Investigating the Effects of Micro Topography on Plant ...



Investigating the Effects of Micro Topography and Elevation on Plant Species in an Alpine Environment.

Group B Final Report

Geography Field Class: Geog2800

July 2006

Mark Ashbourne

Peter Handley

Katie Haynes

Katharine Hughes

Kelvin Hui

Helen McAndrew

Holly Mills

Helen Thompson

Chaya Vaddhanaphuti

Leonie Wright

Table of Contents

Page number

Introduction…………………………………………… 3

Aims…………………………………………………... 5

Objectives…………………………………………….. 5

Hypotheses…………………………………………… 5

Methodology…………………………………………… 6

Site Descriptions………………………………………… 10

Results and analysis…………………………………….. 15

Discussion……………………………………………… 23

Limitations……………………………………………… 25

Conclusions……………………………………………… 27

Bibliography……………………………………………. 28

Appendix 1……………………………………………… 30

Appendix 2……………………………………………… 31

Introduction

This investigation’s purpose was to compare physiochemical variables to find which variable has the dominant effect on species diversity and abundance in two bog sites. In addition it will consider the effect of elevation on these sites to see if vegetation density and abundance varies (Czarnecka, 2005). The physiochemical variables that were considered include pH, soil moisture, wind speed, and direction, air and soil temperature, slope and aspect. These variables are important to consider as they all directly or indirectly affect the growth of vegetation.

Peatlands represent 5% - 8% of the worlds land mass. A bog is a type of peatland and is a waterlogged habitat. Peat is a soil consisting of partially composed remains of dead plants and in its natural state is composed of 90% water (Irish Peatland Conservation Council, 1996). Peat depth in a bog varies from 2 – 12 metres. Bogs are ombrotrophic; meaning that there water supply is from mineral poor rainwater. Hogg et al, 1995 stated the rapid change that ground flora in bog environments experienced. These changes are relevant to the world today. Climate change is a world wide influential issue and ‘peatlands absorb 12% of current human carbon emissions’ (Moore, 2002). It is therefore relevant to study these areas as if anthroprogenic and environmental factors are leading to a decline of movement of these boglands, it may result in carbon being released into the atmosphere. Also in terms of conservation is the habitats to a variety of rare species that a bog supports, meaning that conservation and monitoring of these areas is justified.

Austria has 22, 000 hectares of peat which makes up 2.8% of the land area. Bog vegetation mainly consists of bog moss, some flowering plants, heather sedges and grasses. The lower parts of the moss ‘are continuously shaded, they die and become peat. This means that the bog surface grows upwards to become raised above the surrounded landscape (Irish Peatland Conservation Council, 1996).

Soil acidity, measured in terms of pH, directly affects the growth of bog vegetation. Different plant species can tolerate different levels of pH. Bog environments are typically acidic therefore the species we expect to find here will be adapted to these sensitive environments. Wayda, 2004 stated that pH has an affect on the biodiversity of bog species. It is therefore an especially important variable to study.

Bogs tend to have especially high soil moisture content, which determines which species are able to survive. By comparing between our two sites we should be able to see if there are different soil moisture contents and therefore if there is an effect on species diversity and abundance. Evaporation rates within a bog environment are important to consider as they directly affect the soil moisture content and therefore the growth of vegetation. Evaporation rates are directly affected by wind speed and air temperature, so by measuring these we can get an indication of the levels of evaporation that will occurring at the site.

Aims

1. To investiagte how the diversity and abundance of ground cover species in acidic alpine bogs varies at different elevations.

2. To analyse how abiotic factors such as pH, moisture content and topography also affect ground cover species at the different bogs.

3. To determine if the average height of individual species alters between the elevations.

Hypotheses

From aims 1 – 3 we developed the following hypotheses:

HO – Species diversity and abundance will not vary at different elevations.

H1 – Species diversity and abundance will vary at different elevations.

HO – Species diversity and abundance will not change with varying abiotic factors.

H1 – Species diversity and abundance will be affected by abiotic factors.

HO – Average heights of individual species will not alter at different elevations.

H1 – Average heights of individual species will alter at different elevations.

Objectives

1. To identify plant species at both sites including number and type of plant.

2. To measure physiochemical variables at both sites including pH, soil moisture, soil and air temperature, wind speed and direction, slope and aspect.

3. To record average height and maximum height of each species for each quadrat.

Methodology

By using an OS map and existing knowledge of the study area we selected two sites at different elevations to carry out our investigation. The two acidic alpine bogs that we elected to conduct our study in are of similar sizes and are both under the influence of varying abiotic factors. The location of these two sites is shown in figure 1.

