F.ConserveSu11 - Conservation Ecology Millennium Ecosystem...

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Unformatted text preview: Conservation Ecology Millennium Ecosystem Assessment Millennium Ecosystem Assessment http://www.millennium assessment.org • 2005 Landmark study by 1300 experts from 95 countries. • Reports that humans have disrupted ~60% of earth’s ecological systems to meet demands for food, water, timber and fuel. http://www.millennium assessment.org • “Any progress achieved in addressing . . . poverty and hunger, health and environmental protection is unlikely . . . if most of the ecosystem services on which humanity relies continue to be degraded.” • “Human activity is putting such strain on the natural functions of earth that the ability of the planet’s ecosystems to sustain future generations can no longer be taken for granted.” • Slowing this trend “will require radical changes in the way nature is treated at every level of decisionmaking.” Real and potential human insults to the integrity of the biosphere Regional & global ‹ Loss of biodiversity ‹ Loss of overall life support Real and potential human insults to the integrity of the biosphere 1. 2. 3. 4. 5. 6. Ecology and Environmentalism • The precautionary principle ßBasically states that humans need to be concerned with how their actions affect the environment ßIt is a lot more plausible to prevent environmental degradation than to try to remediate it Heyer Global contamination (pollution) Disrupted biogeochemical cycles Lost biodiversity [HIPPO] Global warming Destruction of the ozone layer Nuclear winter Disrupted biogeochemical cycles • Water cycle – Desertification; contamination; saltwater intrusion • Nitrogen cycle – Nutrient depletion; cultural eutrophication; nitrite contamination; acid rain • Carbon cycle: – Excessive CO2; depleted fossil pools • Soils: – Erosion; nutrient depletion; fire suppression 1 Conservation Ecology Biodiversity Crisis Biodiversity Crisis Birds Plants 13% of known bird species worldwide are threatened with extinction. Density of songbird populations has dropped by 50% in the US in the last 40 years. Biodiversity Crisis Fish About 20% of the known freshwater fishes in the world became extinct during historical times, or are now threatened. About 200 of the 300 species of cichlids in lake Victoria are gone due to introduction of the exotic Nile perch. Biodiversity Crisis Since 1900, the current rate of extinction is 100 to 1000 times “background” rates of prior centuries This past century may represent the greatest extinction event of Earth’s history! Earth’ Heyer In the US, 200 species of plants have disappeared within the past 100 years. Another 730 species are endangered. Biodiversity Crisis Since 1900, ß 123 freshwater vertebrate and invertebrate species have become extinct in North America, and hundreds more are threatened. ß Extinction rates of aquatic species are five times that of terrestrial. TOP (BOTTOM?) TWENTYFIVE BIODIVERSITY HOTSPOTS • Only 1.5% of Earth’s landmass holds 33% of plant and vertebrate species • Many of these hotspot species are endemic • One third of these hotspots have already lost >90% of their area to human development 2 Conservation Ecology Biodiversity Crisis Some local species at risk HIPPO • Habitat destruction & fragmentation Southern sea otter • Invasive species Bald eagle • Pollution • Population (human) Ohlone tiger beetle Habitat destruction & fragmentation Reduction or loss of natural habitat by • housing & industrial developments • agriculture • overgrazing • urbanization • deforestation • mining • oil drilling • fire • erosion etc. • Overexploitation Santa Cruz long-toed salamander Fragmented Habitats Fragmented Habitats • Partial destruction of habitat into patches isolates sub-populations • Less than 10% old growth forest remains in the US Pacific NW Quality of Patches Determines Subpopulation Survival •Source habitat – Reproduction exceeds deaths – High quality patch: old growth forest •Sink habitat – Deaths exceed reproduction •Number of source habitats decreasing Fragmentation of forest by logging LOCAL EXAMPLES OF HABITAT LOSS & FRAGMENTATION SALT MARSH HARVEST MOUSE • Found only in salt marshes ringing SF Bay • Federally and state listed as endangered • About 90%+ of salt marshes