Sampling techniques Sampling techniques and population and population growthgrowth

What is sampling?What is sampling?

Taking a small part of the ecosystem to Taking a small part of the ecosystem to estimate population sizeestimate population size

Taking more and/or larger samples will Taking more and/or larger samples will give you a better estimate than less give you a better estimate than less and/or smaller samplesand/or smaller samples

Types of samplingTypes of samplingType of Type of samplingsampling

What is it?What is it? When is it When is it used?used?

Benefits of Benefits of techniquetechnique

Drawbacks of Drawbacks of techniquetechnique

QuadratsQuadrats Squares of a Squares of a determined determined size, placed on size, placed on the ground to the ground to be sampledbe sampled

When the When the organisms organisms you are you are counting are counting are sessile sessile (immobile)(immobile)

Simple, can easily Simple, can easily sample many sample many times. Good for flat times. Good for flat groundground

Difficult on Difficult on rocky/uneven areas. rocky/uneven areas. Cannot sample fast Cannot sample fast moving organismsmoving organisms

TransectTransect Line or strip Line or strip laid across laid across area to be area to be studied. studied. Organisms Organisms that lay along that lay along strip are strip are countedcounted

Measuring Measuring change over change over time of time of topographytopography

From the airFrom the air

Under the seaUnder the sea

Simple. May be Simple. May be used to sample used to sample different parts of different parts of the ecosystem. the ecosystem. Shows change in Shows change in land as well as land as well as organism organism abundance.abundance.

Can be time Can be time consuming. A width consuming. A width around the transect around the transect line must be adhered line must be adhered to. Not good for fast-to. Not good for fast-moving organismsmoving organisms

Mark and Mark and recapturerecapture

Members of Members of population are population are caught, caught, marked and marked and releasedreleased

To count To count difficult to see difficult to see or fast moving or fast moving animalsanimals

Can be used for Can be used for fast moving fast moving animals.animals.

Very time consuming. Very time consuming. Important to lay traps Important to lay traps that will not just catch that will not just catch the sick/weakthe sick/weak

Examples of quadrat useExamples of quadrat use

http://livingprairie.ca/livinglandscape/quahttp://livingprairie.ca/livinglandscape/quadrats/quadrat.html?q=1drats/quadrat.html?q=1

More than one quadrat is being used at once to sample an area of this cave.

Quadrats can be used under water to sample the bottom of the sea/pond etc

Examples of transect useExamples of transect use

Quadrats and transects can be used together to create an overall idea of the ecosystem

A typical transect diagram shows the topography of the land and labels features. It also notes the organism types along the line

Examples of mark and Examples of mark and recapturerecapture

Cicada marked with white paint. This study was not a study over time. They used this technique to simply estimate the abundance of cicadas in the area

This mark recapture study of Bull Trout was repeated each year to show the change over time of abundance of Bull Trout in this area

Population dynamicsPopulation dynamics

The study of change in population size The study of change in population size over time.over time.

Requires more than one sampling eventRequires more than one sampling event

Factors affecting Factors affecting population sizepopulation size

Birth rate (eg. 55 per year)Birth rate (eg. 55 per year) Death rate (eg. 104 per year)Death rate (eg. 104 per year) Migration rate – includes immigration (moving Migration rate – includes immigration (moving

into the area eg. 20 per year) and emigration into the area eg. 20 per year) and emigration (moving out of the area eg. 31 per year)(moving out of the area eg. 31 per year)

Growth rate = (births + immigration) – (deaths + emigration) per unit time [eg. A year]

(55 + 20) - (104 + 31)- 60

Population grownPopulation grown

Positive result = population growthPositive result = population growth Zero result = zero population growthZero result = zero population growth

Closed population = no migration (maybe Closed population = no migration (maybe due to isolation)due to isolation)

Open population = migration occursOpen population = migration occurs

ActivitiesActivities

Glossary: sampling, quadrat, transect, mark Glossary: sampling, quadrat, transect, mark recapture, population dynamics, birth rate, recapture, population dynamics, birth rate, death rate, migration rate, closed population, death rate, migration rate, closed population, open population, zero population growthopen population, zero population growth

Quick Check pg 487Quick Check pg 487

THEN: catch up on any work, or start working THEN: catch up on any work, or start working aheadahead

- book checks!- book checks!