Nutrient cycling

Ecological productivity

• Production in ecosystems is the accumulation of carbon compounds in biomass

• Biomass (total quantity of living organisms of a species) accumulates when living organism grow

• Both autotrophs and hetertrophs produce biomass by growth and reproduction

Primary production

• Rate at which producers accumulate carbon compounds in their biomass

• Plants and other autotrophs are primary producers because they synthesize carbon compounds from simple substances

• Gross primary production is the total biomass of carbon compounds made in plants by photosynthesis

  • Net primary production is GPP minus the biomass lost due to respiration of the plant (NPP = GPP - R)

• Both GPP and NPP are measured over long time intervals at the ecosystem level 

• Biomes vary in their capacity to accumulate biomass, depending mainly on the rate of photosynthesis

seconday production

• Accumulation of carbon compounds in biomass by animals and other hetertrophs 

• Cell respiration results in the loss of carbon compounds and therefore the loss of biomass in every trophic level

• Consequentnly, net production is always lower than groww production and secondary production is lower than primary production

carbon cycle

• Carbon cycle: process that allows carbon atoms to be exchanged between earth’s systems

• In the carbon cycle, carbon is stored in various reservoirs know as sinks

• A carbon sink is any environment that abbsorbs more CO2 from the atmosphere than it releases

  • Ex: forests, oceans

  • These contributes to increasing levels of CO2

source vs sink

• Whether an ecosystem is a source or sink depends on the balance that exists between photosynthesis and respiration

  • Is photosynthesis excess respiration, then there is net uptake. The ecosystem acts as a sink

  • Is respiration excess photosynthesis, there is a net release. The ecosystem acts as a  source

carbon fluxes

• Flux: movement of carbon between the earth’s spheres (litosphere, atmosphere, hydrosphere, biosphere)

• 3 main types of carbon fluxes

  • Photosynthesis: absorption of carbon dioxide from air or water and it's conversion into carbon compounds

  • Feeding: gaining carbon compounds from other organisms

  • Respiration: release to the atmosphere carbon, dioxide produced by respiring organisms 

• Aerobic respiration relies on O2 produced through photosynthesis

• Respiration produces CO2 as waste → released into atmosphere → used for photosynthesis

  • Reciprocal relationship forms an essential interaction between autotrophic and hetetrophic organisms

combustion

Carbon sink	How it was formed
Natural gas and oil	Deep burial of organic matter under sediments, high temps causes chemical changes and produce oil and natural gas
coal	Accumulation of wood and other plant matter in swaps, burried under sediments
peat	Incomplete decomposition of dead plant matter, acidic and anaerobic conditions in waterlogged soil and swamps
biomass	Plant biomass is derived from photosynthesis

• When any of these material burn in air, CO2 is produced and released in the atmosphere

keeling curve

• Annual fluctuations: Every year the concentration of of CO2 increases between octomber and may, then decreases from May to october, this issue to global imbalances of photosynthesis and cell respiration

• Long term trend: the curve shows a constant increase in CO2 levels over the years, this upward trend is primarly attributed to the significant impact of human activities, particulary the combustion of fossil fuelds

nutrient cycling

• In addition to carbon, all the chemical elements required by living organisms are recylced within ecosystems

• The reclying process ensures the continual availability of essential elements for maintaiining lige

• Decomposers play a vital role in t his recycling of matter by breaking fown organic compounds and returning the nutrients back into their environment

• Recycling of all elements is essential for the sustainability of ecosystems