Investigating the effect of trampling on salt marsh

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A2 BIOLOGY COURSEWORK

Investigating the effect of trampling on salt marsh vegetation?

RESEARCH AND RATIONALE-

The saltmarsh I used for my experiments (sample taking) was the RSPB (Royal Society for Protection of Birds) reserve of Freiston Shore.

Aim of the investigation-

I am aiming to compare three different aspects when investigating the effect of trampling on salt marsh vegetation.

  • Population density
  • Species diversity
  • Types of species found

Two areas in close vicinity will be compared; one area is non-trampled (Area 1) and the other trampled (Area 2).

Justification for the investigation-

I was interested in the affect humans have on different environments, how they interfere as anthroprogenic factor. In the context of this experiment they can be classed as biotic factors. People explore the marsh in wellington boots this tramples some areas heavily and greatly irritates plant life. This can be measured through looking at the population density of the area, one of the aspects I am going to compare. I chose this marsh specifically because it is a RSPB reserve which means it has been protected by government and other organisations for its diversity in wildlife. We have to remember that there are plenty of other animals (that are sustained by plants) involved in a bird’s food chain therefore; Freiston shore has a diverse variety.

Biology behind the investigation-

More detailed diagrams included in the appendix.

A sea shore with very little wave action is one of the causes of the development of a salt marsh. Fine particulate material build up (accretion) in these calm conditions. As the density of the material increases, the river has to then split up around these dense areas, this leads to the formation of tidal creeks. As more mass is deposited, halophytes begin to bind the soil with their roots and in this fashion succession continues, the soil gets more compact. The salinity decreases as more aerobic respiration occurs, the excess salt is broken down and used by the plants. The conditions also change from alkaline to more acidic as salt is removed.

The area I sampled was the high marsh. I didn’t feel that the effect of trampling could be explored in the embryo and building dunes because people seldom explore those areas as they are not very stable.

Resources to support my work-

  • Advanced Biology by Michael Kent. Oxford Press 2000. Page 532-533.
  • SNAB coursebook. Heinemann Publication 2006. Page 26-28, 56.
  • Field Studies Council (FSC). http://www.theseashore.org.uk/index.html.
  • RSPB Freiston Shore Page. http://www.rspb.org.uk/reserves/guide/f/freistonshore/index.asp.  

PLANNING AND IMPLEMENTING-

Null hypothesis-

‘Trampling has no effect on the salt marsh vegetation. The species diversity, population density and types of species found are not affected.’

My hypothesis and prediction-

‘Trampling has an effect on the salt marsh vegetation. However, the species diversity and types of species found are not as affected as population density.’

I think that the trampling is definitely going to have an effect on the population density and types of species found because plant life is definitely going to be disturbed, I would expect a lot more mud to be present in the trampled area. However, I feel that the plant diversity readings (Simpson’s Diversity Index) will be similar for both areas. This is because even thought the density is likely to be smaller the diversity will still be there.

Data collection and Methodology-

There were the obvious data collections regarding the plant species. However, other measurements were also done to make sure the abiotic variables were constant and that they didn’t affect the outcome of the experiment in any way.

  • The species distribution in each area, this was done using a square quadrat (10 by 10 squares). I felt a square quadrat would be better suited as it also gives a percentage cover of the species (one of my comparable aspects) through 100 squares. In comparison, a point quadrat would not be able to provide an accurate percentage cover. In both the areas, the square point quadrat was randomly put down at 30 places between the ranging poles and the species cover was recorded accordingly. The results gained could be then used to find species diversity and also the types of species found in both areas.
  • The distance of the area I was working in had to be measured (20 metres) thus, area between the ranging poles was measured using measuring tape, also the slope angle between the poles was measured using a clinometer gun, to maintain consistency in both the areas. The ranging poles were put in to the ground, next the clinometer gun was pointed from one pole to the other at the equal height (using the colour gradation), this way the angle of the slope between the poles could also be measured.
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  • Soil samples from Non-trampled (Area 1) and Trampled area (Area 2) was obtained using an trowel, collected in a bag and the following tests were performed back at school-
  • To measure Salinity of the samples- Firstly, the soil sample has to be dried out; small sample is weighted into an evaporating dish and then put in an oven (90°C). The dish was removed at intervals and allowed to cool and re-weighed until the mass doesn’t change. The dried soil is mixed in suitable volume of water (enough to wash the soil but not dilute the salt in it). ...

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