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CHAPTER 23 Sustaining Terrestrial Biodiversity: The Ecosystem Approach.

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Presentation on theme: "CHAPTER 23 Sustaining Terrestrial Biodiversity: The Ecosystem Approach."— Presentation transcript:


2 CHAPTER 23 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

3 Key Concepts Human land use Types and uses of US public lands Forests and forest management Implications of deforestation Management of parks Establishment and management of nature preserves Importance of ecological restoration

4 Land Use in the World Fig. 23-2 p. 595

5 I. Land Use In The United States A. PUBLIC LANDS(42%) - 35 % of land in the United States is designated as public and is managed by the Federal Government. - Classified as… 1. Multiple-Use Lands 2. Moderately Restricted-use Lands 3. Restricted-use Lands

6 U.S. Land Ownership Federal 35% Private 55% Native American 3% State and local 7%

7 National parks and preserves National forests National wildlife refuges

8 1. Multiple-Use Lands Include… - 155 Forests and 20 Grasslands of the NATIONAL FOREST SYSTEM -Managed by the U.S. FOREST SERVICE and - NATIONAL RESOURCE LANDS - Managed by the Bureau of Land Management

9 2. Moderately Restricted-Use Lands Include… - 522 NATIONAL WILDLIFE REFUGES - Managed by the U.S. Fish and Wildlife Service

10 3. Restricted-Use Lands Includes…the NATIONAL PARK SYSTEM - 379 units of which include 55 major parks and 324 national recreation areas. - Managed by the National Park Service and - 630 roadless areas of the NATIONAL WILDERNESS PRESERVATION SYSTEM Majority in Alaska

11 National parks and preservesNational forestsNational wildlife refuges

12 How should the lands be managed? Federal public lands contain valuable resources: 20% of oil reserves 30 % of natural gas 40 % forest large amounts of minerals

13 Conservation biologists point of view: 1.Protect biodiversity: habitats should be primary goal 2.No subsidies or tax breaks for using resources 3.Compensation for use of property 4.Take responsibility for any environmental damage Developers point of view: 1.Sell public lands or their resources 2.Unregulate public lands 3.Replace old growth forests with tree plantations 4.Drill, mine, and commercially develop national parks 2 opposing viewpoints

14 23-2 Managing and Sustaining Forests(32% of earth land surface) Ecological Services -Support food webs -Act as sponge to absorb pollution -Influence local climate -Habitat Economic Services -Fuelwood, 50% -Timber and Roundwood -Pulp -Medicines


16 1. OLD-GROWTH FOREST -FRONTIER FOREST -Undisturbed by humans and / or natural disasters -Very BIODIVERSE due to increased recycling of nutrients and good habitat

17 Emergent/Dominant Canopy/Codominant Understory/Intermediate Floor/Suppressed Subsoil Layers of biodiversity

18 2.SECOND GROWTH FORESTS Result from as a result of human activities or natural disaster(s) Result from SECONDARY SUCCESSION as a result of human activities or natural disaster(s)

19 3TREEPLANTATION TREE FARMS 3. TREE PLANTATION or TREE FARMS *An attempt to produce products more efficiently by setting back secondary succession. *Often referred to as MONOCULTURE *GROWS ONLY ONE SPECIES *Harvested as soon as they become VALUABLE and then replanted.

20 C. TYPES OF FOREST MANAGEMENT - The total volume of wood produced by a strand of forest VARIES as it goes through different STAGES of growth and succession Time Short rotation(pulp) Wood volume or wood biomass B C A Long rotations Old-growth harvest (such as hardwoods for furniture)

21 Years of growth 30 25 15 10 5 Clear cut Weak trees removed Seedlings planted

22 - Two basic forest management techniques… 1.Even-Aged Management: - Also called INDUSTRIAL FORESTRY - Trees are kept as same size and age Ex: TREE FARM OR PLANTATION *Extensive research has shown that soil become depleted

23 2. UnEven-Aged Management: -Trees are kept at a variety of ages and sizes. --Goals are; biological diversity, long-term sustainable production of timber, moderate economical return, and multiple use of forests. *The rate of economic return plays a major role in the technique used.

24 D. HARVESTING TECHNIQUES 1. Selective Cutting: - Intermediate-aged or mature trees in an uneven-aged forest are cut singly or in small groups -reduces crowding -encourages growth -protects against soil erosion -maintains uneven growth

25 Selective Cutting

26 Selective Cutting: (continued) -a special type of selective cut is used called… high grading high grading -High Grading is when only the largest and best species are used.

27 2. Shelterwood Cutting: -Removes all mature trees in two / three cuttings over a period of 10 years. -allows natural regeneration -reduces soil erosion -provides good habitat for wildlife

28 Shelterwood Cutting Cut 1 Cut 2

29 3. Seedtree Cutting: -Harvests nearly all a stands trees in one cutting, leaving a few seed- producing trees behind to regenerate the area. -Leads to genetic improvement in new stands

30 Seed-Tree Cutting

31 4. Clear Cutting: -Removal of all trees from an area in a single cutting; either the whole stand, a strip, or a series of patches.

