Forest Trees can be harvested by different methods.
FORESTS ARE IMPORTANT BIOLOGICAL RESOURSES
Un uso sostenible de los bosques implica utilizarlos y cuidarlos de manera que se puedan satisfacer las necesidades y al mismo tiempo protegerlos para el futuro.
los suelos de las selvas tropicales son pobres en nutrientes y tienden a erosionar. todos los bosques son importantes como biomas. estos desempeñar un importante papel en el reciclaje de nutrientes, los humanos hemos usado los bosques como fuentes de energía o para otras necesidades. la expansión humana ha acabado los bosques debido a que se necesitan mas suelos para construir hogares. los bosques se clasifican por su madurez, según el tiempo que llevan los arboles en la tierra. hay zonas que los humanos usan para crear bosques artificiales, esto es rentable debido a que se reintegra la madera que se extrae de la naturaleza, pero esto también puede acabar con terrenos para sembrar arboles.
Forest plays very important role in combating climate change and global warming. It helps to absorb excessive carbon dioxide in the atmosphere through bio engineering.
What is Bio engineering?
Why is forest management treated differently than other land use activities?
Tropical rainforests are being logged at a fast rate to provide farmland. However, soils in rainforests are nutrient poor and prone to erosion by frequent tropical rains. Destruction of rainforest regions may also contribute to global environmental problems such as global warming. Forests of all kinds are very important ecologically. As major biomes, they provide a habitat for living species and support the food webs for those species.
Forests play an environmental role by recycling nutrients (i.e., carbon, nitrogen) and generating oxygen through photosynthesis. They even influence local climatic conditions by affecting air humidity through evaporation and transpiration processes.
Economically, forests are also very important. Humans have utilized forests for thousands of years as a source of energy (i.e., fuel), building materials (lumber) and pulpwood for paper, and these uses remain important. When forest lands hold valuable mineral resources beneath them, they may be cleared to provide access to the minerals.
The United States Forest Service defines forest lands as lands that consist of at least 10% trees of any size. They include: transition zones (such as areas between heavily forested and non-forested lands) and forest areas adjacent to urban areas. In the western states they include pinyon-juniper and chaparral areas.
Forests cover about one-third of the United States, which is about 70% of their extent when European settlement began in the 17th century. About 42% of U.S. forest lands are publicly owned. Of these, about 15% are in national parks or wilderness areas and are thus protected from timber harvest.
Other public forest lands are managed for various uses: recreation, grazing, watershed protection, timber production, wildlife habitat, and mining. Forests in the western states are predominantly publicly owned, while those in eastern states are predominantly privately owned.
Forests can be classified by their relative maturity.
Old-growth forests have been undisturbed for hundreds of years. They contain numerous dead trees and fallen logs which provide species habitats and are eventually recycled through decay.
Second-growth forests are less mature and occur when the original ecological community in a region is destroyed, either by human land-clearing activities or by natural disasters (i.e. fires, storms, volcanic eruptions).
Humans sometimes create artificial forests in the form of tree farms. Usually only one tree species is planted in a tree farm. After maturing enough to be of economic value, the trees are harvested and new trees planted in their place. Forest trees can be harvested by different methods:
• selective cutting,
• seed-tree cutting,
• strip cutting and
• clear cutting.
Most of these methods have distinct effects on the ecology of the harvested area.
Selective cutting is usually least damaging to the local ecosystem. In this method of harvesting, trees that are moderate to fully mature are cut singly or in small groups. This approach allows most of the trees to remain, which helps maintain habitats and prevent soil erosion and allows uninterrupted recreational use.
However, in tropical forests when only the biggest and best trees are removed, selective cutting can lead to significant ecosystem damage. Because the canopy of a tropical forest is thick and intertwined, the removal of one large tree damages a considerable area around it.
Other harvesting methods involve removal of most or all of the trees in a given area.
Seed-tree cutting removes most of the trees in an area, leaving only a few scattered trees to provide seeds for regrowth. The remaining trees provide some habitat for animals and help reduce soil erosion. However, when seed trees are cut, the forest loses its diversity and is often converted to a tree farm.
Clear cutting and strip cutting both remove all trees in an area.
Clear-cutting usually involves large areas of land resulting in the concomitant destruction of a large area of wildlife habitat. The logged areas are susceptible to severe erosion, especially when the clear cutting occurs on slopes.
With strip cutting, trees are removed from consecutive narrow strips of land. The strips are removed over a period of years and as a result some trees (uncut or regrowth) are always available for animal habitat. The cut area is partially protected from erosion by the uncut or regrowth trees in the adjacent areas.
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