Ecosystem

ECOSYSTEMS

Interaction of organisms with their physical environment through a flow of energy and a cycling of nutrients. All ecosystems run on energy captured by:
1. Detritivores: Dine on detritus (small particles of organic matter
2. Consumers: Heterotrophs, they feed of tissues, wastes and remains of producers. They are clasified by their diets:
  1. Herbivores: Feed from plants
  2. Carnivores: eat the flesh from animals
  3. Parasites: Feed of the tissues of their living hosts
  4. Omnivores: devour animal and plant materials
3. Decomposers: feed on organic wastes and remains
4. Primary producers: Autotrophs or self-feeders, they capture energy from the sun and use it in photosynthesi
5. Trophic levels: Positions of every organisms in a food chain. Graphically represented as ecological pyramids.
  1. 1st level: Primary producers
  2. 2nd level: Hervobores
  3. 3rd level: Carnivores
  4. 4th level: Detritivores and consumers
  5. Food chain: Description of who eats whom in one path of energy flow in an ecosystem.
6. Flow of energy through ecosystems:
  1. Biomass pyramid: depicts dry weight of orgnisms at each trophic level of an ecosystem.
  2. Primary production: Primary producers capture energy and convert it into biomass.
  3. Ecological efficiency: Tends to be greatest in aquatic systems, where primary producers usually lack lignin and consumers tend to be ectotherms.
  4. Energy pyramid: Diagram that depicts the energy that enters each trophic level.
BIOGEOCHEMICAL CYCLES:: Slow movement of a nutrient among environmental reservoirs and into and out of food webs.
1. Water cycle: Movement of water among Earth’s atmosphere. Sunlight causes evaporation, forming clouds and they fall as precipitation (rain, snow or hail) going back to the primary source.
  1. Watershed: Land area that drains into a particular stream or river.
  2. Soilwater: Water between soil particles.
  3. Aquifier: Porous rock layer that holds groundwater, drained through soil layers.
  4. Groundwater: Water in soil and aquifiers.
  5. Runoff: Water that flows over soil into streams.
  6. Fresh water makes up a tiny portion of the global water supply. Excessive water withdrawals threaten many sources of drinking water, irrigation methods for example.
  7. Eutrophication: Nutrient enrichment of an aquatic system.
2. Carbon cycle: Movement of carbon, mainly between the oceans, atmosphere and living organisms.
  1. 1. Plants take up carbon dioxide from the air for use in photosyntesis.
  2. 2. Carbon returns to air by aerobic respiration.
  3. 3. Carbon diffuses between the atmosphere and the ocean. (Bicarbonate forms when carbon dioxide dissolves in seawater)
  4. 4. Marine produces use bicarbonate in photosynthesis and marine organisms release carbon dioxide from aerobic respiration.
  5. Atmospheric cycle: Biogeochemical cycle in which a gaseous form of an element plays a significant role.
  6. 5. Some marine organisms incorporate carbon into their shells; when they die become part of sediments and over-time turn in limestone and chalik.
  7. 6. Burning of fossil fuels derived from the ancient remains of plants puts additional carbon dioxide into the atmosphere.
GREENHOUSE GASES AND CLIMATE CHANGE
1. Greenhouse effect: Caused by excess of carbon dioxide.
2. Greenhouse gas: Atmospheric gas that absorbs heat emitted by Earth’s surface and remits it, thus keeping the planet warm.
3. 2. More light energy reaches and warms Earth’s surface.
4. 3. Earth’s warmed surface emits heat energy, some of it goes to space and the rest is absorbed and emitted in all direction by greenhouse gases.
5. 1. Earth’s atmosphere reflects some sunlight energy back into space.
6. Global climate change: Long-term alteration of Earth’s climate.
NITROGEN CYCLE: Atmosphere is 80% nitrogen. Movement of nitrogen among the atmosphere, soil, water and food webs.
1. Nitrogen fixation: Incorporation of nitrogen from gas into ammonia.
2. Ammonification: Breakdown of nitrogen-containing organic material resulting in the release of ammonia an ammonium ions.
3. Nitrification: Conversion of amonium to nitrates.
4. Denitrification: Conversion of nitrates or nitrites to gaseous form of nitrogen.
5. Human activities disrupted the nitrogen cycle:
  1. Burning fossil fuels releases nitrous oxide, which is a greenhouse gas, into the air and destroys the ozone layer.
  2. Wastewater that escapes from septic systems is another source of nitrate pollution.
  3. Use of synthetic fertilizer encourages the production of nitrous oxide by bacteria. It is also a source of nitrates, which pollute drinking water.
PHOSPHORUS CYCLE: Movement of phosphorus among Earth’s rocks and waters, and into and out of food webs.
1. Sedimentary cycle: Biochemical cycle in which the atmosphere plays little role and rocks are the major reservoir. Weathering puts phosphates into water and producers take up dissolved phosphates.
2. Phosphate-rich wastes are a natural fertilizer, and phosphate from rocks can be used to produce fertilizer on an industrial scale.

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