Chapter 12 BIODIVERSITY: PRESERVING LANDSCAPES

Transcription

1 Chapter 12 BIODIVERSITY: PRESERVING LANDSCAPES 1

2 OUTLINE WORLD FORESTS DEFORESTATION OLD GROWTH HARVEST METHODS GRASSLANDS PARKS AND PRESERVES TERRESTRIAL MARINE 2

3 WORLD FORESTS A FOREST is any area where trees cover more than 10% of the land. SAVANNAS - trees cover less than 20% of ground CLOSED CANOPY - tree crowns cover most of ground Most remaining forests are in tropical and boreal (taiga) regions. Highest rates of forest loss in Africa and South America Largest tropical forest is the Amazon 3

4 WORLD FORESTS ECOLOGICAL SERVICES CARBON SINK for carbon dioxide MOISTURE from transpiration contributes to global rainfall. (water cycle) OLD GROWTH FORESTS - cover large areas and have been undisturbed by humans long enough that trees can live out a natural life cycle and ecological processes are normal Home to much of world s biodiversity, endangered species and indigenous people ¾ found in Russia, Canada, Brazil, Indonesia, Papua New Guinea 4

5 WORLD FORESTS ECOLOGICAL SERVICES Habitat for species which creates utilitarian uses: camping, bird watching, hunting Cool air surrounding the forest by evapotranspiration and shade Forests serve as watersheds Parts of biogeochemical cycles (especially: nitrogen/carbon/water) Roots reduce runoff and decrease erosion 5

6 GLOBAL LAND USE Other: cities, arid areas, tundra & wetlands 6

7 MAJOR FOREST TYPES 7

8 UTILITARIAN FOREST USES WOOD AND PAPER Developed countries provide less than half of industrial wood, but 80% of consumption. Paper pulp is 1/5 of all wood consumption. In developing countries fuel (wood/charcoal) accounts for 1/2 of global wood use. One quarter of world s forests are managed for wood production, much of it in single species monoculture forestry. Many developing countries sell exotic woods (teak, mahogany) to developed countries. Mining and rangeland use also damage forests 8

9 FOREST MANAGEMENT FOREST MANAGEMENT: science of maintaining a forest for sustainable harvests EVEN-AGED: all trees are same size/age MONOCULTURE: single species which increases pests and decreases biodiversity, usually clearcut UNEVEN-AGED: trees are different ages/sizes, usually different species. Increases biodiversity, decreases pests & erosion, trees are selectively cut 9

10 TROPICAL FORESTS ARE BEING CLEARED Tropical forests occupy less than 10% of land surface but contain half of all species. FAO estimates that 12.3 million ha are deforested every yr, the equivalent of one football field every second. 10

11 CAUSES OF DEFORESTATION CONVERSION OF FOREST TO AGRICULTURE Accounts for 2/3 of destruction in tropics SLASH & BURN aka: Milpa or Swidden - cut/burn small areas & use for a few years then let return to forest - Slash & Burn can be sustainable if populations are small and plots are left alone for many years. Repeated cropping over time leads to permanent damage. - Usually multiple crops are grown at the same time, harvested separately 11

12 EFFECTS OF DEFORESTATION As forests are cleared, plant transpiration and rainfall decrease. This leads to drought & erosion. Drought kills more vegetation. Fires become more numerous and extensive. More of the forest is then lost. 12

13 FOREST PROTECTION Some places are being reforested (U.S. and China have had greatest gains.) About 12% of world s forests are protected. With industrialization, countries become developed, deforestation decreases and forests are protected instead for other uses DEBT FOR NATURE SWAPS - conservation organizations/banks buy debt obligations, then offer to cancel the debt if the debtor country protects biologically important areas 13

14 FORESTS HAVE COMPETING USES U.S. Forest Service managed for multiple uses but many were conflicting e.g. bird watching and dirt biking. OLD GROWTH FORESTS VS. LOGGING Less than 10% of old growth forest remains in U.S. and 80% of that is scheduled to be logged. Spotted owl vs. logging jobs Compromise forest management plan allows some logging, but protects some prime habitat. May not be enough to save the salmon and steelhead trout in northwestern rivers. 14

15 OLD GROWTH FOREST Temperate rainforest and the spotted owl. 2,000 owl pairs remain in the old growth forests of the Pacific Northwest. Salmon & trout need pristine rivers to spawn 15

