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113 Cards in this Set
- Front
- Back
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spatial scale review |
individual space local patch region landscape biogeographical zone |
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disturbance types |
pulse continuous press
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pulse disturbance |
fire, flood, earthquake, tsunami |
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continuous press disturbance |
drought, tourism, introduced predator, grazing
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slide 5 chapter 14 |
hi
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Case Study (14): Coral Reefs |
disturbed by tropical cyclones Heron island Coral Reefs: -protected inner flat- unaffected by cyclones -this part- 60% cover to 5% cover over 30 years -Exposed crest- severe disturbance in 1967 w/ drop from 70% cover to 0% cover...slow recovery Recruitment based on available free space
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Case Study (14): Coral Reef Fishes |
Niche-Diversification Hyp Variable Recruitment Hyp |
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Niche-Diversification Hypothesis |
Coral Reef fish communities are equilibrium competitive systems in which each species has evolved to fit into a specific niche |
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Variable Recruitment Hypothesis |
Coral reef fish communities are non-equilibrium systems in which recruitment is an unpredictable lottery... who gets there first
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Case Study: Rocky Intertidal Zone |
-Disturbed by wave action and storms -Two seaweed groups: 1. Ephemeral seaweeds 2. Perennial seaweeds -Compete for space and light -Side protected from waves, herbivory by limpets -Side without limpet, exposed to wave action |
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Case Study: Rocky Intertidal Zones |
Coralline algae Herbivores present=induce competitive uncertainty...promotes patchiness and biodiversity Herbivores absent=single alga dominates |
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Fluctuating Environment Model |
Environment changes seasonally or irregularly and competitive rankings of species fluctuate |
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Directional Changing Model
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Dependent upon response of community to change
global warming |
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Slow Competitive Displacement Model
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considers nearly equal competitive abilities and therefore slow competitive exclusion
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Menge-Sutherland Model
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graphs***
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Lake St. George
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READ IN TB
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Disturbance on Islands
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GRAPH
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Multiple Stable States- i don't get this
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Determined by types of disturbance
Four criteria: 1. Must show equilibrium point at which it remains or returns to if perturbed by a disturbing force 2. If perturbed sufficiently, will move toward a 2nd eq. point 3. abiotic environment must be similar in the two communities 4. Must persist for more than one generation of the dominant species |
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Multiple stable states example
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elephants and stuff... look on pp
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Individuals as Machines
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autotrophes- pick up energy from the sun and materials from non-living sources (producers)
heterotrophs- pick up energy and materials from living matter (consumers, ___, decomposers) |
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Studying Ecosystem Metabolism
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1. Biomass
2. Flow of chemical materials 3. Flow of energy DIAGRAM |
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Measuring Primary Production
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Direct Method:
Measure change in [CO2] or [O2] Indirect Method: (Harvest Method) Measure change in biomass=B1-B2 NPP in biomass= deltaB+L+G Specify aerial, root, or while plant production L=loss by death or its parts G=loss to consumer organisms |
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Efficiency of Primary Production***
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Efficiency of GPP%=(100) Energy fixed by GPP/Energy is incident sunlight
only 0.02% of total solar energy hitting the Earth is used for photosynthesis |
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Marine Communities:
North Pacific Central Gyre |
All primary productivity is about 1% light level
primary production is low in surface waters (excessive light) primary productvity is high in warm waters between 10-30m low nutrients (N&P) in surface layers ocean primary production is limited by nutrients rather than by light |
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Marine Communities:
Sargasso Sea |
Low productivity
Clear surface waters limiting nutrient=IRON Iron--> Cyanobacteria--> nitrogen fixation --> phytoplankton |
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Upwelling
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Nutrient-Rich zones in nutrient Poor ocean
cold, nutrient rich deep water is brought to surface casuses burst in phytoplankton and fish abundance |
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Freshwater Communities
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Limits:
-solar radiation(day to day) -Temp -Nutrients Phosphorus limiting nutrient in most freshwater lakes |
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Algae and Eutrophication
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1. Nutrients load up
2. Plants flourish 3. Algae Blooms, oxygen is depleted 4. Decomposition further depletes oxygen 5. "Death" of ecosystem |
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Terrestrial Communities
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-uncouple radiation &temp on land
-major limits: temp, water, nutrients in soil -satellite imagery to detect plant spectral reflectance pattern (NOAA) -Standing terrestrial communities like forests have nutrient stores tied up.. like aquatic systems |
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Efficiency of Secondary production--> read in TB
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Aggregate of growth & reproduction in consumers
Trophic efficiency= net prod at trophic level i+1 / net prod at trophic level i |
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Eltonian Pyramid
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-consequence of low ecological efficiency
-90% energy is lost at each level |
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Why is the world green?
