Unit 1

Ecosystem

Topic 1.1

Definition

• Individual

  • One organism

  • Example: Elk

• Population

  • Group of individuals of same species

  • Example: Herd of elk

• Community

  • All living organisms in an area

• Ecosystem

  • All living & nonliving things in an area

    • Plants, animals, rocks, soil, water, air

• Biome

  • The plants and animals found in a given region

    • Determined by climate

  • Example: Tropical rainforest

• Climate

  • The long-term average weather patterns of a specific region or area

• Coevolution

  • Two or more different species evolve in response to each other’s adaptations

• Symbiosis

  • Any close and long-term interaction between two organisms of different species

• Competition

  • Organisms fighting over a resource like food or shelter

  • Limits population size

  •  1 Negative 2 Negative

• Predation

  • One organism using another for energy source

  • Hunters, parasites, even herbivores

  • 1 Positive 2 Negative

• Herbivory

  • The act of animals eating plants for energy

  • Example: Rabbit & lettuce

• Parasitism

  • One organism (the parasite) benefits by living on or within another organism (the host) which it harms in the process by taking nutrients, shelter and other resources from

  • Example: Mosquito & human

  • 1 Positive 2 Negative

• Mutualism

  • Relationship that benefits both organisms

  • Example: Coral reef

  • 1 Positive 2 Positive

• Commensalism

  • Relationship that benefits one organism and doesn’t impact the other

  • Example: Birds nest in trees

  • 1 Positive 2 Equal

Predation (+/-)

• Herbivores

  • Plant eaters

  • Eat plants for energy

  • Example: Giraffe & tree

• True Predators

  • Carnivores

  • Kill and eat prey for energy

  • Example: Leopard & Giraffe

• Parasites

  • Use a host organism for energy, often without killing the host & often living inside host

  • Example: Mosquitoes, tapeworms, sea lamprey

• Parasitoids

  • Lay eggs inside a host organism

  • Eggs hatch & larvae eat host for energy

  • Example: Parasitic wasps, bot fly

Symbiosis

• Any close and long-term interaction between two organisms of different species

  • Mutualism (+/+), commensalism (+/=), and parasitism (+/-) are all symbiotic relationships

• Word breakdown

  • Sym = together

  • Bio = living

  • Osis = condition

• Mutualism

  • Organisms of different species living close together in a way that benefits both

  • Coral (animals) provide reef structure & CO2 for algae; algae provides sugars for coral to use as energy

  • Lichen = composite organism of fungi living with algae; algae provides sugars (energy) & fungi provides nutrients

Competition

• Reduces population size since there are fewer resources available & fewer organisms can survive

• Resource partitioning

  • Different species using the same resource in different ways to reduce competition

• Temporal partitioning

  • Using resource at different times

    • Wolve & coyotes hunting at different times (night vs day)

• Spatial partitioning

  • Using different areas of a shared habitat

    • Different length roots

• Morphological partitioning

  • Using different resources based on different evolved body features

Biomes

Topic 1.2

• Biome

  • An area that share a combination of average, yearly temp + precipitation (climate)

  • Example: rain forest, taiga, temperate deciduous forest, grasslands, desert, tundra

• The community of organisms (plants & animals) in a biome are uniquely adapted to live in that biome

  • Example: camels and cacti in deserts. They have water preserving adaptations. Shrubs & wildflowers store lots of energy in roots to recover quickly from fires in grasslands

• Biome chart can predict where on earth biomes are found

  • Tundra & boreal

    • Higher latitude (60°+)

  • Temperate

    • Mid latitude (30°-60°)

  • Tropical

    • Closer to the equator

• Latitude (distance from equator) determines temperature & precipitation which is why biomes exist in predictable pattern on Earth

• Shifting biomes

  • Biomes shift in location on Earth as climate changes

  • Example: Warming climate will shift boreal forests further north as tundra permafrost soil melts & lower latitudes become too warm for aspen & spruce

