Ecosystem, Biome, and Biogeochemical Cycle Review for Students

Community

All living organisms in an area

Individual

One organism (elk)

Population

Group of individuals of the same species (elk herd)

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)

Mutualism

Relationship that benefits both organisms (coral reef)

Commensalism

Relationship that benefits one organism & doesn't impact the other (birds nest in trees)

Competition

Organisms fighting over a resource like food or shelter; limits population size

Predation

One organism using another for energy source (hunters, parasites)

Parasitism

Relationship that benefits one organism & harms the other

Herbivores

(Plant eaters) eat plants for energy (giraffe & tree)

True predators

(Carnivores) kill and eat prey for energy (leopard & giraffe)

Parasites

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

Parasitoids

Lay eggs inside a host organism; eggs hatch & larvae eat host for energy

Symbiosis

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

Interspecific competition

Two different species competing for the same resource

Intraspecific competition

Two of the same species competing for the same resource

Resource partitioning

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

Temporal partitioning

Using resource at different times, such as wolves & 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

Biome characteristics

Defined by average annual temperature & precipitation

Nutrient availability in Tropical Rainforest

Nutrient-poor soil

Nutrient availability in Boreal forest

Nutrient-poor

Nutrient availability in Temperate forest

Nutrient-rich soil

Wetland

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

Estuaries

Areas where rivers empty into the ocean; mix of fresh & salt water

Salt Marsh

Estuary habitat along coast in temperate climates; breeding ground for many fish & shellfish species

Mangrove Trees

Trees with long, stilt roots that stabilize shorelines and provide habitat for many species of fish and shellfish.

Coral Reef

Warm shallow waters beyond the shoreline; most diverse marine biome on earth.

Mutualistic Relationship

Relationship between coral (animals) and algae (producers) where both species rely on each other.

Coral's Role in Carbon Cycle

Coral takes CO2 out of the ocean to create calcium carbonate exoskeleton and provides CO2 to algae.

Algae's Role in Carbon Cycle

Algae live in the reef and provide sugar (energy) to coral through photosynthesis.

Intertidal Zones

Narrow band of coastline between high and low tide where organisms must adapt to survive.

Adaptations in Intertidal Zones

Organisms like barnacles, sea stars, and crabs attach to rocks and have shells to prevent desiccation.

Open Ocean

So large that algae and phytoplankton produce a lot of earth's O2 and absorb a lot of atmospheric CO2.

Photic Zone

Area where sunlight can reach, allowing for photosynthesis.

Aphotic Zone

Area too deep for sunlight, where species rely on detritus or chemosynthetic microbes for energy.

Carbon Cycle

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

Carbon Sink

Reservoir that takes in more carbon than it releases, such as oceans, plants, and soil.

Carbon Source

Reservoir that releases more carbon than it takes in, such as fossil fuel combustion and deforestation.

Photosynthesis

Process that removes CO2 from the atmosphere and converts it to glucose.

Cellular Respiration

Process done by plants, animals, and microbes to release stored energy and releases CO2 into the atmosphere.

Direct Exchange

CO2 moves directly between atmosphere and the ocean by dissolving into and out of ocean water.

Ocean Acidification

Result of increased atmospheric CO2 leading to net movement of CO2 into the ocean.

Sedimentation

Process where calcium carbonate precipitates out as sediment and settles on the ocean floor.

Burial

Slow geological process that stores carbon in underground sinks like sedimentary rock or fossil fuels.

Fossil Fuels

Formed from fossilized remains of organic matter; their decomposition produces natural gas (CH4).

Extraction and Combustion

Digging up or mining fossil fuels and burning them as energy sources, releasing CO2 into the atmosphere.

Rate of Carbon Transfer

The rate at which fossil fuels are transferred into the atmosphere has altered the carbon cycle over the past 250 years.

