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76 Cards in this Set
- Front
- Back
Connel - Slayter models of succession
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1)Facilitation: linear seral stages; each stage allows the next to form (shrub -> aspen -> lodgpole) ending in climax.
2)Tolerance: No set order, but eventually most tolerant species are established as climax 3)Inhibition: Random who returns and whoever gets there first prevents others from colonizing. Stages last until that each stage dies. |
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Types of Succession
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-Primary: From nothing (ie glacial retreat or volcanic eruption) and must create soil
-Secondary: Comes from something (fire or abandoned farmland), have soil and probably a seed bank |
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Community
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A group of interacting species that occur together in the time and space. (Puddle to a coral reef)
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Community Characteristics
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-Species diversity
-Relative abundance -Dominance -Succession -Spatial scale variation (local v global) |
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Difference b/t Ecosystem and Community
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Ecosystem includes the abiotic factors influencing the community.
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Ex of succession in Glacier Bay
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Have all models: Early its facilitation to provide soil, alder inhibits and spruce is most tolerant
Over time changes to environment: 1)Incr in soil depth, N content, organic matter 2)Decrease is soil pH 3)Increase in moisture |
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Ex of Succession
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1)Glacier Bay: Primary, Facilitation by pioneer mosses, alder inhibits, and spruce is most tolerant.
2)Sand Dunes: primary, facilitation b/c need grass to start, tolerance b/c conditions determine end community. (wet=prairie or maple swamp, dry=oaks, wet/nutrient rich=hemlock forest) 3)Old-Field: Secondary, facilitation up to large trees then cycle w/in climax. (Inhibition b/c different species combinations change community). 4)Mt. St. Helens: Both primary (where lava and pumice) and secondary (blowdown /scorch zones), lupin facilitated by N-fixing. |
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Climax Community
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A stable end point that experiences little change unless hit with intense disturbance.
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4 types of climax communities
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1)Monoclimax: Each set of environmental conditions gets one endpoint.
2)Gradient Pattern: Variation of climax along a gradient 3)Shifting-Mosaic: Always little pockets of disturbance (eg tree fall) 4)Cyclic pattern: Climax rotates between a few different species w/ minor disturbance. |
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Species diversity and ways to calculate?
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Species richness (#) and species evenness (distribution)
1)Shannon index: H = -∑(pi*ln(pi)) 2)Simpson index: D = 1 - ∑(pi)^2 (D ranges from 0 to 1-(1/s)) where pi = proportion of a species # ind of species / # total individuals s = # of species larger H or D = greater diversity |
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Calculating equitability
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== H/Hmax
where H is the Shannon index H mas is if have perfectly even distribution, so each species is the same proportion of the total number of individuals. (therefore max diversity) |
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Species richness
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Number of species within a set. How many are there compared to individuals of other species.
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General Conclusions from Succession
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1)Late successional community is different from the early one. (Different life histories in particular)
2)Most communities have a typical late stage (climax) 3)Must understand succession to manage communities |
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Levels of species diversity and why impt?
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-Gamma: diversity at regional level
-Beta: Change in diversity as one moves from one community to another. (called turnover) -Alpha: Species diversity at local/community level Important b/c diversity can very tremendously based on the area measured. --plotting local (alpha) against regional (gamma) on x axis tells which is relatively more important-- m=1 means equal, m<1, but sloping up means regional processes dominate, m<1 and levels off means local processes dominate |
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MacArthur and Wilson's model predictions
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1)Larger the island = greater the # of species
2)Equilibrium # maintained by turnover 3)Immigration decr w/ distance from mainland 4)Smaller the island the higher the extinction rate •Draw graph of extinction and immigration based on distance and size p381 |
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MacArthur and Wilson's model strengths and weaknesses
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•Strengths:
--Simple so good for baseline comparisons --Stimulated many studies •Weaknesses --Ignores abiotic factors of island --All species counted as equal --Ignores evolution --No species interaction considered --Ignores migrants and non-reproducing species |
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Implications of biogeography for reserve design
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1)Area should be circular to reduce edge effects
2)Area should be larger to reduce edge effects 3)Areas should be connected by corridors 4)Avoid fragmentation (ex: road affect) 5)Corea area w/ buffer --Neutral on SLOSS debate (single large or several small) --Lovejoy did a big study = found need large area |
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Explanations of global species diversity?
