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67 Cards in this Set
- Front
- Back
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Ecosystem
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The biotic community and its abiotic environment functioning as a system
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Energy transformations
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Solar energy (photosynthesis) -> Plant Production -> Carnivores
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Nutrient Cycling
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CO2->C6H12O6->Hemoglobin->CO2
abiotic to biotic to abiotic |
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Energy flows through ecosystems one way
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Energy enters as light from sun, photosynthesis and chemosynthesis (Primary Producers) leaves as heat or is consumed by (Secondary Producers) leaves as heat or death eaten by (Detritivores) leaves as heat
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1st Law of Thermodynamics
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Energy is neither created or destroyed
-Can transfer energy from one form to another and move it all around, but you can't make it from scratch |
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2nd Law of Thermodynamics
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Whenever energy is transferred or transformed, some of it assumes a form that cannot pass on further
-Ecological corollary: No energy transformation is 100% efficient; energy will be lost as heat |
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A.G. Tansley
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Promoted the view of communities as associations not independant of the physical factors of the environment; coined the term ecosystem
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Charles Elton
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Focused on feeding relationships among community members
-More # of plants, less herivores, less carnovires (less and less Biomass) |
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Raymond Lindeman
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Trophic-dynamic system
-Energy less available to higher trophic, B/C of deficency at low levels |
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E.P. Odum
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Promoted energy as the common currency for ecosystem structure and function
-Assimilated, stored, loss as heat |
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Gross Primary Production (GGP)
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The total energy assimilated by plants
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Net Primary Production (NPP)
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The rate of energy storage after respirational losses
-Measured as unit/area/time |
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Autotroph
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Make own energy
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Heterotroph
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Obtain energy else where
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Two methods to measure primary production
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1. Carbon Dioxide Flux
2. Satellite Imagery |
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Carbon Dioxide Flux
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-CO2 very limiting
-Plants uptake CO2 -CO2 Loss in an isolated chamber containing photosynthetically active plant tissue is due to plant uptake (aka: Production) -Measured as unit/area/time |
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Satellite Imagery
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-Plant tissue reflects light differently than bare ground
-Reflectance is directly related to leaf area index or chorophyll concentration |
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Geographic Distribution of Primary Production
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East more productive because of rainshadows in west
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Secondary Production
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-Energy of heterotrophs, which, after allocation to maintenance and respiration, is used for growth and reproduction
-1st maintain homeostatis -2nd what energy is left will go towards efficency and deficency |
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Energy Ingested
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Energy Ingested
v v Energy is Energy egested Assimilated as waste Into Body products v v Respiration 2ndardy Prod. (Heat loss) (New biomass) (Weight Gain) |
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Assimilation Efficiency
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Efficiency at getting E out of Food
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Growth Efficiency
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Efficiency of converting ingested E into new biomass
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Eltonian pyramid of production
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1. Producers 10,000 K/cal
2. Primary Consumers 1,000 3. Secondary Consumers 100 4. Tertiary Consumers 10 -Energy associated is rapidly diminishing |
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Length of food chains limited by ecological efficiency
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-Ecological efficiency (consumer production/prey production), influenced by:
-Assimilation Effiency -Growth Efficiency -Exploitation Efficiency-the efficiency with which the biological production of an entire trophic level is consumed by a higher trophic level E.G.-Ingestion of prey/prey production |
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Food availability to humans at different trophic levels
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1. Human Vegtarians-primary consumers
2. Human Meat-Eaters-secondary consumers |
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Decomposers break down....
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Mineralize-organic matter, making nutrients available to plants for uptake (some nutrients remain unavailable, are immobilized-by being taken up by the decomposers)
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Some nutrients are leached, or...
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lost, from the system into the groundwater, or runoff
-without decomposers we would all be in trouble |
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Decomposer food webs
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Terrestial and aquatic systems have complex decomposer food webs, with a variety of different kinds of organisms ranging from microscopic, to small visible animals and fungi, to larger organisms
examples: -Springtails- an insect -Soil mite from Australia -Nematode |
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How many species
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Approximately 1.4 million species, not distributed evenly across taxa, most life on planet is insects
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Diversity is associated with what?
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Latitude
-decrease in latitude increase inspecies -Increase in latitude decrease in species -High diversity even in marine systems at lower latitudes |
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Biogeography
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The study of past and present spatial distributions of organisms
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What might explain biogeographic pattrens?
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-Species-area relationships
-island biogeography -Niche -Spatial Heterogeneity-how similar in space -Evolutionary speed-how rapid speciation occurs -Time-how constant have things been -Productivity |
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Species-area relationship
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Species richness increases with habitat size
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Niche Theory
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a) Original condition-all similar in niche breath
b)Increased resource diversity- add resource niche identical c)Increased ecological overlap-Tolerance broaden niche breath, increase overlap in use of resources (smalles pop size) d)Increased specialization-More species in community if species specialize (largest pop size) |
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Competition between temperate and tropics
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Tropics: much less seasonality, longer growing season, and more resources available
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Pollinator Theory
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Temperate: High wind/Less pollinators
Tropics: Low wind/More pollinators |
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Predator Theory
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Temperate: Fewer predators and parasites leads to high herbivore densities: Low richness.
