The influence of the January storm on the succession process on the

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The influence of the January storm on

the succession process on the "Hors" on

the island of Texel.

By: G.J. van Houselt

Student number: 10738525

Supervisor: mw. dr. A.M. Kooijman

2nd supervisor: dhr. dr. J.G.B. Oostermeijer

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Abstract

Dune slacks are important habitats, and protected by the EU-habitat directive. Dune slacks are characterized by pioneer plants, such as the orchid Liparis loeselii. One of the largest populations of this species in Europe is found on the "Hors" on the island of Texel. This orchid emerges six years after the formation of a new dune slack, peak values are being observed after 11-16 years (Kooijman et al. 2016). After that values slowly decline due to decreasing pH and increasing soil organic matter content. Nevertheless, succession can be countered due to rejuvenation of the area, a process in which aeolian activity blows fresh sand into the slack. This aim of this project is to measure the influence of last Januarys storm on the population of the Liparis loeselii. Fieldwork is executed on Texel in two dune slacks. T6 an older slack with possible rejuvenation of soil due to the storm and T8 a relatively new slack with high amounts of aeolian activity in the surroundings. During laboratorial work pH, EC, SOM and bulk density is measured from which ArcGIS maps are derived.

It could be concluded that for this project the effect of the January 2018 storm could not be measured, due to a lack of sufficient data from previous years. It was impossible to draw the same conclusion for this research. Additionally, there was a 3-year gap between the last data collected and that of this year. Therefore conclusions drawn from this research are not scientifically justified because no data has been collected since 2015 to 2018. During this time period of 3 years, other factors may have influenced the succession.

Furthermore, other research states that pH is the defining factor determining the occurrence of the

L. loeseli, however in these slacks is the amount of vegetation cover. Because the pH values are not

below the 5.8 pH-H2O threshold. Additionally, it is recommended that in older slacks with higher vegetation cover, mowing is needed for these plants to survive.

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Introduction

New sandbanks attach to the island of Texel every 100 years (Ballarini et al. 2003), as they attach new dunes are formed as well. In between dune slacks form, which are an important habitat for pioneer species. For instance, the Liparis loeselii, this little orchid is in rapid decline and listed as endangered. Therefore, it is included in the Habitat Directive. This orchid shows itself after six years. However due to succession and acidification the population slowly declines after 11 years.

Nevertheless, succession can be countered by aeolian activity of new sand. In this research the influence of last January storm on the Liparis loeselii population is determined.

The main goal of this research is to provide sufficient answers on the following research question and sub-questions:

Research question:

What is the role of aeolian activity in resetting succession in two dune slacks (T6/T8) on the "Hors" on the southern tip of the island of Texel?

Sub-questions:

1. What was the impact of the large January storm of 2018 on the succession in T6/T8? 2. To what extent can we see the influence of this storm on the population of L. loeselii in this research area?

1. Research area

The area of this research is on the "Hors" on the southern tip of the Wadden island Texel. This point of the island is formed in a rather special way. As these islands have ebb-tidal deltas where sediment accumulates on the seaward side of the tidal inlet. These deltas are dominated by the ebb-tidal, however the shallower channels on the sides, shoals and swash bars are dominated by flood (Fig. 1). Marsdiep, the inlet of the Wadden Sea at the southern point of Texel and Den Helder on the

mainland, is thought to be formed between 800 and 1303 AD (Oost et al., 2004). The accumulation of sediments pushed out through the Marsdiep inlet is the driving force of the active coast process that is going on in on the southern point of Texel, the "Hors". The main ebb-channel which stretches out far into sea disrupts the tidal current parallel to the shore. The washed out sediments are deposited further into sea and build up into a large shoal. When the shoal emerges above the water the sand is transported eastward due to the western wind and

Figure 2. Movements of "Onrust" and "Razende Bol" (Klijn, 1981).

Figure 1. Morphology of ebb-tidal deltas based on Texel inlet (Marsdiep) (Sha, 1990).

