Ecosystem concepts

Ecosystem concepts

1. Biosphere

   • Area between Earth and atmosphere where all life exists.
     • Includes all three parts of the physical environment; atmosphere, hydrosphere, lithosphere.

2. Biomass

   • Sum total of all living matter within biosphere at any given time.
     • expressed as dry weight of tissue per unit area E.g. tonnes/hectare
   • Mainly of terrestrial origin due to veg efficiency on ratios of 100 to 1 compared to oceans.
   • Animal biomass greatest in rainforests.
   • Oceanic biomass greatest in tropical reefs.

3. Standing crop

   • Characteristic biomass of a particular ecosystem accumulated over time.

4. Environment

   • Collective term, includes all conditions in which an organism lives.
   • Abiotic (physical, non-living) Biotic (living).
     • Abiotic includes temp, water, light, wind, gases, pH, nutrients. Biotic is all living organisms.

5. Ecosystem

   • A community of living organisms and non-living things working together. Life cycles of all organisms are interlinked to the environment.

6. Community

   • describes all populations of species within a habitat.

7. Population

   • All individuals within a particular species within a habitat.

8. Biome

   • Large global ecosystem.
     • It is named after the most dominant veg found there E.g. tropical rainforest.
   • will contain climax communities
   • Biome type is usually controlled by climate but economic development has changed the nature of some biomes.
     • typography, soil (edaphic) and biotic factors control biome nature too.

9. Dead organic matter (DOM)

   • All dead, decaying plant and animal remains that make up surface litter and soil humus.
   • Important to ecosystem, may be greatly in excess of biomass in weight.
     • E.g. greater in temperate grasslands where DOM exceeds living biomass 5:1.

10. Habitat

    • The physical env within which an organism lives.
    • Used on three different scales: macro (continental) - meso (regional) and micro (small microscopic scale).
    • Organisms must be adapted to suit habitat. It must fall within the ecosystems ecological niche.
    • Four factors influence habitat: Climate (light, temp, moisture, exposure) Topography (altitude, temp, slope angle), Edaphic aspects (soil chemistry, nutrients, moisture) and biotic aspects (grazing influences and human activity).
      • In aquatic habitats, water chemistry and light penetration also vital.