Dynamics of Ecosystems Flashcards
What is included in an ecosystem?
- organisms
- abiotic environment: the non living components of any environment
- these two aspect co-occur and interact
What are biogeochemical cycles?
- chemicals moving through ecosystems
- biotic and abiotic
- usually cross boundaries of ecosystem
What ways can carbon be changed?
- Carbon fixation: metabolic reactions that make non-gaseous organic compounds from gaseous inorganic ones
ex. photosynthesis - Aerobic cellular respiration releases CO2 from organic compounds
- Methanogens: produce methane by anaerobic cellular respiration
- Carbon can pool in certain places during the cycle (oceans, atmosphere, sediment as fossil fuels, layers of rock, burning of fossil fuels)
Describe aspects of the hydrologic cycle?
- availability determines nature and abundance of organisms present
- can be synthesized and broken down: synthesized during cellular respiration, broken down during photosynthesis
Describe the water cycle?
- liquid water from earth’s surface evaporates into atmosphere directly from oceans, lakes, etc
- this then cools and falls to surface as precipitation
- groundwater: aquifers are permeable underground layers of rock/sand/gravel that are saturated with water
What are some effects of the disruption of the water cycle?
- changes in water supply can alter nature of ecosystem
- deforestation disrupts local water cycle
What four forms does the Nitrogen cycle occur in?
- Molecular nitrogen
- Ammonia
- Nitrate
- Organic molecules
Describe the Nitrogen cycle?
- some organisms can change it with nitrogen fixation: N2 to NH3 to NO3-
- or they can change it back: NO3- to N2
- rest is tied up in organisms and their metabolic and digestive wastes
- nitrogenous wastes and fertilizer alter global nitrogen cycle
- humans have double amount of useable nitrogen form in soil and water
Describe the Phosphorus cycle?
- Plants and algae absorb free inorganic phosphate
- animals eat plants/other animals to obtain phosphorus and excrete much of it
Describe limiting nutrients?
- Nitrogen limited soil has resulted in carnivorous plants
- Nitrogen is the limiting nutrient for algal populations in 1/3 of world’s oceans
- Nitrogen and phosphorus can be limiting nutrients for terrestrial and aquatic ecosystems
Describe thermodynamics?
- concerns heat, energy, and work
- first law: energy is neither created/destroyed, it changes forms
- second law: whenever organisms use energy, some is converted to heat
What are trophic levels?
-it’s the level an organism feeds at
What is the bottom trophic level?
- Producers: synthesize organic compounds of their bodies from inorganic precursors
- AKA autotrophs
- Photoautotrophs: light as energy source
- Chemoautotrophs: energy from inorganic oxidation reactions
What are upper trophic levels?
- Consumers: can’t synthesize organic compounds from inorganic precursors
- must consume their organics
- AKA heterotrophs
- herbivores: eat plants
- primary carnivores: eat herbivores
- secondary carnivores: eat primary carnivores or herbivores
- detritivores: eat decaying matter
Describe what happens to the chemical-bond energy when autotrophs are consumed?
- some chemical bond energy is left in the autotrophs they eat
- amount of chemical bond energy decreases as energy is passed from one trophic level to the next
Describe the relationship between trophic levels and available energy?
- the number of trophic levels is limited by the energy available
- the decline of chemical bond energy limits top carnivores an ecosystem can support
- reduction of energy and productivity also reduces biomass and number of individuals as you move up trophic levels
What is a trophic cascade?
-process by which effects exerted at one level flow to influence two or more other levels
What is the top-down effects and the bottom-up effects?
- Top-down: when effects flow down through a trophic chain
- Bottom-up: when effect flows up through trophic chain
Describe island biogeography?
- Island is like a tiny ecosystem
- They have limited room and resources