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Figure 4, Map of the dune slacks in SW-Texel. Encircled dune slacks T6 and T8 (Kooijman et al., 2016).

waves. The canal north of the shoal is forced into an eastward clockwise rotation, resulting in the attachment of the shoal to the coast of Texel (Fig. 2.) (Klijn, 1981). During large storm events, like the one of last January, this is more likely to be caused. This is how the research area the "Hors" became attached to the southern tip of Texel in 1749 (Oost et al., 2004) and later the "Onrust" between 1908-1916. Since 1925 "Razende Bol" is above the water line and moving toward the southern tip of Texel (Fig. 2).

2. Dune slacks

Dunes are formed when sand is trapped on the beach plain by grasses. These little embryo dunes start to grow higher when more sand gets trapped, in time these embryo dunes become attached and new fore dunes originate. Between the fore dunes and the main dunes dune slacks are formed. These dune slacks are formed in two ways: Primary dune slacks are formed where fast accreting coasts are cut off from the sea. Therefore, they are long, narrow and parallel to the coast. Secondary

dune slacks are the result of a blowout, a form of erosion so deep the water table will be visible. If this form of aeolian erosion is extensive, a large flat area of wet sand will be exposed (Kooijman et al., 2016) (Fig. 3). This research is done within two dune slacks (T6/T8). The oldest dune slack, T6 consists out of three parts: (T8-t1) a rejuvenated dune slack with plant numbers still increasing, possibly due to high aeolian activity, (T8-t2) probably rejuvenated dune slack with high numbers of L. loeselii, but now rapidly declining and (T8-t3) an existing dune slack without rejuvenation and low plant numbers. The younger dune slack can be separated into four parts: (T8-t1) the stable part, (T8-t2) an area with higher numbers in recent years, (T8-t3) an area

Figure 3. Photograph of a secondary dune slack (Egan, Liverpool Hope University College).

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6 with increasing numbers from 2015 till 2017, and (T8-t4) and area with possible high aeolian activity and therefore high increasing numbers (Fig. 4).

3. Liparis loeselii (Groenknolorchis).

The perennial orchid (Liparis loeselii) (Fig. 5) is a 10 - 25 cm high plant. This species is mainly found in base-rich, nutrient poor, young, calcareous inland fens and coastal dune slacks. The L. loeselii is a pioneer species, which settles quickly, but also quickly disappears when favourable conditions do not apply. These conditions include a high pH (>6), combined with a low availability of nutrients and low amounts of soil organic matter (SOM) (Kooijman et al., 2016). Due to the fact that L. loeselii has high extinction rates and short-living populations it can only be maintained in dynamic dune

areas where there is an ongoing process of young dune slacks formation (Eriksson, 1996; Oostermeijer and Hartman, 2014). In the Netherlands the species can be found along the coast of the Wadden islands and in the dunes of South Holland and Zeeland (Odé and Bolier, 2003). Large populations are found especially on the southern tip of Texel (the Hors) (Fig. 6).

However due to the serious decline of the populations, the species in now listed as endangered. Both in the Habitat Directive, the Bern Convention and the Dutch Red List as well as by the Dutch law "Flora and Fauna law" (Bakker, 2005). As a result of, it has the highest level of

conservation priority(Jones, 1998). Several factors contributing to its decline are: decalcification, acidification and eutrophication (Odé and Bolier, 2003). The latter three are related to the natural process of succession and mainly effect the dune slack populations.

5. Succession & rejuvenation

Succession is the process in which the structure of species of an ecological community change over time. This process is triggered by the change in abiotic and biotic factors. For this research change of the following factors determine the extent of succession: the amount accumulated soil organic matter, the availability of solid of dissolved calcium carbonate (pH) and the vegetation cover of the soil (Grootjans et al., 1995). Succession is controlled by the development of a soil, which depends on the accumulation of soil organic matter (Grootjans et al., 1998). SOM consists of decomposing plant and animal residues, whom have a positive effect on the properties of the soil (Brady & Weil., 1999). Particularly, SOM being essential for the nutrient availability for plant growth in the soil. (Beare., et al 1994). A higher amount of SOM, the better plants thrive in these soils.