The equipment used to carry out our investigation is shown in figure 2.

|Equipment |Use |

|1 x tape measure (measurements taken in meters and centimetres) |Measure the outer edges of the study area |

|2 x quadrat (1m2 x 1m2) |Placed on the ground to give a 1m2 area for analysis |

|2 x alpine flowers identification book |To allow us to identify what is in the quadrat |

|2 x identification sheet for grasses and other common species |To allow us to identify what is in the quadrat |

|1 x ananometer (measurements in ms-1) |To measure wind speed |

|1 x pH probe (taken to one decimal place) |To measure pH |

|1 x trowel |To dig up soil to analyse its pH |

|1 x container |To place water and soil in to be mixed up before the pH probe is placed |

| |in it |

|1 x compass |To work out aspect and wind direction |

|1 x clinometer |To calculate slope |

|1 x tape measure (measurements taken in centimetres and millimetres) |To measure species height |

|1 x thermometer with soil probe (measured in degrees celcius) |To record air and soil temperatures |

Figure 2

In order to gain a representation of each bog we decided to conduct a random sampling study (see figure 1 A and 1B). In order to do this when we arrived at each study area the outer edges of the bog area were measured and a grid overlaid on a scale sketch of the study site. This grid coincided to a random number that we produced from a calculator. To do this you enter: (Shift RAN) x, where x is the maximum of the length or width that you want the random number for. Having calculated a random width and length reading, you are left with a randomly produced coordinate. As with any coordinates we travelled along our x axis first followed by our y axis. For example the first site has coordinates of 17, 7; therefore from our origin point we moved 17 metres along the x axis and 7 metres along the y axis.

Figure 1 A. Site 1 quadrat location Figure 1B Site 2 quadrat location

Where the random grid square coordinate had been chosen we placed a quadrat at this location. In this quadrat we analysed what ground cover species were present, their percentage cover and a maximum and average height for each species. At each site we decided that ten quadrats would give a reliable representation of each area. The percentage cover was determined by roughly evaluating to what degree each species covered the ground inside the quadrat. This was then recorded.

[pic]

Fig. 3. A photograph to show the species inside a quadrat being analysed.

Also noted was the maximum height of each species; simply be locating the highest individual of each species and measuring with a tape measure. Five heights of each species were taken in order to allow average heights to be calculated. The plant guides aided the identification of all the species in the quadrat. At each site pH was measured using a pH probe placed in 25ml of water containing 5 grams of soil from the relevant quadrat. The temperature of the soil and air was taken using a thermometer with a metal probe. Aspect and slope readings, using a compass and clinometer respectively were taken in order to give a topographic analysis at each quadrat site. Moisture was measured at each quadrat using a moisture probe. Four readings were taken from all areas of the quadrat to allow for an average value to be calculated. Wind speed was measured using an anemometer, with its direction calculated at the same time using a compass.

Site Descriptions:

Figure.1

Site 1:

Site 2:

Site 1:

Located at the lower elevation on the edge of a forested area (altitude 1530 metres), with a road running along one edge (see Figure1 above). The presence of the surrounding forest meant that the

majority of the site was shaded.

[pic]

Figure 4a Elevation of site 1

|Site 1 |Description |

|17,7 |In sunlight, 2 metres to left of tree, and 7 metres left of rocks and |

| |boulders. |

|13,10 |Tree stump in quadrat, near forest edge, trees next to quadrat and |

| |seedlings within. |

|13,2 |In sunlight, near boundary edge, 2 metres from boulders and in rocky |

| |area. |

|5,8 |In sunlight, competely covered with vegetation. |

|20,4 |At boundary, in shade, tree stump. |

|21,11 |In shade, near treeline, very wet underfoot, multiple layered. |

|11,4 |Mottled sunshine, one very wet patch, |

|17,5 |In sunlight, thick vegetation. |

|2,2 |In sunlight, grass dominant. |

|17,10 |In sunlight, could be shaded in part of day. |

Site 2

Located 200 metres higher than the middle cable car station at an altitude of 1732 metres. Area was clear forested to enable the cable cars to pass through. A river ran alongside the bottom of the transect, and it appeared to be small drainage baisin. Pinus mugo was the dominant tree in the area.

