1.1 Ecosystems

Learning Objective

• Explain how the availability of resources influences species interactions

Ecosystem Basics

• Individual (elk)

  • one organism

• Population (elk herd)

  • group of individuals of same species

• Community

  • all living organisms in an area

• Ecosystem

  • all living and nonliving things in an area

    • Ex. plants, animals, rocks, soil, water, air

• Biome

  • large area with similar climate conditions that determines the plant and animal species that live will there

    • Ex. tropical rainforest

Organism Interactions

Competition

• Organisms fighting over a resource like food or shelter

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

Resource partitioning - different species using the same resource in different way to reduce competition

Temporal partitioning - using resources at different times

• wolves and coyotes hunting at different times

Spatial partitioning - using different areas of a shared habitat

• different length roots

Morphological partitioning - using different resources based on different evolved body features

Predation

• One organism using another for energy (hunters, parasites, even herbivores)

  • Herbivores (plant eaters) eat plants for energy

    • Ex. giraffe and tree

  • True predators (carnivores) kill and eat prey for energy

    • Ex. leopard and giraffe

  • Parasites use a host for energy often without killing the host and whilst living inside the host

    • Ex. mosquitoes, tapeworms, sea lamprey

  • Parasitoids lays eggs inside hosts which hatch and eat the host for energy

    • Ex. parasitic wasps, bot fly

Symbiosis

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

Mutualism - Both organisms benefit from the relationship (coral reef)

• Coral provide reef structure and CO2 for algae who provides sugars for coral to use as energy

• Lichen is a composite organism of fungi living with algae and algae provide sugars and fungi provides nutrients

Commensalism - One organism benefits from the relationship while the other is not impacted (birds nest in trees)

1.2 Terrestrial Biomes

Learning Objective

• Describe the global distribution and principal environmental aspects of terrestrial biomes

Biome

• an area that shares a combination of average yearly temperature and precipitation

Note: Latitude (distance from equator) determines temperature and precipitation which is why biomes exist in a predictable pattern on earth.

Tundra and Boreal - Higher Latitude (60 degrees +)

Temperate - Middle Latitude (30 - 60 degrees)

Tropical - closer to the equator

Nutrient Availability

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

• Tropical Rainforest

  • nutrient poor soil

  • high competition from so many different plant species

• Boreal Forest

  • nutrient poor soil

  • low temperature

  • low decomposition rate of dead organic matter

• Temperate Forest

  • nutrient rich soil

  • lots of dead organic matter

Shifting Biomes

• Biomes shift in location on earth as climate changes

1.3 Aquatic Biomes

Learning Objective

• Describe the global distribution and principal environmental aspects of aquatic biomes

Characteristics

Salinity

• How much salt there is in a body of water

  • determines which species can survive and usability for drinking

Depth

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

Temperature

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

Flow

• How much oxygen can dissolve into water

  • Determines which plants and organisms can survive

Freshwater

Rivers

• have high oxygen due to flow mixing water and air

• also carry nutrient rich sediments

Lakes

• standing bodies of freshwater

  • Littoral Zone - shallow water with emergent plants

  • Limnetic Zone - where light can reach

  • Profundal Zone - too deep for sunlight

  • Benthic Zone - murky bottom where inverts live, nutrient rich sediments

Wetlands

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

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

Benefits of Wetlands

• Stores excess water during storms, lessening floods

• Recharges groundwater by absorbing rainfall into soil

• Roots of wetland plans filter pollutants from water draining through

• High plant growth due to lots of water and nutrients in sediments

Estuaries

Estuaries are areas where rivers empty into the ocean

• mix of fresh and salt water

• high productivity (plant growth)

Types of Estuaries

• Salt Marsh

  • Estuary habitat along coast in temperate climates

  • Breeding ground for many fish and shellfish species

• Mangrove Swamps

  • Estuary habitat along coast of tropical climates

  • Mangrove trees with long, stilt roots stabilize shoreline and provide habitat for many species of fish and shellfish