Another cause of succession is the availability of solid of dissolved calcium carbonate, because this is the only factor influencing the pH (Grootjans et al., 1995). The buffer capacity of CaCO3 keeps the pH of the soil high or neutral, which in turn affects the SOM (Formula 1. and 2.). When pH is low, decomposition of organic material will be high and thus will speed up succession.

Both of these factors will influence the vegetation cover. The vegetation will influence the SOM and

Figure 5. Liparis loeselii

Figure 6. Dispersal and population size of L. loeselii (Odé and Bolier, 2003).

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7 pH on its turn. When vegetation increases more SOM will be formed in the soil. Furthermore, will an increase of vegetation lead to an increase in pH of the soil.

However, a soil can be rejuvenated, this happens when fresh sand is deposited onto the soil, mostly due to aeolian activity. This can increase the pH, by which new L. loeselii can colonize the area again.

Methodology

This study was carried out in several stages: first a literature study, secondly the gathering of data and at last the analysis of data. Overlapping a full report was written. Table 1 shows the three main phases.

In the first phase of this research a literature study was done to collect information about the biological and earth scientific processes in the study area. Literature about geomorphologic processes as well as literature of earlier studies in this area will be used.

Table 1. Overview of the research.

Literature study Data gathering Data analysis

- Research Proposal - Introduction - Theoretical Framework - Fieldwork - Transect sampling - Transect soil profile description

- Grid point sampling - Grid point profile description

- Laboratory work - Bulk density - pH and EC values - Organic matter content

- GIS analysis - Transect analysis - Grid point analysis - Aerial photographs - Statistical analysis - Conclusions - Discussion

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Fieldwork

The second phase consisted of data gathering and was conducted in 2018 from may the 5th till may the 11th on the "Hors" on the island of Texel. Two dune slacks were selected to conduct the research (T6 and T8). Within these dune slacks seven transects were selected. As T8 is the larger one, it

therefore has four transects in it. Whereas, T6 is the smaller one and has three inside it (Fig. 7 and 8).

The distribution of transects within the dune slacks is based on where the L. loeselii was expected to grow. T6 is the older dune slack (1999) and has three parts: (1) a more stable part (T6-t3), two more dynamic parts (T6-t1/2) where T6-t2 has declining numbers and T6-t1 increasing. The latter is where we expected to find the highest population density of L. loeselii, due to the expected atomization of

Figure 7. Overview of transect T6-(t1/t2/t3).

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9 fresh sand (rejuvenation).

T8 however, the younger dune slack (2003) has four transects in it. Where T8-t1 is the stable part, T8-t2 has decreasing numbers, T8-t3 has increasing numbers and T8-t4 has strong increasing numbers due to possible rejuvenation.

For each transect 10 sampling points were gathered and documented in a field form (Appendix A). Each field form contains the following: a GPS location, a soil profile description and soil surface characteristics where special attention was given to the thin sand layer of topsoil.

The GPS location is needed to make detailed maps in GIS, so that our research can be displayed spatially. Furthermore, these allow the same research to be carried out again at the same location later on. Additionally, in July the L. loeselii will be counted, therefore the exact locations are needed as well.

The surface profile description consists of a vegetation survey of 1 by 1 meter. In this survey the total vegetation cover in percentages is included as well as the coverage of shrubs, herbs, mosses and bare sand (al in percentages). This is noted because the cover of other plant species influences the

presence of the L. loeselii, due to the fact that they block sunlight that is needed to grow and acidify the soil.