16 HARVEST METHODS ALL HARVEST METHODS REQUIRE ROADS Building roads to remove trees also allows entry to forest by farmers, miners, hunters. Lead to increased erosion, soil compaction, increased runoff of sediment into rivers Sedimentation of rivers reduces biodiversity and decreases spawning CLEAR CUTTING most popular with logging companies. Every tree in an area is cut regardless of size Increases erosion and decimates habitat Loss of recreational space Can be replanted or go through succession 16

17 HARVEST METHODS SHELTERWOOD HARVESTING - mature trees are removed in a series of two or more cuts STRIP CUTTING - all the trees in a narrow corridor are harvested COPPICING leaving stumps to regenerate (a few species can do this: oak, maple, ash) SEED TREE CUTTING clear cutting but leaves a few trees to reproduce and drop seeds SELECTIVE CUTTING - only a small percentage of the mature trees are taken in each 10 to 20 year rotation (best method environmentally) 17

18 HARVESTING CLEAR CUTTING Clear cutting (removal of all trees) in Washington s Gifford Pinchot National Forest. 18

19 SHELTERWOOD HARVEST SELECTIVE HARVEST COPPICING STRIP CUTTING 19

20 LOGGING ON PUBLIC LANDS? Some are calling for an end to all logging on public lands. Lands provide ECOLOGICAL SERVICES such as clean water, rivers for fish, irrigation, recreation. Worth $224 billion. Federal government builds roads, manages forests, fights fires and then sells the timber to logging companies for less than their costs. This is a subsidy for the logging industry. Worth $4 billion. 20

21 HISTORY OF US FORESTS 1897 Forest Management Act created Forest Reserves for timber, mining & grazing 1905 US Forestry Service forest reserves are now national forests 1960 Multiple Use Sustained Yield Act replaced FMA. Requires forests to be managed for lumber, recreation and wildlife USFS sells logging rights to timber companies (highly subsidized) 21

22 LOGGING ON PUBLIC LANDS? Timber companies claim logging produces jobs, supports rural communities, keeps forests healthy. Roads on public lands are another controversy. Economists argue it opens up land for motorized recreation and industrial uses. Wildlife supporters see it as disruptive. Clinton protected 23.7 million ha of wilderness from roads; Bush overturned this and ordered expedited logging and mining. Obama protected additional lands... Trump? 22

23 FIRE MANAGEMENT 23

24 FIRE MANAGEMENT U.S. adopted a policy of aggressive fire control in the 1930s. Recent studies indicate many biological communities are fire-adapted and require periodic burning for regeneration. Eliminating fires has caused woody debris to accumulate over the years. Fires are now larger and more severe. 40 million Americans now live in areas of high wildfire risk. Collection of debris and small prescribed fires can prevent large scale fires 24

25 ECOSYSTEM MANAGEMENT Ecosystem management attempts to integrate sustainable ecological, economic, and social goals in a unified systems approach. Managing across whole landscapes over ecological time scales Considering human needs and promoting sustainable economic development Maintaining biological diversity and ecosystem processes Utilizing cooperative institutional arrangements Generating meaningful stakeholder and public involvement and facilitating collective decision making Adapting management over time based on conscious experimentation and routine monitoring. 25

26 SUSTAINABLE FORESTRY Consumers can make better choices & demand sustainable products Home Depot all wood is sustainably raised and managed Staples uses 30% recycled paper in many of their products Forests can be used sustainably for other products: nuts, fruits, mushrooms, latex (rubber) and chicle (gum) that doesn t remove the trees 26

27 GRASSLANDS Occupy about 1/4 of world s land surface (prairies, savannas, steppes, open woodlands) Frequently converted to cropland, urban areas, or other human use More threatened plants in rangelands than in any other American biome Can be used sustainably PASTORALISTS move their animals to adjust to variations in rainfall and seasonal conditions. Reducing negative impact on land 27

28 RANGELAND vs PASTURE RANGELANDS - have natural vegetation managed by grazing, usually dry/poor for agriculture PASTURES - have forage that is adapted for livestock and managed, by seeding, mowing, fertilization and irrigation. OVERGRAZING results from too many animals on the land for too long a period of time. Plant roots die and soil compaction occurs. Often overgrazed areas lead to DESERTIFICATION 28

29 OVERGRAZING 15% of US livestock feed on native grasslands. 90% of US grain crop (corn, alfalfa, oats) is used to feed livestock 75% of rangelands in the world are degraded; one-third of that is due to overgrazing. 55% of U.S. public lands are in poor condition due to overgrazing. Grazing fees charged for use of public lands are below market value and represent a hidden subsidy to ranchers. Ranchers claim that without a viable ranch economy, western lands would be further subdivided. 29

