Final Exam ISB 202

ecology

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

Spartina as ecosystem engineer

the rhizome system is the primary way the plants spread locally, rhizome and shoot system creates baffle that traps sediment, creates the habitat for many other species

important salt marsh ecosystem services

protect coastline against erosion, absorb nutrients, absorb pollutants, serve as nurseries for fishes and shellfish, major touristic destinations

The Rocky Intertidal

worldwide in distribution, stable position but largely impenetrable and extremely variable in salinity/temperature/moisture

vertical zonation in the intertidal

vertical zonation is typical in the intertidal, zonation is usually much less distinct on sandflats and mudflats than on rocky shores

high intertidal challenges

upper intertidal species have much less feeding time than lower or subtidal species, grazers like limpets and snails stop feeding when hot and dry, suspension feeders cannot feed when exposed

soft sediment intertidal

sandy/muddy areas, very different characteristics than rocky areas, sand doesn’t hold water so when exposed is like a desert with low biodiversity, most soft sediment organisms are either highly mobile or burrowers

estuaries

where seawater and freshwater from watershed meet and mix, bordered by other intertidal habitats, many factors influence salinity levels

estuary shelf life histories

many estuarine species spend entire life cycle there, many other species spend part of their lives in estuary and part on the shelf

oyster reefs

oysters form reeds in estuaries and protected coasts in temperate zone worldwide, single species dominate habitat but many other species live with them, ecosystem engineers, long exploited as prized food source

sea grass beds

highly productive/diverse subtidal benthic coastal communities, fix carbon but also structure the habitat, ecosystem engineers or foundation species

importance of sea grass

main food source for animals, stabilizes soft sediment, absorbs some excess nutrients, provides major habitat for invertebrates, important egg substrate for some herring species, nursery for flounder/crab/lobster/squid/blackfish, roots oxygenate sediments

kelp forests are dominated by fast growing large brown algae

large kelp forests in water <20 degrees celsius, water mostly <15 m, some grow very rapidly, some are mainly large blades supported by stem, some have long stems and floats, some have complex blade morphology

holdfast habitats formed by kelps

forms shelter for many different organisms, most complex kelp habitat formed by holdfasts, older holdfasts host the most species

sargassum

2 planktonic species of Sargassum, since 2011 huge rafts have been washing up on beaches

What are coral reefs?

wave resistant constructions built by multiple species, mainly formed by one main group of hard corals, framework builders are the dominant reef building organisms, sponges/coralline algae and microbes also contribute but much less to reef growth

the rainforests of the sea

coral reefs are structurally extremely complex, both rainforests and coral reefs occur in low nutrient environments, coral reefs are animal dominated