BIOL4: Populations & Ecosystems pt 1

What are the six stages in succession? Name them in order.

1) Migration 2) Colonisation 3) Establishment 4) Competition 5) Stabilisation 6) Climax

What does ACFOR stand for and what does it do?

Abundant Common Frequent Occasional Rare Says how abundant species are.

Define environment.

All of the conditions surrounding an organism.

Define seres.

Different stages in a succession when particular communities dominate.

What is primary succession?

Newly formed habitats that have not previously supported a community undergo succession. e.g. sand dunes, rocks exposed by volcanic activity.

Define abundance.

The number of individuals of a species in a given area.

How can we manage succession in moorlands?

Via burning heather and letting sheep graze. This prevents succession into deciduous woodland.

Define fundamental niche.

What an organism can occupy, given the right conditions.

Define realised niche.

What an organism is actually occupying.

What are four features of pioneer species?

1) Can tolerate harsh conditions. 2) Are able to photosynthesise and grow when minerals are in short supply. 3) Have the advantageous ability to fix nitrogen. 4) Production of lots of spores/pollen which can germinate rapidly.

Give three reasons for conservation.

1) Ethical reasons - we should have respect for living things that have been on Earth longer than we have. 2) Economic reasons - it maintains gene pools which may have some potentially useful genes. Productivity is greater in natural systems. 3) Cultural/aesthetic reasons - the great variety of natural ecosystems enriches our lives and inspires creativity.

What are the advantages and disadvantages with relying on percentage cover measurements in quadrats?

1) Gives specific information. 2) Subjective.

What are the four common features of succession?

1) Harsh conditions progress to less harsh conditions. 2) Only highly adapted species can thrive progress to many more species can thrive. 3) Low diversity progresses to high diversity but then progresses to reduced diversity. 4) Pioneer species progresses to a climax community.

What five assumptions are you making when using the mark-release-recapture technique?

1) None have died/left/immigrated/were born 2) Marked animals have had enough time to mix thoroughly with the population. 3) Marking must not affect the chances of survival. 4) The mark will not rub off. 5) Marked 1st sample/total population = marked 2nd sample/total 2nd sample. i.e. the proportion of marked and unmarked in the sample is the same as the proportion of marked and unmarked in the whole population.

What are the two types of quadrats that exist?

1) Point quadrat 2) Frame quadrat

What are the three types of succession?

1) Primary 2) Secondary 3) Deflected

What are the advantages and disadvantages of relying on ACFOR measurements in quadrats?

1) Quick 2) Subjective

What are the advantages and disadvantages with relying on frequency measurements in quadrats?

1) Repeatable. 2) Doesn't give density.

How do you carry out a random sample?

1) Set out two measuring tapes at right angles to each other. 2) Choose pairs of random numbers. 3) These numbers will give you coordinates of where to place the quadrat.

Describe the mark-release-recapture technique.

1) Set traps and catch animals. 2) Count number of animals in the first sample and mark them (e.g. with tippex). 3) Release these marked animals. 4) After a few days, set traps again and catch a second sample. 5) Count the number of marked animals. 6) Use the population size formula to figure out the population size.

What is the advantage of relying on population density measurements in quadrats?

1) They are accurate.

What are the ethical issues involved in population sampling?

1) You hurt wildlife when carrying sampling out. 2) Potential destroying of natural beauty. 3) May disturb breeding/nesting animals. 4) Species investigated might be endangered.

Describe the process of succession.

<b>1) Migration</b> Seeds & spores arrive. Germinate & grow. <b>2) Colonisation</b> Physical conditions unfavourable; much bare ground; only pioneer species move to get established. <b>3) Establishment</b> Species become established, modifying physical conditions. Increased diversity of species. Little bare ground. <b>4) Competition</b> No. of species is still increasing; plants compete for light, space, nutrients, water; pioneer species die out, having been outcompeted. <b>5) Stabilisation</b> Few (if any) new species added as competition resolves itself. Each species occupies its own niche and therefore avoids strong competition with other species. <b>6) Climax</b> No new species added; community stays the same; community in 'equilibrium' with the environment.

Define community.

A group of organisms of different species, living & interacting in the same place at the same time.

Define climax community.

A stage where no further changes take place. Equilibrium with the environment.

Define succession.

An ecological process resulting from activities of organisms themselves. The gradual replacement of some of the species of organisms living in a community by others.

When investigating populations, how do you increase validity of the experiment?

By making sure you use random sampling and choose an appropriate statistical test.

When investigating populations, how do you increase reliability of the experiment?

By making sure your experiment is repeatable and that you have a large sample size.

How can we manage succession in oak woodland?

Clear them for grazing and cultivation, which results in many grasslands.

When taking samples with quadrats, how do you record the percentage cover of a species?

Estimate the area within a particular quadrat that a particular species of plant or sessile animal covers.

Define population.

Group of organisms of the same species, living & interacting & breeding in the same place at the same time.

What is a point quadrat like?

It is a horizontal bar with holes along it.

What is a frame quadrat like?

It is subdivided into smaller squares.

Why do scientists use random sampling?

It negates any confounding factors such as bias.

Define biotic factors.

Living things within the environment (e.g. predation, prey, ability to reproduce, competition, disease).

Define ecosystem.

Made up of living organisms and the abiotic factors that affect them.

Define abiotic factors.

Physical or non-living conditions in the environment (e.g. water, temperature, light).

Define habitat.

Place where a community of organisms live.

What is the population size formula for mark-release-recapture?

Population size = (marked 1st sample * total 2nd sample) / marked 2nd sample

What is secondary succession?

Sites where a community has been supported before, but a major environmental disturbance disrupted the previous succession (e.g. forest fire).

Define microhabitat.

Smaller parts of a habitat (e.g. bottom/top of pond).

What is deflected succession?

Succession does not proceed through to climax community (e.g. mowing a lawn).

Why do scientists use systematic sampling?

Systematic sampling is for recording changes in abundance and distribution of species.

Define pioneer species.

The first species to colonise an area.

Define biosphere.

The land, vegetation, air, and water surrounding the Earth that supports life.

Define conservation.

The management of the Earth's natural resources in such a way that maximum use can be made of them in the future. Humans need to maintain ecosystems and biodiversity.

Define population density.

The measurement of a population per unit area.

Define ecological niche.

The role an organism plays in its environment. The way of life of the organism in its natural surroundings. Only one species can occupy a niche.

Define ecology.

The study of how living organisms interact with each other and their environment. Living organisms' relationship with their physical surroundings and individuals of same & other species.

Define competitive exclusion.

Where one species out-competes another for the niche, and the other species becomes extinct.

How do you carry out a line transect?

You lay a measuring tape across the sample area. Any species touching the tape are recorded.

How do you carry out a belt transect?

You lay a measuring tape across the sample area. Quadrats are set down at regular intervals along the tape. Species inside the quadrats are recorded.

When taking samples with quadrats, how do you record the frequency of a species?

You note if the species is presenet in each quadrat.