    • Aka climate change

• Nutrient Availability

  • Plants need soil nutrients to grow, so availability determines which plants can survive in a biome

  • Example: frozen soils of tundra don’t allow nutrients in dead organic matter to be broken down by decomposers

    • Low soil nutrients

    • Low water availability

    • Few plants survive here

Topic 1.3

Characteristics of Aquatic Biomes

• Salinity

  • How much salt there is in a body of water

    • Determines which species can survive & usability for drinking

    • Fresh water vs Estuary vs Ocean

• Flow

  • Determines which plants & organisms can survive

  • How much O2 can dissolve into water

  • Lentic (stagnant) vs Latic 

• Depth

  • Influences how much sunlight can penetrate and reach plants below the surface

    • For photosynthesis

• Temperature

  • Warmer water holds less dissolved O2 so it can support fewer aquatic organisms

Freshwater: Rivers & Lakes

• Rivers have high O2

  • Due to flow mixing water & air

  • Also carries nutrient-rich sediments

    • Deltas & flood plains = fertile soil

• Lakes

  • Standing bodies of fresh H2O

    • Key drinking H2O source

• Littoral

  • Shallow water with emergent plants

• Limnetic

  • Where light can reach

    • Photosynthesis occurs here

    • No rooted plants, only phytoplankton

• Profundal

  • Too deep for sunlight

    • No photosynthesis

• Benthic

  • Murky bottom

  • Invertebrates (bugs) live here

  • Nutrient-rich sediments

Freshwater: Wetlands

• Wetland

  • Area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants

  • Plants living here have to be adapted to living with roots submerged in standing water

    • Cattails, Lily Pads, Reeds

• Benefits of Wetlands

  • Stores excess water during storms, lessening floods

  • Recharges groundwater by absorbing rainfall into soil

  • Roots of wetland plants filter pollutants from water draining through

  • Highly plant growth due to lots of water & nutrients in sediment

    • Nutrients is dead organic matter

  • Wetland Examples

    • Swamp

      • Cyprus Trees

    • Marsh

      • Reeds & Cattails

    • Bog

      • Spruce

      • Sphagnum Moss

Estuaries

• Areas where rivers empty into the ocean

  • Mix of fresh & salt water

    • Species adapt to this

      • Mangrove trees

  • High productivity due to nutrients in sediments deposited by estuaries by river

    • Plant growth = high productivity

• Salt Marsh

  • Estuary habitat along coast in temperate climates

  • Breeding ground for many fish and shellfish species

  • Example

    • Georgia Salt Marsh

      • Halophytes (Saltwater Grasses)

• Mangrove Swamps

  • Estuary habitat along coast of tropical climates

  • Mangrove trees with long, stilt roots stabilize shoreline & provide habitat for many aquatic species

  • Example

    • Florida Mangrove Swamp

      • Mangrove Trees (Saltwater Trees)

Coral Reef

• Warm shallow waters beyond the shoreline

• Most diverse marine (ocean) biome on Earth

• Mutualistic relationship between coral (animals) & algae (plants)

  • Coral takes CO2 out of ocean to create calcium carbonate exoskeleton (the reef) & also provide CO2 to the algae

  • Algae live in the reef & provie sugar (energy) to the coral through photosynthesis

  • Both species rely on the other

    • Coral couldn’t survive without energy from algae

    • Algae needs the home of the reef & CO2 from the coral

• 3 Types of Reefs

  • Fringing Reef

  • Barrier Reef

  • Atoll

Intertidal Zones

• Narrow band of coastline between high & low tide

• Organisms must be adapted to survive crashing waves & direct sunlight/heat during low tide

  • Examples

    • Barnacles

    • Sea Stars

    • Crabs that can attach themselves to rocks

  • Shells & tough outer skin can prevent drying out (desiccation) during low tides

• Different organisms are adapted to live in different zones

  • Spiral wrack (type of seaweed) curls up & secretes mucus to retain water during low tide

