part one principles for understanding our environment
TRANSCRIPT
AP ExamPart One Principles for Understanding
Our Environment
Orderly change of species in an ecosystem over time
Primary succession occurs when an area is newly exposed and has previously not had a biological community. The area lacks soil.◦ Cooled volcanic lava or a boulder rock slide
Secondary succession is more rapid b/c soil is already there.◦ Burned field
Climax community
Succession
Carbon cycle◦ Carbon sink-absorbs carbon (ocean, atm,etc)
Nitrogen cycle◦ nitrogen fixation, nitrification, assimilation,
ammonification, denitrification Phosphorus Cycle Sulfur Cycle Water Cycle
Cycles
Nitrogen fixationThe process of converting inorganic, molecular nitrogen in the atmosphere (N2)to ammonia. In nature it is carried out by a few species of bacteria, on which all life depends.
NitrificationThe process of oxidizing ammonia to nitrites (NO2
-) which are harmful to plants and then into nitrates (NO3
-) which are beneficial.
DenitrificationThe process of releasing fixed nitrogen back to molecular nitrogen (N2).
AssimilationThe process by which plants take in nitrates through their root hairs.
AmmonificationThe process of breaking down nitrogenous wastes and organic matter found in animal waste and dead plants and animals and converting into ammonia (NH3) for absorption by plants as ammonium ions. Therefore, decomposition rates affect the level of nutrients available to plants.
Human interventions◦ Ground and surface water depletion◦ Ground and surface water pollution◦ The clearing of vegetation, particularly in
temperate and tropical rainforests, interferes with the cycle by decreasing transpiration
Hydrologic cycle is powered by the sun and gravity
Water Cycle
Since the industrial revolution, we have dramatically increased the CO2 in our atm due to:◦ Deforestation, which decreases the plants available
for photosynthesis, thus decreasing CO2 uptake◦ Forest burning and returning the carbon in the
biomass of the forest to the atm by releasing it from the sink
◦ Increased combustion of fossil fuels, releasing carbon from the sink
Carbon Cycle
Some bacteria are capable of breaking the triple bond of nitrogen gas
Human Intervention◦ NO is released when fossil fuels are combusted.◦ NO forms nitric acid in atm making acid deposition◦ N2O gas is a greenhouse gas, from livestock waste
and commercial fertilizer◦ Nitrogen starts eutrophication when added to
water
Nitrogen
Very slow b/c there is no atm stage. Nearly all is in rocks or living organisms, b/c
ions do not dissolve well in water Human Intervention
◦ Phophate mines that form large pits can result in runoff pollution
◦ Removing vegetation lowers phosphorus availability
◦ Phosphorus addition can lead to eutrophication
Phosphorus
Most sulfur found as iron disufide (pyrite) or as mineral salt: calcium sulfate (gypsum)
Released by weathering and volcanic activity
Human Intervention◦ Fossil fuel combustion, especially coal◦ Refining of petroleum and smelting◦ Coal mining damages aquatic ecosystems◦ Large amounts of sulfur dioxide and sulfate
aerosols cool the atmosphere b/c they prevent UV radiation
Sulfur
Law of tolerance: bell curve Symbiosis
◦ Mutualism: lichen (fungus and algae/cyanobacteria)◦ Parasitism: ticks, fleas◦ Commensalism: barnacles on a whale
Keystone species: abundance does not reflect importance- ie. Top predators
Vocab/concepts
Anthropogenic◦ From man
Biocentric Environmental Justice Intrinsic value Negative feedback loops
◦ Considered good Positive feedback loops
◦ Considered bad
Vocab
Pyramid of biomass- the mass of living matter at each level
Pyramid of energy- how much energy is passed on at each trophic level◦ Reasons for lost energy
Can’t digest May use more energy to catch food Consumer may not eat entire killed organism Loss to thermal energy Average transfer is 10% range is about 80-95%
Pyramid of numbers -how many individuals at each trophic level◦ Can be inverted if a few trees supporting lots of
insects and birds
Pyramids
Diffuse energy is considered low quality (ocean)
Concentrated energy is high quality (coal) Potential energy is stored energy in food,
etc A calorie is the amount of energy needed to
increase the temperature of 1 g of water 1°C
One calorie = 4.184 J (joules)
Energy
The study of energy conversion The first law- Law of Conservation of Energy
◦ Energy can neither be created not destroyed; it can only change from one form to another
The second law of Thermodynamics◦ With each energy conversion in a closed system,
the energy change proceeds toward entropy◦ Disorganization is favored in nature
Stack of soda can example
Thermodynamics
Individual Species: group that reproduce fertile
offspring Population: a single species in an area Community: group of interacting
populations Ecosystem includes biotic and abiotic
factors Biosphere
Ecosystem Hierarchy
Coevolution: selective pressures on each other Selective pressures include:
◦ Physiological stress, predation, competition and chance
Divergent Evolution◦ Adaptive radiation- Galapagos finches
Convergent Evolution◦ Lacks recent ancestor but develop similar features
ie. Wings on a bird and wings on an insect Competitive exclusion: two organisms cannot
occupy the same niche for an indefinite period with out one eventually migrating, dying or undergoing resource partitioning.
