Forestral Types And Their Impo Essay, Research Paper
Forests by definition are a biome with enough average annual precipitation (at least 76 centimeters) to support growth of various species of trees and smaller forms of vegetation. The world s forests can be classified according to their site, vegetation, general location, and other characteristics. They are broadly classified into northern or boreal, central, southern, tropical, interior, coast, montane, and sub alpine types.
The Coniferous Forest:
These trees-these forests of trees-so enchain the sense of the grand and so enchant the sense of the beautiful that I linger on the theme and am loth to depart. Forests in which you cannot ride a horse-in which you cannot possibly recover game you have shot without the help of a good retriever-forests into which you cannot see, and which are almost dark under a bright midday sun-such forests, containing firs, cedar, pine, spruce and hemlock, envelop Puget Sound and cover a large part of Washington Territory, surpassing the woods of all the rest of the globe in the size, quantity and quality of the timber. (Samuel Wilkeson) (Notes on Puget Sound 1869)(Burton 52)
Conifererous forests (cone bearing) consist of cedars, pines firs, spruces, larches, and hemlocks. They are found in high sub polar latitudes, below the snow on mountain ranges, or on drought prone hillsides in lower latitudes. Over half of the world s coniferous forests are found in Asia, they also occur in Europe and North America.
To survive, grow, and continue to live a long dominant life the coniferous has adaptations that resist drought, low temperatures, and damage from the snow and wind. They also have a friend that helps them provide vital nutrients to the soil and host plants something that they otherwise could not do. These adaptations include their slender tapering habits that protect them from the snow and wind, their long living, narrow leaves (needles), coated with wax and imbedded with resins which prevents excessive transpiration. They also have an important relationship with a group of fungi called mycorrhiza that ensures that the soil doesn t run out of its vital properties. Conifer trees leave undecomposed acid litter beneath them due to their leaching characteristic, this drains most of the nitrogen and other elements out of the needles before they hit he ground. Also, the needles are unpalatable to birds and animals, so there is no input to the soil from their waste products. These fungi are so important because they populate the coniferous forest s litter and ensure that the mineral elements are transferred directly to the host trees before they can be leached downward and out of reach.
The Taiga:
The taiga is the circumpolar high latitude forest of the northern hemisphere and it stretches across the great continents of Eurasia and America. It forms the most widespread forest zone and includes the largest forest in the world, the Siberian forest. The Siberian forest extends over an area that is larger than the United States. The taiga is mainly a coniferous forest that are dominated by species of spruce, pine, fir, and larch, but there are areas that have been cleared in which some broadleaf (deciduous) species have grown. These are very important areas that provide food for birds, insects, and other animals.
The taiga forests growing season is very short and its weather conditions are severe, two factors that hinder the development of the trees. In the northern sections the trees remain small and misshapen. Some of the Siberian pines and larches have as many as sixty annual rings to an inch of radial growth on the trunk. (Burton 64). In the southern sections where the forests blend with the temperate woodlands, the trees can grow too much larger sizes.
Mountain forests:
These forests are able to withstand some of the harshest conditions in the world and are able to develop their own adaptations to the altitude and condition in which they live. The set up of mountain forests makes it a place where animals can readily find fresh feeding grounds. Also, the mountain forests serve as the greatest protection for the people that live there. The forests surround alpine meadows and summer pastures, which gives shelter from the cold winds. It is a barrier between the people living in a village and an avalanche, and it also prevents landslides by binding the soil with the roots of it s trees to the steep hillsides. Without the protection that mountain forests provide floods and erosion would soon make vast areas of the lowlands unlivable.
Southern Hemisphere conifers:
The southern hemisphere has no pines, firs, spruces, true cedars, or cypresses, but there is a coniferous element among the dominant trees there. They differ in leaf form from those in the north and with few exceptions they are much smaller in size. The major coniferous families that are found in the south include agathis, araucarias, podcarps, and cypresses.
The Olympic Rain forest:
The Olympic Rain Forest is the only rainforest growing in the northern hemisphere and it is found on the west side of the Olympic Peninsula in Washington State of the northwest United States. The trees here include conifers such as firs, hemlocks, spruce, and red cedars, and the redwoods. The trees are enormous with some of their crowns reaching three hundred feet. One hundred and forty five inches of rain falls annually and the temperature never falls below freezing or above eighty-five degrees farenheight. This forest is what we call a temperate rain forest.
Tropical Forests:
Tropical rain forests are formed around the equator and thrive in climate of constant rainfall and even temperatures. They occur where rainfall exceeds eighty to ninety inches per year. There are no seasons and the temperature changes from day to night are greater than those from day to day. Tropical rainforests lie in four main geographical regions: Central and South America, Africa and Madagascar, South and South East Asia, New Guinea and Australia. There are several types of tropical rainforests, and the type depends on altitude, temperature, and average rainfall. They all have a tremendous biological diversity and no single tree species dominate.
Five layers of vegetation are can be identified in tropical rainforests due to the struggle for sunlight. The emergent trees occupy the first story. The canopy of densely packed trees is beneath them and below it the tree crown are narrower. Farther down are shrubs and young trees, and on the ground herbs. These layers are not always distinct and some may not be there. In tropical rainforests most of the mineral nutrients are not held in the soil. When a plant or animal dies, soil fungi, the micorrhiza, quickly break down the dead organic litter and transfer it to the living cells of plant roots. This allows few minerals to be leached out of the soil by high rainfall.