have been lost to development & salt ponds Heyer Northern spotted owl LOCAL EXAMPLES OF HABITAT LOSS & FRAGMENTATION PRESIDIO MANZANITA • Shrub found today only on north end of S.F. peninsula • Just ONE plant remains, in the Presidio • Former range is now under S.F. itself • Federally and state listed as endangered 3 Conservation Ecology LOCAL EXAMPLES OF HABITAT LOSS & FRAGMENTATION INVASIVE SPECIES CHARACTERISTICS Invasive exotic species are bad news because they tend to be BURROWING OWL • Lives in burrows usually dug by ground squirrels • Flat, open land around SF Bay is preferred territory • Also preferred by developers! • Owl was to be listed as threatened, but CA DF&G denied appeal • Competitive • Quick reproducers • Adapted to human disturbance • Adapted to most domestic animal disturbance (grazing, trampling etc.) • Rapid dispersers • Without their native predators • Just overall “weedy” LOCAL EXAMPLES OF INVASIVE SPECIES INVASIVE SPECIES • Introduced species that gain a foothold in a new habitat (a) Brown tree snake, introduced accidentally to Guam in cargo Figure 55.6 – Usually disrupt their adopted community WILD PIG • Introduced to CA in 1930’s for hunting • Now found throughout lower elevation hills, from the coast to Sierra • Will eat anything it finds--bulbs, fawns, acorns, snakes etc. etc. • Considered one of California’s most destructive exotics (b) Introduced kudzu thriving in South Carolina LOCAL EXAMPLES OF INVASIVE SPECIES YELLOW STAR THISTLE • Originally from Europe, introduced accidentally • Almost impossible to control or eradicate • Out-competes all native grasses and forbs • Now covers over 7 million acres in California Heyer MORE EXAMPLES OF CALIFORNIA’S INVASIVES • Eucalyptus (trees, Australia) • French broom (shrub, Europe) • Medusa-head grass (Europe) • Ailanthus (“tree of heaven,” China) • House mouse (Europe, Asia) • Chinese mitten crab (Asia) • Northern pike (fish, eastern US) • Starling (Europe) • English sparrow 4 Conservation Ecology Invaders of SF Bay Invaders of SF Bay Atlantic Cordgrass • Water Hyacinth The invasive Asian clam , Corbula amurensis , has changed the food web in San Francisco Bay estuary by severely restricting phytoplankton blooms in the northern embayment Channeled Whelk Mitten Crab Yellowfin Goby Striped Bass Eastern softshell clam Atlantic Mudsnail Asian clam Oyster drill Cuthona - Sea Slug Green Crab LOCAL EXAMPLES OF POLLUTION PROBLEMS CALIFORNIA CONDOR • Captive breeding program is successful, but reintroduced birds now have high lead levels, likely from ingesting bullet fragments in scavenged food. • Several reintroduced condors have died from drinking ethylene glycol (antifreeze) in contaminated puddles. POPULATION (OURS) LOCAL EXAMPLES OF POLLUTION PROBLEMS RED-LEGGED FROG • Many male frogs are now intersex in some ponds polluted with atrazine. • Atrazine is the most widely used, potent agricultural weed-killer in the US. OVER-EXPLOITATION OF WILD “RESOURCES” • California’s population is about 35 million. • It’s expected to double within 50 years. • Human pressures are at the base of most of our conservation problems. • Clear-cutting of forests Heyer 5 Conservation Ecology OVER-EXPLOITATION OF WILD “RESOURCES” Fish “Factory ships” with fleets of fishing boats cruise from area to area, moving on when nothing left worth catching Stocks of large food fish (tuna, shark, grouper, swordfish etc.) have declined to just 10% of their numbers of 20 years ago due to overfishing. OVER-EXPLOITATION OF WILD “RESOURCES” Sharks worldwide are threatened by the shark fin industry. Typically, only the fins are taken; the rest of the shark is discarded. Sharks are slow to mature and produce few young – All shark fisheries crash quickly Figure 55.7 By-catch By-catch • In some cases these by-catch species are already endangered. Often, species other than those targeted by modern fishing fleets are caught too. This is called by-catch. These animals are discarded, and add to the depletion of marine species. albatross caught on longline OVER-HARVEST OF SPECIES IN CALIFORNIA BLACK BEAR • Legal hunting limit is ~1500 statewide per year. • More than double that is estimated to be killed yearly, illegally, for their gall bladders and paws, which are exported to Asian markets as medicinals. Heyer vSea turtle caught