ENVIRONMENTAL SCIENCE CHAPTER 9: Sustaining Biodiversity: The Ecosystem Approach

9-1: What Are Major Threats to Forest Ecosystems? Concept To Learn in Sect. 9-1: Ecologically valuable forest ecosystems are being cut and burned at unsustainable rates in many parts of the world.

Types (categories) of Forests Forests cover 30% of earth’s land surface, and are of three types: 1. Old-growth forests: uncut or regenerated forest, which haven’t been disturbed by humans or natural disasters for hundreds of years. 2. Second-growth forests: a forest which grows after deforestation by humans or natural disaster.

Types (categories) of Forests 3. Tree plantations (commercial forest): one to two species are grown on a tract of land to a point where they reach commercial value, then are clear-cut a. Examples? b. Downside to tree plantations?

Science Focus: Putting a Price Tag on Nature’s Ecological Services Estimated value of earth’s ecological services: 1. $33.2 trillion per year 2. $4.7 trillion per year for forests Need to start factoring these values into land use. Why?? Ecological services can be a sustainable source of ecological income

Steps in Harvesting Forests: Step one: build roads to transport timber, and will lead to: 1. Erosion of soil & run-off into waterways 2. An increase in invasive species 3. Easier access for human invasion Step two: logging operations; Types: 1. Selective cutting- small areas are cleared 2. Clear cutting- entire areas are cleared 3. Strip cutting- strip is cut along land contour

Types of Fires Affecting Forests Surface fires: natures “beneficial” fire 1. Burn undergrowth only (not tree tops) 2. Cool fire (comparatively) 3. Ecological benefits (frees seeds & minerals, controls disease & insects) Crown fires: destroys almost everything! 1. Burns the entire tree 2. Much hotter fire 3. Occurs in forests with lack of surface fires

Loss of Original Forests Deforestation: temporary/permanent removal of large expanses of forests 1. done for agriculture or expansion 2. 46% loss in 8,000 years (60% since 1950) 3. Most deforestation has occurred in tropical areas & developing countries 4. If this rate continues, there will be an estimated additional loss of 40% intact forests within next 20 years

Good News on Forests! 2000–2007 has seen our “net” total forested area as stabilized or increased Most of the increase due to tree plantations Overall though, there is a net loss of terrestrial biodiversity

Return of Forests in the United States U.S. forests presently: 1. Cover ~30% of land 2. Contain ~80% of wildlife species 3. Supply ~67% of nation’s surface water Forest cover is greater now than in 1920 Forests have grown back in areas previously cleared by secondary succession

Return of Forests in the United States Second and third-growth forests are becoming fairly diverse At present, more wood grown than is cut 40% of forests are now “protected” in the National Forest System Some forests transformed into tree plantations 1. but now have less biodiversity

Tropical Forests: see the most deforestation! Cover 6% of earth’s land area Habitat for 50% of terrestrial plants and animals 1. Houses the species most vulnerable to extinction (contain specialized niches) See rapid losses of 50,000–170,000 km 2 per year Some second-growth forests exist

Causes of Tropical Forest Deforestation and Degradation Population growth and poverty Economic reasons 1. Logging 2. Ranching 3. Farming Government subsidies Fires lead to raised temperatures and cause reduced rainfall.

Sect. 9-2: How Should We Manage and Sustain Forests? Concept to Learn in Sect. 9-2: We can sustain forests by emphasizing the economic value of their ecological services, removing government subsidies that hasten their destruction, protecting old-growth forests, harvesting trees no faster than they are replenished, and planting trees.

Management of Forest Fires Our current education campaign has saved lives, trees & wildlife. Our current education campaign has also lead to: 1. Fire suppression in all types of forests 2. Increased amounts of underbrush 3. Increased probability of crown fires

Management of Forest Fires Ecologists are now recommending: 1. Prescribed fires to get rid of underbrush 2. Allowing some fires to burn 3. Thinning vegetation from forests 4. Thinning forests around vulnerable homes 5. Decreasing the flammability of homes

Science Focus: Certifying Sustainably Grown Timber Forest Steward Council: a certification group, which evaluates companies for sustainable timber practices, reviewing: 1. Environmentally sound practices 2. Sustainable yield harvest (??) 3. Minimal erosion from operations 4.Retention of dead wood for wildlife habitat Should our government give tax breaks to grow timber this way? Explain.