Tropics: More predators and parasites leads to low herbivore densities: high richness |
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Janzen-Connell Hypothesis
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-Predator of seeds
-Seeds larger in tropics but wind doesn't disperse them -Seed predator-seeds under tree more likely to die b/c of pathogens and predators |
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Niche Theory
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a) Original condition-all similar in niche breath
b)Increased resource diversity- add resource niche identical c)Increased ecological overlap-Tolerance broaden niche breath, increase overlap in use of resources (smalles pop size) d)Increased specialization-More species in community if species specialize (largest pop size) |
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Competition between temperate and tropics
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Tropics: much less seasonality, longer growing season, and more resources available
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Pollinator Theory
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Temperate: High wind/Less pollinators
Tropics: Low wind/More pollinators |
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Predator Theory
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Temperate: Fewer predators and parasites leads to high herbivore densities: Low richness.
Tropics: More predators and parasites leads to low herbivore densities: high richness |
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Janzen-Connell Hypothesis
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-Predator of seeds
-Seeds larger in tropics but wind doesn't disperse them -Seed predator-seeds under tree more likely to die b/c of pathogens and predators |
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Are species more rapidly produced in the tropics?
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Temperate: Speciation slow, little energy from sun, slow generation times, slow maturation rates
Tropics:Speciation fast, abundant sunlight energy, fast generation times, high mutation rates |
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Expectations and Support
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-Species/Genus ratios-if rapid speciation is occuring, then more species per genus in Tropics
-In fact, diversity seen more at the family level in tropics- temperate genus sometimes more species rich -phylogenetic support |
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Time Theory
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Tropical regions have experienced less large scale disturbances, greater time for species diversification
-30 million years ago, Tropics expanded as far north as Canada -Tropical regions experienced expanison and contraction of pluvial regions, conditions weren't constant, water fall was heterogeneous |
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Productivity Theory
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Temperate: Low Temp and rain/ Low productivity = Low richness
Tropics: High temperature and rain, High productivity = high richness |
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Reconciliation and Synthesis
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Local/Deterministic
-Niche -Competition -Predation (equilibrium thinking) Regional/Historical -Time -Fossil/phylogeny -Geography (disturbance/disequilibruim thinking) |
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Some common players in decomposer food webs
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-Largest-scavenger animals (hyenas, vultures; also insects like maggots
-Dung beetles hold a unique place of honor -Intermediate scale-earthworms, termites: consume and alter OM, decompose wood -Smallest multicellular animals insects and arachnids (microarthropods) |
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More common soil animals
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-Collembola (springtails) eat fungi
-Mites (arachnids) consume litter, fungi, bacteria -Nematodes- herbivores that eat living and dead plant roots, carnivores that eat soil animals, also eat bacteria and fungi-hugely abundant and diverse |
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Most critical and important soil decomposers
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-Fungi-break down non-living plant organic matter for energy and carbon
-Bacteria- break down living and dead cells of plant, animals, fungi and other bacteria; responsible for major nutrient cycling in soils |
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Rates of Decomposition vary with:
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1. Temperature
2. Availability of oxygen and moisture 3. Quality or chemical composition, of material being decomposed |
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Community Structure
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1. Spatial pattern or arrangement
2. How many species are present 3. Relative abundance of those species 4. The relationship to physical features of the environment 5. The result of ecological interactions that affect species prescence and/or abundance |
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Diversity
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How many species are present and in what relative abundance
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Species Richness
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Species are present in a given area
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Evenness
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How close to equal they are in abundance
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Dominance
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the degree to which species control resources(reverse of evenness)
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Niches
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describes the role of a species in a community
-species role incorporates ability and manner of resource utilization -niche availability may control diversity and/or species relative abundance |
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Models to predict species relative abundance
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-geometric series or niche preemption model
-each successive species utilizes a constant fraction of available resources -suggests highs similarity in species ability to use availiable resources |
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Random Niche Model aka Broken stick
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-Species abundance is determined by size of resultant units
-Segements are sorted and plotted by rank -represents small communities |
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Lognormal distribution
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-Few very abundant species
-Most species with small population sizes -has been observed for a wide variety of organisms ranging from trees to diatoms |
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The spatial pattern or arrangement
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-Vertical Stratification
-Horizontal one -Horizontal two |
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Vertical stratification
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-Biological strata in forests
-physical strata in aquatic communities More that it varies vertically more ability to be diverse |
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Horizontal Stratification 1
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Latitudinal gradients of climate
Ecological question: why are there more species of birds/plants in the tropics |
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Horizontal Stratification 2
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Elevation gradients of moisture in wetlands
Ecological question: How does elevation affect plant distribution in a tidal salt marsh |
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Keystone Species
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those that influence community characteristics like diversity much more than you would predict from their abundance
-dominants are differ than keystone species because they have great influence on the community but are also very abundant |
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Succession-changes in community structure over time
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Autogenic, Allogenic, Primary Succession, Secondary Succesion,
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