Coral Reef

Warm shallow waters beyond the shoreline

• most diverse marine (ocean) biome on earth

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

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

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

Intertidal Zones

Narrow band of coastline between high and low tide

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

• Different organisms are adapted to live in different zones

Open Ocean

• low productivity

• so large that the ocean produce a lot of the earth’s oxygen and absorbs a lot of carbon dioxide

Photic Zone

• area where sunlight can reach

Aphotic Zone

• area too deep for sunlight

1.4 Carbon Cycle

Learning Objective

• Explain the steps and reservoir interactions in the carbon cycle

Overview

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

• Some steps are very quick (FF combustion); some are very slow (sedimentation & burial)

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

  Atmosphere is a key carbon reservoir

  • increasing levels of carbon in atmosphere leads to global warming

Sinks and Sources

• Carbon sink: a carbon reservoir that stores more carbon than it releases
  ○ Ocean (algae & sediments), plants, soil

• Carbon source: processes that add C to atm.
  ○ Fossil fuel (oil, coal, natural gas) combustion
  ○ Animal ag. (cow burps & farts = CH4)
  ○ Deforestation, releases CO2 from trees

Photosynthesis and Cellular Respiration

Photosynthesis (Carbon Sink)

Removes CO2 from the atmosphere and converts it to glucose

• Glucose

  • biological form of carbon

  • stored energy in form of sugar

Cellular Respiration (Carbon Source)

Uses oxygen to break glucose down and release energy (Done by plants and animals to release stored energy). Releases carbon dioxide into atmosphere

Both processes are very quick and cycle carbon between biosphere and atmosphere in balanced amount

Ocean and 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 atm. & ocean.

• Because of direct exchange, increasing atm. CO2 also increases ocean CO2, leading to ocean acidification
  Sedimentation

• when marine org. die, their bodies sink to ocean
  floor where they’re broken down into sediments that contain C

Burial, Extraction, and Combustion

Burial

• slow, geological process that stores C in underground sinks
  like sedimentary rock or fossil fuels

  • Sediments (bits of rock, soil, organic matter) compressed into sed. rock, or
    FF, by pressure from overlying rock layers or water

Fossil Fuels (FF):

• coal, oil, and Nat. gas are formed from fossilized remains of org. matter.

Extraction & Combustion

• digging up or mining FFs & burning them as energy source; releases CO2 into atm.

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

1.5 Nitrogen Cycle

Learning Objective

• Explain the steps and reservoir interactions in the Nitrogen Cycle

Nitrogen Cycle Overview

Movement of nitrogen-containing molecules between sources and sinks

Note: Atmosphere is the main reservoir

• Nitrogen is a critical plant and animal nutrient

Nitrogen Fixation

Process of N2 gas being converted into biologically available ammonia or nitrate

• Bacterial Fixation

  • certain bacteria that live in the soil, or in symbiotic relations with plant root nodules convert N2 into ammonia

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

• Synthetic Fixation

  • humans combust FFs to convert N2 gas into nitrate

More N Cycle Steps

• Assimilation

  • plants and animals taking N in and incorporation it into their body

• Ammonification

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

• Nitrification

  • conversion of NH4 into nitrite and then nitrate by soil bacteria

• Denitrification

  • conversion of soil N into nitrous oxide gas which returns to the atmosphere

Human Impacts

• Climate

  • Nitrous oxide (a greenhouse gas) warms the earth’s climate

• Ammonia Volatilization

  • excess fertilizer use can led to ammonia gas entering the atmosphere

    • can lead to acid raid and respiratory irritation for humans and animals

• Leaching

  • synthetic fertilizer use leads to nitrates leaching or being carried out of soil by water

1.6 Phosphorus Cycle

Learning Objective

• Explain the steps and reservoir interactions in the phosphorus cycle

Phosphorus Cycle Basics

Movement of phosphorus atoms and molecules between sources and sinks (very slow compared to other cycles)

• no gas phase

• because it cycles so slowly, phosphorus is a limiting nutrient

  • this means that plant growth in ecosystems is often limited by phosphorus availability

Note: rocks and sediments containing phosphorus are major reservoirs

Phosphorus Sources

Major natural source of P is weathering of rocks that contain P minerals.

