Chapter 7 Climate and terrestrial biodiversity

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Chapter 7 Climate and terrestrial biodiversity Powered By Docstoc
					Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach

Core case study: reintroducing wolves to Yellowstone
 1. Wolf’s function in ecology:
     (1) cull herds of bison, elk, …, stabilize stream banks
     (2) kept down coyote populations
     (3) provided uneaten meat for scavengers
2. The amount change of wolf in US
     (1) 1850-1900 250 thousand wolves were shot
     (2) 1973 400-500 gray wolves
      (3) 1987 proposed reintroducing to Yellowstone NP
      (4) 1995 relocated 41 wolves to Y. NP from Canada
      (5) 2007 171 wolves in Y. NP
      (6) 2008 remove from Endangered Species Act; however, conservation groups filed
suits to have the courts overturn this decision.

10-1 What are the major threats to forest ecosystem?
10-2 How should we manage and sustain forests?
10-3 How should we manage and sustain grasslands?
10-4 How should we manage and sustain parks and nature reserves?
10-5 What is the ecosystem approach to sustaining biodiversity?

10-1 What are the major threats to forest ecosystem?
1. Forests: at least 10% tree cover occupy about 30 % of the earth’s land surface. Based
on climate:
          (1) tropical (47%)
          (2) subtropical (9%)
          (3) temperate (11%)
           (4) polar or boreal (33%)
2. Major types of forests
     (1) old-growth forest: not disturbed (36%) (fig. 10-2)
     (2) second-growth forest: (60%)
           a. human activities: cutting
           b. natural forces: fire, typhoon, …
     (3) tree plantation forests or tree farms (4%) (fig. 10-3)
3. Functions of forests: (fig. 10-4)
     (1) ecological services
     (2) economic services
4. World’s forests
     (1) forests are renewable resources
     (2) deforestation: for crop, grazing, …
     (3) harmful environmental effects of deforestation
5. Harvesting trees
     (1) road building (fig. 10-5)
           a. increase erosion and sediment
           b. habitat fragmentation and biodiversity loss
          c. exposure for disease invasion
          d. accessible for other developments
     (2) Selective cutting (fig. 10-6a)
          a. reduces crowding
          b. encourages growth of younger trees
          c. maintains an uneven-aged forest
          d. natural regeneration
          e. protect site from erosion and wind
          f. remove diseased trees
           g. forest for multiple purposes
     (3) clear-cutting: remove all trees (fig. 10-6b, 10-7, 10-8)
           a. Pro:
                 (a) increase timber yield
                 (b) reforesting with fast-growing trees
                 (c) shortens the time
                 (d) takes less skill and planning
                 (e) maximum economic return
                 (f) harvest tree farms
          b. Con:
                (a) leaving forest opening
                (b) eliminates recreational value
                (c) reduces biodiversity
                (d) more blown down by wind
                (e) soil erosion and sediment
     (4) Strip cutting (fig. 10.6c)
          a. clear-cutting along the contour
            b. natural regeneration
            c. after regeneration, another strip is cut
6. Fires affect forest ecosystem
      (1) fire types:
            a. surface fires (fig. 10-9 left)
                  (a) burn away ground material
                  (b) release nutrients
                  (c) increase nitrogen-fixing bacteria
                  (d) stimulate the germination of seed
                  (e) control pathogen and insect
          b. Crown fires: (fig. 10.9 right)
                (a) damaged most vegetation
                (b) kill wildlife
                (c) increase soil erosion
          c. Ground fires: underground
7. Nonnative insect species and disease organisms (fig. 10-10)
8. Deforestation: temporary or permanent removal of forests for agriculture, settlements,
or other uses. (fig. 10-11, 12)
9. Tropical forests: 6% of Earth’s land, and 47% of the world’s forest cover
     (1) rain forests
     (2) deciduous forest
     (3) dry deciduous forest
     (4) forest on hill and mountain
 10. Tropical forest being cleared and degraded
     (1) most destruction since 1950
     (2) Brazil lost 16% tropical forest, lost 93% coastal forest
     (3) 50,000-170,000 km2/year lost
11. Importance of tropical forests:
     (1) 50-90% earth’s terrestrial species
     (2) removing excess CO2
     (3) ecological and economic importance: About 2,100 of the 3,000 plants identified
by the National Cancer Institute as sources of cancer-fighting chemicals come from
tropical forests.
12. Causes of tropical deforestation and degradation (fig 10-15)
     (1) basic causes
           a. not valuing ecological services
          b. exports
          c. government policies
          d. poverty
          e. population growth
     (2) secondary causes
          a. oil drilling
          b. mining
          c. flooding from dams
          d. tree plantations
          e. cattle ranching
          f. settler farming
          g. fires
          h. logging
          i. roads