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1)Continental Drift: Continents separated and evolution diverged (vicariance)
2)Abiotic factors: ---Greater divergence in larger homogenous areas (larger pops) ---Greater divergence w/ longer evolutionary time (no glaciers) ---Greater divergence when warmer, wetter, more nutrients (more NPP) 3)Biotic: ---Other organisms create homogenous landscape (trees) ---Less human development ---Greater div w/ more competition and predation |
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Global patterns of species distribution
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1)More species in tropics and temperate
2)More species w/ more varied terrain (W over E US) |
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Why concerned abt species extinction in tropical ecosystems?
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1)>2/3 of world's species
2)inherent value 3)aesthetic value 4)Pharmaceuticals 5)Timber 6)Climate Services |
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Factors influencing species diversity at local scale? (Out of regional pool)
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-Determined by what species of regional pool live in the local community:
1)Can disperse there? 2)Can survive abiotic factors? 3)Can interact successfully? (coexist) --Coexist by partitioning resources (warbler tree space) or by using resources in different ratios (diatom experiment) |
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Processes that promote coexistence?
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1)Variable conditions (why so many plankton survive in lakes)
2)Intermediate disturbance (algae on boulder) 3)Competition (dynamic equil model is comp w/ disturbance, get highest div w/ both low) 4)Predation (Menge-Sutherland model = add predation to dyn equil) 5)Variable recruitment after disturbance (Lottery Model) -- different species win each time have a minor/intermediate distrubance |
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Disturbance
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An abiotic event that kills/damages some individuals and thereby creates opportunities for other individuals.
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Hysteresis
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Community is changed to a different stable state and won't go back to original.
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Measuring and types of disturbance?
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-Intensity (amount of damage /death) and frequency
-Transient or persistent change --Persistent if change stable state |
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Relationship b/t diversity and stability
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Greater species richness is the greater the community stability (tendency to remain in same structure and function) to a point.
--curve up to right then lvls off p403 |
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Hypothesis about diversity and function (why positively correlated)
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•Graphs: p404
1)Complementarity: Each species has an equal affect on function 2)Redundancy: At a threshold incr species richness no longer increases function 3)Drive and passenger: Certain driver species have a larger effect when added 4)Driver and passenger w/ overlap: Adds a threshold |
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Measures of recovery from disturbance
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Resistance: How stable a community is (ex higher in forests)
Resilience: Time to recover (ex higher in prairie) |
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Primary production (measures and descriptions)
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•Organisms to introduce E to the food web by fixing carbon (photosynthesis or chemsynthesis)
•Descriptions: 1)GPP = total E produced (AKA productivity) 2)NPP = E left after respiration (AKA biomass in mass/area) 3)Efficiency (NPP/GPP) ranges 30-85% •Measure in mass of carbon/unit area/yr 1)Harvest method: collect biomass at end of growing season -----via dimensional analysis where cut down a few and use a ratio for rest of biomass 2)chlorophyll count 3)CO2 flux in closed system 4)Eddy covariance: ∆ in CO2 in and above canopy at night&day 5)Radioactive CO2 isotopes-- particularly in aquatic systems 6)Light/dark bottle method: Final O2 in light vs dark tells GPP, final vs initial in light tells NPP, final vs initial in dark tells resp 7)Remote sensing •NPP peaks awhile after disturbance |
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Shoot: Root ratio of tundra and forest
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1:2 = tundra
1:0.5= forest 1:0.2 = rain forest |
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Nutrient Limits to PP
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Aquatic: N or ratio of N:P (increases in areas of upwelling)
Terrestrial: N and P limits; also incr w/ annual precipitation so water limits; incr w/ mean annual temp |
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Bioaccumulation / Biomagnification
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-Bioaccu: increase in concentration in PP as pollutant is absorbed and stored in fatty tissue
-Biomag: increase in [pol] as go up food chain |
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Relative comparisons of ecosystems (NPP, species div, PP structure)
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Look at sheet from 1st unit
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Trophic cascades and examples
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•Series of opposite reaction as move along a food web
1)Bottom-up: Control by abundance of lower lvl (ie limited resource) 2)Top-down: Wolves in yellowstone or sharks in reefs decr meso predators which increases herbivors and decr PP |
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Why ∆ in NPP efficiency?
