Obj 2- Section A Flashcards
(45 cards)
Ecology
the study of the interrelationships of living organisms with each other and with their environment.
Environment
the combination of factors that surround and act upon an organism
Biotic factors:
all the other living organisms that are present such as predators, prey, competitors, parasites and pathogens
Abiotic factors
Abiotic factors: all the non-living chemical and physical factors
Habitat:
the place where a particular organism lives.
For example, the habitat of an earthworm is the upper layers of the soil.
Species
a group of organisms of common ancestry that closely resemble each other and are normally capable of interbreeding to produce fertile offspring
Population:
all the members of a particular species living together in a particular habitat. For example, all the sea urchins living in a sea grass bed form a population.
Community
all the populations of different species living together in a particular habitat. For example, a woodland community consists of all the plants, animals and decomposers that inhabit the wood.
Ecosystem
a community of living organisms interacting with each other and with their abiotic environment
Niche
the position or role of an organism within an ecosystem. For example, an earthworm’s niche is to burrow through the soil, improving its aeration, drainage and fertility.
Why carry out an ecological study?
- identify diff species present
- where they live
- determine their numbers
- study relationships that they have with each other and with the abiotic factors
Why collect organisms?
-identify organisms
in which way can organisms be collected?
Pooters, pitfall traps, nets, plankton nets and a Tullgren funnel may be used
List the 4 sampling techniques
- Observations
- Quadrats
- Line transects
- Belt transects
Observation
The ecosystem should first be observed and the common species of plants and animals recorded. Any adaptations that enable the organisms to survive in the ecosystem should be noted, together
with any interrelationships between the organisms
Quadrat
- square frame with a known area
- placed at random several times
- num. of individuals of each species found within is counted.
- the quadrat can be made into a grid using string and the percentage of the quadrat area covered can be estimated.
Why do people use quadrats
Used to study the distribution and abundance of plants and stationary or slow moving animals in uniform ecosystems
Why do people use line transects
Line transects are useful where there is a transition of organisms across the ecosystem, e.g. down a rocky seashore. They give a quick idea of the species present and how they change across the ecosystem
How is a belt transect used?
made by placing two parallel line transects across an ecosystem. The species found between the lines are recorded. Alternatively, a quadrat
can be placed alongside one line transect and the number of individuals of each species found within its boundaries is counted. The quadrat is then moved along the line and counting is repeated at regular intervals.
How to find species density ( average number of individuals of a given species per m2)
tot. no. of species ÷ (area of quadrat x amount of quadrats used )
How to find the total population (total number of individuals of a given species in the area under study)
species density x tot. area of ecosystem studied
How to find the species cover ( percentage of ground covered by a given species)
(if quadrat is 1m2)
total percentage of ground that the species covered ÷ # of quadrats used
Species frequency
This is the percentage of quadrats in which the given species was found.
how does the recapture method work?
It is used to estimate the population size of moving animals (eg. sharks, sea turtles etc.) by collecting a sample of animals of the species and counting them, they are then marked (tag or paint) and released back into the same area and given time to mix with the original population.
A second sample is then collected, counted and the # of marked organisms counted
