B4a-ecology In The Local Environment Flashcards
What is a population?
All the organisms of one species in a habitat
What are two ways to estimate population size?
- scaling up from a small sample area
- capture recapture method
Describe a method to estimate population size by scaling up from a small sample area?
1) count all organisms in a 1m2 quadrat
2) multiply the number of organisms by the total area of the habitat
What is the effect of sample size on the accuracy of an estimate of population size?
The bigger the sample size, the more accurate your estimate of the total population is likely to be
Describe the capture recapture method
1) capture a sample of population and mark the animals
2) release them back into the environment
3) recapture another sample of the population
4) count how many are marked
5) use equation
What are the assumptions when using the capture recapture method?
- no death, immigration or emigration
- identical sampling methods
- marking not affecting survival rate
What is an ecosystem?
All the organisms living in a particular area, as well as all the non living conditions
What is a habitat?
The place where an organisms lives
What is a community?
Populations of different species in habitat
How are ecosystems self supporting?
They contain everything they need to maintain themselves. Water, nutrients and essential elements
Describe how to map the distribution of organisms in a habitat using a transect line
- mark out a line using a tape measure
- place quadrats next to each other all the way along the line
- count and record the organisms you find in the quadrats
What is zonation?
Zonation is the gradual change in the distribution of species across a habitat
How can a gradual change of an abiotic factor result in the zonation of organisms in a habitat?
Example:
In a coastal habitat, changes in salinity and soul depth result in zones where different types of plants grow
What are abiotic factors?
Non living, physical factors in an environment
Eg light, temperature, water, oxygen, salinity and soil quality
What is biodiversity?
A measure of the variety of life in an area
Why do natural ecosystems have a higher biodiversity than artificial ones?
- Natural ecosystems maintain themselves without any major interference from humans eg native woodlands
- artificial ecosystems are created and maintained by humans eg fish farms
What are the differences between native woodlands and forestry plantations?
Native woodlands:
- variety of tree species
- trees different sizes and ages
- variety of plant species
- variety of habitats
- variety of animal species
Forestry plantations:
- one species of tree
- trees planted at the same time/same age
- fewer plant species
- fewer habitats
- fewer animal species
Why are there fewer plant species in a forestry plantations?
Trees densely packed, leaving less room and light for other plants
Why are there fewer habitats in a forestry plantation?
There arent enough plant species to create them
Habitats are disturbed or destroyed when trees are felled
Why are there fewer animal species in a forestry plantation?
There aren’t as many habitats or sources of food
What are the differences between lakes and fish farms?
Lakes:
- many different fish species
- variety of plant species
- variety pf animal species
Fish farms:
- one fish species
- fewer plants species
- fewer animals species
Why is there one fish species in fish farms?
They are farmed for food
Why are there fewer plant species in fish farms?
Fish food is added and food waste can cause algal blooms.
Algal blooms block out the light, killing plants
Why are there fewer animal species in fish farms?
Predators are kept out
Pests are killed
Less food and fewer habitats because of lack of plants
