(or the other way round - it depends on the tides...)
Check other parts of the site for various images of the SALT MARSHES (from earlier trips)
You should have done the following preparation for the fieldtrip prior to the day itself.
a) Be aware of what a SALT MARSH ecosystem is like.
b) Read about what causes the TIDES, and how the height of the tides varies through the year, and what we mean by SPRING and NEAP tides. Please note that Spring tides don't just occur in Spring !
Need to have a location map which fairly precisely shows the areas that were studied. This is essential, as the fieldwork day will form the basis for one of the questions on the skills exam you will be taking at the end of the year.
Each session had an aim. Need to remember this for the exam.
Remember that both landscape features are essentially similar in that they are formed by the accretion of material which has been transported to the area, but that the method of transport and material are different.
Vegetation is important in both environments. In the salt marsh the pattern of vegetation we considered was one of zonation; in the sand dunes it was a pattern determined by succession. The first was a spatial variation, the second was temporal.
Need to explain the difference between Spring Tides and Neap Tides.
Remember that succession is also a feature of salt marsh. As one goes towards the back of the marsh, the vegetation is more established, more woody and has taken longer to develop.
At each location, we also decided on a number of hypotheses or ideas to be tested once we had collected the data.
These included statements of this type:
The __________ of vegetation changes with distance from the sea
The __________ of species changes from the front of the dune to the back etc.
In order to determine whether our hypothesis was correct, we undertook data collection.
This could have involved:
plant enumeration: the different numbers of species within the quadrat
percentage of ground cover / bare ground
identification of dominant plant species
This involved a transect – a straight line following a bearing. Why did we use this method: what type of sampling is this ?
At each known interval, a quadrat was used to assess vegetation cover. What is this, and why is it used ?
A key and illustrated guide was used to identify the plants which were found along the line of the transect. Bear in mind that different zones are inundated for different lengths of time, with different intervals. Which particular species did we discover, and what were the key methods used to distinguish between species ?
Used ranging poles, 20m tapes, gun clinometers and compass to keep on bearing. How was bearing worked out ? Which bearing was used ? Problems in keeping in a straight line ?
How did we decide where to place our quadrat ?
At the dunes, we also took samples of the soil, and tried to determine pH using indicator strips and organic content by using colour and visible signs of organic build up.
There were also 2 data loggers to measure temperature and moisture, and an anemometer to measure wind speed. Why are these factors important ?
Transect at salt marsh was from the slob zone through to the sward zone. Plants developed from halophytic algae through to shrubs in the area above the normal high-tide level, some such as Suaeda Vera were nationally rare species.
We saw also the very well developed creek system, and the presence of pans. What are these features ? Why are they important to the salt marsh ?
How did plants survive not only the salty conditions, but the anaerobic conditions in the areas near the toe of the salt marsh ? (evidence of which was the black mud produced by Wellingtons sinking in)
Salicornia (or samphire – however your pronounce it…) were pioneer species. What are these ?
Transect at the dunes was inland from the top of the beach (fore dunes) through to ‘climax’ vegetation in the pine-wood of Holkham Meals.
Data needs to be tabulated: set out neatly, so that it can be used to produce diagrams.
One of the things we didn’t measure but which would be valuable to find out along the salt marsh transect in particular is soil salinity. How would we be able to determine this ?
Kite diagrams: help to illustrate zonation by showing how the amount of different vegetation types and amount of bare ground change as one moves along the transect.
Dune profile: remember that there will be a certain amount of vertical exaggeration in the profile, as you are altering the horizontal scale.
Dunes should grow in size up to a point, and then diminish in size inland as the amount of sediment available is reduced.
Data tabulation / relevant graphs – sketch maps.
Bear in mind that there is an expected or ‘model’ way in which each of these ecosystems would be expected to behave.
Waugh: pp. 141-3; 268-9 has details on the succession across a sand dune system and saltmarsh: important terms are psammosere and halosere.
Need to bring in the aspect of management: human impact on the marshes and the dune systems. A lot of this is to do with the impact of trampling. Rabbits etc can also lead to blow-outs: deflation of large quantities of sand. Their droppings can however lead to increased accumulations of sand in certain areas. Why is this ?
Need to consider the limitations of the methods that were used.
Remember also that we were on the marsh in October, when a lot of the plants had finished flowering, which is one of the main ways of identifying them.
Mention also safety considerations. We made sure that we were off the salt marsh well before the tide turned (the sirens sounding when we were on the lunch stop in Wells were the warning that the tide was on its way back in…)
Field Sketches: an important technique for capturing the place
Camera: I saw no one with one of these – they would have been very useful: close up photos of the plants could have been very useful.
Cord Grass (Spartina anglica)
Saltmarsh Grass (Puccinellia maritime)
Glasswort / Samphire (Salicornia europaea)
Sea Aster and Sea Lavender – very similar
Sea Purslane – silvery grey leaves
Annual and Shrubby Seablite
Sea Spurry and Scurvy Grass were found higher up the marsh.
Sea Rush near the pile of glacial moraine which guarded the second area of marsh behind.
These need to be related back to the aims and the hypothesis.
Extra research:
As with all the work you are given, you need to ‘flesh out’ the basics with additional reading and Internet searches. The Biology section of the library will contain books which may be more related to the plant identification etc than some of the Geography texts as this is one area where this a bit of overlap between the subjects.
Anyone who is serious about completing 'AS' will show evidence of a lot of effort on this piece of work !
http://water.dnr.state.sc.us/marine/pub/seascience/dynamic.html
http://linnaeus.nrm.se/flora/di/chenopodia/salic/salieur3.jpg
http://members.aol.com/WellsMaps/Maps/Walkers/nature2.JPG - useful map of Holkham
http://members.aol.com/Wellsnextthesea/Harbour/Holkham.html
http://www.geobytes.org.uk - Rob Chambers goes to the same dunes as we do
http://www.heckgrammar.kirklees.sch.uk/old_site/content/departments/science/biology/merlin.htm - free software to download which will draw kite diagrams and other diagrams for you, and also work out your statistical tests - this could be well worth a visit
Also check out earlier fieldtrips complete with images HERE.
