ecology
study of how organisms interact with one another and with their nonliving environment
what are nonliving (abiotic) factors?
sunlight, temperature, moisture, nutrients, pH/chemistry/pressure
major components of ecosystems
abiotic: nonliving (water, air, nutrients, solar energy) and biotic: living (plants, animals, fungi, microorganisms)
major LIVING components of ecosystems
producers (autotrophs) and consumers (heterotrophs)
producers (autotrophs)
make own food from compounds taken from environment: green plants, bacteria, algae
consumers (heterotrophs)
depend on food made by producers
flow of matter and energy
survival of all organisms depends on flow of matter and energy through body, ecosystem survives mainly through matter recycling and energy flow, decomposers vital
3 factors that sustain life on earth
one way flow of high quality energy from the sun, cycling of matter or nutrients, gravity
How does “one way flow of high quality energy from sun” sustain life on earth?
through materials and living things in feeding interactions, into the environment as low-quality energy (heat), back into space as infrared radiation
how does the cycling of matter or nutrients sustain life on earth?
atoms/molecules needed for life
how does gravity sustain life on earth
allows planet to hold on to atmosphere and causes downward movement in matter cycles
how producers make food
capture sunlight and inorganic nutrients through photosynthesis to make sugars
photosynthesis overall reaction formula
carbon dioxide + water + solar energy = glucose + oxygen
consumers
obtain energy, nutrients by eating other organism
herbivores
primary consumers, feed directly on producers (plants, algae, photosynthetic microbes, plant parasites)
carnivores
feed on other consumers
Carnivores: secondary consumers
carnivores feeding directly on herbivores
carnivores: tertiary (higher-level) consumers
carnivores feeding only on other carnivores, rare except parasites
omnivores
feed both on plants and animals
decomposers
break down complex compounds into simple inorganic compounds by releasing them into soil and water and biodegradable materials.
cellular respiration (energy metabolism)
all producers and consumers use sugars to fuel life processes through aerobic and anaerobic respiration
aerobic respiration
most organisms, use oxygen to convert organic nutrients back into carbon dioxide and water and energy
anaerobic respiration (some decomposers)
get energy by breaking down sugars without oxygen, gives off ethanol/lactic acid/methane
relationship between photosynthesis and aerobic respiration
net chemical change of aerobic respiration is the opposite of photosynthesis
respiration formula
glucose + oxygen = carbon dioxide + water + energy
photosynthesis formula
carbon dioxide + water + solar energy = glucose + oxygen
food chain
how energy and nutrients move from one organism to another through ecosystem
trophic level
feeding level in food web of any given organism: producers: first tropic level, primary consumers: second level, secondary consumers: third level, detritivores process detritus from all trophic levels
ecological efficiency
percentage of energy transferred from one trophic level to another, the more trophic levels in a food chain/web: the greater the cumulative loss of energy, pyramids of energy flow always upright
Global NPP compared with Global rainforest distribution
Close match between NPP and distribution of rainforests
Terrestrial vs. Marine Productivity
Differing global patterns
Matter Cycling in Ecosystems
Biogeochemical (nutrient) cycles: Continuous cycling of nutrients from non-living environment through living organisms and back, atoms in us are ancient (used before and will be again), Driven by solar energy and gravity
What are the main cycles of matter cycling in ecosystems?
water (hydrologic), oxygen, carbon, nitrogen, phosphorus, sulfur
The Water Cycle
essential to all organisms
What are the reservoirs of the water cycle
97% of surface water in oceans, 2% in glaciers/polar ice caps, 1% in lakes/rivers, small amount in groundwater, a fraction in organisms/atmosphere
What does the water cycle move by
evaporation (mostly from ocean), transpiration, condensation, precipitation (mostly over land), percolation, runoff
The Carbon Cycle
carbon-based organic molecules are major constituents of all organisms
What are the carbon reservoirs in The Carbon Cycle?
fossil fuels, soils and sediments, solutes in oceans, organismal biomass, the atmosphere
What is CO2 is taken up and release through in The Carbon Cycle?
photosynthesis, respiration, volcanoes, burning, warming oceans, cement production
The Terrestrial Nitrogen Cycle
essential for amino acids, proteins, and nucleic acids of all life
What is main reservoir in the Terrestrial Nitrogen Cycle?
the atmosphere (N2), which must be converted to ammonia (NH4+) or nitrate (NO3-) for uptake by plants via nitrogen fixation by bacteria
How is organic nitrogen decomposed and dentrified?
decomposed to NH4+ by ammonification (decomposed to NO3- by nitrification), dentrification converts NO3- back to N2
Distribution of biomes
abiotic factors, especially climate: latitudinal climatic factors lead to latitudinal patterns of biome distribution, determined by temperature, precipitation and latitude
What determines distribution of terrestrial biomes?