Open Ocean

• Low productivity/area as only algae & phytoplankton can survive in most of ocean

• So large though, that algar & phytoplankton of ocean produce a lot of earth’s O2 & absorb a lot of atmospheric CO2

• Photic zone

  • Area where sunlight can reach (photosynthesis)

• Aphotic zone (abyssal)

  • Area too deep for sunlight

Carbon Cycle

Topic 1.4

• Movement of molecules that contain Carbon (CO2, glucose, CH4) between sources and sinks

  • Some steps are very quick (fossil fuel combustion), some steps are very slow (sedimentation & burial)

    • Leads to imbalance in which reservoirs or sinks are storing carbon

• Atmosphere is key Carbon reservoir

  • Increasing levels of Carbon in atmosphere leads to global warming

• Carbon sink

  • Reservoir that take in more carbon than it releases

  • Example

    • Ocean (algae & sediments)

    • Plants

    • Soil

• Carbon source

  • Reservoir that releases more carbon than it takes in

  • Examples

    • Fossil fuel (oil, coal, natural gas) combustion

    • Animal agriculture

      • Cow burps + farts = CH4

    • Deforestation

      • Releases CO2 from trees

Photosynthesis & Cellular Respiration

• Both processes are very quick

• Cycles Carbon between biosphere & atmosphere in balanced amount (no net Carbon increase in atmosphere)

• Photosynthesis

  • Plants, algae, phytoplankton

  • Removes CO2 from the atmosphere & converts it to glucose

  • Glucose = biological form of C & stored (chemical) energy in form of sugar

  • CO2 sink

• Cellular Respiration

  • Done by plants & animals to release stored energy

  • Uses O2 to break glucose down & release energy

  • Releases CO2 into atmosphere

  • CO2 source (adds CO2 to atmosphere)

Ocean & Atmosphere

• Direct exchange

  • CO2 moves directly between atmosphere & the ocean by dissolving into & out of ocean water at the surface

  • Happens very quickly & in equal directions

    • Balancing levels of CO2 between atmosphere & ocean

• Because of direct exchange, increasing atmospheric CO2 also increases ocean CO2, leading to ocean acidification

• Algae & phytoplankton

  • Takes CO2 out of the ocean & atmosphere through photosynthesis

  • Coral reef & marine organisms with shells also take CO2 out of the ocean to make calcium carbonate exoskeleton

• Sedimentation

  • Calcium carbonate precipitates out as sediment & settles on ocean floor

• Burial

  • Over long periods of time, pressure of water compresses Carbon-containing sediments on ocean floor into sedimentary stone (limestone, sandstone)

  • Long-term Carbon reservoir

Burial, Extraction & Combustion

• Burial

  • Slow, geological process that stores Carbon in underground sinks like sedimentary rock or fossil fuels

  • Sediments (bits of rock, soil, organic matter) compressed into sedimentary rock, or fossil fuels, by pressure from overlying rock layers or water

• Fossil Fuels (FF)

  • Coal, oil and natural gas are formed from fossilized remains of organic matter

  • Example

    • Dead ferns (coal)

    • Marine algae & plankton (oil)

• Extraction & Combustion

  • Digging up or mining Fossil Fuels & burning them as energy source: releases CO2 into atmosphere

• Burial (formation of FFs) takes far longer than extraction & combustion, which means they increase concentration of CO2 in atmosphere

Nitrogen Cycle

Topic 1.5

Overview

• Movement of Nitrogen containing molecules between sources & sinks/reservoirs

  • Sources release Nitrogen into atmosphere

  • Sinks take NItrogen out of the atmosphere in increasing amounts

• Nitrogen reservoirs hold Nitrogen for relatively short period of time compared to Carbon cycle