10-2 How should we manage and sustain forests?
1. Manage forests more sustainable (fig. 10-17)
2. Improve and management of forest fires
     (1) prescribed fires
     (2) allow many fires on public lands to burn
     (3) protect houses and buildings
     (4) thin forest areas vulnerable
3. Deforestation and fuelwood crisis
     (1) people use fuelwood in developing countries. Ex. Haiti
     (2) unsustainable use: environmental degradation, poverty, disease, social injustice,
crime, and violence
     (3) community forestry projects: involve local people
     (4) reforestation: plant trees
4. Sustaining tropical forests (fig. 10-19)
     (1) prevention
     (2) restoration

10-3 How should we manage and sustain grasslands?
1. Rangelands and overgrazing
     (1) rangelands: unfenced grasslands, wild
     (2) pastures: planted grasses or forage, domestic
     (3) overgrazing: when too many animals graze for too long and exceed carrying
capacity of a grassland area. (fig. 10-20)
2. Managing rangelands more sustainable
     (1) rotational grazing
     (2) protect riparian zones (fig. 10-21)
3. Grazing and urban development
     (1) many people move to SW US in 1980
     (2) ranchettes: ranch converts to housing development
     (3) conservation easements: land trust groups that pay ranchers with key grazing
areas from developing houses.

10-4 How should we manage and sustain parks and nature reserves?
1. Popular in the world
     (1) 1,100 NP larger than 10 km2 in 120 countries
     (2) 58 NP in US: America’s crown jewels
     (3) 273 million visitors now in US
2. How are parks being threatened?
     (1) 1% are protected in developing country
          99% paper parks: no protection
           a. local people need wood, cropland, …
           b. logger, miner, …
     (2) too small to sustain species
     (3) popularity is a big problem (fig. 10-22)
     (4) nonnative species invaded
     (5) development damaged ecosystem
3. How much should we protect?
     (1) 12% land is protected in the world
     (2) minimum of 20% land should be protected
4. Designing and connecting nature reserves
     (1) establish protected habitat corridors
     (2) buffer zone concept (fig. 10-24)
5. Case study: Costa Rica
     (1) 1963-1983 cut forests for grazing
     (2) mid-1970s established parks and reserves
     (3) 2006 ¼ lands reserved; megareserves (fig. 10-25)
     (4) 1986-2006 forest cover grew from 26% to 51%
10-5 What is the ecosystem approach to sustaining biodiversity?
1. Protecting global biodiversity hot spots
     (1) 34 biodiversity hot spots in the world (fig. 10-26, 27)
     (2) 2% land cover, 50% world’s plants, 42% terrestrial vertebrates
     (3) identifying and protecting hot spots is very important
2. Ecological restoration:
     (1) process of repairing damage caused by humans to the biodiversity and dynamics
of natural ecosystems.
     (2) back to ecological structure and function as possible
3. Approaches:
     (1) restoration: return to predegraded state
     (2) rehabilitation: remove pollutant or replanting
     (3) replacement: ex: degraded forest be replaced with a pasture
     (4) creating artificial ecosystems: human-designed ecosystem.
           Ex: wastewater to wetland
4. Best approach????
     environmental restoration = environmental destruction?
5. Applied ecology: learn how to share with other species some of the spaces we
dominate. Win-win ecology.
6. Community-based conservation: