D4.2 Stability and Change Flashcards
(21 cards)
Stability
Ability of a system to persist indefinitely due to mechanisms operating within it
Requirements for stability in ecosystems
- Sufficient supply of energy
- Recycling of nutrients
- Genetic diversity
- Climatic variables in tolerance levels
Tipping point
Point at which an ecosystem can no longer cope with environmental change, and ecosystem shits from one state to another
Mesocosm
Self contained system set up for ecological experiments
Keystone species
Species whose activity has disproportionate effects on the structure of an ecological community
Factors effecting sustainability of agriculture
- Soil erosion
- Leaching of nutrients
- Supply of fertilizers and inputs
- Pollution due to agrochemicals
- Carbon footprint
Soil erosion
When land is cleared, thin layer of topsoil can be eroded, results in decrease in productivity of soil
Leaching of nutrients
When rainfall/irrigation dissolves nutrients in soil and carries them away, they end up in waterways and contribute to algae growth and eutrophication
Supply of fertilizers
Farmers use chemical fertilizers to increase levels of nutrients in soil, production is expensive and energy inefficient
Pollution due to agrochemicals
Chemical pesticides can contaminate soils and be carried away to waterways
Carbon footprint
Total amount of greenhouse gases generated by activities
Eutrophication
Aquatic environment becomes enriched with nutrients from runoff and leaching
Chain reaction from eutrophication
Excess nitrates and phosphates -> growth of algae -> blocks sunlight -> plants under surface die -> increase amount of organic material available to decomposers -> increase in bacterial populations -> more oxygen needed for respiration -> less oxygen in water -> aquatic animals cannot get enough O2, die
Biochemical oxygen demand (BOD)
Oxygen needed by bacteria in a body of water
Biomagnification
Increase in concentration of a toxic at each successive trophic level in food chain
Rewilding
Approach to restoring ecosystems that reduces human intervention
Rewilding strategies
Reintroduction of apex predators and keystone species
Re-establishment of connectivity of habitats over large areas
Minimization of human impact
Ecological succession
Series of progressive changes in species composition of ecological community over time
Primary succession
Newly exposed rock is colonized by living things for the first time
Secondary succession
Area that was previously occupied by living things is disturbed then re-colonized
Climax community
Final, stable stage of ecological succession, most adapted community