Paper production: From Trees or From Something Else? Many trees are cut for paper production Alternatives to trees: 1. Pulp from rice straw and agricultural residues (China) 2. Kenaf (U.S.) = non-tree fibers, from plants like the Kudzu vine 3. Hemp = a type of non-tree fiber

Ways to Reduce Tropical Deforestation Debt-for-nature swaps: 1. A country will protect its rainforests in exchange for financial aid or debt relief from a participating country. Conservation concessions: similar to above Gentler logging methods: 1. Strip cutting, selective cutting Encourage use of wood substitutes: use of bamboo, recycled wood products, plastic, etc.

Sect. 9-3 How Should We Manage and Sustain Grasslands? Concept to Learn in Sect. 9-3: We can sustain the productivity of rangeland by controlling the number and distribution of grazing livestock and by restoring degraded grasslands.

Grasslands Provide important ecological services Second most used and altered ecosystem by humans 42% are grazed by cattle, sheep, and goats. Two types: 1. Rangeland: open, unfenced grasslands a. Supply forage (vegetation) for animals 2. Pasture: managed, enclosed grasslands a. Planted with domesticated grasses

Overgrazing of Grasslands Overgrazing: when grazing exceeds the carrying capacity of the rangeland. 1. Leads to: a. Soil erosion b. Soil compaction c. Enhances growth of invasive species

Our Job: Manage Rangelands Sustainably! Can be accomplished by: 1. Practice rotational grazing 2. Fence out riparian zone areas a. Areas near bodies of water 3. Suppress invader plants by: a. Using herbicides b. Mechanical removal c. Controlled burning d. Short-term trampling

Sect. 9-4: How Should We Manage and Sustain Parks and Nature Reserves? Concept to Learn in Sect. 9-4: We need to put more resources into sustaining existing parks and nature reserves and into protecting much more of the earth’s remaining undisturbed land area.

National Parks There are presently 1,100 national parks in 120 countries Only 1% of parks in developing countries are protected (due to lack of funding) –Local people invade parks to survive –Logging –Mining –Poaching

Problems Protecting National Parks Illegal logging Illegal mining Wildlife poaching (for tusks, etc) Most of the existing parks are too small to protect large animals Invasion of nonnative species cause competition for the protected species.

Stresses on U.S. National Parks There are 58 major national parks in US Biggest problem for them is popularity 1. attract dune buggies, dirt bikes, etc. 2. causes destruction of vegetation Damage from nonnative species 1. Ex: intro of wild boars Threatened islands of biodiversity 1. surrounding human activity threaten them Need $6 billion for overdue repairs

Nature Reserves Occupy a Fraction of Earth 12% of earth’s land protected, but not fully Only 5% is fully protected – 95% reserved for human use Needed for conservation: 1. Minimum 20% of land in biodiversity reserves 2. Protection for all biomes

Reasons/Solutions for Protection of natures reserves They serve as an “Ecological insurance policy” for all species Use of buffer zones around protected areas 1. inner, protected core 2. just outside inner core, can extract resources Locals to manage reserves and buffer zones United Nations: has created 531 biosphere reserves in 105 countries

Science Focus: Reintroducing the Gray Wolf to Yellowstone National Park Reduced to a few hundred (from 350,000) in lower 48 by 1973 Gray wolves are a keystone species, by controlling the populations of other species Restoration proposal angered ranchers, hunters & loggers reintroduced in Yellowstone, growing to 124 by 2008 Positive ripple effect after reintroduction to the ecosystem.

Costa Rica: A leader in conservation A “superpower” of biodiversity Conserves 25% of its land (more than any other country!) **We’re 42 nd on the list! Has 8 mega-reserves (inner core, with 2 buffer zones) Government eliminated deforestation subsidies 1. Instead, paid landowners to maintain and restore tree coverage Boosts ecotourism ( those who come to see it!)