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1. Plants aren't passive agents
2. Nutrients limit herbivores, not energy 3. Abiotic factors limit some predators 4. Herbivores limit their own numbers 5. Spatial variation reduces availability of plants 6. Enemies limit herbivore numbers |
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Is grazing by sustained game better than sustained domestic cattle/sheep?
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agricultural species are better at grazing
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Macronutrients
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needed in large amounts
primary- N,P,K secondary- Ca, Mg, S |
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Micronutrients
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trace elements, needed in small amounts
B, Cu, Fe, Cl, Mn, Zn, Mb |
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Biogeochemical cycle
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the pathway by which a nutrient or chemical moves through the biotic & abiotic compartments of the environment
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Bioelement
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elements that cycle through living organisms
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Flux
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rate of movement of nutrients between compartments
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carbon cycles
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Global cycle
Today's atmospheric CO2 reservoir is largest in past 650,000 years -fossil fuel extraction-->burning fuels--> atmosphere -volcanic eruptions--> atmosphere -runoff-->water |
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Phosphorus Cycle
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Local Cycle
Mineable rock--> Mining weathering-->runoff-->water geographical uplift-->mineable rock |
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Nitrogen Cycle
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Haber Bosch Process
Global cycle Fossil fuels-->extraction land plants-->consumers |
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Nutrient cycling in forests
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-mass balance:inputs-outputs= delta storage
-turnover time- the time an average atom will remain in the soil before recycled into trees & shrubs -Boreal deciduous forests retain little organic matter about ground |
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Nutrient use efficiency
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-Previously glaciated northern hemisphere has nutrient rich soils(eutrophic)
-Ancient, highly weathered soils in Australia, South America, & India -nutrient poor (oligotrophic) -Nutrient use efficiency-how much biomass a plant can produce from a given amount of a specific nutrients -forest clearing..no recovery in oligotrophic systems.. nutrient leach out a system |
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Case Study: Brooktrout Lake
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idk.. something with trouts
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Dryland Salinity Problem
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-shallow roots cause ground water to rise
-solutions: 1. Grow salt tolerant crops 2. Irrigate w/ more water (lose $) 3. Replant native vegetation to lower water table (lose land) -can affect other ecosystems -not necessarily one ecosystem -dense monoculture |
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Landscape ecology
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-The ecology of regions that contain different ecosystems
-Two versions: 1. Analytical 2. Practical - land use, landscape planning conservation Terms: patches, edges, connectivity, mosaic |
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Measurement of Landscape Attributes
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1. Determine scale of analysis
2. Define a patch (fine-grained v. coarse) 3. Consider life history of species of interest 4. Define patch type (matrix?) 5. Measure area of patch, distance around edge, longest length, shape, distance between patches etc. 5. How do all of these elements influence communities/ecosystems? |
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Landscape Fragmentation
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-humans-farmland
-climate change -weather events Two Hyps: 1. Species richness increases with area (large patches= more species) 2. Population abundance increases with area (increase mortality, decrease reproductive rates in small patches) |
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Edge effects (quail)
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Many game species, like bobwhite quail prefer the edge.. especially when nesting in coveys
Law of interspersion -quail benefit from fragmentation |