• Wind & rain break down rock & phosphate is released and dissolved into water; rain water carries phosphate into nearby soils & bodies of water

Synthetic (human) sources of P

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

Assimilation and Excretion

Phosphorus is absorbed and assimilated into tissues for plants, animals assimilate by eating plants or other animals

Phosphorus is excreted through animal water, plant matter, and other biomass that is broken down by decomposers that return phosphate to the soil

Sedimentation and Geological Uplift

Sedimentation

• Phosphate doesn’t dissolve well in water and will form solid bits that fall to the bottom of water as sediment which can be compressed into rock over long periods of time

Geological Uplift

• tectonic plate collision forcing up rock layers that form mountains; P cycle can start over again with weathering and release of phosphate from rock

Eutrophication

The excess of nutrients

• fuels algae growth and can lead to a positive feedback loop

Algae blooms → Surface of Water becomes blocked → Sunlight does not reach plants killing them → Algae dies→ Decomposers use up oxygen in water to break down algae → Low Oxygen Levels kills fish → More Decomposers Use More Oxygen

1.7 The Hydrologic Cycle

Learning Objective

• Explain the steps and reservoir interactions in the hydrologic cycle

Water Cycle Overview

Movement of water between sources and sinks. States of matter as well as where water is moving are key in the water cycle.

Note: the ocean is the largest water reservoir whilst ice caps and ground water are some of the smallest (this water is fresh and useable for humans)

Evaporation

Sometimes called vaporization, is the process in which liquid water becomes water vapor (gas) in the atmosphere. (driven by the sun)

Transpiration

• process plants use to draw ground water from roots up to their leaves (driven by the sun)

Evapotranspiration

• amount of water that enters the atmosphere from transpiration and evaporation combines

Runoff

• rain that flows over earth’s surface and into a body of water

Recharges surface waters but can also carry pollutants into water sources.

Infiltration

• rain that trickles through the soil down into groundwater reservoirs

Recharges groundwater with rain but only if the ground is permeable.

• Permeable

  • able to let water pass through

1.8 Primary Productivity

Learning Objective

• Explain how solar energy is acquired and transferred by living organisms

Primary Productivity Basics

units: kcal/m^2/yr

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

High PP

• high plant growth

  • lots of food and shelter for animals

Ecosystems with high PP are usually more biodiverse than ecosystems with low PP

Calculating PP

Net Primary Productivity

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

Gross Primary Productivity

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

Respiration Loss

• Energy used up for respiration

Ecological Efficiency

• The portion of incoming solar energy that is captured by plants and converted into biomass

Note: Some ecosystems are more efficient than others

Trends in Productivity

• the more productive a biome is, the wider the diversity of animal life it can support

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

• shortage of any of these factors will lead to decreased NPP

1.9 Trophic Levels

Learning Objective

Explain how energy flows and matter cycles through trophic levels.

Trophic Levels

• Tertiary Consumers

  • animals that eat secondary consumers or carnivores and omnivores

• Secondary Consumers

  • animals that eat primary consumers or herbivores

• Primary Consumers

  • animals that eat plants

• Producers

  • plants “produce” (convert) sun’s light energy into glucose

1.10 Energy Flow and the 10% Rule

Learning Objective

• Determine how the energy decreases as it flows through ecosystems

Conservation of Matter and Energy

Matter & energy are never created or destroyed; they only change forms
1st law of thermodynamics:

• energy is never created or destroyed

2nd law of thermodynamics:

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

Biogeochemical cycles demonstrate conservation of matter (C/N/H2O/P)

Food webs demonstrate conservation of energy

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

1.11 Food Chains and Food Webs

Learning Objective

• Describe food chains and food webs, and their constituent members by trophic level

Food Web Basics

Shows how matter and energy flow through an ecosystem, from organism to organism

• Arrows in food webs indicate direction of energy flow

Food Web v Food Chain

Food chains just show one, linear path of energy and matter

Food webs have at least 2 different interconnected food chains

Interactions and Trophic Cascade

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

Trophic Cascade

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