Evolution
Tropics between 23°N and 23°S Temperate between tropics and Polar Polar region starts at 66°N or 66°S Two most important aspects of climate are
precipitation and temperature Temperature cools as you move away from
the equator Altitude affects the biome-vertical zonation
Biomes
Stationary, so adapted for weather Succulents store water in stem Stems might need to photosynthesize
(spines) Broadleaf evergreens keep their leaves all
year (live oak) Broadleaf deciduous-expend lots of energy to
grow back leaves in the spring Conifers-most evergreens, needles decrease
water loss Allelopathy- plants secrete toxins into soil
Plants
Freshwater Biomes◦ Rivers, streams, lakes, ponds and all inland
wetlands including swamps, bogs, marshes and fens
Marine Biomes◦ Coral reefs, coastal marshes and swamps,
estuaries, barrier islands and the open ocean
Aquatic Biomes
Plankton: float or swim weakly◦ Phytoplankton: cyanobacteria and algae◦ Zooplankton: herbivores and carnivores
Nekton: swim and are consumers◦ Sharks, tuna, bass and perch
Benthic: live on the bottom◦ Often decomposers or detritovores
Aquatic Organisms
Nutrients Dissolved oxygen Temperature depth Turbidity
Aquatic Limiting Factors
Equivalent to tropical rainforest Shallow, clear, warm water Mutualistic relationship between a
carnivorous cnidarians and an autotrophic alga
The coral polyps protect the algae within its tissues, algae provide food
Coral secrete shell of calcium carbonate Reefs sensitive to pH change and increases in
turbidity
Coral Reefs
Tropical trees that grow along coastlines They function to catch sediment, remove
nutrients, and serve to protect coastlines by preventing erosion
Large biodiversity Serve as nurseries and nesting areas Fallen leaves provide food for detritovores Humans threaten mangroves by:
◦ Use wood for lumber and charcoal◦ Aquacluture - raise saltwater species◦ Urbaninzation and coastline development
Mangrove Swamps
Where freshwater empties into salt water Varying levels of salinity=brackish water Tremendous biodiversity Nutrient rich, turbid, large amounts of sediment Flowing water may contain numerous
pollutants-oil, nitrogen, phosphorus + fecal High NPP and serves as a nursery for shrimp,
oysters, clams and numerous nekton species Humans interventions include
◦ -recreation, fishing and aquaculture and development
Estuaries
Exponential Growth- J shaped curve◦ Growth without restrictions◦ r(N)=ΔN/ Δt [r=growth rate, N= number, t= time]◦ Same as biotic potential
Logistic Growth- S shaped curve◦ Carrying capacity(K): max pop that can be
sustained indefinitely. It is not fixed. Changes by season.
◦ ΔN/ Δt=rN(1-N/K) Rule of 70
◦ Doubling time = 70/r
Population Biology
Resistance increases with population Density dependent factors
◦ Disease, competition, predation and parasitism, territoriality, increased stress and aggression, decreased immunity and fertility
Density Independent factors◦ Floods, fires, hurricanes, human-induced
disruption Dispersion
◦ Clumped, uniform, random
Environmental Resistance
Selected strategists
R-selected K-selected
Short life Rapid growth Early maturity Many small offspring Little parental care Little investment in individual
offspring Adapted to unstable environment Pioneers, colonizers Niche generalists Prey Regulated mainly by extrinsic
factors Low trophic level
Long life Slower growth Later maturity Fewer large offspring High parental care High investment in individual
offspring Adapted to stable environment Later stages of succession Niche specialists Predators Regulated mainly by extrinsic
factors High-trophic level
Natality-production of new individuals by birth, hatching, germination or cloning
Fecundity-physical ability to reproduce Fertility-is a measure of the number of offspring produced
by a female Mortality- number that die in a particular time frame
divided by the number living at the beginning of the time frame
Survivorship-proportion in a population that survive to a particular age.
Life expectancy-probable number of years of survival for an individual of a certain age
Life span- longest period of life reached by a given organism
Survivorship
Late-loss curve: more deaths in older organisms◦ Top consumers and K strategists
Constant-loss curve: death equal in all ages◦ Sea gulls, rodents, and some plants
Early-loss curve: probability of survival increases as these organisms age◦ Turtles and redwood trees
Type IV curve: early life mortality, which levels then rises again later◦ Deer and crabs
Survivorship curves