The soil profile description was made as follows. A care was made with a shovel thereafter we used the drill till we reached the water table, then the soil profile was described including the following when present: the thickness of the humus layer (O), the thickness of the Ah horizon and the

thickness of different layers of C horizon. The latter could be present in three different forms. As C1, which is beneath the Ah horizon and is mainly oxidized. Below this one the C2 layer with a mix of oxidation and reduction, occasionally with signs of mottling. C3, a completely reduced layer with a grey blue colour, which smells. For each C horizon also the colour was determined by using the Munsell scale. Later, after fifteen minutes the water table was measured inside the care when it has stabilized. During our research the water table had dropped, probably due to evaporation which were the effect of the high temperatures. Therefore a stick was placed in an inland fen on the day of arrival, this way the drop in water level of the entire week could be monitored. Thus a correction of the water table could be made.

Furthermore, at each transect point two soil samples were taken. For this we used 5 cm deep metal pF rings, containing 100cm3 of topsoil. These samples were stored each in individual bags and later on used in the lab. One sample was used to measure the bulk density and the other for the soil organic matter content, pH and EC values.

In addition, detailed measurements of surface and soil characteristics were conducted in a grid around the transects. For transect T6 92 grid point were performed, and for T8 180 grid point. On a second field form (Appendix B) the GPS location, surface characteristics and topsoil features of these grid points are documented.

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Laboratorial work

The third phase was conducted in the lab, here the bulk density, EC, pH and SOM will be measured. Table 2 gives a description of the methods used.

Data analysis

For the last part of the research some statistical analysis will be made using Microsoft office 365 Excel 2016 and Matlab 2016. Using Matlab, visualizations were made in the form of box plots. Through a box plots comparisons could be made between data from previous years and data collected this year. "NA" was filled in when there was a lack of data.

Furthermore, Excel was used to make a linear regression. Linear regression calculates an equation that minimizes the distance between the fitted line and all of the data points. This approach calculates an equation that explains the relationship between a dependent and predictor variable. For instance between: vegetation cover and pH or soil organic matter.

In addition, Excel was used as interpolation tool for some variables. Using the linear regression model, interpolations could be made from the transect point for the grid point.

At last, ArcGIS was used for the visualization of the transects and grids. Using interpolated data from Excel the spatial relationship between laboratory data and spatial data is made clear.

Table 2. Description of used methods during this research.

Soil measurement Laboratory method

Bulk Density of soil

20 grams of the soil sample will be put in the over for 48 hours at 105°c. After the soil is dried in the oven the sample will be weighted again. Knowing the volume and weight of the original sample, the bulk density can be calculated as:

Total wet weight x Dry sample weight

Bulk density = ________________________________________ Wet sample weight x Volume original sample

pH and EC value of soil 25 ml of demineralised water will be mixed with 10 grams of the soil sample. It will be shaken for 2 hours, followed by a resting period overnight and another 20 minutes in the shaker the next day. The values will be measured using a pH and EC electrode.

Soil Organic Matter content (SOM)

The soil sample will be weighted and be placed in the over for 16 hours at 375°c. The soil sample will be weighted again after this process and the SOM can be calculated as:

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Results

T6 - relation

From the data collected in the field and used in Excel, some linear relations where established. In T6 the relation between soil organic matter content and pH was found. This relation states that when the SOM increases, the pH decreases. The R2 = 0.4345 is larger than the significance level of 0.4. Therefore, this relationship is significant (Fig. 9).

Furthermore, for T6-t2 another linear relationship was distinguished. The relationship between the vegetation cover (%) and the pH. This relation states that when the vegetation cover increases, the pH decreases. As the R2 = 0.4598, this relation is significant as well (Fig. 10).

T6 - Maps

Figure 9. Relationship between SOM and pH in T6. Figure 10. Relationship between veg. cov. and pH in T6-t2.

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T6 - maps

By means of these relations, different maps were produces in ArcGIS. In these maps the relation appears again clearly. Figure 11 and 12 show the relation between SOM and pH, where SOM are high (T6-t3) the pH is relatively low and where SOM is low (T6-t1) the pH is relatively high.