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With warmer climate more E used in respiration so decr efficiency. Higher in temperate
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Ectotherm and endotherm assimilation and net production efficiency?
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•Assimilation = metabolizable E in system (w/o fecal and urinary waste)
•Prod eff = finally used to grow / reproduce (w/o respiration) Assimilation eff: (assimilation/ingestion) - high in endotherms Production eff: (net production/ assimilation) - high in ectotherms 9-50% and low in endotherms 1-3% |
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NPP by aquatic and terrestrial ecosystems
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54% aquatic and 46% terrestrial
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Relative NPP consumed in different ecosystems? (Efficiency)
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13% in terrestrial
35% in aquatic -> phytoplankton are easier to consume and digest; C:nutrient ratio is closer to that of herbivore |
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trophic efficiency
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•E @ a trophic lvl / E @ one lvl lower
-Ranges fron 2-20% |
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Biomass/number pyramids vs. E pyramids
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-E is always a broad base and decreasing as one goes up the pyramid
-Biomass is normal on land and inverted in ocean, b/c plankton are eaten so fast that they never accumulate |
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Sources of E in an ecosystem
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Autochtononous: E from w/in eco
Allochthonous: E from outside eco (detritus into stream) |
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Factors determining # of trophic lvls and some examples of #?
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1)Size -> bigger = more niches and more lvls
2)Efficiency --> less energy lost = more available for upper lvls 3)Frequency of disturbance 4)Total amount of E available •Ocean ~ 7lvls •Coastal marine ~5 •Grassland ~4 •Tropic forest ~3lvls |
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Why does most NPP go to detritus?
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1)Parts of producers are hard to digest / low nutrition / hard to reach
2)Predation keeps herbivore #'s down 3)2˚ Compound make producer poisonous |
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4 Basic Nutrient Cycles
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1)Carbon (Global gaseous)
---Photosynthesis binds CO2 in sugars ---Respiration rel CO2 ---Carbon sinks: fossil fuels, oceans, soil 2)Nitrogen (Global gaseous) --Cyanobacteria and lightening fix N2 to NH3/NH4+ --Nitrification by bacteria turns NH4+ to NO3- --Ammonification releases NH4+ from detritus --Plants uptake NO3- and NH4+ and denitrify to N2 3)Phosphorus (Local sedimentary) --Weathering introduces new P --marine sediments are a sink --cycles b/t organism and soil 4)Sulfur (Local sedimentary) --Weathering and volcanoes release new S --decomposition releases back into soil --ocean aerosol sprays introd to atmosphere |
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Interactions among trophic lvls
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-Direct (predation) or indirect (competition or cascades)
-Strong or weak |
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Human effects on 4 key nutrient cycles?
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1)Deforestation
-Increased run-off of C,N, and P -Red Carbon sink in forests 2)Agriculture -Fertilizer introduces extra N and P -Crops replace forest and sink less C -Aminals release greenhouse gasses (CO2) 3)Industry -mining and buring of fossil fuels released S into atmosphere (incr by 160%) -Burning fossil fuels releases CO2 into atmosphere 4)Urbanization -Autoexhaust releases CO2 and P -None point source pollution increases N and P (lawns/sewage) |
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Residence times in diff ecosystems?
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-100-400 yrs in boreal forest vs 0.4 to 2yrs in tropics.
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Availability of N at succession stages?
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-lots of nut lost after disturbance
-intermediate stage has lowest lvl lost -N limits when young -P limits in older ecosystems |
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What did Hubbard Brook show us?
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-in intact ecosystem nut in/out is small compared to amnt stored in biomass
-nut loss ∆ed with average stream flow, but no net loss in long run -disturbance tends to help recycle nutrient (rodents or fire) -Introd. species can ∆ nutrient availability |
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Nutrient cycling?
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•Decompostion makes the N and P from detritus available. In steps:
1)Fragmentation: Litter into smaller pieces w/ higher SA:V 2)Mineralization: Bact. and fungi convert organic macromolecules to soluble nutrients |
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Limiting nutrients in different ecosystems?
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Usually N or P though water can.
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Soil properties influencing availability of nutrients?
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-All formed from parent rock w/ varying amounts of nutrients
-Leaching creates soil layers. -Texture: sand>silt>clay -Clays have weak neg charge and therefore hold K,Ca,Mg = cation exchange capacity |
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Sources of nutrients
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-Nutrients originate from weathering, decomposition, and the atmosphere.
