Populations and sustainability Flashcards
What is meant by carrying capacity?
The maximum population size that can be maintained over a period in a particular habitat.
What are density independent limiting factors?
- Examples?
Limiting factors that act irrespective of the size of population.
- Temperature, pollutants, natural disasters
What are density dependent limiting factors?
- Examples?
Limiting factors that influence a population more or less strongly as population size changes.
- Food, water, light, shelter, nesting sites, parasitism
What is preservation?
Maintenance of habitats and ecosystems in their present condition, minimising human impact/ intervention.
What is conservation?
An active management process involving human intervention to maintain biodiversity.
What are ethical reasons for conservation?
Every species has value and humans have an ethical responsibility to look after them (subjective argument).
What are some examples of conservation strategies?
- Provide extra food to raise carrying capacity
- Move individuals to enlarge populations or encourage dispersion of individuals between fragmented habitats
- Control predators and poachers
- Vaccinate individuals against disease
- Restrict process of succession by coppicing, mowing or grazing
- Restrict dispersal of individuals by fencing
What are economic and social reasons for conservation?
- Plants and animals are a valuable food source. Genetic diversity in wild strains could be used to improve yield in animals and plants through disease resistance and drought tolerance
- Valuable source for potential beneficial drugs
- Natural predators of pests can act as biological control agents, rather than causing pollution with artificial chemicals
How is small scale timber production made sustainable?
Coppicing- stem of a deciduous tree is cut close to the ground and new shoots grow from the cut surface and mature into narrow stems. The process is repeated.
Rotational coppicing - cut a different section of the wood each year
What are standards?
Tress that are left to grow larger without being coppiced.
How is large scale timber production made sustainable?
- Any tree that is harvested is replaced by another tree, either grown or naturally planted
- Local people should benefit from the forest
- Selective cutting - removing only the largest, most valuable trees
- controlling pests and pathogens
- Only plant particular species where they will definitely grow well
- Position trees at an optimum distance apart to reduce competition
This ensures trees supply more wood so less trees have to be harvest.
How are fisheries made sustainable?
Raising fish stocks in aquaculture restricts the impact on oceanic fish stocks.
Marine Stewardship council has 3 principles:
- Over-fishing must be avoided and if it occurs, reduce fishing to let stocks recover
- No permanent damage to local habitat and effect on species is minimised
- A fishery must adapt to changes in circumstances and comply with local, national and international regulations.
What are human impacts on UK peat bogs?
Overgrazing by farmers causes a loss of moss species, soil compaction, increases water run off and erosion.
What is the conservation activity to protect peat bogs
The Environmental Stewardship Scheme supports sustainable use of peat bogs by reducing the amount of livestock, removing livestock over winter and reducing water run off.
What are some negative human impacts on the Terai region in Nepal?
- Expansion of agriculture into forested areas
- Grazing from farm animals
- Over-exploitation of forest resources
- Replacement of traditional crops with modern ones