30 NEW GRAZING METHODS ROTATIONAL GRAZING - encloses livestock in a small area for a short time within a movable electric fence to force them to eat vegetation evenly and fertilize (manure) the area evenly. Can raise wild species such as bison or elk, which forage more efficiently and fend off predators, diseases and pests better than cattle Grazing multiple species together is beneficial as each eats a different type or part of the plant. 30

31 PARKS AND PRESERVES 12% OF EARTH S LAND AREA IS PROTECTED. 31

32 PARKS AND PRESERVES In the developing world, some parks exist only on paper because they do not have money for staff and management. Brazil has the largest protected area 19% of its land. With more than 25% of the world s tropical forests, Brazil is especially important to biodiversity. US has 16% of its land in protected status. 2/3 is sustainable use public lands 32

33 PRESERVES NOT SAFE FROM EXPLOITATION Excessive stock grazing in Greece Dam building in Columbia Oil drilling in the Amazon Mining & Logging in Peru Coral reefs in Palau damaged by dynamite fishing Eggs from endangered sea turtles are taken by hunters in Indonesia Overuse by the public Yellowstone, Zion, Grand Canyon very popular, but create issues 33

34 OVERUSE OF NATIONAL PARKS IN U.S. Entertainment trumped nature protection. Fire suppression resulted in large fires. Traffic congestion Surrounding areas clear cut or mined Air pollution and smog Parks are profitable, but do not get to keep the money they generate. 34

35 HISTORY OF US NATIONAL PARKS 1872 President Grant established first national park in the world Yellowstone 1912 US National Park System was created 1916 National Park Service (Dept. of Interior) was created. Stephen Mather was first director. Currently there are 388 parks ranging from national parks to historic sites, to memorials and recreation areas 35

36 WILDERNESS AREAS Areas of undeveloped land, undisturbed by human activities that people can visit but can not inhabit Wilderness Act allows public areas to be protected WILDLIFE REFUGES 1901 Theodore Roosevelt started the National Refuge System. 545 now exist. Managed for multiple use (camping, hiking, fishing, hunting, mining, etc.) Arctic National Wildlife Refuge (ANWR) in Alaska has been debated for oil drilling 36

37 WORLD CONSERVATION STRATEGY Developed by the IUCN Has 3 objectives: Maintain essential ecological processes and life support systems Preserve genetic diversity essential to improving cultivated plants and domestic animals Ensure that utilization of wild species and ecosystems is sustainable. 37

38 MARINE ECOSYSTEMS NEED PROTECTION Global fish stocks are becoming depleted and biologists are calling for protected areas where species can be sheltered. 20% of nearshore territory should be marine refuge area. Refuge can replenish nearby areas. Coral reefs are threatened by rising temperatures, destructive fishing, coral mining and sediment runoff. If conditions persist, all will be gone in 50 years. 38

39 MARINE ECOSYSTEMS NEED PROTECTION Australia has the largest marine reserve in the Great Barrier Reef. The U.S. 13 underwater parks such as the Northwest Hawaiian Islands National Monument and the Florida Keys 39

40 CONSERVATION & ECONOMIC DEVELOPMENT Struggle to save ecosystems cannot be divorced from struggle to meet human needs. ECOTOURISM - tourism that is ecologically and socially sustainable NATIVE PEOPLE have valuable ecological knowledge that can be used in ecosystem management. UNESCO initiated Man and Biosphere program (MAB) calling for the establishment of BIOSPHERE RESERVES, protected areas divided into zones with different purposes. 40

41 A MODEL BIOSPHERE RESERVE 41

42 SIZE & DESIGN OF NATURE PRESERVES SLOSS debate - Is it better to have Single Large Or Several Small reserves? Edge effects Corridors of natural habitat essential 42

43 SIZE & DESIGN OF NATURE PRESERVES One of the reasons that large preserves are considered better than small reserves is that they have more CORE HABITAT, area deep within the interior of the habitat that has better conditions for specialized species. As human disturbance fragments the ecosystem, habitat is broken into increasingly isolated islands with less core and more edge, supporting fewer species. 43

44 LANDSCAPE ECOLOGY LANDSCAPE ECOLOGY - science that examines the relationship between spatial patterns and ecological processes such as species movement or survival Variables: - Habitat size - Shape - Relative amount of core and edge - Kinds of land cover surrounding habitat 44

45 HOW SMALL CAN A HABITAT BE? 45