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Case Study: Rural Dieback in Australia
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-improved soil nutrients-> increase in leaf nutrients-> increase in insect repro-> increase in tree defoliation-> tree stress/infection -> Dieback
Tested Solutions: 1. Fencing trees from cattle in pastures, plant additional trees& shrubs to encourage more birds -Problem-> Bell Minor bird domination, psyllid (plant louse) increase, and more dieback |
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Landscape connectivity (corridors)
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connections between patches in a landscape
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potential advantages of corridors
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-increase immigration rate to reserve (Increase richness, diversity, abundance)
-Provide increased foraging area -Provide predator escape cover for movement between patches -provide mix of habitats -provide alternative refuges from disturbance -provide greenbelts to limit urban sprawl |
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Potential disadvantages of corridors
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-increase immigration rate to reserve (diseases, pests, disrupt social organization)
-facilitate spread from fire & other disturbances -increase exposure of wildlife to hunters, poachers, and other predators -May not enhance dispersal or survival of upland species -cost -conflicts w/ land preservation strategies |
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Movement along corridors
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Assumption: corridors increase animal and plant movement between fragments of habitats
-ex:variegated fritillary butterfly- proved theory |
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Impacts of Oil & Gas Exploration
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-1% land use change in Canada- roads, seismic lines, oil & gas wells
-Caribou stay 1000m away from wells, 250m away from roads -reduced use of 22-48% of whole study area -major loss in caribou |
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Urban Greenway Planning
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-should comprise 40-70% of land in each new neighborhood in a coordinated way
-avoid clearing native habitats -preserve corridors& other connecting habitat routes -maintain environmental heterogeneity at landscape level -identify important microhabitats |
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Simple harvesting model for Fisheries
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S2= S1+R+G-M-F
S2=stock at end of year S1=stock at year start R=recruits G=growth M=natural mortality F=fishery mortality |
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Sigmoid Curve Theory
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Max yield is obtained from populations at less than max density
-keep population at half carrying capacity/ max population size |
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Four Principles of Exploitation
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1. Exploitation of a pop. decreases its abundance .. the greater the exploit, the smaller the pop becomes
2. Below a certain level, pops are resilient and compensate for removals by surviving or growing at increased rates 3. Exp. rates may be raised to a point where they cause extinction of a resource 4. Somewhere between no exploit and excessive exploit exists maximum sustainable yield |
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Case Study: Peruvian Anchovy
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READ IN TB
-Restricted to areas of upwelling -Big problem was collapse in recruitment in 1971.. -Strong El Nino |
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Match/Mismatch Hypothesis
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-Short period of maximum sensitivity to environmental factors
-Timing between spawning & food supply availability is crucial |
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Why overfishing?
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1. Economics of harvesting
-Discounting future returns -If total cost=total revenue..exceed max yield 2. Tragedy of the Commons -over-exploitation of a common resource 3. Ratchet Effect -The restrained ability of a human process to be reversed -Exploitation rates pushed toward collapse |
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Case Study: Northern Cod Fishery
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Errors:
1. Estimates of stock size were too high 2. Mortality rate grossly underestimated (discarded young cod) Casues: 1. Changed oceanic conditions -salinity, temp, increased predation by harp seal 2. over-fishing |
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Case Study: Antarctic Whaling
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-Most whales do not follow sigmoid curve model..
