On The Wild Side Flashcards
Biosphere
The part of the Earth and its atmosphere that is inhabited by living organisms
Abiotic factors definition
Physical and chemical factors (soil type, climate)
Biotic factors definition
Factors determined by organisms (density dependent: related to the size of the population relative to area available)
Why does a particular species live in a particular area?
Because it is adapted and is able to survive and reproduce there. (or it was deliberately introduced and maintained by humans)
Abiotic factors examples:
Solar energy input
Climate
Topography (altitude, slope, aspect)
Oxygen availability
Edaphic factors (soil factors)
Pollution (air, water, land)
Catastrophes (earthquakes, floods, volcanic eruptions, fires)
Biotic factors example:
Competition
Grazing, predation, parasitism (one organism benefits another in this relationship)
Mutualism (relationship where both partners benefit)
What may there be competition for?
Food, water, light, space
Interspecific or intraspecific
What is solar energy input affected by?
Latitude, season, cloud cover, changes in the Earth’s orbit
When is oxygen availability particularly important?
In aquatic systems (eg fast flowing streams better oxygenated than stagnant pools)
What are edaphic factors and what are they affected by?
Factors relating to soil: pH, mineral salt availability, soil texture,
Affected by geology
What are anthropogenic factors?
Factors arising from human activity (biotic or biotic)
The impact of humans on the world environment is far greater than that of any other species.
Examples of anthropogenic factors:
Deforestation, grazing, moor/burning
Adaptations of a polar bear:
Thick fur - insulation
Long oily outer hairs - easily shed water
Finer inner hairs - provide insulation by trapping air
Small ears and tail
Long nose w several passages
Thick layer of fat under skin
Why can the tundra grasses better withstand grazing than other tundra vegetation?
(All grass) grow from the base, rather than the tips
What is the tundra?
The worlds most northerly land ecosystems where the tree growth is hindered by very low temperatures. Not a lot of rain or wind.
(In the Arctic and tops of mountains are tundra ecosystems)
Succession
The ecological process in which one community progressively changes into another.
(Eg The first organisms to colonise bare rock, for example, are algae and lichens - they’re the only organisms which can survive in the demanding conditions, they start to break up the rock surface allowing organic material to accumulate and soil to form…in this way they change the habitat and make it suitable for other species)
Primary succession
Starts in newly formed habitats where there has never been a community before
Pioneer species
First organisms to colonise a newly formed habitat/ a habitat that has been cleared of vegetation
(the only species that can cope w the demanding conditions eg extremes of temperature, lack of soil)
What are the pioneer species on bare rock?
Lichens and algae
Climax community
The different species of organisms that make up the final stage of an ecological succession.
(The nature of the climax community depends on environmental conditions eg climate)
Secondary succession
A succession which starts where an existing community has been cleared.
Eg Successions that start after fires
Deflected succession
A community that remains stable only because human activity prevents succession from running its course.
Eg sheep grazing prevents grassland to develop into woodland
