Chapter 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach Human Population Size and resource use Human Activities Agriculture, industry, economic production and consumption, recreation Direct Effects Degradation and destruction Changes in number and of natural ecosystems distribution of species Alteration of natural chemical Pollution of air, water, cycles and energy flows and soil Climate change Indirect Effects Loss of Biodiversity Fig. 10-2, p. 192 Human Impact on Terrestrial Biodiversity Why should we care? Intrinsic value: Instrumental value: Managing and Sustaining Forests 3 types of forests based on age: Old-growth forests: Second growth forests: Tree plantation or tree farms: Governments own 84% of forests Weak trees removed Clear cut 25 30 Seedlings planted 15 Years of growth 10 5 Fig. 10-6, p. 195 Natural Capital Forests Ecological Services Support energy flow and chemical cycling Reduce soil erosion Absorb and release water Economic Services Fuelwood Lumber Pulp to make paper Mining Purify water and air Livestock grazing Influence local and regional climate Recreation Store atmospheric carbon Jobs Provide numerous wildlife habitats Fig. 10-4, p. 193 Managing and Sustaining Forests Estimate: worlds forests are being cleared or degraded exponentially at a rate of 0.3-0.8%/year. Most is used for fuel wood in developing countries. Ex- Haiti used to be covered in forests but now only 2% of land is covered in trees. Managing and Sustaining Forests Solutions: 1. Plant small plantations of fast growing fuel wood trees and shrubs (community forest) 2. Burn wood more efficently by providing people with cheap, more efficient and less polluting wood stoves or solar ovens. 3. start burning renewable sun-dried roots of various plants Managing and Sustaining Forests Harvesting trees Causes damage by: Building roads Increases erosion Sediment runoff Habitat fragmentation Biodiversity loss Invasion of non-native species, pests, disease Harvesting Trees Trees can be harvested individually from diverse forests (selective cutting), an entire forest can be cut down (clear cutting), or portions of the forest is harvested (e.g. strip cutting). Figure 10-9 Natural Capital Degradation Deforestation • Decreased soil fertility from erosion • Runoff of eroded soil into aquatic systems • Premature extinction of species with specialized niches • Loss of habitat for native species and migratory species such as birds and butterflies • Regional climate change from extensive clearing • Release of CO2 into atmosphere • Acceleration of flooding Fig. 10-7, p. 196 Solutions Sustainable Forestry • Identify and protect forest areas high in biodiversity • Grow more timber on long rotations • Rely more on selective cutting and strip cutting • Stop clear-cutting on steep slopes • Cease logging of old-growth forests • Prohibit fragmentation of remaining large blocks of forest • Sharply reduce road building into uncut forest areas • Leave most standing dead trees and fallen timber for wildlife habitat and nutrient recycling • Certify timber grown by sustainable methods • Include ecological services of forests in estimating their economic value • Plant tree plantations on deforested and degraded land • Shift government subsidies from harvesting trees to planting trees Fig. 10-12, p. 199 Managing and Sustaining Forests Forest Fires Surface fires: Crown fires: Advantages: help prevent worse fires, release nutrients, release some seeds, and control pathogens Can kill wildlife Prescribed fires: Helps clear leaf litter. Trade-Offs Logging in U.S. National Forests Advantages Disadvantages Helps meet country’s timber needs Provides only 4% of timber needs Cut areas grow back Ample private forest land to meet timber needs Keeps lumber and paper prices down Has little effect on timber and paper prices Provides jobs in nearby communities Damages nearby rivers and fisheries Promotes economic growth in nearby communities Recreation in national forests provides more local jobs and income for local communities than logging Decreases recreational opportunities Fig. 10-14, p. 202 Tropical Rainforest Deforestation and Degradation Deforested to: Build infrastructure Set up cattle ranches/crops Logging FYI: loose 50,000-170,000 km/yr. Less then 5% of TRF are managed sustainably Why should they be protected Medicines!!! Solutions Sustaining Tropical Forests Prevention Protect most diverse and endangered areas Restoration Reforestation Educate settlers about sustainable agriculture and forestry Phase out subsidies that encourage unsustainable forest use Add subsidies that encourage sustainable forest use Rehabilitation of degraded areas Protect forests with debt-for-nature swaps and conservation easements Certify sustainably grown timber Reduce illegal cutting Reduce poverty Slow population growth Concentrate farming and ranching on already-cleared areas Fig. 10-20, p. 207 Managing and Sustaining Grasslands Rangelands: Pastures: Grazers are main problem As long as only the upper half of the grass blade is eaten then grass is a renewable resource Overgrazing: Undergrazing: Managing and Sustaining Grasslands Solutions: Control the number of grazing animals and the duration of their grazing in a given area. Rotational grazing: Suppress the growth of unwanted invader plants Replanting native seeds to barren areas can restore rangelands but can be expensive National Parks There are more then 1,100 national parks larger then 4 sq miles located in 120 countries Only 1% of Parks in developing countries are actually protected.