Protecting Wilderness Protects Biodiversity Wilderness: large areas of undeveloped land 1. Preserves biodiversity 2. allows for micro-evolution in response to unpredictable environmental changes Preserving wilderness has been controversial. 1. constant opposition to it. 2. only 4.6% of US is protected wilderness, & mostly in Alaska. 3. only 2% in the continental US!

Protecting Wilderness Protects Biodiversity 1964 Wilderness Act was put into use 1. prevented undeveloped public land from being used 2. placed land into the “National Wilderness Preservation System” Ten-fold increase from 1970 to 2008, but still US ranks 42 nd in the world in preserving wilderness.

9-5 How Can We Help to Sustain Terrestrial Biodiversity? Concept to Learn in Sect. 9-5: We can help to sustain terrestrial biodiversity by identifying and protecting severely threatened areas (biodiversity hotspots), rehabilitating damaged ecosystems (using restoration ecology), and sharing with other species much of the land we dominate (using reconciliation ecology).

Three Principles We Can Use to Protect Ecosystems: 1. Map and inventory the world’s terrestrial and aquatic ecosystems: a. All species b. Ecosystem services it provides 2. Locate and protect the most endangered ecosystems, with a focus on protecting biodiversity 3. Seek to restore as many degraded ecosystems as possible

Protecting Global Biodiversity Hotspots: A Priority! 17 mega-diversity countries, mostly in tropics and subtropics, contain two-thirds of the world’s biodiversity Developing countries are economically poor and biodiversity rich! Protect biodiversity hotspots 1. areas rich in plant species that are in great danger of extinction. 2. are vulnerable to human population growth and the resulting pressure on natural resources

Ecological Restoration Ecological Restoration: the process of repairing damage caused by humans to the biodiversity & natural dynamics of natural ecosystems, accomplished thru; 1. Restoration to natural state 2. Rehabilitation to functional ecosystem 3. Replacement with another ecosystem 4. Creating artificial ecosystems

Science-based Principles for Restoration Identify cause of degradation Stop abuse by reducing factors Reintroduce species if necessary Protect area from further degradation

Restoration Ecology Creating new habitats to conserve species diversity in areas where people live, work, play People learn to protect local species and ecosystems Sustainable ecotourism Golden Gate Park in San Francisco: an example of “reconciliation ecology” 1. Purposeful planning of areas for preserving biodiversity, in places that we live

9-6 How Can We Help to Sustain Aquatic Biodiversity? Concept to Learn in sect 9-6: We can help to sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.

Impacts on Aquatic Ecosystems Destroyed or degraded by human activities Coastal habitats disappearing 2-10 times faster than tropical forest Rising sea levels will destroy coral reefs and some low islands Ocean floor degradation 150 times larger than area clear-cut annually

Impacts on Aquatic Ecosystems Freshwater habitat disruption 1. Dams 2. Water withdrawals from rivers Likely extinction 1. 34% marine fish species 2. 71% freshwater species 3. Greater than any other group of species

Overfishing Fishery: a concentration of an aquatic species that is suitable for commercial harvesting 1. A competitive field. 2. At present, we consume more than is sustainable 3. Fishprint: the area of ocean necessary to sustain the consumption of the average person a. Globally shows157% overfishing rate!! 90% of large open-ocean fishes have disappeared since 1950

Case Study: Industrial Fish Harvesting Methods Use gps & sonar to find fish 1.Trawler fishing: drags net on ocean floor, catching shellfish (ie shrimp) & cod 2.Purse-seine fishing: like a giant, open purse that has a drawstring closure at top. a. Good for top-swimming fish (tuna) 3. Longlining: long lines, with 100’s of hooks 4. Drift-net fishing: long nets, which stretch deep into water.

Why Is Protection of Marine Biodiversity So Difficult? Human aquatic ecological footprint expanding 1. difficult to monitor the impact it has Not visible to most people (out of sight….) Viewed as an inexhaustible resource Most ocean areas outside jurisdiction of a country 1. makes it an open-access resource

Solutions for Marine Ecosystems Protect endangered and threatened species Establish protected marine sanctuaries 1. don’t prevent dredging/trawling Marine reserves – work well and quickly Integrated coastal management Protect existing coastal wetlands