Furthermore, the relation in T6-t2 between vegetation cover and pH becomes clear as the dotted pattern is clearly visible in both figures 12 and 13. A decrease of vegetation is followed by a increase in pH and visa versa. The relations that were significant are used to interpolate data. This

interpolated data is used to make grid-point maps, which show the overall change of a factor in the area more detailed.

Figure 11. Soil organic matter map of transect T6. Figure 12. pH map of transect T6.

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T6 - plots.

For T6-t1 the relation, caused by succession, between pH and bulk density is clarified (Fig. 14a & Fig. 14d). Caused by succession the pH decreases and so does the bulk density.

For T6-t2 this relation caused by succession does not hold. As pH decreases, bulk density increases (Fig. 14b & Fig. 14e).

For transect T6-t3 the same applies as for T6-t3. What is clarified however, is the that the pH has increased from 2010 to 2015. Adversely, the bulk density decreased in that same period (Fig. 14c & Fig. 14f).

Figure 14a. Box plot of pH in T6-t1 in

years 2015 and 2018. Figure 14b. Box plot of pH in T6-t2 in years 2015 and 2018. Figure 14c. Box plot of pH in T6-t3 in years 2015 -2018.

Figure 14d. Box plot of the bulk density

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T8 - relation

For dune slack T8 the relation between vegetation cover and pH could be distinguished too. For dune slack T8 it holds again that when the amount of vegetation increases, the pH of the soil that

vegetation grows in, decreases (Fig. 15). As R2 = 0.4967, it could be stated that this relation is significant.

T8 - maps

For T8 the same relation between vegetation cover and pH was found as for T6-t2. Again this relation becomes clear when visualised in figures 16 and 17. When vegetation cover is low the pH will be relatively high and when more vegetation starts to grow, the pH will decrease due to the succession.

Figure 15. Relationship between vegetation cover and pH in T8.

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T8 - plots

Stated first, T8-t1/2 are the plots of which the data in previous years (2010-2015) is shown. A decrease in pH over the years becomes clear, from around 7.2 to 6.5. A decrease in bulk density is followed in that same period of time. Furthermore, the pH is relatively high in T8-t3/4 which corresponds with the vegetation cover (Fig. 18a/b). Additionally, the bulk density follows the same pattern as the pH. When pH is high the bulk density is too and vice versa.

In addition, other relations within T6 were found. Such as the relation between vegetation cover and pH and between vegetation cover and the SOM. However, the R2_{was below 0.4 and therefore these} relations were not significant. Within T8 the same applied for the following relationships: SOM and pH (T8-T2/3/4) and vegetation cover and pH (T8-T2/3/4) (Appendix C). An overview of all R2 values is given below (Table 3).

pH Vegetation cover (%) Soil Organic Matter

(SOM) T6 - pH x 0.4598 0.4345 T6 - Vegetation cover 0.4598 x 0.2619 T6 - SOM 0.4345 0.2619 x T8 - pH x 0.4967 0.2535 T8 - Vegetation cover 0.4967 x 0.1822 T8 - SOM 0.2535 0.1822 x

Table 3. Overview of R2_{values produced during this research.}

Figure 18a. Box plot of pH values in transect T8 over time (2010 - 2018).

Figure 18b. Box plot of bulk density values in transect T8 over time (2010 - 2018).

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Discussion

Analysis results.

The maps clearly illustrates the age differences within T6. T6-t1 has the lowest values for SOM. In addition, it has the highest measured pH values, on average above 6.7 with outliers up to 6.9. The vegetation map shows mainly values of 100%, but for the most part these were mosses.

T6-t3 has the highest values of SOM, the lowest pH values and almost a complete vegetation cover of 100% within the whole area.

T6-t2 is the intermediate transect, with values fluctuating between those of T6-t1 and T6-t3, either on the SOM map as well as on the pH and vegetation map.

This corresponds to what we know in terms of succession. Soil pH values gradually and significantly decreased with slack age (Kooijman et al., 2016) and SOM content increases as more vegetation grows.