32 Clear-Cutting



35 5. Strip Cutting: -Type of clear-cut that removes a strip of trees along the contour of the land, narrow enough to allow for natural regeneration -Strips are harvested every 30-40 years

36 Strip Cutting Uncut Cut Uncut 6–10 years ago 3–5 years ago 1 year ago

37 F. FOREST SUSTAINABILITY F. FOREST SUSTAINABILITY HOW?? HOW?? -Longer rotation of timber growth -Emphasize selective cutting and strip -Minimize fragmentation -Leave snags and down timber -Use proper anti-erosion techniques

38 F. FOREST PESTS/DISEASE 1.Parasitic Fungi: accidental chestnut blight (China) dutch elm (Asia) white pine blister (Europe)

39 2. Parasitic Insects: Bark beetle Gypsy moth Hemlock woolly adelgid


41 G. FOREST AND FOREST FIRES - important part of ecological cycle of some forests and grasslands Types of Forest Fires: 1. Surface Fires- 1. Surface Fires- burn leaf litter and ground clutter

42 Surface fire Fig. 23.12a, p. 599

43 2. Crown fire- 2. Crown fire- Burn in the treetops -most dangerous of all fires

44 Crown fire


46 3. Ground Fires- 3. Ground Fires- Underground and burn partially decayed or peat -Common in pet bogs

47 H. Forest Fire Prevention: -Fire prevention Techniques are a controversial subject -Since 1972, the policy on forest fires has been to let them burn themselves out as long as not a danger to humans. -After fires of 1994 and 2000, many calls for change.

48 Techniques Used- *prevention *prescribed burning *pre-suppression *supression


50 23-3 Forest Resources/Management in the US 1.Todays Status: Forest covers about 1/3 of the lower 48 United States. Forest are generally bigger and healthier than in 1920. Among most diverse in the world

51 National Forest Resources in US 30% of US land, provides 80% of wildlife habitats, supply 2/3 of all surface water runoff Economic benefits -grazing lands, mineral resources, 3% of softwood timber Ecological benefits -habitat for threatened/endangered species, clean drinking water Recreational benefits -camping, hunting, fishing

52 Since 1960, vast increase in the number of tree plantations – reduces biodiversity Between 1620-1998, most of existing old-growth forests in lower 48 states were cut

53 Virgin forests, 1620

54 Virgin forests, 1998

55 MANAGEMENT CONTROVERSY Timber Companies -Want to increase logging to satisfy demand… -Improvement of forest health… -Provides jobs… -Provide cheap timber Environmentalists -Timber from national forest is small % of wood used -Timber from national forests do little to drop prices -Recreation use of forest should be most important use of forest

56 3. How To Reduce Tree Needs -Increase the efficiency of wood use -Increase paper recycling -Use fibers that do not come from trees for paper (Kenaf)

57 23-4 Tropical Rainforest Deforestation and the Fuelwood Crisis They cover 6% of Earths land area Brazil, Indonesia, Zaire, and Peru have more than half of the worlds tropical forests Over half of the worlds tropical forests have already been cleared or degraded Greatest destruction is taking place in South America (Brazil) Provide food products, ecological services, industrial materials Less than 1% of the plant species in the worlds tropical forests have been examined closely for their possible use as human resources

58 Tropical deforestation is caused by: Population growth Poverty Government policies Forest Depletion and Degradation is caused by: Commercial logging Cattle ranching Unsustainable form of farming Replacing forest with cash crops Increasing forest fires Mining Dams

59 Solutions: Reducing deforestation and degradation Education programs – learn sustainable practices Make it profitable to protect forests (debt-for-nature swaps, conservation easements, and conservation concessions Carefully harvesting trees National and global efforts to reforest and rehabilitate degraded forests and watersheds Reducing waste and consumption of timber, paper, and other resources Planting more fast-growing fuelwood trees or shrubs Burning wood more efficiently Switching to other fuels

60 Fuelwood Crisis Fuelwood provides 7% of the worlds energy supply Most common use of trees is for fuelwood. Used for heat and cooking accounts for 80% of the wood harvested in developing countries 2.7 billion people did not get enough fuelwood to meet their basic needs and were forced to meet their needs by using wood faster than it is replenished. Burn charcoal instead (uses twice as much wood)

61 23-5 Managing and Sustaining National Parks 1,100 parks First national park system was created in the U.S. In developed countries, parks are threatened by air and water pollution, invasion of alien species, roads and noise Biggest problem of US parks is increased number of park visitors Currently, the greatest danger to the national parks is human activities (mining, logging, grazing, coal- burning plants, dams, urban development)

62 23-6 Establishing, Designing and Managing Nature Reserves Principals used to establish and manage reserves: 1. ecosystems are rarely stable 2.Ecosystems and communities that experience disturbances have the greatest diversity of species (intermediate disturbance hypothesis) 3.View reserves as habitat islands surrounded by a sea of developed and fragmented land 4.Include local people in the planning and design 5.Create use-friendly reserves that allow sustainable logging, grazing, crops, hunting, and fishing.

63 Wilderness Reasons to protect wilderness are: 1.Preserve biodiversity 2.Centers for evolution 3.Provide undisturbed habitats 4.Protect diverse biomes from damage 5.Provides a natural laboratory

64 Wilderness management Designate camping sites Limit the number of people using sites Use volunteers to collect trash

65 What is Ecological Restoration? 1. Restoration ecology- Research and scientific study devoted to restoring, repairing, and reconstructing damaged ecosystems

66 Rehabilitation and Restoration Almost every place on the earth has been degraded to some degree by humans Methods 1. Restoration-problems include lack of knowledge about the system, changes in climate, and ecosystem are naturally changeing. 2. Rehabilitation- examples include removing pollutants, replanting 3. Replacement-example: a productive pasture replaced by a degraded forest 4. Creating artificial ecosystem- wastewater treatment systems and artificial wetlands

67 Save a piece of country… and it does not matter in the slightest that only a few people every year will go into it. This is precisely its value…We simply need that wild country available to us, even if we never do more that drive to its edge and look in. For it can be a means of reassuring ourselves of our sanity as creatures, a part of the geography of hope. Wallace Stegner

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