An investigation of the effect of a named abiotic factor upon Marram grass distribution in a sand dune system

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An investigation of the effect of a named abiotic factor upon Marram grass distribution in a sand dune system

Aim: to investigate the effect of a named abiotic factor upon Marram grass distribution in a sand dune system

Background information:  Marram grass is a xerophytic plant, meaning that it is a plant that is adapted to living in a dry arid habitat. Therefore it is most likely to be found on sand dunes, where the water is minimal and also where, closer to the shore (if the sand dunes are by the sea), there is a higher salt content, lowering the water potential. Marram grass has many adaptations to living in the sand dunes, for example its leaf blades curve with the stomata on the inside, to reduce evaporation due to heat or wind (transpiration), also this provides a moist microclimate around the stomata (ref. Biozone international). Marram grass blades also have leaf hairs, which hold moist air around the leaf to prevent evaporation. Marram grass has an extensive root system to gain as much water as possible from the water deficient habitat. Furthermore Marram grass has a thick waxy cuticle, reducing water loss by evaporation and also, because it is shiny, reflects some of the heat.

Sand Dune Succession

Sand is deposited by the sea on the shore, and the sand is blown by the wind away from the sea, an object on the beach causes eddy currents and thus the sand is deposited around the object, the sand dune has began. The youngest dunes will be closest to the sea, in these dunes there aren’t likely to be any plant, as the dune has no water, or its water potential is too low due to the minerals from the seawater. Further on we come onto pioneer stage dunes, also called the foredunes, this is where pioneer plants begin to grow, yet it is unlikely that we will find any Marram grass here, due to the conditions. Next there are the white dunes, this is where the Marram grass community is likely to be found. Here the Marram grass stabilizes the dunes, through its roots; clumps of Marram grass are continually being buried only to regrow again. The sand dunes go on to become stable dunes and then we get dune scrub, finally having a woodland. In the lower areas of the dunes or in between, there are very likely to be slacks, these are wet areas where there is little vegetation, if the water is too salty, thus having a low water potential, which affects transpiration, or maybe the water is suitable for plant growth yet no Marram grass grows there.

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Proposed Method

Based upon the above information, I can conduct an experiment that will allow me to investigate an abiotic factor upon Marram grass distribution. We know that Marram grass is a xerophyte, and therefore has adaptations in order for it to lower its transpiration rate, and thus reducing water loss. Therefore, it is sensible to investigate an abiotic factor, which causes the plants to loose water. Hence, I can either investigate the salt content causing a difference in water potential, meaning that it would be hard for the plant to draw water through its roots, or I could ...

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