  • Plants

  • Soil

  • Atmosphere

• Atmosphere = Main Nitrogen reservoir

  • Nitrogen in atmosphere exists mostly as N2 gas

    • Not useable by plants or animals

• Nitrogen = critical plant & animal nutrient

  • All living things need Nitrogen for DNA & amino acids to make proteins

Nitrogen Fixation

• Process of N2 gas being converted into biologically available (useable by plants) NH3 (ammonia) or No3 (Nitrate)

• Bacterial fixation

  • Certain bacteria that live in the soil or in symbiotic relationship with plant root nodules convert N2 into ammonia (NH3)

  • Rhizobacteria live in root nodules of legumes (peas, beans) & fix Nitrogen for them in return for amino acids from the plant

• Synthetic fixation

  • Fossil Fuel combustion converts N2 gas into ammonia (NH3)

  • NH3 is added to synthetic fertilizer and applied to agricultural soils where it is converted into nitrate

Other Nitrogen Cycle Steps

• Assimilation

  • Plants & animals taking Nitrogen in and incorporating it into their body

    • Plant roots take in NO3 or NH3 from soil

    • Animals assimilate Nitrogen by eating plants or other animals

• Ammonification

  • Soil bacteria, microbes & decomposers converting waste & dead biomass back into NH3 and returning it to soil

• Nitrification

  • Conversion of NH4 into nitrite (NO2) & then nitrate (NO3) by soil bacteria

• Denitrification

  • Conversion of soil Nitrogen (NO3) into nitrous oxide (N2O) gas which returns to atmosphere

Human Impacts on Nitrogen Cycle

• Climate

  • N2O (nitrous oxide) = greenhouse gas which warm Earth’s climate

    • Produced by denitrification of nitrate in agricultural soils

      • Especially when waterlogged/over watered

  • Ammonia Volatilization

    • Excess fertilizer use can lead to NH3 gas entering atmosphere

    • NH3 gas in atmosphere causes respiratory irritation in humans & animals

  • Leaching & Eutropication

    • Synthetic fertilizer use leads to nitrates (NO3) leaching, or being carried out of soil by water

      • Nitrates runoff into local waters, causing algae blooms that block sun & kill other aquatic plants

Phosphorous Cycle

Topic 1.6

Phosphorous Cycle Basics

• Movement of Phosphorous atoms & molecules between sources & sinks/reservoirs

• Rocks & sediments containing Phosphorus minerals = major reservoirs

• Phosphorous cycle is very slow compared to C/H2O/N cycles

  • Takes a long time for Phosphorous minerals to be weathered out of rocks & carried into soil/bodies

    • No gas phase of Phosphorus (doesn’t enter atmosphere)

  • Because it cycles so slowly, it is a limiting nutrient

    • Plant growth in ecosystems is often limited by Phosphorus availability in soil/water

• Phosphorus is needed by all organisms for DNA, ATP (energy), bone & tooth enamel in some animals

Phosphorus Sources

• Major natural source of Phosphorus is weathering of rocks that contain phosphorus minerals

  • Wind & rain break down rock

    • Phosphate (PO4-3) is released and dissolved into water

    • Rain water carriers phosphate into nearby soils & bodies of water

    • Weathering is so slow that phosphorus is often a limiting nutrient in aquatic & terrestrial ecosystems

  • Synthetic (human) sources of Phosphorus

    • Mining phosphate minerals & adding to products like synthetic fertilizers & detergents/cleaners

    • Synthetic fertilizers containing phosphates are added to lawns or agriculture fields

      • Runoff carries phosphorus into nearby bodies of water

    • Phosphates from detergents & cleaners enter bodies of water via wastewater from homes

Assimilation & Excretion/Decomposition

• Just like Nitrogen, Phosphorus is absorbed by plant roots & assimilate into tissues

  • Animals assimilate Phosphorus by eating plants or other animals

• Animal waste plant matter & other biomass is broken down by bacteria/soil decomposers that return phosphate to soil