[pic]

Figure 4b elevation of site 2

|Site 2 |Description |

|4,8 |In sunlight, at boundary, near trees. |

|3,3 |In sunlight, near raised rock area boundary, some bare soil. |

|12,7 |In sunlight, rocks in quadrat. |

|13,1 |In sunlight, near rock boundary, water at surface. |

|9,5 |In sunlight, bare soil with rocks present. |

|16,1 |In sunlight, near rock boundary (surrounding 2 sides of quadrat) |

|14,3 |In sunlight, very boggy, water at surface. |

|12,1 |In sunlight, pools of water at surface, |

|9,8 |In sunlight, very wet, near pinus mugo tree. |

|16,6 |In sunlight, lots of moss, cloudy at time of sampling. |

|1,1 |In sunlight, near rocky area, drier than most areas. |

Species Examples

[pic] Fig. 5 Crepis palodosa

[pic] Fig. 5aEpilobium amagullidifolium

[pic] Fig. 5b Ductylarhiza fuchfii

Results

Physiochemical variables and species abundance

Using Minitab, regression analysis was carried out to identify any significant correlation between species abundance and the other abiotic factors, i.e. pH, soil moisture, air temperature and soil temperature. Only species that were present at both sites were selected for the analysis. This was done to eliminate elevation as a variable and concentrate only on the abiotic factors. The null hypothesis stated that there would be no significant link between the abiotic factors and species abundance. The alternate hypothesis stated that there would be a significant link between the abiotic factors and species abundance. The confidence level was set at 95% or 0.05%.

Figure 6 below shows the results for the regression, including the P-value and the R2 (adj) values.

|  |  |Grass Spikey |

|Species richness |24 |13 |

|Simpsons 1-D |0.78 |0.75 |

Fig. 8.

From figure 9. it can be seen that the percentage similarity value between the two sites is 56% indicating that although there is some similarities, which we expected as the sites are relatively close, there is also differences.

|Beta diversity |  |

|Whittakers beta w |0.51 |

|Rekonens percentage similarity |0.56 |

Fig. 9

Figure 10 shows the species found at each site and gives an indication of beta and alpha diversity. If we look at the species found at both sites we can see that the majority of the species composition are grasses and moss showing they are more tolerant to varying conditions.

|Species at site 1 only |Species at site 2 only |Species at both sites |

|Crepis paludosa |bog cotton |Grass - spikey head |

|lychnis flos-cuculi |saxifiga stellaris |grass 1 |

|Potentiaa erecta |epilobium amagallidifolium |grass 2 |

|Hercleum austriacum |veratrum album |grass 3 |

|tussalago farfara |  |grass 4 |

|stiff stem buds top |  |cardamine amara |

|Myosotis laxa |  |taraxacum fontanum (Crepis X) |

|prunella vulgaris |  |green moss |

|Dactylorhiza fuchsii |  |pond weed |

|Hydrocotyle vulgaris |  |  |

|Epilobium palustre |  |  |

|euphrasia officinalis |  |  |

|pedicalaris sylvutica |  |  |

|vaccinium vitis-idaea |  |  |

|Alder |  |  |

Fig. 10 Table to show species found at both sites

[pic]

Fig. 11

Figure 11 shows visually that percentage cover varies between site 1 and 2. Species abundance is higher at the different sites depending on the type of species and adaptations.

Height difference between sites

From figure 12 we can see that average height for species found at both sites differ. At site one the plant species height is larger than at site 2 with the exception of cardamine amara and pondweed.

[pic]

Fig. 12

The graph shows a visual trend but we needed to test this statistically, as we were looking to find whether the average height of the same species varied between the two sites. We used chi-squared which is a test of difference. Chi-squared critical values (fig 10) were calculated by using the formula seen below were O=observed and E=expected.

( = (O –E)2

E

|Species name |Site 1 critical |Site 2 critical values |

| |values | |

|Grass - spikey head |2.485 |1.422 |

|grass 1 |1.009 |4.727 |

|grass 2 |3.357 |6.479 |

|grass 3 |4.598 |0.204 |

|grass 4 |0.145 |7.706 |

|cardamine amara |5.467 |0.653 |

|taraxacum fontanum (Crepis X) |0.464 |0.003 |

|green moss |0.002 |68.080 |

|pond weed |48.32 |3.502 |

|TOTAL |65.847 |92.776 |

Fig. 13

From figure 13 we can see that the total critical values are 92.776 and 65.847, by comparing these values to those in the significance table figure 14. Along the top of the table is confidence level, whereas degrees of freedom are along the side. Degrees of freedom are calculated by using the formula (rows-1)(columns-1).

|Confidence level |0.50 |0.25 |0.10 |0.005 |

|Significance value |15.50731 |17.53455 |20.090924 |21.95495 |

Fig. 14

As the value for 8 degrees of freedom at a confidence level of 0.005 is less than the total critical values for chi-squared we can significantly accept that there is a difference in average height of species seen in both of the sample sites.

Using GIS to map the sample areas

By using Arc View and Arc GIS four separate maps were produced to show us the differences and similarities between our two sample sites.

