5 ecosystem
DESCRIPTION
TRANSCRIPT
Ecosystems and Communities
Ecosystem
• All the communities plus the physical factors in the environment in a given area, and how they relate to each other
Topics
• Energy
• Trophic levels
• Food chains and webs
• Chemical recycling
• Management practices
Energy
Light energy
PhotosynthesisGlucose Starch
Respiration
Released as ATP
ATP
• Provides energy for all living processes– Mechanical (movement)– Chemical (new molecules or cells)– Active transport (absorb nutrients)– Electrical (for nerves)– Bioluminescence (e.g. glow worms)
• One way energy flow
Humans
• Upset energy flow– Block out light– Remove food source
Trophic Levels
Energy Pyramids
• 1% light used for photosynthesis– Light falling on a leaf is
• Transmitted• Reflected • Absorbed
Food Chains and Webs
Human Affects
• Biological magnification– Chemicals and poisons become more
concentrated in body tissues as you go higher up the pyramid
– Top predators have the highest dose
• Remove part of the food chain– Cut down forests
• Remove producer• Remove prey - predator suffers• Remove predators - prey population “booms”
then “busts”
• Introduce exotic species– Rabbits eat grassland– Stoats and weasels
introduced to eat rabbits - ate native birds instead
– Deer (for sport) ate out beech forests
– Possums eat out pohutakawa
– German wasp competes with native birds (honey dew)
• Removal of too much of an organism
–Overfishing - not enough older fish to reproduce
–Overfarming - don’t return nutrients to soil - create dust bowls covered in weeds