry technique could be used.
Sustainable forestry is a process of maintaining forests in order to meet the needs for present and future generations alike. The concept of sustainable forestry is always evolving with knowledge learned through research and experience. There are many reasons for practicing sustainable forestry. The economic sustainability of some communities is directly related to the long-term success of the forest product industry. Sustainable forest management is also a means by which the forest is able to meet multiple demands.
Sustainable forestry has many benefits, some of which are as follows:
- Cleaner air
- Conservation of soil
- Enhancing wildlife habitat quality
- Wood utilization improvement
- Recreational activities and protection of water quality
In order to achieve sustainable forestry we have to manage our timber resources. To make this possible there has to be a balance between the amount of trees harvested and the amount of new trees growing. This balance is called the sustained yield. Through sustained yield management we ensure ourselves a continued supply of timber. (5)
Sustainable forestry practices create financial gains for landowners and consumers of wood products. These practices also result in more stable prices for wood products such as lumber and paper, because the supply of timber is more constant.
Under sustainable forestry, social wants and needs are fully considered and forests are managed to produce a variety of values and benefits. Values that go beyond the direct sustainability of the forest ecosystem include: aesthetics, wilderness, recreation, biodiversity, and non-traditional forest products. For this reason this stage is sometimes referred to as "social forestry." A strong economy and strong local communities are essential for this stage to exist.
The deforestation of forests is threat to life worldwide. Deforestation may have profound effects on global climate and cause the extinction of thousands of species. Stopping deforestation has become an international movement, seeking ways to stop the loss of rain forests. (6)
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References:
- N.P.O Green et al, (1990) Biological Science-Organisms, Energy and Environment,
Second edition. Published by the Press Syndicate of the University of
Cambridge.
- “The World Guide”, Dec. 1998, page 30-35
- “Forestry” Jan. 1991, Vol. 7, (57-59)
- Janet L. Hopson & Norman K. Wessells, (1990) Essentials of Biology, international edition. Published by McGraw-Hill, Inc
