Aim: How and why does vegetation change across a psammosere at Llobregat delta, Barcelona? Data Collection & Sampling Techniques

Theoretical background Expectations: High wind and high pH values to develop the embryo dune. Grasses such as lyme grass and sea couch grass then appear. A humus layer builds up which traps both water and nutrients. Marram grass is the most common species. Vegetation reaches 100%. Sand sedge and sea spurge start to dominate and small shrubs appear for the first time. Shelter from winds and a true soil begins to develop. Dune slacks. Climatic climax vegetation is reached at the mature dune. Develops a soil which can support shrubs and trees.

Debrief from their sheets and show / see end of teacher pack

Why is it important to use sampling strategies? Data Collection & Sampling Techniques Discuss question

Sampling Strategies Why Sample? –Impossible to measure all variables –Not enough time or money –Certain information may be unknown ie population figures and only estimated Bias? –The aim of sampling is to get a representative picture, removing bias –Need several readings –Times of year, locations and weather can all create bias.

What are the strengths and weaknesses of different sampling strategies? Data Collection & Sampling Techniques Discuss question

What is this sampling technique? Random What are its strengths & weaknesses?

Random Sampling Sampling using random numbers –generated by a random number sheet or number generator. Advantages –Easy to sample –Can be effective and easy to apply Disadvantages –Can create unrepresentative sample by chance if a small sample size is used.

Systematic What is this sampling technique? What are its strengths & weaknesses?

Systematic Sampling Sampling using a designed strategy –e.g. every 3 rd car, –every village in a transect, –every 20m Advantages –Easy –Cover whole area Disadvantages –Bias if a pattern is picked up e.g. only questioned elderly people –Could miss out anomalies

Stratified What is this sampling technique? What are its strengths & weaknesses?

Used when data could have sub groups –Sample using proportions –E.g. Two different towns but same strategies applied Advantages –Easy to apply and replicate Disadvantages –Can miss out areas and get unrepresentative data Stratified Sampling

Can you combine different sampling techniques? It is possible to combine sampling techniques. For example: Recording vegetation density & diversity 1.Line transect 2.Systematic sampling – 3 metre intervals 3.Random sampling – placement of quadrat at each site Discuss & click to reveal

Why is piloting data collection techniques important? Benefits: Allows practice of the technique Improve accuracy Identify & solve practical problems e.g. transporting the equipment safely. Adjust techniques to suit conditions or available equipment Identifies mechanical problems with equipment Remember: The centre staff demonstrated how to use the equipment & checked the equipment before data was collected in the field All of the above can be included in the risk assessment

What were the methods of data collection? Discuss difference between primary & secondary data collection

Some of the equipment used …

In pairs 4 mins Incl sampling techniques / then speed date

Methodology table Incl sampling techniques Clinometer

START Need to click mouse to go to timer (2 mins)

You have only………..

MOVE IT! One student moves, the other stays throughout / Need to click mouse to go to timer (3 mins)

You have only………..

MOVE IT! One student moves, the other stays throughout / Need to click mouse to go to timer (4 mins)

You have only………..

MOVE IT! One student moves, the other stays throughout / Need to click mouse to go to timer (4 mins)

You have only………..

MOVE IT! One student moves, the other stays throughout / Need to click mouse to go to timer (4 mins)

You have only………..

MOVE IT! One student moves, the other stays throughout / Need to click mouse to go to timer (4 mins)

You have only………..

MOVE BACK!

In pairs 4 mins Incl sampling techniques / then speed date

Methodology table Incl sampling techniques Clinometer

Discuss – recorded on piloted data collection sheets / Refer to back of revision guide notes

Fieldwork: A risky business

Outline the risks associated with carrying out your fieldwork and assess the effectiveness of strategies used to minimise the risks Task: a.Identify the risks associated with carrying out this sort of fieldwork. b.Suggest strategies that could be used to minimise or avoid such hazards taking place. Discuss command words – outline & assess / Complete task in groups (could draw a table on A2 sugar paper & pen) & feedback to class

Starter lesson 4 Question 1Question 5Question 9 Question 2Question 6Question 10 Question 3Question 7Question 11 Question 4Question 8Question 12

Outline and justify the method used in the collection of one item of primary data Discuss difference between outline & describe / Students write title / complete – 6 mins / peer asses / click 4 timer

You have only……….. Outline and justify the method used in the collection of one item of primary data

Should choose recording veg / Peer assess mark to level – WWW & EBI Outline and justify the method used in the collection of one item of primary data

Should choose recording veg / Peer assess mark to level – WWW & EBI Outline and justify the method used in the collection of one item of primary data

What are other likely opening questions at AS Level?

What are other likely opening questions at A2 Level? Refer to ‘assess / explain / justify’ questions that predominate and distinguish between A2 & AS

Some of the equipment used …