in a trawler netting. It may take a turtle an hour or more to drown. vDrift nets may be the leading cause of mortality today of marine mammals such as dolphins, whales and seals OVER-HARVEST OF SPECIES IN CALIFORNIA ABALONE • Despite strict regulation and monitoring, all species of abalone are in decline. Two are nearing extinction. • Most taken illegally are exported to Asia. 6 Conservation Ecology OVER-HARVEST OF SPECIES IN CALIFORNIA The Symbol of California • A mammal hunted to extinction by 1922 – California grizzly (“golden bear”) BLUE OAKS • Blue oak woodlands are being devastated in the Sierra foothills by development and cutting for firewood. • In many cases, woodcutters “poach” trees from private and public lands. Global habitat impact: the Greenhouse effect • Green house effect: excess CO2 in atmosphere “Greenhouse gases” (esp.., CO 2 ) are transparent to sunlight but absorb infrared radiation trap heat within atmosphere Increase in atmospheric CO2 correlates with increase in global temperature Other Greenhouse Gases 1.05 390 0.90 380 0.75 370 0.60 0.45 350 0.30 340 CO 2 0.15 330 Temperature variation (°C) CO2 concentration (ppm ) Temperature 360 0 320 -0.15 310 - 0.30 300 - 0.45 1960 1965 1970 1975 1980 1985 Year Heyer 1990 1995 2000 2005 Figure 54.24 7 Conservation Ecology Sources of CO2 Emissions Ecological Modeling the combined effects of climate drivers Probable consequences of the greenhouse effect • Melt polar ice caps, raise sea levels – Flood heavily populated coastal areas Global Climate Drivers Global warming & the ocean’s thermal budget IMPACTS OF GLOBAL WARMING • Change in sea level – Coastlines – Islands • Alterations in global precipitation patterns – Desertification of agricultural areas – Deplete snow-pack water reserves • Shift of great ocean current patterns – Decreased heat transfer away from tropics – More extreme climates between equator and poles • Major changes in habitats leading to population shifts and loss of biodiversity Heyer 8 Conservation Ecology • Geographical shifts –Animals –Plants • Sociological & political shifts –Food supply Deterioration of the Ozone Layer • • • Ozone (O 3) layer — region ~20km up in atmosphere Absorbs much of the UV radiation from the sun Chlorofluorocarbons (CFCs) from industrial processes (e.g., refrigerants, propellants, insulation) rise to upper atmosphere and degrade to release chlorine Chlorine catalyzes degradation of O 3 to O2 Æ decreases thickness of ozone layer • 350 Chlorine atoms 1 Chlorine from CFCs interacts with ozone (O ), 3 forming chlorine monoxide (ClO) and oxygen (O 2). O2 Chlorine O3 ClO O2 3 Sunlight causes Cl2O 2 to break down into O2 and free chlorine atoms. The chlorine atoms can begin the cycle again. ClO Cl2O 2 Sunlight 2 Two ClO molecules react, forming chlorine peroxide (Cl 2O 2). Ozone layer thickness (Dobson units) IMPACTS OF GLOBAL WARMING 250 200 150 100 50 0 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Figure 54.27 Deterioration of the Ozone Layer • Upper atmospheric winds concentrate CFCs toward poles • Thinning of ozone layer most severe over arctic/antarctic – “Ozone hole” • But even temperate latitudes have thinned 2–10% over past 20 years Figure 54.26 300 Year (Average for the month of October) Deterioration of the Ozone Layer Increased UV radiation exposure: • Increased rate of skin burn and melanoma q “Tan today … cancer tomorrow” • Increased rate of cataracts q Argentinan cattle • Possible destruction or inhibition of phytoplankton q (a) October 1979 Potential major disruption of global food webs and maybe even weather (b) October 2000 Human societies are changing the planet’s biosphere! Option A: Planned & implemented changes Option B: No plans Æ sudden catastrophic sudden deterioration 1. Choose A and plan well: maybe maintain biodiversity & human carrying capacity 2. Choose A and plan poorly: get option B anyway 3. Avoid making the choice: option B is inevitable default Ecology and Environmentalism • Ecology — Provides the scientific understanding underlying environmental issues • Sustainable Development ß Long-term prosperity of both humans and ecosystems ß Commitment to protect and preserve biodiversity ß “Stewards of the land” • Decisions that benefit future generations Figure 50.1 Heyer 9 Conservation Ecology CONSERVATION