-Max sustainable yield occurs at 80% of equilibrium density -Blue whale commercially extinct by 1950's |
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Case Study: Rock Lobster Fishery
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-understood background history of species
-laws on them |
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Risk-Aversive Management Strategies for harvesting
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1. Impose constant percentage harvest on population
2. Harvest individuals above threshold population size 3. Impose protected "no-take" zones |
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Evolutionary Changes because of harvesting
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size-selection in fisheries can lead to evolutionary changes in the population
-snapper -1962 -21lbs -1985 - 7.2lbs -TODAY- 1lbs |
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Pest Control Strategies(5)
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-Natural Control
-Pesticide Suppression -Cultural Control -Biological Control -Integrated Control |
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Natural Control
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expose to naturally occurring predators, parasites, diseases, and competitors
-understand ecology of that organism |
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Pesticide Suppression
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treatment with various poisons to reduce abundance
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Cultural Control
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reduction by agricultural manipulation, or other land use manipulation
-ex: rotating crops, no dense monoculture, change topography |
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Biological control
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biological introductions of predators, parasites, diseases... genetic manipulations, pheromones
ex. myxomatosis |
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Integrated control
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combo of above.. minimize pesticide use, maximize natural control
-ex: yellow stone and wolves |
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DDT
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"In nature nothing exists alone"
-Rachel Carson -DDT affecting bird eggs -eggs very thing -would not survive to hatching -100% mortality -no longer used |
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Case Study: Prickly Pear Cactus
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-Spread rapidly across Australia in early 1900s
-The cactus moth, cactoblastis cactorum, was successful at eradicating the cactus -currently exists as stable metapop. at low density, maintained by moth grazing -why so successful? -no natural predators, fragmentation, CAM plant, gets a head start b/c it didn't coevolve w/native species |
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Case Study: Giant Water Fern
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-Forms thick mats (~1m) & covers lakes, canals, rivers,& irrigation channels
-cyrtobagous salviniae-weevil controls plants (1000 adults per m2) -story illustrates importance of proper taxonomy -incorrectly identified at first |
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Genetic Control of pests
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1. Agricultural crop plants can be bred or engineered to be resistant to certain "pest" species
-Breeding is indirect..when you find plants w/some level of resistance, keep those genes going in the population -Plants can be engineered to create their own "bio-pesticides" 2. Pest species can be genetically altered to reduce abundance- reproductive control |
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Reproductive control of pests
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1.Sterilization:
-sterilize by radiation/chemicals then release to mate w/ population -transgenic methods w/out reducing vigor 2. Immunocontraception -contraceptive vaccines delivered via bait or virus -(ZPG) facilitate sperm penetration of egg, major target for reproductive control |
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Integrated Pest Management
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Objective: minimize economic, environmental & health risks to humans
DIAGRAM |
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Case Study: Rice Blast Disease
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-Implemented an interplanting scheme (cultural control)
-Avoided other types of control -no monoculture -rice____rice____rice -successful IPM |
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Case Study: Alfalfa Weevil
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-consider life cycle of weevil
-determine appropriate action based upon larval abundance: ex: <1 per stem = no action -action includes larval sprays, parasite/predator intro, early cutting, planting of resistant varieties, adult sprays, burning etc. |
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Pitfalls and Generalizations about pests
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-bio control programs- max out at 3 years
-gambling w/timing, organism, and abundance -Major lack of ecological data, especially after intro... limited to: did it work? |
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Resource concentration hypothesis
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-why doe these pest outbreaks occur anyway?
-monocultures permit higher herbivore densities and more crop damage -co-evolved systems don't exist in this case -high levels of disturbance..low density |
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When Biological agents become pests
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mongoose-into hawaii to control rats in sugar cane fields.. also preys on birds/reptiles- extinctions
snail- intro for food in pacific & indian ocean island.. now eats 100's plant types & is being controlled by a new snail cane toad- lower abundance of cane beetle.. seasonal & daily timing differences, poisonous, so few predators |
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Conservation Biology
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-concerted with population decline and scarcity
-rarity should be just as important in ecology as abundance -what causes decline? -what can be done to remove threats to endangered populations? |
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Small population approach
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-Are there attributes to small populations that can help us figure out how to reduct their risk of extinction?
-extinction vortex |
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Declining Population Approach
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What are the endangered species of the future & how can we alleviate their decline
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Minimum Viable Populations
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-The population size that ensures population persistence for a specified time
-ex: endangered butterfly has 90% chance of surviving 100 years at population size of 100 -once a population is small, extinction can be caused by: -Demographic variability, genetic variability, environmental variability |
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Demographic variability
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fate of each individual is critical to population size
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Genetic variability
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can be lost by genetic drift-(loss of allele) or inbreeding(causes lose of vigor)
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environmental variability
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can have strong effect on birth/death rates
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inbreeding and fitness
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-inbreeding- mating of close relatives
-reduction of reproductive outputs -white-footed mouse -slight reduction of survival in lab -large reduction of survival in field (low body weight) |
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50/500 Rule
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-How small is small?
