D4.2 Stability & Change

Stability depends on:

• Constant energy supply

• Nutrient Cycling

• Genetic variation within a species

• Stable climate

Eutrophication

Water bodies having too many nutrients

Tipping point

A level of disturbance that causes quick change that is difficult to reverse

Mesocosms

Small replicates of ecosystems that allow for controlled experiments

Advantages + disadvantages of mesocosms

Advantage	Disadvantage
replicable, easy control factors	impossible to replicate all-natural factors

Keystone species

Organism that has a disproportionate effect in a community

Sustainable harvesting

Replacement must be greater or equal to harvesting rate

Strategies to increase harvesting in Brazil nuts

• Do not harvest all of the nuts

• Leave enough to grow into new trees → This is the stable harvesting

Strategies to increase harvesting in Cod fish

• Protected breeding zones (no fishing)

• Increase net hole size (allow young, small fish to escape)

• Set harvesting limits

• Monitor populations

Tilling

Process of turning the soil at the end of a season

Nutrient leaching

Fertilisers dissolving (leaking) into the water bodies next to it

Carbon footprint

How much energy and fuel it takes to keep agricultural progress going

Process of eutrophication

• Nitrogen and phosphorus-rich fertilizers on farmland

• Runs off into bodies of water

• Algae bloom on the surface

• Block light

• Kills plants on the bottom

• Decomposition consumes all of the oxygen

• Increases BOD (biological oxygen demand)

Bioaccumulation

Increase in toxin levels throughout an organism’s life

Biomagnification

Increase in toxin levels throughout trophic levels

Non-biodegradable

Unable to break down fully (e.g: plastic)

Macroplastic

Large, visible waste

Microplastic

Small plastic fragments that come from degradation of large pieces

Rewilding

Removing effect of human intervention to allow natural processes to restore ecosystems

Ecological Succession

Succession starting with an environment with few living thing organisms

Cyclical Succession

Patterns of change and succession that occur either naturally or due to periodic disturbances

Climax community

A stable, unchanging ecosystem

Plagioclimax

An alternative climax community that results from human activity