Appendix 2 figure A, shows an area of relatively low moisture with the highest moisture content being in the north eastern side and western side of the sample site. This could be due to the shade provided by the rock formations and the tall vegetations at the edge of the sample site. Alternatively Figure B (Appendix 2), sample site 2 shows and area of extremely high moisture with the majority being highly saturated with only relatively dry spots mainly in the southwest despite having the same aspect and only being 200metress higher in elevation.

Appendix 2 figure C shows that only 2 main areas were of relatively low pH, mainly in the northwest, compared to the sample site. This could be due to the presence of coniferous trees in that particular area whose leaves may contribute to a lowering of soil pH.

Conversely the soil found in the second site is relatively acid through out the sample site. The most neutral point being the northern part of the sample area and the most acid in the south. This is interesting due to the relatively similar aspect and only a few hundred metres difference in elevation.

Species composition along a gradient

Principal Component Analysis (PCA) was to analyse how different abiotic factors affect species composition at the two sites. On PC1 axis (fig. 12) the plot shows a almost a clear separation between species at site 1 and species at site 2. Species at site 1 cluster at one group because they prefer certain abiotic factors which are different from that of site 2. However, there are some overlaps of three species from site 1 in the plots of site 2 species. (see figure 15). The plots on PC2 axis (fig.15) does not show a clear pattern of how abiotic factors have an effect on these species.

By observing closely on the species from site 1 that overlap, it is found that at quadrat (21,11) of site 1, 70% of the species are dominated by hercleum austriacum with very high soil moisture content (90%) and pH of 6.3. At quadrat (20,4) vaccinium vitis-idaea to cover 80% of the area. Contrast to quadrat (21,11), pH as lower, of 4.6 and soil moisture was only 50%. The last quadrat (13,10) was dominated by green moss (50%) and Grass 1 (30%). The pH was 5.5 and moisture was about 60%.

[pic]

Fig 15

The points are plotted along a hidden gradient which, through observations of site descriptions, we think that the gradient of pc1 is soil moisture. This being due to site 1 having low soil moisture and plotted on the left. The anomaly seen at the bottom of the graph had higher soil moisture in comparison to the rest of site 1, hence why the x value is similar to that of site 2.

Discussion

From our results it was seen that species abundance and diversity decreased and differed with increased elevation. This may be explained by different species having different tolerance levels to atmospheric variables caused by adiabatic lapse rates. Some plants can tolerate harsher climate (found at higher elevations) whilst others are much more sensitive and therefore cannot survive these higher elevations. One example of this is the myosotis laxa which cannot survive above an elevation of 1600 metres and this was seen in our results (refer to Appendix 1). Although elevation is an important factor to consider, there are many other variables that may explain or influence the differences observed in species diversity and abundance.

The first of the variables that will be discussed is soil moisture content. At site 2 soil moisture content was greater than at site 1. This may be due to the absence of trees at the site, therefore less water will be absorbed and interception will not occur. Living conditions are made more difficult for plants with excessively raised soil moisture. Grasses, moss and pond weed are best adapted to these high water conditions and dominate the higher elevation site. Pond weed growth was positively correlated with increased soil moisture content therefore it can be assumed that it is more adapted to these wetter environments. It was noted that at the edge of site 2 the soil was notably drier and increased species diversity was found. This again suggests that the majority of species survive better in drier environments (Hogg et al 1995).

Site 2 had a smaller area therefore there may have been more competition between the species. This may be an explanation for reduced species diversity.

Site 2 was noticeably more managed due to tree clearance along the track of the cable car. This may have restricted succession and therefore species diversity. Disturbance by cattle and people will also have the same affect on the species diversity.

Site 2 had a larger humus layer therefore moss roots die more easily (IPCC, 2006) and so the nutrient levels could differ greatly. Also water conducts heat faster than land due to a lower specific heat capacity, which may explain why site 2 ground water was slightly lower.

Site 2 macroenvionments were similar throughout but in site 1 the environment varied much more therefore the number of niches is much greater thus the species number is also higher as there are more plants to fill these niches.

The overlap of some species obtained from PCA may be because they prefer the physical factors that feature site 2 or that their behaviour and habitats are similar to that of species in site 2 or the species are able to cope in a wide range of environments.

The detail for the habitats and behaviour for the species hercleum austriacum, vaccinium Vitis-idaea, green moss and Grass 1, should be explored in further detail for a better explanation for results obtained from PCA for example the tolerance and response in elevation, pH, soil moisture and sunlight.

Limitations

Our main limitation was the lack of time which limited the number of quadrat samples we were able to take. With a greater number of samples a better representation of the sites would have been given thus making our results more reliable.