-Answered by pop. genetics studies -50: #of individuals needed to prevent inbreeding depression (&extinction vortex) -500: #of individuals needed to prevent genetic drift (change in allele frequency due to some random sampling) |
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Declining Populations
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-More "action-based" approach
-Downward trend is main concern -four causes of extinction in declining populations 1. Overkill 2. Habitat destruction& fragmentation 3. Introduced species 4. Chains of extinction |
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1. Overkill
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-Poaching of African Elephant for ivory continues to increase
-only reach sexual maturity after 10-11 years -single calf born every 3-9 years -slow population growth rate |
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2. Habitat Destruction& Fragmentation (woodpecker)
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-red-cockaded woodpecker endangered species now endemic to south-eastern US
-Adapted to pine savannahs& require cavities in old pine bushes -compete for existing cavities v. construct new ones -logging has significantly reduced cavity availability |
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2. Habitat Destruction& Fragmentation (Java)
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-Bogor Botanical Garden established in 1817 on 86 ha in west java
-Previously connected w/ eastern forested areas -has been increasingly isolated over past 60 years.. nearest forest is 5 km away -At least 20 bird species have disappeared since isolation |
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3. Introduced species
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-50% of mammal extinctions in past 200 years occurred in Australia
-Red fox as major cause of marsupial extinctions in Australia -prey hasn't evolved to run away |
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4. Chains of extinction
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-usually require special obligate relationships
-parasite & host -predator & prey -often occurs in tropical areas, rather than temperate or polar regions -more specific, more obligatory relationships, more organisms- more competition- more mutualistic relationships -ex: new Zealand eagle and Moa |
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Parks & Reserves
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objective of reserves:
1. Conserver specific animal/plant community by some kind of management/intervention 2. to allow system to exist in natural state w/out any management or intervention -Yellowstone not big enough to support MVP of grizzly bear (50/500) |
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Case Study: Furbish's Lousewort
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-small herb, once thought to be extinct
-found along st. john rover in maine -requires ecological disturbance, namely ice scour -too much-> reduces pop -too little-> competition w/neighbors intermediate disturbance hypothesis |
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Case Study: Northern Spotted Owl
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-each pair: 250-1000 ha of old-growth forest
-heavy login has destroyed most habitat -total population in pacific northwest is <1200 pairs -connection between land area needed & prey-base (more prey available =less space needed) ->80% of nests were in 300 year old trees& over 1.2 m in diameter |
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Problems with human impacts
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-pollution
-habitat destruction -natural resource exploitation -loss of biodiversity |
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Good impacts by humans
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-edge effects
-grazing -pine bush -generalists that benefit -plants in disturbed soils -algae levels |
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Current Patterns of population growth
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-Demographic transition model
-lower death rate- increased use of medical care -lower birth rate- contraceptive |
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Carrying Capacity of Earth
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-assumes food is limiting resource
-(ha land)(yield per ha)(kJ per crop unit)/ #kJ needed per person per year -food is not the only limiting factor |
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Ecological Footprint
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-calculate aggregate land & water in various ecosystem categories that is appropriated by that nation to produce all resources it consumes & to absorb all waste it generates
-6 types of ecologically productive areas: -arable land, pasture, forest, ocean, built-up land, fossil energy land |
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Global water cycle
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-use 26% evapotranspiration & 54% of freshwater runoff
-must increase efficiency of water use, reduce amount of water used for irrigation, & address availability of clean water use |
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Plant Community Response to Rising CO2
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-NPP has increased over time throughout all ecosystem types
-Biomass change |
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Climate change
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-Greenhouse effect
-earths atmos traps heat near surface -water vapor, CO2, & other trace gases absorb longer, infrared wavelengths emitted by earth -increase in greenhouse gases warms Earth by "re-radiation" -other gases of importance -methane, nitrous oxide, ozone, CFCs |
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Changes in Land Use bc of global warming
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-conversion of land from forest to agriculture leads to large increase in CO2 emissions
-an increase in forest cover serves as sink for carbon |
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Species Range (Climate Change)
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-climate change leads to geographical range shift
-speed of climate change is much greater than in past -land use has disrupted corridors |
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Biosphere Services
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ex:-purification of air& H2O-generation & preservation of soils-pollination of crops/veggies-nutrient cycling
-dollar amount: $33 trillion/year-Fail of biosphere 2 project |
