Ecosystem: Temperate Forests - Essay Example

Ecosystem – Temperate Forests The physical characteristics that define the temperate forest include thetypes of trees and other plants that are prevalent, the particular climate in which it is located, average and type of rainfall per year and the types of animals that make these forests home. Temperate forests typically encourage the growth of trees that have broader leaves than tropical areas and that are deciduous. These include species such as oak, hickory, maple, beech, hemlock, basswood, cottonwood, elm, willow, poplar and sycamore in addition to developing a diversified understory stratification. The animals that live in this type of forest generally include squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, bears, foxes and other wildcats although most of the larger predators have been killed off or displaced by the human population. The climate goes through well-defined seasonal changes, trending toward long warm summers, moderately cold winters and an evenly spread level of precipitation throughout the year, providing the trees and other plants with sufficient moisture year round for growth while not drowning them. This seasonal shift causes the trees to drop their leaves in the fall, becoming dormant in the winter, only waking in the spring with a new crop of fresh leaves. The process of dropping the old leaves in the fall results in the brilliantly colorful displays of reds, oranges and yellows that characterize this time of year. Many other plants in the temperate forest will also go dormant during the colder months of the year and many of the animals devote their summers preparing for a winter hibernation period. These types of trees require a high level of soil fertility to grow, requiring soils high in nutrients for the development of a new crop of leaves every year. The annual drop of leaves in the fall provide many of these nutrients as they begin to decay and the leaf litter covering the forest floor also serves to reduce the amount of runoff during spring rains, allowing more of the precious nutrients to remain where the tree roots can get them. Where the soil nutrients are reduced in areas such as the more weathered soils of the Southwest or the sandy soils of coastal plains, the trees are characterized by less showy species with narrower leaves or pines. Isolation of these forests leads to a prevalence of only a few types of tree species and a specialized set of characteristics among the animal-life, such as a dominance of black bears in one region and brown bears in another, allowing them to better blend into their natural habitat. Organisms in this ecosystem are dependent ultimately on the richness of the soils under the trees. The trees pull these nutrients from the soil to facilitate their growth of new leaves and for their daily nutrition needs throughout the spring, summer and fall. The new leaves they create also work to convert light from the sun into energy through a process called photosynthesis. Photosynthesis works because of a green pigment found in the leaves called chlorophyll. The process uses water and carbon dioxide filtered into the leaf where energy from the sun, filtered through the chlorophyll, converts these chemical compounds into sugar and oxygen, providing the tree with the energy it needs to produce more leaves and, more importantly for many of the animals of the forest, oxygen to breathe. With this energy, the trees are also able to produce the nuts and fruits that carry their seeds in order to provide for new tree growth. Smaller animals in the forest will feed upon these fruits and nuts, as well as leaves and bark, in order to survive and larger animals will feed on these smaller creatures. In the fall, though, the cycle of life begins to change. Animals begin harvesting as much food as they can, either to sustain them through the winter months in small hordes or to fatten them up in preparation for a period of hibernation. The trees stop producing new leaves, instead pulling their resources back into their core, which causes the leaves to change colors, producing the brilliant reds, oranges and yellows associated with the fall season. Eventually, the leaves fall from the trees to blanket the forest floor. These leaves return some nutrients to the soil as they decompose throughout the fall, winter and early spring. This decomposition process is helped by the presence of several different types of microorganisms, insects and burrowing animals to break down the leaf structure and work the nutrients into the soil in preparation for the trees to wake up in the spring and begin drawing the nutrients back out of the soil. One of the greatest causes of nutrient loss in these forests remains deforestation as the land is cleared for grazing animals or farming uses. As the trees are cut down, the cycle of nutrient replenishment is lost since the trees no longer pull these nutrients up into their branches and drop them back down in the form of leaf litter. At the same time, nutrients are leached from the soil as the leaf litter no longer protects the soil and as the root systems necessary to reduce soil runoff into the streams disappear. This ecosystem is recognizable through the presence of a specific range of plant and animal life. These include species such as oak, hickory, maple, beech, hemlock, basswood, cottonwood, elm, willow, poplar and sycamore in addition to the development of a diversified understory stratification. These forests are typically comprised of a small range of these trees as dictated by the quality and maturity of the soil in which they grow. Broadleaf trees require a large amount of specific nutrients present in the soil in order to grow to their full potential. In areas where the soil is relatively immature, it appears brown and provides these trees with many of the nutrients they require. Their extreme height helps to reduce the number of other types of trees while still allowing enough sunlight to filter through to the forest floor to support a richly diverse understory that would not be possible in other types of forests where less sunlight is able to filter through the taller trees. This understory further contributes to nutrient replenishment and animal support even while it reduces the density of taller tree growth by preventing some of the seeds from reaching the forest floor and taking