Pattern of climatic variation can be as important as average climatic conditions (seasonality), disturbance modifies biomes (fire, storms, volcanic activity, asteroid impact, human activity)
tropical rainforest floras
vast majority of biomass is in trees: many tee species, low number of individuals per tree species, trees mostly broad-leaved evergreens, buttressed tree trunks/roots
rainforest biodiversity, stratification
rainforests are highly stratified with several distinct layers, only 2% of earth’s land surface covered with tropical rainforest
tropical rainforest cycling
continuous dropping of dead leaves, warm/moist conditions: hordes of decomposers and rapid cycling of nutrients
some tropical rainforest characteristics
dense vegetation higher up, little wing inside the forest (favors animal pollination)
temperate deciduous forests
grow in areas with moderate average temperatures, abundant precipitation, primary productivity <6 mos.
temperate deciduous forest
few species of broadleaf deciduous trees: survive cold winters by dropping leaves in fall becoming dormant and grows all-new leaves each spring, low rate of decomposition: thick humus layer of decaying leaf litter full of nutrients
evergreen coniferous forests
= boreal forests, taiga; just south of arctic tundra across N Hemisphere (winters long/dry/extremely cold, summers short/mild to warm)
evergreen coniferous forests
dominated by a few species of coniferous evergreen trees that keep their needles year-round and have waxy-coated needles, plant diversity low because few species can survive long period of frozen water
What are characteristics of a Montane rainforest in a tropical cloud forest?
gnarled/shorter trees with many branches and small leaves, lots of moss/tree ferns, horizontal cloud precipitation, windy, little sun, fewer species than lowland tropical rainforest but many narrow endemics
tropical moist forest
often looks just like rainforest during rainy season: more seaonsal, evergreen or partly evergreen
rainforest gaps
rainforests long thought extremely stable, natural disturbance by storms/lightning/tree fall/disease, now humans a major factor
understory trees
many understory trees are saplings of canopy species: grow slowly then grow rapidly to reach canopy ahead of others
jungles
mature undisturbed rainforest with an open understory letting very little light through, jungles are regenerating gaps or second growth, may eventually revert to climax forest
emergents
extremely tall trees rising above canopy: obtain plenty of light, subject to high winds and dry conditions, often wind pollinated, seeds often wind dispersed
flowers
trees often have large, fragrant, brilliant flowers for animal pollination
red, orange, yellow flowers for animal pollination by what species?
birds
white, purple, yellow, orange and green flowers are foranimal pollination for what species?
insects
fragrant flowers are for animal pollination for what species?
insects
white, night flowering, musty flowers are for animal pollination for what species?
bats
nectar rich on long stalks or trunk flowers are for animal pollination for what species?
bats, birds, large butterflies and moths
fruits
are a plant tactic for getting seeds dispersed otherwise energy for production of pulp/sugars is wasted, often brightly colored to signal ripeness
desert biomes
where evaporation exceeds precipitation, hot by day/cold by night, two basic adaptive themes: maximize loss of heat and obtaining and conserving water
grassland biomes
enough rainfall for grass growth, mostly in interiors of continents, renewable on short time scale
what is afforestation prevented by in grassland biomes?
erratic rainfall, frequent fires, large grazing herbivores
what are the three main types of grassland biomes
tropical, temperate, tundra (polar, alpine)
some plant adaptations to grasslands
fire and grazing adapted, wind pollinated, tolerance of: extreme temperatures, drought, wind damage, survival in saline soil
polar grassland (arctic tundra)
just south of polar ice cap, bitterly cold most of the year, winters long, growing season very short, precipitation mostly as snow, vegetation thick/low growing
tundra permafrost
caused by extreme cold, short summers, liquid water can’t percolate into lower layers, melting will release vast amounts of stored carbon
alpine tundra
very like arctic tundra, vegetation much like that in arctic tundra but: more sunlight, daily temperature conditions can fluctuate wildly, no permafrost layer, usually steep relief
aquatic life zones
largest part of the biosphere water, freshwater vs. saltwater, most rainfall by evaporation from ocean, ocean temperature affects land climate and winds, photosynthetic marine organisms important in oxygen and carbon cycles
freshwater ecosystems
zonation: distance from shore, light penetration, depth
Characteristics of a freshwater life zone: Lake
standing bodies of water: deep enough to have light and temperature stratification, oligotrophic: nutrient poor and oxygen rich, eutrophic: nutrient rich and often oxygen poor
Characteristics of a freshwater life zone: Wetlands
shallow/inundated areas, extremely productive, high biodiversity
Characteristics of a freshwater life zone: streams and rivers
narrow/some current, great variation from headwaters to downstream parts
Characteristics of a freshwater life zone: Estuaries
transition between river and sea, moderate salinity, highly productive
mangroves
coastal hypersaline forests: mangal, widespread on tropical coasts/islands/lagoons/lower rivers, slow growing/regenerating, ecological community or guild not phylogenetic grouping: based on physiological adaptations
adaptations shared among mangroves
high salt tolerance, salt excretion, occur in tidal areas where other trees can’t, often form pure stands, often reproduced by viviparity, aerial roots for oxygen uptake, tolerant of saltwater immersion, generally related to upland species, leaves small/oval/thick, usually small trees
importance of mangroves
shelter coastline: reduce erosion, provide good conditions for nearby coral reefs, bear brunt of storms, fisheries: nurseries for many fishes, permanent home for many crabs, many endemic species in above water trees
The Intertidal zone
highly productive, primary feeding and nursery grounds for many species, relative accessibility has led to these habitats being better studied than many, includes many different types such as salt marsh/bare mudflats/rocky shores/mangroves
Spartina salt marshes
saline marshes along low lying temperate coastlines, grow in quiet water areas then trap sediment
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