Does the biodiversity of the sand dunes at Holkham follow the expected pattern?

The data gathered indicates that the hypothesis is valid. With increasing distance from the HWM, Holkham's biodiversity rises until the late climax stage, when it starts to decline. The biodiversity improves from 0 at site 2 to 0.815 at site 19, then declines to 0.501 at site 21, as shown in Fig. 17.

The enhanced biodiversity was discovered to be caused by the form of the dunes, which create areas of slack. These locations are better protected, creating favourable conditions for various species. Figures 15 and 16 at sites 5-7 depict this. Of the three sites, Site 6 has the least biodiversity (0.122). Sites 5 and 7 have biodiversity indices of 0.485 and 0.514, as opposed to those of those two sites. Site 6 is much more exposed, as seen in Fig. 15, thus only specialized plants, such as marram grass, may live there.

Up to the late climax stage, the introduction thought that declining pH was a cause of growing biodiversity. It was found that pH did decrease over the transect from 7.4 at site 1 to 5.0 at site 21. Figures 15 and 18 show this, and Spearmen's correlation supports it. As may be seen in fig.21, no association with biodiversity was discovered. Therefore, it is necessary to disprove this theory.

Since pH was probably not a significant influence on the plants at Holkham, no correlation was likely discovered. The pH was not severe enough to hinder the development of the vegetation. In determining the growth of the flora and hence the biodiversity, other elements like shelter and soil nutrition/moisture were probably more important.

Question: Does the biodiversity of the sand dunes at Holkham follow the expected pattern?

Hypothesis: The sand dunes at Holkham follow the expected pattern in fig.2. This is based on the premise that forested area can be seen on fig.1, at the end of the dune. Option B: Oceans and Coastal Margins Sub-Section 2: Interactions between oceans and coastal places linked to sand dune development

Holkham: Located on the North Norfolk coast, the Holkham National Nature Reserve is England's largest national nature reserve, making it a prime location for physical geography data collection. Fig.1 shows an area of the reserve, from which data was collected

Prior to data collection, a pilot study was conducted to decide on the appropriate equipment, practise data collecting, and test several clinometers, quadrants, and pH kits.

On March 12, 2019, a variety of data were gathered using a group sampling method. The information in fig.1 was gathered in Holkham on the North Norfolk coast.

Sadly, there were bad weather conditions, with plenty of rain and strong winds. It was decided wind speed data would not be collected as inconsistent winds would have led to unreliable results.

Data were gathered via stratified systematic sampling along a transect. Typically, data were gathered every 10 m, with the exception of the gradient, which was captured at a slope break. However, the distance was increased to 20 m if comparable results were acquired at three sites in a row. Since there were no paths for collecting the data, stratified sampling was employed. Changes could be noticed throughout the dune system thanks to the data collection method and sampling size.

A 250 m tape measure was used to measure the transect, however, only 50 m was surveyed at a time to improve accuracy. The tape was typically extended in more protected regions after being cut to 25 m owing to the weather.

There would be two ways of gathering pH data. A pH kit and probe. The probe needed to remain buried for a considerable amount of time in order to collect reliable data, according to the pilot study. Therefore, just the pH kit was utilized that day. The techniques table, fig.4, lists the precautions that must be taken while using this method to assure accuracy.

Despite data collection, the recording sheet was no longer usable because of the circumstances. As a result, data from a prior year was used; this group data is displayed in fig. 15.

A diversity index can be used to measure diversity. Values for the Simpson-Yule diversity index range from 0 to 1.

0 = Monoculture

1 = High biodiversity

The index is calculated using the equation:

\(Diversity\ =\ 1\ -\sum{(\frac{Pi}{Ni}})^2\)

Pi = Species percentage cover

Ni = Total percentage cover (excluding bare ground)

Site: 13

The variety of species found within an environment is measured by biodiversity. This is typically quantified in terms of plant species in an ecosystem of sand dunes. Biodiversity can be used to assess an area's status and gauge how favourable the circumstances are at a given time. The biodiversity of a sand dune ecosystem, in theory, rises with distance inland but falls in the late climax region. This is in line with fig. 2.

The biodiversity will increase with distance from the HWM, as conditions near the HWM are harsh, allowing a few pioneer species to survive. These species have halophytic adaptations, adaptations to reduce water loss and increase water absorption, e.g. marram grass. These species provide shelter from the conditions and release nutrients into the soil through decomposition, thus changing the conditions. They also stabilize the ground, promoting the development of soil, which retains moisture.

These factors make the environment more habitable for other species, increasing biodiversity. Away from the shoreline, the dunes increase in height, producing areas of slack (see fig.3). These areas are sheltered and are closer to freshwater stores, encouraging plant growth, and thus increasing biodiversity. Fig.3 shows this via the marked water table. Soil pH also changes, near the HWM the pH is very alkaline meaning few species can grow. Plant decomposition neutralizes the soil, meaning more species can grow, increasing biodiversity. However, biodiversity decreases in the late climax stage (see fig.2) as the area is likely to be dominated by fewer species. In the lowlands of the UK, these are expected to be oak or ash, which block sunlight to the forest floor, preventing the growth of smaller plants