Chapter 13: Forests, Parks an Landscapes

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

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

6. Modern Conflicts over Forestland and Forest Resources • Public service functions • Indirect benefits that people and the environment receive from forests • Improving watersheds • Wildlife habitat • Recreation • Climate

8. The Life of a Tree • How a tree grows • Leaves of a tree take up CO2 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

9. 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

11. 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

13. A Forester’s View of a Forest • Traditionally managed in stands • Stand- an informal term foresters use to refer to a group of trees • Usually the same specie and successional age • Even- aged stands • Uneven-aged stands • Forest that has never been cute is virgin forest • Old growth forest • A forest cut and regrown is secondary growth forest

14. A Forester’s View of a Forest • Rotation time- the time between cuts of a stand • Foresters and forest ecologists group the trees in a forest into • Dominants • Codominants • Intermediate • Suppressed • Site quality- max timber crop the site can produce in a given time

15. 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

16. Clear-cutting • Clear-cutting- the cutting of all trees in a stand at the same time

18. 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

19. 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

20. 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

24. 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

25. 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

27. 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.

28. 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

29. Certification of Forest Practices • Compare the actual practices of a specific corporation or government agencies w/ practices that are believed to be consistent w/ sustainability. • Don’t know if beliefs are correct or practices really sustainable • Movement to call them “well-managed forests” or “improved management”

30. 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.

31. 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.

33. World Forest Area, Global Production and Consumption of Forest Resources • Countries differ greatly in their forest resources • Potential of their land and climate for tree growth • History of land use and deforestation

36. 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

38. World Forest Area, Global Production and Consumption of Forest Resources • In recent years world trade in timber has not grown substantially. • The fundamental questions are • Whether forests can continue to produce at least this amount of timber for an infinite period • Whether they can produce even more as the population grows

39. 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

41. Deforestation: A Global Dilemma • Is forested area increasing or decreasing? • Information is lacking on which to base an accurate evaluation • Forest cover is large, often remote • Difficult to assess the total amount of forest area • Estimates suggest an annual loss each year of 7.3 million hectares

42. 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

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

46. 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

47. 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

48. 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

50. 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