• Assimilation & excretion/decomposition form a mini-loop within Phosphorus cycle just like assimilation & ammonification in Nitrogen cycle and photosynthesis & respiration in Carbon cycle

Sedimentation & Geological Uplift

• Phosphate doesn’t dissolve very well into water

  • Much of it forms solid bits of phosphate that fall to the bottom as sediment (sedimentation)

• Phosphorus sediments can be compressed into sedimentary rock over long time periods by pressure of overlying water

• Geological Uplift

  • Tectonic plate collision forcing up rock layers that form mountains

    • Phosphorus cycle can start over again with weathering & release of phosphate from rock

Eutrophication (too much N & P)

• Can occur from fertilizer runoff, human/animal waste contamination

• Because they’re limiting nutrients in aquatic ecosystems, extra input of Nitrogen & Phosphorus lead to eutrophication (excess nutrients) which fuels algae growth

  • Algae bloom covers surface of water, blocking sunlight & killing plants below surface

  • Algae eventually dies-off

    • Bacteria that breaks down dead algae use up O2 in the water (because decomposition = aerobic process)

  • Lower O2 levels (dissolved oxygen) in water kills aquatic animals, especially fish

  • Bacteria uses up even more O2 to decompose dead aquatic animals

  • Creates positive feedback loop

    • Less O2 -> more dead organisms -> more bacterial decomposition -> less O2

Hydrologic (Water) Cycle

Topic 1.7

Water Cycle Overview

• Movement of H2O (in different states) between sources & sinks

• State of matter (solid/liquid/gas) as well as where water is moving are key in H2O cycle

  • Example

    • Precipitation = atmosphere (gas) -> land or surface water (liquid)

• Energy from sun drives the H2O cycle

  • Example

    • Heat from sun causes liquid water in ocean to become a gas (evaporation) in atmosphere

• Ocean = largest water reservoir

• Ice caps & groundwater are smaller reservoirs, but contain fresh, useable water for humans

Evaporation & Evapotranspiration

• 2 main sources of water (processes that cycle it from liquid on Earth back into the atmosphere)

• Sometimes called vaporization since liquid water becomes water vapor (gas) in atmosphere

• Transpiration

  • Process plants use to draw groundwater from roots up to their leaves

  • Leaf openings called stomata open, allowing water to evaporate into atmosphere from leaf

  • Movement of H2O out of leaf creates low H2O potential in leaf, pulling H2O up from roots

• Evapotranspiration

  • Amount of H2O that enters atmosphere from transpiration & evaporation combined

• Both processes are driven by energy from the Sun

Runoff & Infiltration

• Precipitation (rain) either flows over Earth’s surface into a body of water (runoff) or trickles through soil down into groundwater aquifers (infiltration)

• Groundwater (aquifers) & surface waters (lakes/rivers) are important freshwater reservoirs for humans & animals

• Precipitation recharges groundwater through infiltration, but only if ground is permeable (able to let water pass through)

• Runoff recharges surface waters, but can also carry pollutants into water sources

Primary Productivity

Topic 1.8

PP Basics

• Units

  • kcal/m^2/yr

  • Energy/Area/Time

  • kcal/yr OVER m^2

• High PP

  • High plant growth

    • Lots of food & shelter for animals

  • Ecosystems with high PP are usually more biodiverse (more diversity of species) than ecosystems with low PP

• Primary Productivity

  • Rate that solar energy is converted into organic compounds via photosynthesis over a unit of time

  • Rate of photosynthesis of all producers in an area over a given period of time

  • Since photosynthesis leads to growth, you can also think of PP as the amount of plant growth in an area over a given period of time

Calculating PP

• NPP = GPP - RL

• Net Primary Productivity (NPP)

  • The amount of energy (biomass) leftover for consumers after plants have used some for respiration

  • What is left over after respiration

  • Think of it as the amount of the paycheck that is kept after taxes

• GPP

  • Total energy captured

  • The total amount of sun energy (light) that plants capture and convert to energy (glucose) through photosynthesis