STRATEGIES RESEARCH! In genetics, forensics, habitat quality assessment, home range analysis, systematics, rapid assessment in critical areas, cultural anthropology . . . All needed! Quick! • Research and more research • Sound bio-reserve design • Corridors • Re-introduction • Captive breeding • Conservation of foundation species • Conservation of umbrella species • Habitat restoration • Education and more education Understanding community dynamics • allows biomanipulation to restore polluted ecosystem Restoration of Lake Vesijarvi, Finland • Cultural eutrophication (sewage) allowed overgrowth of noxious alga and cyanobacteria • 1. Sewage treatment alone did not restore lake ecosystem Food Chain Polluted State Restored State Abundant Rare Zooplankton Rare Abundant Algae Abundant BIO-RESERVE DESIGN Large reserves are better than small. • large species • large home range • higher diversity • less edge effect Rare Fish • 2. fl the fish population fi allowed › zooplankton population • fi abundant zooplankton reduced alga & cyano populations BIO-RESERVE DESIGN Large, circular or square reserves are better than long, strip-like reserves. • less edge effect • less wind damage • fewer opportunistic predators Heyer BIO-RESERVE DESIGN Corridors between reserves help • maintain population contacts. • allow dispersal of young. • aid migrating species. 10 Conservation Ecology Movement corridors to connect habitat patches • Movement corridors promote dispersal, help sustain populations • Esp. to maintain contact from source habitats • Multiple patches may be better than one big area – For some species – Only if connections are sufficient Underpass serves as a movement corridor CAPTIVE BREEDING Animals/plants are held in captivity until enough are available for reintroduction. Examples: blackfooted ferret, Przewalski horse, Pere David’s deer, Arabian oryx. PRZEWALSKI’S HORSE (TAKHI) • Declared extinct in native Mongolia in 1960’s • Again, captive herds in the US, England & Europe became the nucleus of new groups. • Horse reintroduced to Mongolia in mid1990’s. Heyer REINTRODUCTION Populations of recovered species are brought back to their native habitat (assuming it still exists). Examples: tule elk, pronghorn, condor in CA. (Right, tule elk photo by Stasia McGehee, De Anza ES 85A class) PERE DAVID’S DEER • Last individuals in native China were eaten by troops during the Boxer Rebellion, early 1900’s. • Fortunately, small captive herds existed in England, and provided the start of a new population. THE ARABIAN ORYX • Last wild group run down and shot for “fun” by Saudi soldiers in 1970’s; antelope was extinct in the wild. • Captive-bred herds since reintroduced into former range in Saudi Arabia & Oman. 11 Conservation Ecology Figure 53.18 FOUNDATION SPECIES CONSERVATION Foundation species help determine the make-up and integrity of ecosystems; without them, ecosystems become less stable. • Keystone predators • Ecosystem engineers • Critical pollinators FOUNDATION SPECIES • Some foundation species act as facilitators that have positive effects on the survival and reproduction of many of the other species in the community • Black rush ( Juncus ): shade reduces evaporation; snorkelroots oxygenate sediment Figure 55.8 Number of plant species 8 4 2 0 Salt marsh with Juncus (foreground) UMBRELLA SPECIES CONSERVATION Grizzly bear 6 Umbrella species tend to be big, charismatic species with big ranges. Protect them, and you protect everything else by default. Restoration: Habitat Recovery With Juncus Without Juncus Conditions Figure 53.19 UMBRELLA SPECIES Because the Endangered Species Act (as it stands currently) mandates protection of habitat in addition to the species itself, umbrella species help protect many others. Remembering our connections to the natural world • Bioremediation – Lichens to remove heavy metals – Bacteria to detoxify oil spills • Ecosystem Augmentation – Replenish factors limiting recovery – Legumes in tropical soils Metal-concentrating lichens Paleolithic mural, Lascaux, France Heyer Figure 55.24 12 ...
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This note was uploaded on 09/02/2011 for the course BIOL 6C taught by Professor Sundram during the Spring '09 term at DeAnza College.

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