The plots (Fig. 14a/d ) make the process of succession within T6-t1 clearly visible. The soil pH

gradually decreased over time and so did the bulk density between 2015 and 2018. This is a result of the accumulation of SOM, which is lighter than sand. Also stated by Kooijman et al., 2016.

However, plots in T6-t2 the contrary happened (Fig. 14b/e): while aging, there was a gradual

decrease in pH but an increase in bulk density. This could be the result of bare sand cover of the soil. As in previous research fresh sand resulted in a significantly higher bulk density, this could be the case.

Since T6-t3 is the oldest slack, its plots give more insight in what happened previous years. An increase in pH over the years can be observed, possibly due to fresh sand blowing in as result of the 2012 winter storm (Kooijman et al., 2016). Then a strong decrease over the last three years which is the result of succession, based on the observed vegetation in this part of the slack. However, the bulk density remains quite steady, an explanation for this might be the presence of sand form 2012 in the soil.

Within T8 the oldest part T8-t1 clearly shows aging, pH values are low and vegetation cover is 100% due to succession. The vegetation growing in this area are mainly shrubs. More to the south-east however in T8-t4, parts remain where bare sand cover is 100 percent. These areas have higher pH values, which is a consequence of the high aeolian activity in the surroundings (Kooijman et al., 2016).

For T8, the plots from 2010-2015 can be compared to transects T8-t1/2. The pH in 2010 is relatively high due to large amounts of bare sand covering the soil. This corresponds to what is found in the literature: "As substantial numbers (L. loeselii) were only found in T5–T8, which still had relatively large bare sand cover in 2010." (Kooijman et al., 2016). Four years later pH had decreased due to succession, one year later in 2015 the pH had increased again, probably due to high aeolian activity in the surroundings (Kooijman et al., 2016). From then the pH had gradually decreased as result of new vegetation growing, mainly shrubs covering the area. However, the bulk density does not correspond to what the pH does in these years. These values stay relatively stable from 2010-2015 however in 2018 the bulk density in T8-t1 decreases considerably. Again this probably is the result of succession as Kooijman et al., 2016 states: "bulk density significantly decreases during succession, and also, due to accumulation of soil organic matter, which is much lighter than sand." This too explains why the bulk density remains high in the other parts of T8. The bare sand cover was higher in these parts.

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Reliability results.

During the fieldwork conducted on Texel, samples were taken to measure several values. For this 5 cm deep metal pF rings were used containing 100cm3 of topsoil. With these samples the bulk density, soil organic matter content, pH and EC values were derived. However, when sampling the 5 cm topsoil, other material can also end up in here, for instance plant roots. In one specific case a bead was found in one of the samples. This way a sample is erroneously and the conclusions derived from this sample cannot be used.

In this research this was the case for the sample with the bead in it. Furthermore there were samples with some plant roots in them. Both of these examples lead to bulk density results that could not be used to draw conclusions from.

Furthermore, within the vegetation cover maps a value of 100% can be deceptive. 100% cover represents 100% cover of the bare soil. However, what kind of vegetation of vegetation is not clear from the map. 100% can be fully covered with shrubs, but could also mean fully covered with mosses. As shrubs have a completely different influence on the population L. loeselii than mosses have, it is difficult to draw conclusions based on the 100% cover parts. For example, in areas where 100% cover of moss is the L. loeselii can grow, however when there is 100% cover of shrubs, it does not.

Missing data

The main goal of this research was to find out what the effect was of the last December storm of the population of L. loeselii. However the issue for this was the lack of data from previous years. The samples derived in previous was taken on different locations and in lesser quantities. Whereas the research of recent years was broader (13 transects)and less detailed (4 transects points), this year's research was less broad (two transects) and more detailed (70 transect points). Therefore, the datasets could not be compared easily and the obtained results were not really representative.

