ecosystems

• ecosystems are an open system and are a defined community of various organisms interacting with each other in a particular environment. these organisms are highly interdependent on one another to keep a balance in the equilibrium of the ecosystem, but the equilibrium is dependent on the influence of the biotic and abiotic factors which can cause positive feedback causing the environment to adapt to the change. as a result, the ecosystem may have surpassed its threshold to adapt due to significant change reducing resilience and sustainability it provides globally.
• primary productivity:

  • usually expressed in units of energy or dry organic matter
  • globally 243bn tonnes of dry plant biomass annually
  • total fixed energy by plants in a community through photosynthesis is know as gross primary productivity
• net primary productivity:

  • defined as the rate of accumulation of biomass/ energy
  • energy utilised during metabolic processes such as respiration are excluded from gross primary productivity
  • npp calculated primarily by an increase in the biomass in a unit per unit area
  • amounts of carbon retained in an ecosystem (biomass)nis equal to the difference between the amount of carbon produced through photosynthesis and the amount of energy that is used for respiration
• biomass:

  • term used in ecology for the mass of living organisms in a given ecosystem and it can refer to: mass of all living species in a given ecosystem known as the community biomass or the mass of one specie in the ecosystem the mass of decaying material inc leaf litter and decaying organic material on the forest floor, which can be a substantial component of an ecosytem
• biodiversity is the variety of life on earth in all forms and interactions. it's the most complex and sophisticated feature of the planet and is extremely vital in sustainability and keeping a balanced equilbrium
• decline of biodiversity by region:

  • north america 70%
  • latin america and carribean 94%
  • africa 60%
  • europe and centeral asia 18%
  • asia and centeral pacific 55%
• why does biodiversity matter:

  • food variety of insects and vertabrates
  • variety increase survival of disturbed plants increase resilience and stability
  • variety of genetics useful in survival and stability of the ecosystem
  • different organisms fulfill different roles e.g soil improved nitrogen fixers, deep rotted plants bring up nutrients from deep soil
  • some species work together so that both can survive commensalism e.g coral and zooxanthellae and fig wasps
• issues with high plant biodiversity:

  • diverse communities can be a result of fragmented and degraded sites where species richness due to presence of disturbance species e.g poppies
  • plant communities difficult to manage as different requirements
  • not always stable plant communities that are in equilibrium with the prevailing site characteristic climax vegetation more later usually have a lower biodiversity that preceding stages in succession ditto as dominant plants out compete others which then disappear
• simpsons diversity index:

  • measure used in ecology to quantify the diversity of a habitat/ community
  • takes into account both species richness and species eveness
  • index 0-1 0 means no diversity one dominant specie, 1 means infinite diversity species are in equal abundance
• biotic factors:

  • autotroph is an organism that can produce its own food using light, carbon dioxide and water and other chemical such as maghoghany trees
  • saprotroph is an organism that feeds on non living organic matter known as detruits at a microscopic level, and are considered critical to decomposition and nutrient cycle inc fungi
  • hetrotroph is an organism that cannot produce its own food instead takes nutrition from other sources or organic carbon mainly plant or animal inc brown throated sloth
• abiotic factors

  • influence the structure, distribution and behaviour and interrelationship between all organism in the system
  • varies among ecosystems
  • acquatic: ph, water depth, turbidity, salinity, and dissolved oxygen
  • terrestrial ecosystems: precipitation, temperature, altitude, soil nutrients, and sunlight