6.5 Ecosystems

• Niche

  role and organism plays in its habitat. no two organisms can of the same niche can exist in the same ecosystem- competition
• Abiotic factor - oxygen availability

  water logged - less oxygen. less aerobic respiration, less ATP, less active transport and the uptake of mineral ions and water cannot enter via osmosis
• Importance of soil

  1. provides minerals
  2. water for photosynthesis
  3. anchorage for roots
• Biomass transfers through ecosystems

  1. Transfer of biomass from one trophic level to another
  2. Producers - make their own food
  3. Primary consumers - herbivoers that consume producers
  4. Secondary consumers --> tertiary
  5. Saprobionts - decomposers - release nutrients back into ecosystem
• Formula for efficiency of biomass transfer

  .

  A) transferred

  B) intake

  
• How human activity can manipulate transfer of biomass

  Manipulate environment to favour plant species that we can eat. create simple food chains by reducing number of trophic levels ensures that as much energy as possible transferred into biomass that humans can then eat
• How do u measure biomass

  Land - grams per square metre $gm^{-2}$

  Water - grams per cubic metre $gm^{-3}$
• Energy losses at each trophic level

  1. Not all energy avalibe is used for photosynthesis; not correct wavelength, reflected or transmitted
  2. water avalibitly limits photosynthesis
  3. No all parts of biomass are edible or digestible by consumers
  4. Energy lost as heat during movement/respiration or in excretory materials
• Gross primary production

  Total amount of solar energy that plants convert to organic matter, store it as chemical energy in their biomass
• Net Primary Production

  chemical energy available to the next trophic level after accounting for respiratory losses
• How to calculate net primary production

  NPP = GPP - R

  (R = respiratory losses)
• Nitrogen Cycle

  1. Nitrogen fixation; N2 converted into NH4+. reduction reaction. Azotobacter - decomposed by saprobionts, nitrogen-rich compounds are released, Rhizobium - in nodule of leguminous plants. obtain carbohydrates from plants while providing it with amino acids
  2. Nitriifcation (1) - nitrosomans convert NH4+ into nitrite ions (NO2-). oxidation.
  3. Nitrification (2) - nitrobacter convert NO2- into NO3-. oxidation
  4. Ammonification - converts nitrogen-containing compounds into NH3 or NH4+. eecreted and the saprobiotic microorganisms fed then release NH4+
  5. Dentrification - NO3- back into N2, anaerobic and waterlogged conditions. reduction
• Carbon Cycle

  1. Photosynthesis - removes CO2 from atmosphere and converts it into organic compounds
  2. Respiration - release CO2 back into atmosphere
  3. Decomposition- Dead organic matter broken down by microorganisms and release CO2
  4. Feeding - passed from autotroph to heterotroph. biomass transfer
  5. Combustion of fossil fuels - relates CO2
  6. Dissolution of CO2 in oceans removes
  7. volcanic activity
• Importance of carbon cycle

  Ensures continuous avalibitly fo carbon for organisms. used to produce glucose and other organic matter which is passed through food chains
• Carrying Capacity

  Maximum population size that can be indefinitely supported by an environment
• Climax community

  Stable community of organisms that exists as at the final stage of sucession
• Deflected Succession

  type of secondary succession where human activity/external influence interferes with natural progression preventing it from reaching climax community
• Plagioclimax

  stable ecosystem that has formed due to ongoing human activity, prevents natural succession
• Primary succession

  1. Pioneer species (such as lichen) colonies bare rock. they can survive harsh abiotic factors. their death and decay make a thin layer of soil
  2. Moss and smaller plants can serve and increase the depth of the soil and nutrient content. abiotic becomes less harsh
  3. cycle continues - larger plants can survive
  4. Environment becomes less suitable for the species before, gets outcompeted
  5. Species richness and biodiversity increases
• Secondary Succession

  Sucession has been disrupted. Succession starts again but soil is already there. no starting on bare rock