-Decomp faster where warmer and wetter so more nut available in soil |
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Conservation Biology and characteristics
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Applied science of maintaining biological diversity. Different b/c attempts to make recommendations.
1)Crisis discipline 2)Multidisciplinary 3)Studies dynamic systems 4)Mission oriented 5)Uses evolutionary scale 6)Long-term vigilance |
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Goals of Conservation bio
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1)Document Biodiversity
2)Investigate Human impact 3)Prevent extinction 4)maintain/restore communities |
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# species on earth?
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-1.6million described
-estimate of 3-30million species |
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Main conservation biology organizations?
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Society for Conservation Biology - 1985
Nature Conservancy - 1951 Ecological Society - 1915 - Publishes Ecology |
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Famous extinctions
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1)Dodo in 1680
2)Passenger Pigeon - 1914 |
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What species groups are most endangered/ threatened?
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Lichens, Fungi, amphibians, and plants were most threatened w/ 70-100% of those species evaluated being imperiled.
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Primary Threats to biodiversity?
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1)Habitat loss
2)Invasive species 3)Overexploitation 4)Disease 5)Climate change 6)Pollution |
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What info need to know to know what to protect?
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Rate of biodiversity decrease.
-Use Al Gentry's Rapid Assessment Program where count all stems in a series of transects. ---W/ this can compare ecosystems Genetic Diversity -The lower it is in a population the more susceptible to genetic drift. PVA's = population viability analysis --Demographic models that predict the future status of a species |
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Bird and mammal extinction rate
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Background: 1/200yrs
Current: 1/1yr = 200x background rate |
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Pos and neg of ex situ conservation?
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When move species to a zoo to preserve.
-Ex: Black footed ferret, condor Pos: can save species on verge of extinction, incr publicity Neg: Costs a lot and takes lots of logistical work, can change behavior, can expose to disease |
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Types of Conservation species?
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1)Surrogates species: Protecting that one serves to protect a general area and therefore many other species (red-cockaded woodpecker)
2)Flagship species = charismatic animals that garner public support (panda) 3)Umbrella species = Selected so its habitat can serve as an umbrella to protect other species w/ similar habitats, more targeted than just surrogate (Grizzly or other species w/ large area requirements) |
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Adaptive management?
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A data based management system with clear goals, in which the managers are constantly studying, adapting their techniques.
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Seven forms of rarity?
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1-restricted geographic range
2-narrow habitat tolerance 3-small local pop 4-Rest range and narr habitat tolerance 5-rest range and small pop 6-Narrow tolerance and small pop 7-All three |
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Landscape ecology?
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Study of relationship between spatial patterns and ecological processes over ranges of scale
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Important features of habitat fragments?
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1)Shape: more circular the better, b/c has less edge
2)Size: anything less than 30a is all edge |
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Controversial vs. well-documented aspects of global climate change?
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Well known:
1-CO2 is increasing 2-Temperature has increased Controversial: 1-range of future increase will be 2-4˚C 2-Amount of range shifts and extinction that will occur |
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Why is repair of ozone considered a success story?
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•Volatile C compounds like CFC's were banned w/ Montreal Protocol in 1987 and now the hole is shrinking.
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Environmental affects of agriculture?
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1)Expansion: incr in greenhouse gasses, decr in C storage, and reduction of biodiversity
2)Intensification: Increase in water use and runoff |
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Strategies to sustainably increase food production?
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1)Continue to research types resistant to herbivores and pathogens, w/ resistance to abiotic stress, and w/ increased nutrient content
2)Change eating habits to more poultry and vegetarian 3)Increase productivity via closing the yield gap and not expanding range (what's left is marginal) |
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What affects decomposition rate?
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1)Temperature
2)Moisture content 3)Lignin content |
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Interpreting variance to mean ratio?
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1 = randomly spaced
<1 = even spacing >1 = clumping •That is mean density/ variance of mean density |
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Abiotic factors to determine health of a community?
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1)Direct effects
--Temperatrue --pH --wind 2)Resources --Light --soil moisture (other water measures) --nutrient (soil organic content, nitrates, phosphates, oxygen in water) |
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Why study phenology?
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Study of the timing of life cycle events. Useful for agriculture, climate research, and resource management.
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