Chapter 13: Forests, Parks an Landscapes

Transcription

1 Chapter 13: Forests, Parks an Landscapes

2 Modern Conflicts over Forestland and Forest Resources In recent decades forest conservation has become an international cause NA Pacific Northwest Tropical rain forest Forestry has a long history Silviculture- professional growing of trees What should forest be used for? Resources vs. conservation

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4 W h a t a r e t h e m a j o

5 Modern Conflicts over Forestland and Forest Resources Forest and civilization closely linked Wood major building material and source of fuel Spiritual and aesthetic value Public service functions Indirect benefits that people and the environment receive from forests

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7 The Life of a Tree How a tree grows Leaves of a tree take up CO 2 and absorb sunlight Water transported up from roots Leaves carry out photosynthesis Products = simple sugar and oxygen Roots have symbiotic fungi that help extract minerals from the soil

8 How a Tree Grows Leaves and roots connected by two transport systems Phloem- on the inside of the living side of bark, transports sugars and other organic compounds down to stems and roots Xylem- farther inside, transports water and inorganic molecules upward to the leaves Sun-powered pump

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10 Tree Niches Each species of tree has its own niche and adapted to specific environmental conditions E.g., water content of the soil Tolerance of shade Some adapted to early succession, others to later stages

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12 A Forester s View of a Forest Traditionally managed in stands Stand- an informal term foresters use to refer to a group of trees Forest that has never been cut is virgin forest Old growth forest A forest cut and regrown is secondary growth forest

13 Approaches to Forest Management Managing forests can involve removing poorly formed and unproductive trees to permit larger trees to grow Planting genetically controlled seedlings Controlling pests and diseases Fertilizing the soil

14 Clear-cutting Clear-cutting- the cutting of all trees in a stand at the same time

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16 Alternatives to Clear-Cutting Selective cutting- individual trees are marked and cut (thinning) Strip-cutting- narrow rows of forest are cut, leaving wooded corridors whose trees provide seeds Shelterwood-cutting- practice of cutting dead and less desirable trees first and later cutting mature trees. Seed-tree cutting- removes all but a few seed trees to promote regeneration of the forest

17 Experimental Test of Clear-Cutting Scientist have tested the effects of clear cutting Hubbard Brook experimental forest in NH Erosion increased and pattern of water runoff changed substantially Exposed soil decayed more rapidly Stream water exceeded public health standards for nitrates

18 Experimental Test of Clear-Cutting HJ Andrews Experimental Forest in OR Increase in the frequency of landslides after clear cutting C-c also changes chemical cycling in forests and causes the soil to lose chemical elements necessary for life

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22 Experimental Test of Clear-Cutting Experiments show Clear-cutting can be a poor practice on steep slopes in areas of moderate to heavy rainfall Clear-cutting on an appropriate spatial scale may be useful to regenerate desirable species Where ground is level, rainfall moderate, and desirable species require open ground to grow

23 Plantation Forestry Plantation- a stand of a single species typically planted in straight rows Much like agriculture Fertilizers added, mechanized harvesting Offer a solution to the pressure on natural forests. High-yield forests could provide all the world s timber

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25 Sustainable Forestry A sustainable forest is one from which a resource can be harvested at a rate that does not decrease the ability of the forest ecosystem to continue to provide that same rate of harvest indefinitely.

26 What is Sustainability and How is it Applied to Forests Two basic kinds of ecological sustainability Sustainability of the harvest of a specific resource w/in an ecosystem (harvest of timber) Sustainability of the entire ecosystem (forest as an ecosystem) Lack scientific data to demonstrate that either type ever achieved in forests

27 A Global Perspective on Forests Vegetation of any kind can affect the atmosphere in four ways 1. By changing the color of the surface and therefore the amount of sunlight reflected and absorbed. 2. By increasing the amount of water transpired and evaporated from the surface to the atmosphere.

28 A Global Perspective on Forests 3. By changing the rate at which greenhouse gases are released from Earth s surface into the atmosphere. 4. By changing surface roughness, which affects wind speed at the surface.

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31 World Forest Area, Global Production and Consumption of Forest Resources Developed countries account foe 70% of world s total production and consumption of industrial wood products Developing countries produce and consume about 90% of wood used as firewood 90% of world timber trade Construction, pulp and paper NA is the dominant supplier

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33 Deforestation: A Global Dilemma Deforestation is estimated to have increased erosion and caused the loss of 562 million hectares of soil. Deforestation in one country can affects countries downstream E.g. Nepal and India

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35 History of Deforestation Has occurred in all societies from Early Greece and Roman Empire Prehistoric farmers in Denmark Medieval Great Britain Upon colonization of the New World The greatest losses in the present century taken place in South America

36 Causes of Deforestation Two most common reasons Clear land for agriculture and settlement To use to sell timber for lumber, paper products, or fuel

37 The World Firewood Shortage In many parts of the world, wood is a major energy source. As the human population grows, use of firewood increases. Management is essential

38 Indirect Deforestation The death of trees from pollution or disease Acid rain Ozone Other air pollutants All can increase susceptibility to disease Global climate change may lead to Major die-off and shift in areas of potential growth

39 Parks, Nature Preserves, and Wilderness Landscapes may be protected in different ways Government established parks, nature preserves, and wilderness areas Private organizations buying land and maintaining it as nature preserves

40 Parks and Preserves Park- an area set aside for use by people Nature preserve- may be use by people but primary purpose the conservation of some resource Both create ecological islands Island biogeography used in design and management

41 Parks and Preserves as Islands The size of the park and the diversity of habitats determine the # of species that can be maintained. The further the park is from other parks or sources of species, the fewer species are found.

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43 Brief History of Parks The French work parc once referred to an enclosed area for keeping wildlife to be hunted. E.g., Coto Donana National Park on the coast of Spain Once country home of nobles Now a stop over for 80% of birds migrating between Europe and Africa

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46 Brief History of Parks First public park Victoria Park in Great Britain, 1842 Concept of national park originated in NA in the 19 th century Yosemite designated in 1864 Preserve unique awesome landscapes 20 th century emphasis more ecological

47 Conflicts in Managing Parks Major conflicts generally have to do with Size What kinds and levels of access and activities will be available

48 How Much Land Should be in Parks What percentage of the landscape should be in parks or nature preserves? If parks are to function as biological preserves, they must be adequate in size and habitat diversity.

49 Conserving Wilderness As a modern legal concept, wilderness is an area undisturbed by people. New idea introduced in the second half of the 20 th century US Wilderness Act of 1964 First time wilderness recognized by national law land retaining its primeval character and influence

50 Conserving Wilderness Wilderness 1. Imprint of human work is unnoticeable 2. There are opportunities for solitude and primitive and unconfined recreation 3. There are at least 5,000 acres Wilderness vs Wildness

51 Conflicts in Managing Wilderness Legal definition given rise to several controversies Desire to include more land as wilderness Desire to develop this land and its natural resources Can view goal of managing 1. To preserve nature undisturbed by people 2. To provide people w/ a wilderness experience

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