  • Think of as the total paycheck earned

• RL

  • Energy used up by respiration (lost as heat)

  • Plants use up some of the energy they generate via photosynthesis by doing cellular respiration (movement, internal transportation, etc)

  • Similar to taxes

Ecological Efficiency

• The portion of incoming solar energy that is captured by plants & converted into biomass (NPP or food available for consumers)

• Generally, only 1% of all incoming sunlight is captured & converted into GPP via photosynthesis

• Of that 1%, only about 40% (or .4% of total incoming solar energy) is converted

Trends in Productivity

• The more productive a biome is, the wider the diversity of animal life it can support (highest biodiversity)

• Water availability, higher temperature and nutrient availability are all factors that lead to high NPP

  • Shortage of any three of these factors will lead to decreased NPP

  • Example

    • Desert (low H2O & nutrients)

    • Tundra (low temperature & liquid H2O)

    • Open ocean (low nutrients)

Trophic Levels & The 10% Rule

Topic 1.9 & 1.10

Conservation of Matter & Energy

• Matter & energy are never created or destroyed; they only change forms

  • Examples

    • Tree dies & the C/N/H2O/P are returned to the soil & atmosphere

    • Sun rays (light energy) hit leaves & are converted into glucose (chemical energy)

• 1st law of thermodynamics

  • Energy is never created or destroyed

• Biogeochem cycles demonstrates conservation of matter (C/N/H2O/P)

• Food webs demonstrate conservation of energy

  • Example

    • When a rabbit eats a leaf, the energy from the leaf (glucose) is transferred to the rabbit & stored as body tissue like fat/muscle

2nd Law of Thermodynamics

• Each time energy is transferred, some of it is lost as heat

• Applied to food webs

  • The amount of useable energy decreases as you move up the food chain

    • Organisms use up most of it for movement, development, etc

• Because available energy decreases with each step up the food chain, a trophic pyramid is used to model how energy moves through an ecosystem

  • Troph

    • Nourishment or growth

• 10% Rule

  • In trophic pyramids, only about 10% of the energy from one level makes it to the next level

  • The other 90% is used by the organism & lost as heat

Trophic Levels & 10% Biomass

• Tertiary Consumers

  • Animals that eat secondary consumers or carnivores & omnivores

    • Top/apex predators

• Secondary Consumers

  • Animals that eat primary consumers or herbivores

    • Carnivores & omnivores

• Primary Consumers

  • Animals that eat plants

    • Herbivores

• Producers

  • Plants - “produce”

  • Really convert sun’s light energy into chemical energy (glucose)

• 10% rule also applies to biomass 

Calculating Biomass & Energy

• To calculate biomass or energy available at the next level, move the decimal place one spot to the left (divide by 10)

Food Chains and Food Webs

Topic 1.11

Food Web Basics

• Shows how matter & energy flow through an ecosystem

  • From organism to organism

• When one organism preys on (eats) another, the matter (Carbon/Nitrogen/H2O/Potassium) and energy (glucose/muscle tissue/etc) are passed on to the predator

• Arrows in food webs indicate direction of energy flow

  • Point to the organism taking in the energy

Food Web vs Chain

• Food chains just show one, linear path of energy & matter

• Food webs have at least 2 different, interconnected food chains

  • Webs show that organisms can exist at different tropic levels

    • Grass -> Hare -> Owl (secondary consumer)

    • Grass -> Grasshopper -> Robin -> Owl (tertiary consumer)

Interactions & Trophic Cascade

• Food webs show how increase or decrease in population size of a given species impact the rest of the food web

  • Example: Increase in python population

    • Decrease in frog & rat populations

    • Increase in grasshopper populations

    • Decrease in corn

• Trophic Cascade

  • Removal or addition of a top predator has a ripple effect down through lower trophic levels

  • Example

    • Decline in wolf population results in increase in deer population which leads to overgrazing & decline in trees