Nitrogen Cycle

Movement of N-containing molecules between sources & sinks/reservoirs

Fixation

Conversion of atmospheric nitrogen (N2) into usable forms like NH3 or NH4

Assimilation

Process where plants take in NH4 or NO3 and incorporate it into new biomass

Ammonification

Conversion of organic nitrogen into ammonium (NH4) by soil microbes/decomposers

Nitrification

Aerobic bacteria convert ammonium (NH4) into nitrite (NO2-) and then nitrate (NO3)

Denitrification

Bacteria convert nitrate (NO3) into N2 gas, returning it to the atmosphere

Nitrogen Fixation

Conversion of atmospheric nitrogen (N2) into ammonium (NH4) or nitrate (NO3) for plant use

Biotic Fixation

Bacteria in soil and root nodules convert N2 into ammonia (NH3)

Abiotic Fixation

Processes like lightning or fossil fuel combustion convert N2 into usable forms

Limiting Nutrient

A nutrient that limits primary productivity, such as nitrogen in soil

Phosphorus Cycle

Movement of phosphorus compounds between sources, sinks, and reservoirs

Phosphorus Reservoirs

Rocks and ocean sediments are the largest reservoirs of phosphorus

Weathering

Slow breakdown of phosphorus-containing rocks releasing phosphate (PO4-3)

Eutrophication

Excess nutrients in aquatic ecosystems leading to algae blooms and oxygen depletion

Synthetic Sources of Phosphorus

Mining phosphate minerals and adding phosphates to fertilizers and detergents

Assimilation in Phosphorus Cycle

Plants absorb phosphorus and incorporate it into their tissues

Geological Uplift

Tectonic plate collision forcing up rock layers, restarting the phosphorus cycle

Human Impacts on Nitrogen Cycle

N2O (nitrous oxide) produced by denitrification contributes to climate change

Algae Blooms

Rapid increase in algae due to excess nutrients, blocking sunlight and killing aquatic plants

Positive Feedback Loop in Eutrophication

Lower oxygen levels lead to more dead organisms, which further deplete oxygen

Nitrogen Cycle Steps

Fixation, assimilation, ammonification, nitrification, and denitrification

Main Nitrogen Reservoir

Atmosphere, primarily as N2 gas, which is not usable by plants or animals

Importance of Nitrogen

Essential for building DNA, proteins, and chlorophyll in plants

Phosphorus as a Limiting Nutrient

Phosphorus is often limiting in aquatic and terrestrial ecosystems due to slow cycling

Animal Assimilation of Phosphorus

Animals assimilate phosphorus by consuming plants or other animals

Hydrologic Cycle

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

Water Cycle

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

Precipitation

Atmospheric gas that becomes liquid on land or surface water.

Evaporation

Process where liquid water becomes water vapor (gas) in the atmosphere.

Evapotranspiration

Amount of H2O that enters atmosphere from transpiration + evaporation combined.

Transpiration

Loss of water vapor from leaves into atmosphere.

Stomata

Leaf openings that allow water to evaporate into the atmosphere from the leaf.

Runoff

Precipitation that flows over earth's surface into a body of water.

Infiltration

Precipitation that trickles through soil down into groundwater aquifers.

Groundwater

Aquifers that are important freshwater reservoirs for humans & animals.

Primary Productivity

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

Net Primary Productivity (NPP)

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

Gross Primary Productivity (GPP)

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

Respiration Loss (RL)

Plants use up some of the energy they generate via photosynthesis by doing cellular respiration.

Ecological Efficiency

The portion of consumed (or captured) energy that can be passed from one trophic level to the next.

10% Rule

Energy transfer is roughly ~10% efficient from trophic level to trophic level.

Biodiversity

Ecosystems with high primary productivity are usually more biodiverse than ecosystems with low primary productivity.

Factors affecting NPP

Water availability, higher temperature, and nutrient availability lead to high NPP.

Conservation of Matter & Energy

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

1st Law of Thermodynamics

Energy is never created or destroyed.

Biogeochemical Cycles

Cycles that involve the movement of elements and compounds through living organisms and the environment.

Pollutants in Runoff

Runoff can carry pollutants into water sources.

Reservoirs of Water

Groundwater (aquifers) & surface waters (lakes/rivers) are important freshwater reservoirs.

Energy from the Sun

Drives the hydrologic cycle.

Conservation of Matter

Cycles demonstrate conservation of matter (C/N/H2O/P)