This investigation is intended to determine whether or not the hypothesis that biodiversity increases inland at the sand dunes in Crymlyn Burrows. Biological diversity is the variety and variability among living organisms and the ecological complexes in which they occur Diversity can be defined as the number of different items and their relative frequency. For biological diversity, these items are organized at many levels, ranging from complete ecosystems to the chemical structures that are the molecular basis of heredity. Thus, the term encompasses different ecosystems, species, genes, and their relative abundance.
Sand dunes are formed naturally over a period of time so long as there is a good supply of sand and powerful onshore prevailing winds to blow dried sand from a large tidal range. The sand dunes develop during a process of psammoseral succession whereby the whole ecosystem eventually develops into a Climax Community. It must be taken into account whilst doing the hypothesis that there is a possibility that biodiversity would be different if it had not been for external interference. Nevertheless the primary information needed for the basis of this investigation was the type and individual quantity of plants distributed over a selected area.
We sampled herbs and grasses of many different species to give an idea of how they play a part in biodiversity. Various plants are suited to different biological conditions so by studying the plants’ locations in relation to their surroundings the distribution of biodiversity along the transect becomes apparent. The information that can be obtained from the analysis of the data allows us to determine the accuracy of the hypothesis. . Other factors, which may also have affected biodiversity (soil temperature for example), were also measured so as to ascertain how biodiversity was related to the designated ecosystem. All of this information was recorded on a pre-prepared table.
Before the investigation began it was necessary to establish a suitable site from which the transect could begin. This site should start on an embryo dune and the transect should be plotted in a straight-line inland from that location. Before beginning it was necessary to survey the area and check for any inconsistencies in the land profile and plant species. This means checking for any areas where the plants may have been trampled, cleared away or if there were any interferences with the land profile i.e. removal of sand or dumping of foreign materials. Once an appropriate site one had been found, the transect was mapped out into fifteen stations each at 15m intervals.
At site 1 on the fore dune the only plant to be found was marram grass. This a typical plant to start and stabilize sand dunes and is particularly suited to this as it needs little water due to xeromorphic adaptations. As the dunes progress inland more species are found at each site. Moss soon appears, as does evening primrose, vetch, wild parsnip and other such plants not suited to the most arid of soils but perfectly adapted to gathering as much moisture as possible from the yellow and grey dunes.
After site seven there is a large increase in the variety and quantity of species. For example the vetch increased from 16 % in site 7 to 60 % in site 11. Mouse’s Ear, broomrape and shepherd’s cress are amongst the species found inland on the transect. The plants found at this end of the transect often have a shallower root system and leaves more adapted for photosynthesising rather than conserving water. The soil has also changed inland. The samples and data analysis show that pH has decreased from 8.5 to 7.1 over 225 meters from site 1 to 15. This is because as the dunes progress inland, there are fewer shells of marine organisms. These are made of calcium carbonate, which is alkaline. Hence the reason why the dunes become more acidic further inland; there are simply fewer marine exoskeletons.
The dunes also display varying degrees of moisture, with the fore- dunes having little moisture, the yellow dunes having more and the grey dunes showing a drop and then a very large increase. There was also a temperature decrease along the transect in both ground and air temperature which can be seen on the graph entitled “Factors possibly affecting biodiversity”. The latter may have been caused by the wind, which can also be seen to be increasing from 0.5 m/s in the early stages of the survey to 3.9 m/s later on. Air temperature and time of day and the position of the sites also affected ground temperatures. For example, the ground temperature on the for- dunes was 17 C further inland where there was a wide dip in the dune profile.
Overall the graph that shows vegetation heights doesn’t change very much along the transect. This is because the results used were taken from the mode of the average plant height in each transect at each site. Marram grass was present along most of the transect so the average plant height was brought up higher than it would be if there were no marram grass. The huge decrease in site seven is because marram grass is the only tall plant here. Moss is the other predominant species and it is very short so the average is brought down. After site 12 the vegetation height progressively decreases because of the increase in short herbs that bring down the average plant height.
There is a relationship between temperatures; wind and soil moisture and these contribute to biodiversity. Certain plants prefer different conditions or are not adapted to extremes. That is why i.e. that Marram and Lynne grass live on fore- dunes. They can tolerate salinity and a lack of water whilst i.e. moss needs more water and salinity damages root nodules.