root. At the same time, these immature soils typically do not contain the acidic content necessary for needle-leaved trees or other types of trees. The animals that live in this type of forest generally include squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, bears, foxes and other wildcats although most of the larger predators have been killed off or displaced by the human population. These animals are able to survive here because of their ability to use the food sources available and their adaptive qualities of either hoarding or hibernating in preparation for winters in which food supplies are low. Animals such as wolves and wild cats are able to survive on those burrowing animals that do not hibernate for the winter, but must come out of their holes periodically for water or additional food. In addition, these animals have highly developed means of camouflaging themselves within the forest environment, seeming to disappear in the foliage. Despite the greater numbers of organisms such as microorganisms and insects, the trees remain the dominant life forms in the temperate forest as it is only through the presence of the trees that any of the other organisms present are able to maintain life. Without the trees, the soil loses its rich quality and the animals lose not only their food supply, but also their homes and protective covering. There are generally five layers recognized in the vertical structure of a temperate forest. The dominant life forms, the trees themselves, occupy the top layer at a level of approximately 60-100 feet. The regional location of the forest will determine the specific types of trees as well as the overall height to which these trees will reach. As the protective cover of leaves disappears from the trees in the fall, the wildlife occupying the branches typically seeks new homes, either at lower levels or by migrating to warmer climates. The next level down is comprised of the small tree and sapling layer. Because of the amount of sunlight that is able to reach the forest floor, there is typically enough light left to support the growth of new trees sprouted from those around them as well as for smaller trees such as dogwood and redbud. The shrub layer is typically made up of members of the heath family like rhododendron, azaleas and huckleberries. The herb layer is largely noticeable in the early spring when most of these types of plants bloom, kept from being the bottom layer by the mosses and lichens that carpet the forest floor. These carpet plants tend to be found growing on the trees and rocks as well and lianas like Virginia creeper and grape vines tend to climb the barks of trees as well, making their presence known even as high as the top layer. Because these plants also die back in the colder weather, they provide little support or additional food supply for the animals living in these forests. With most of the plant life dormant through the colder months, the winter forest differs significantly from the summer forest in terms of the number of animals to be found. Fires in the forest can serve a helpful purpose by burning away much of the dead and dry older trees and eliminating many of the smaller trees, making room for new vegetation to grow and releasing additional nutrients into the soil. One type of controlled fire is called a surface fire and is set deliberately on a regular yearly or every other year basis to burn just the undergrowth and leaf litter of the forest, typically allowing the mature trees and most of the animals to escape serious damage. This prevents the outbreak of larger, uncontrolled fires like crown fires, which are very hot fires that leap from treetop to treetop and kill most of the vegetation and animals in the area. Trees that typify this ecosystem start their lives as seeds that typically fall from the trees in fruit form, encouraging animals to eat them and redistribute the seeds elsewhere through their leavings. These tiny trees often resemble small potting plants at first, comprised of a thin, weak green trunk and small leaves to begin catching the rays of the sun. Many of these tree species have special leaves that sprout at the beginning of their lives designed specifically to amplify the tree’s ability to capture light in a relatively shady world. In its second stage, the tree is spindly with thin branches and a pointy top. The tree at this stage is struggling to reach higher levels where light levels are typically stronger, but the tree remains vulnerable and generally easy to damage. Stage 3 represents the tree’s prime of life. It has reached its full height potential and expands its crown to a more rounded appearance, giving rise to the occasional dead branch on the underlayer. As trees enter middle age, or the fourth stage, they begin to take on a more flattened look and main branches begin to thicken. Reaching stage 5, the tree is in old age which is apparent by the appearance of gaps in the flattened crown system as main branch systems begin to die out. In stage 6, the tree is still alive, but only barely, with few leaf systems supported in the crown by one or two main branches, the rest having died off. In stage seven, the tree is dead, but its fallen trunk and branch system provides homes and food for a great community of creatures both large and small. As the tree decays back into the soil, it releases important nutrients and other minerals back into the soil. To survive through all these stages, which can sometimes last as long as 50 years or more, the trees have several adaptations that allow them to survive times of draught or cold. In low water conditions, trees have the ability to restrict the flow of water through their cells, conserving as much as possible while still providing them with the energy needed to survive. In flooded areas, some trees have developed the ability to thrive in standing water by restricting the amount of water uptake that occurs in their root systems and maximizing the level of energy produced in the upper canopy. Drooping limbs can also provide a convenient conveyance for a tree to shed excess water when necessary. When the weather turns cold, the trees begin to withdraw the chlorophyll from their leaves, reducing their effectiveness and shedding the need to continue supporting these extremities. The trees then go dormant through the cold period, further conserving their energy. Read More