Reliability regression analysis

For the analysis of the data, a regression analysis was used and the R2 value was determined. This value During this research a significance level of 0.4 was chosen. Finding R2 values between 0.43 and 0.5, assumed was that the relation between the factors was significant. The regression model of 0.4345 accounts for 43.0% of the variance, this is however for scientific research mediocre. A R2 value of 0.6 is required for scientific research.

Conclusion

The aim of this research was to measure the influence of the January 2018 storm on the succession process in slacks T6/8. However, during the research is became clear that finding an answer to this question impossible. Previous research supported that aeolian activity has a rejuvenating influence on soils in dune slacks (Kooijman et al., 2016). However due to a lack of sufficient data from previous years this research, it was impossible to draw the same conclusion for this research. Additionally, there was a 3-year gap between the last data collected and that of this year. Therefore conclusions drawn from this research are not scientifically justified because no data has been collected since 2015 to 2018. During this time period of 3 years, other factors may have influenced the succession. Furthermore, the population decreases when the pH of the soil gets too low and the vegetation

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18 cover too high. As all pH values within dune slacks T6/8 are not below the threshold of 5.8 pH-H2O and 5.6 pH-KCI. These areas are suitable for the flower. In contrast to what Oostermeijer & Hartmann 2014., state the main factor determining the occurrence of the L. loeseli in these slacks is the amount of vegetation cover. Whereas vegetation cover is defined as shrubs in contrary to cover of mosses, where L. loeseli still thrives.

Therefore, the highest numbers of L. loeseli are expected to grow in T8-t4. Here vegetation cover was 0 to 10%, pH values relatively high and aeolian activity present.

Furthermore, a recommendation may be that in older slacks where vegetation cover (shrubs) have increased, but pH values still remains relatively high, an intervention is made. For example by mowing, this way the L. loeseli can continue to thrive in these parts of the dunes.

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Literature

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Oostermeijer, J.G.B., Hartman, Y., 2014.Inferring population and metapopulation dynamics of liparis loeselii from single-census and inventory data. Acta Oecol. 60, 30–39.

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20 Sha, L.P., 1990, Sedimentological studies of the ebb-tidal deltas along the West Frisian Islands, NL.

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Appendices A.

TRANSECT FIELDFORM GPS coordinates: Dune slack (T6/T8): Transect (1/2/3/4): Sampling point: Date: Notes: Samples to take:

Two pF-ring soil samples (100cm3)

Soil profile description Thickness of top sand layer (mm): Water Table:

Surface characteristics

Coverage of bare sand (%):

Type(s) of vegetation and % when present

Moss: Herbs: Shrubs: Vegetation cover (%): TRANSECT FIELDFORM GPS coordinates: Dune slack (T6/T8): Transect (1/2/3/4): Sampling point: Date: Notes: Samples to take:

Two pF-ring soil samples (100cm3)

Soil profile description Thickness of top sand layer (mm): Water Table:

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Coverage of bare sand (%):

Moss: Herbs: Shrubs:

Appendices B.

Vegetation cover (%): GRIDPOINT FIELDFORM GPS coordinates: Dune slack (T6/T8): Sampling point: Date: Notes:

Topsoil layer Thickness of top sand layer (mm):

Depth: Type:

Coverage of bare sand (%):

Moss: Herbs: Shrubs: Vegetation coverage (%): GRIDPOINT FIELDFORM GPS coordinates: Dune slack (T6/T8): Sampling point: Date: Notes:

Topsoil layer Thickness of top sand layer (mm):

Depth: Type:

Moss: Herbs: Shrubs: Vegetation coverage (%): GRIDPOINT FIELDFORM GPS coordinates: Dune slack (T6/T8): Sampling point: Date: Notes:

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Depth: Type:

Moss: Herbs: Shrubs: Vegetation coverage (%):

Appendices C.

Figure 19. Transect T6 relation vegetation cover and pH. Figure 20. Transect T6 relation vegetation cover and SOM.

The influence of the January storm on the succession process on the