Most of the plants have evolved specialized ways to grow in the rain forest. For example, almost all the plant roots have a relationship with mycorrizae, the fungi I explained earlier in the paper, and the roots of many of the trees have buttresses which are large bulges at their bases that aid in support due to the moist, thin soil they are anchored into. There is very little wind in the rainforest, eliminating the possibility of pollination by air. Thus, many of the plants have developed flowers that attract birds, insects, or bats that will aid in the pollination process.
Farther from the Equator the tropical forests become semi-deciduous and are sometimes called tropical monsoon forests or tropical seasonal forests. These forests are warm year round and usually have one or more dry seasons. Most of the rain occurs during a wet monsoon season. These forests differ from tropical rainforests in that they have a lower canopy and contain a mixture of deciduous trees and drought tolerant evergreen trees.
Temperate Deciduous Forests:
Temperate deciduous forests grow in moist and moderate climates. The areas usually have long and warm summers and winters that are cold, but not to severe. Also, the precipitation that falls is plentiful and spread out evenly from season to season. The major species that characterize temperate deciduous forests include: Oaks, maples, beeches, hornbeams, populars, limes, elms, birches, ashes, and hickories. All of these trees survive the winters by dropping their leaves in the fall, becoming dormant. When spring comes they grow their leaves until the fall returns.
A typical deciduous forests structure would look as follows. Large trees such as oaks, hickories, and some pines that would form the canopy with trees such as maples and birches that would form a secondary layer. Beneath the secondary layer would come trees such as dogwoods, hawthorns, and hollies. These trees shade a ground flora that is extremely diverse and soil that is nurtured by the seasonal leaf fall
The main deciduous forests are found in Eastern Europe, North America, and Asia. The warm temperature deciduous forests are found on the eastern sides of the continents, but in lower latitudes, where there is a Mediterranean climate.
Why these forests are important to mankind:
Even more important than the pleasure we may experience when walking through a magnificent old forest, or the scientific knowledge we may gain there, is the long-term value the forest provides in regulating the earth s climate and protecting our watersheds.
When rain falls on the forest, it seeps through the leaves and branches to the forest floor. If the rain falls on a large area that has been stripped of trees, such as a clear-cut, the bare ground of the clear-cut receives the full force of the rain, and soil washes into the streams. Mud and silt can sully the water, endangering fish and increasing the risk of flooding.
Forests hold moisture, remaining cool and damp long after a rain. Clearcuts reduce the humidity in the air, affecting the climate of the surrounding forest and robbing young trees of needed moisture. In California, scientists found that one and a half times as much water evaporates from exposed soil as from the shaded ground of a mature forest.
Forest protects the land and the rivers. The forest s canopy and the thick layers of duff shield the ground from the force of the raindrops. Roots hold the soil in place on steep slopes. Also, the canopy and branches of a forest can support large quantities of snow, which allows it to melt slowly instead of piling up on the ground. That way, if a warm rain follows a snowstorm, catastrophic flooding is less likely because the snow will have already melted.
Human beings cannot put a price on the vital work that plant life performs in maintaining a livable climate for all of the earth s creatures. A growing forest removes carbon dioxide from the air in a process common to all green plants, called photosynthesis. In the process, trees release oxygen into the atmosphere. A single acre of temperate forest is an incredible oxygen factory, giving off more than 6 tons of oxygen every year.
Deforestation, together with the burning of fossil fuels, has raised the amount of carbon dioxide in the air by more than 25 percent since the mid-19th century (Zuckerman 55). In a process known as the greenhouse effect, this colorless, odorless gas traps heat nears the earth s surface, preventing the heat from escaping into space. The more carbon dioxide, the warmer the climate. Forests store carbon, preventing it from escaping to the air as carbon dioxide. Acre for acre, ancient forests contain more carbon than any other land-based ecosystem. But when an area is logged, three-quarters of the carbon stored in trees, leaves and fallen logs are released into the atmosphere, contributing to the greenhouse effect.
Apart from the loss of human life and ways of life, the most catastrophic result of tropical deforestation may be the mass extinction of hundreds of thousands, perhaps millions, of plant and animal species. The number of species that live on the earth is unknown. So far, about 1.4 million species have been named and described. Remarkably, states Harvard biologist E.O. Wilson in Biodiversity, we do not know the true number of species on Earth, even to the nearest order of magnitude (Zuckerman 108). Wilson s highly educated guess is that the number falls somewhere between 5 and 30 million (Zuckerman 108). At least half the species catalogued so far live in moist tropical forests.
Some species extinctions will be particularly painful for Homo sapiens. Tropical rain forests, with their dizzying array of plants and animals, offer the promise of new medical treatments for age-old and newfound human ills. Most of the natural compounds used in medicines come from toxins that plant produce to keep from being eaten. Tropical forests boast an incredible arsenal of these defensive chemicals because they are home to more species of plants and plant predators than any other ecosystem. Less than 1 percent of tropical plant species have been screened for medical applications, but even that tiny sample has yielded enormous benefits.
The Forest is crucial for mans survival and our inability to see whole forests, to understand that each structure has an indipensable function is leading us towards forest destruction (Berger 49).