- Forests are becoming major casualties of civilization as human populations have increased over the past several thousand years, bringing deforestation, pollution, and industrial usage problems to this important biome.
There are three major types of forests, classed according to latitude:
- Tropical
-Temperate
- Boreal (Taiga)
Tropical Forests
- Tropical forests are characterized by the greatest diversity of species.
- They occur near the equator, within the area bounded by latitudes 23.5 degrees N and 23.5 degrees S.
- One of the major characteristics of tropical forests is their distinct seasonality: winter is absent, and only two seasons are present (rainy and dry).
- The length of daylight is 12 hours and varies little.
- Temperature is on average 20-25° C and varies little throughout the year: the average temperatures of the three warmest and three coldest months do not differ by more than 5 degrees.
- Precipitation is evenly distributed throughout the year, with annual rainfall exceeding 200 cm.
- Soil is nutrient-poor and acidic.
- Decomposition is rapid and soils are subject to heavy leaching.
- Canopy in tropical forests is multilayered and continuous, allowing little light penetration.
- Flora is highly diverse: one square kilometer may contain as many as 100 different tree species.
- Trees are 25-35 m tall, with buttressed trunks and shallow roots, mostly evergreen, with large dark green leaves.
- Plants such as orchids, bromeliads, vines (lianas), ferns, mosses, and palms are present in tropical forests.
- Fauna include numerous birds, bats, small mammals, and insects.
More than one half of tropical forests have already been destroyed.
Temperate Forest
- Temperate forests occur in eastern North America, northeastern Asia, and western and central Europe.
- Well-defined seasons with a distinct winter characterize this forest biome.
- Moderate climate and a growing season of 140-200 days during 4-6 frost-free months distinguish temperate forests.
- Temperature varies from -30° C to 30° C.
- Precipitation (75-150 cm) is distributed evenly throughout the year.
- Soil is fertile, enriched with decaying litter.
- Canopy is moderately dense and allows light to penetrate, resulting in well-developed and richly diversified understory vegetation and stratification of animals.
- Flora is characterized by 3-4 tree species per square kilometer. Trees are distinguished by broad leaves that are lost annually and include such species as oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, willow, and spring-flowering herbs.
- Fauna is represented by squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear.
Only scattered remnants of original temperate forests remain.
Boreal Forest
- Boreal forests, or taiga, represent the largest terrestial biome. Occuring between 50 and 60 degrees north latitudes, boreal forests can be found in the broad belt of Eurasia and North America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada.
- Seasons are divided into short, moist, and moderately warm summers and long, cold, and dry winters.
- The length of the growing season in boreal forests is 130 days.
- Temperatures are very low.
- Precipitation is primarily in the form of snow, 40-100 cm annually.
- Soil is thin, nutrient-poor, and acidic.
- Canopy permits low light penetration, and as a result, understory is limited.
- Flora consist mostly of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce.
- Fauna include woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats.
Current extensive logging in boreal forests may soon cause their disappearance.
Threats on Forest Biomes
- People live too close to the deciduous forest biome
- Acid rain is caused by industrial and vehicle emissions and this causes damage to the leaves.
- Cutting trees for timber and to clear land for agriculture. THis leaves thousands of species of animals without a home.
- Also there is an introduction of non- native organisms which upsets the balance of the ecosystem by competing for food with native organisms.
- Diseases and insects, both native and foreign, are weakening and destroying forests across the country, even driving some species to the edge of extinction.
- With increased human activity and shifting climate patterns, we are seeing more frequent and intense wildfires, many of which can damage forests beyond the point of natural regeneration.
- Invasive plant species, which have few natural controls in our country, are overtaking native ecosystems, and driving out native plant and animal species.
- Increased development has led to loss of biodiversity and fragmentation of ecosystems and habitats.
- Mismanagement and unsustainable forestry practices are diminishing forests around the world faster than they can be regrown.
Why is this important to teach to students?
Biodiversity
A greater variety of life makes a forest better able to withstand and recover from disease, harmful infestations, wildfires, and other threats.
Clean Air & Water
Forests supply most of the freshwater flow in the US, and clean our atmosphere by intercepting airborne particles, carbon dioxide, and other greenhouse gases.
Medicine & Health
Trees not only create a healthier environment, they also provide a wide variety of medicines.
Social Benefits
Greener urban areas encourage more healthy social interaction between adults and children. They’ve also been a proven deterrent to graffiti, property crime, and even violent crime.
Recreation
Forests are a big part of why Americans love to get outdoors. They provide places for hikers, bicyclists, fishermen, hunters, and families of all ages to play and exercise.
Climate
Forests and climate are directly linked, both on the local and global scale. Healthy forests contribute to regular weather patterns, and help to combat the drastic changes that come from global climate change.
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