APES Test 2. Ecosystem Slides Flashcards
Ecosystem Definition
A biological community of interacting organisms and their physical environment.”
Biological community: an interacting group of various species in a common location.
interaction between abiotic and biotic factors structures ecosystems
Things like……
Weather/Climate
Soil Type
Topography
Natural Features (Rivers, Lakes, Oceans, etc.)
Influence what plants and animals can live in an ecosystem
Symbiosis is a close and long-term interaction between two species in an ecosystem. Types of symbiosis include:
Mutualism: Both Benefit
Commensalism: One Benefits
Parasitism: One Benefits, One is Harmed
Competition
Competition can occur within or between species in an ecosystem where there are limited resources.
Resource partitioning
using the resources in different ways, places, or at different times—can reduce the negative impact of competition on survival.
Niche
the role an organism plays in an ecosystem- is usually similar between competitors in some aspect- but not always
Biomes
Geographical region characterized by specific climatic conditions, flora and fauna.
You need to know the biomes and their general climate conditions (wet/dry, warm/cold, seasons, etc.)
A biome contains characteristic communities of plants and animals that result from, and are adapted to, its climate.
Biomes are recognizable places if you know what you are looking for, because they have a specific community of organisms.
The worldwide distribution of biomes is dynamic; the distribution has changed in the past and may again shift as a result of global climate changes.
Range loss and range change……sound familiar??
Biomes can shift to new areas as climatic conditions change
Ice Age ~ 25,000 years ago- we had glaciers here, boreal forest, and even some tundra
A lot changes in a short period of time!
Freshwater biomes include streams, rivers, ponds, and lakes. These freshwater biomes are a vital resource for drinking water.
97% water= saltwater
Very little fresh water on earth
Desalination is expensive- drinking water is critical for human and ecosystem survival
Streams and Rivers- discharge water, narrow and long, flow (generally N- S)
Ponds and Lakes- stores of water, usually discharged by streams and rivers
marine biomes
Marine biomes include oceans, coral reefs, marshland, and estuaries. Algae in marine biomes supply a large portion of the Earth’s oxygen, and also take in carbon dioxide from the atmosphere.
Know these different types and memorize them.
Recognize that critical role that algae play in providing oxygen for the planet
The global distribution of nonmineral marine natural resources, such as different types of fish, varies because of some combination of salinity, depth, turbidity, nutrient availability, and temperature.
Salinity- varies by depth temperature. Different organisms have different tolerances
Turbidity- clarity of the water (amount of light that can pass through). Note amount of light itself also varies with depth.
Nutrient Availability- depends on organisms and ecological community, terrestrial inputs are relatively insignificant
Temperature: Varies considerably with latitude and depth; ocean currents can circulate heat and break this relationship to some degree
The Nitrogen Cycle
Nitrogen starts in the atmosphere as Nitrogen Gas (N2)- it comprises about 78%!
This nitrogen is poorly reactive and not useful to organisms
It must be fixed- by nitrogen fixing bacteria, to become biologically available
Nitrogen Fixation
Biological demand for nitrogen is high, but N2 gas is useless to plants
Bacteria, often in the root nodules of legumes, can ‘fix’ nitrogen gas
Nitrogenase (enzyme) ——> Nitrogen gas to ammonia
Ammonia is more biologically available, but can be ‘fixed’ further to other forms
Lightning can also fix nitrogen, but this accounts for <10%
The Nitrogen Cycle (2)
Ammonia is the product of nitrogen fixation
Nitrifying bacteria can ‘nitrify’ ammonia into nitrites and nitrates
NO2- (nitrite) and NO3- (nitrate) are different forms of biologically available nitrogen and are useful to a wide range of plants- but nitrates are broadly a much more useful form of nitrogen
The Nitrogen Cycle (3)
NO3 (nitrate) is now able to be used by plants- assimilation is the absorption of nitrogen into plants as nitrate
Animals eat plants that have incorporated nitrates into their tissue
Animals die, and ammonification (mineralization), a part of the decomposition process, breaks this nitrogen down into ammonium
Ammonium is nitrified into nitrite and then nitrate
The Nitrogen Cycle (4)
Nitrogen can reenter the atmosphere from the terrestrial realm by the process of denitrification- also performed by bacteria
Nitrogen is a limiting nutrient for NPP and plant growth- some plants require much more of it than others
PHosphorus Cycle
Major Takeaways:
Phosphorus in small amounts is critical for plant growth via cell division
Phosphorus is found mostly in rocks (naturally) and can enter ecological systems via volcanoes and leaching from rocks/sediments
Fertilizer often contains phosphorus which can runoff in excessive quantities
Water Cycle
Major Takeaways:
Sun drives processes via thermal energy; oceans, glaciers, and lakes can be major sinks
Carbon Cycle
Major Takeaways:
Long and short term processes; ‘fast’ and ‘slow’ carbon cycles work together
High amounts carbon typically stored in long term sinks- like limestone, shale (oil), peat
Geological Carbon Cycle
Fast carbon cycle, biological- carbon from atmosphere is photosynthesized by plants, accumulates in soils; decomposition and respiration return carbon to atmosphere
Ocean can dissolve atmospheric carbon dioxide into carbonic acid, which can be used by phytoplankton for photosynthesis; some accumulates in deep ocean sediments where it will eventually lithify into rock (limestone)
