Impact of Environmental Change | Biology for Grade 10 PDF Download

Changing Environments

• Environmental change (often as a result of human activity) can affect the distribution of species within ecosystems. Being able to evaluate these changes when provided with appropriate information is an important biological skill
• Changes in the environment can cause the distribution of living organisms to change
• A change in distribution means a change in where an organism lives
• Some changing environmental factors that can affect the distribution of organisms include:
  • Temperature
  • Availability of water
  • Composition of atmospheric gases
• These changes may be seasonal, geographic or caused by human interaction

Effects on Distribution

Temperature

• Organisms have adaptations that enable them to survive within a certain temperature range
• As climate change occurs and average temperatures rise, the distribution of species is changing
• Eg. the distribution of some plant, bird and insect species in Europe is spreading northwards into areas they were not previously able to inhabit, as these areas now have higher average temperatures as a result of global warming

Solved Example

Their results table is shown below. 

What does the result table show happened to the temperature along the mountain transect?

As The Student Moved Up The Mountain And Height Above Sea Level Increased, The Temperature Steadily Decreased. For Example, At 400 M The Temperature Was 17.3 °C And At 1200 M The Temperature Was 13.1 °C.

What does the result table show happened to plant species richness along the mountain transect? 

As The Student Moved Up The Mountain And Height Above Sea Level Increased, The Mean Number Of Plant Species Per Quadrat Decreased, Indicating That Plant Species Richness Is Decreasing. For Example, At 400 M The Mean Number Of Plant Species Per Quadrat Was 6 And At 1200 M The Mean Number Of Plant Species Per Quadrat Was 2.7.

What limitations might there be in drawing this conclusion?

We Cannot Say For Certain Whether The Decrease In Plant Species Richness Was Caused By Height Above Sea Level, Temperature Or Another Abiotic Factor Such As Moisture Or Light. Without Further Investigation, Such As Sampling At Other Sites With Similar Altitudes But Different Temperatures, We Are Only Able To Say That These Factors Are Linked To Plant Species Richness.

Availability of water

• All organisms require water to survive, either directly (water is essential for the biological processes that sustain living organisms) or indirectly (water may provide a habitat for species and is essential for the growth of plants that support whole food chains and food webs)
• Eg. every year in Africa, wildebeest migrate first northwards and then southwards again, following the rainfall as this provides them with fresh grazing and water 

Composition of atmospheric gases

• There are many ways in which the distribution of organisms can be affected by atmospheric gases:
  • Oxygen is required for aerobic respiration in plants and animals
  • Some aquatic animals (such as fish) can only survive in water with high oxygen concentrations
    • As pollution increases in freshwater systems, growth of anaerobic microorganisms is encouraged which can lead to a drop in oxygen when they die as a result of decomposition, fish cannot survive in these conditions
• Carbon dioxide is required for photosynthesis in plants (CO₂ concentration affects the rate of photosynthesis)
• Some species are very sensitive to air pollution
  • Eg. some species of lichen are not able to grow where sulphur dioxide is present (produced during certain industrial processes due to the combustion of fossil fuels)