Sampling method limitations:

1. When setting up the site we walked on areas that were later sampled. This may have affected our plant height readings due to damage incurred. Smaller and more delicate plant species may also have been hidden under other vegetation due to disturbance and subsequently not have been counted.

2. Our random sampling technique resulted in an uneven distribution of quadrats in each site. Our results therefore may not be representative of the entire site at each elevation.

3. Species identification was very subjective, there was a limited key available and the code names given for unidentified plants by different groups led to some confusion when compiling our overall data set.

4. The probe available for measuring soil moisture had an upper limit on soil moisture content. This limit was reached numerous times at our sampling sites. This meant that distinguishing between different moisture contents was relatively inaccurate. In addition, we were unable to measure soil moisture for the entire area of the quadrat, so the average value gained may not have given a fair representation of the actual soil moisture content.

Furthermore, the daily air temperature averaged at approximately 25˚C which meant the upper layer of the soil began to dry out. The moisture probe takes readings from the top 10cm of soil therefore soil moisture readings would have been affected by diurnal heating.

5. Temperature varied diurnally, so ideally we would have taken our readings for both sites at the same time. This would have increased the accuracy of our results by minimising the influence of external variables.

6. Further lab analysis of pH would have given much more accurate readings, however this was not possible given the equipment available.

7. Temperature was originally measured from the central point of each quadrat to keep technique consistent. Towards the end of sampling, temperature was measured more randomly due to obstructions such as water pools within the quadrat.

8. We measured the overall slope at each quadrat, however it was seen that slope varied within each quadrat which in turn may have affected the microenvironment of the quadrat and therefore the vegetation cover.

9. Many of our wind speed readings were zero due to the insensitivity of the anemometer used. Only one reading was recorded for each quadrat which may not have given a representative measurement. Additional secondary data would have given us a comparable source on which to base our analysis.

10. Site descriptions were subjective and written to different levels of detail.

11. We took five height measurements to calculate the average height for each species. Subconsciously, taller examples of each species may have been measured as they were more obvious. This may have led to the omission of younger plants in our measurements therefore not giving a representative sample.

Sample site limitations:

1. Our first site had been investigated two days prior to our sampling. The bog may not have recovered fully from this disturbance and therefore affected the height measurements taken.

2. Our original choice for our second site had to be changed as it had been severely trampled by cattle. Our final site choice was in an open area with a river running by it which was different from Site 1, therefore we no longer had a direct comparison.

3. The second site was located under the cable car line, and as a result tree clearance is common and may have affected species diversity and abundance of the area.

Soil nutrient content at each site was not measured due to a lack of equipment available. This would have helped us understand more about the abiotic influences.

Conclusion

In conclusion we found that species abundance and diversity does vary with elevation. We can see from our results that diversity and abundance decreases with increased elevation, therefore we can accept our alternate Hypothesis 1.

In relation to our second hypothesis, our investigation has highlighted that there are many other physiochemical variables that affect species diversity and abundance. Of these, soil moisture content appears to exert the greatest influence.

We have seen that species height decreases with increased elevation, which means we accept our alternate Hypothesis 3. As mentioned previously this difference in height could be due to many factors, but from our results it is likely that soil moisture content is the major factor affecting this.

To extend this study further, the optimum growing condition could be established to find out where the most stable environment for each species is. By studying a larger area over a longer period of time, for example a season, flowering times could be established for each species. Variation of this could be explained by elevation, or climate change as suggested by Fitter and Fitter (2002).

A further dimension could be added to the study by recording what soil nutrients were found at each quadrat to see whether they have any impact on vegetation growth. It would be interesting as a more abstract extension of the investigation, to establish whether the bogs act as a sink or a source of atmospheric carbon, and to see if this is affected by current climate change (Moore, 2002).

Bibliography

Czarnecka, B. (2005) Plant cover of the Szum River Valley, Acta Societatis botanicorum Poloniae

Dellucmo, A. (1993) Desmids of a small pit bog in the Lomasona fen, Cryptogamie Algogie, 14 (4): 191-198

Grey-Wilson, C. and Blamey, M (1995) Alpine flowers, Harper Collins Publishers, London

Hogg, P. (1995) Acidification, nitrogen deposition and rapid vegetation change in a small valley mire in Yorkshire, Biological conservation, 71 (2):143-153

Irish Peatland Conservation Council (1996) Last accessed 21st July 2006, IPCC information sheet – How bogs form, Available on the World Wide Web

Moore, P.D. (2002) The future of cool temparate bogs, Environmental conservation, 29 (1): 3-20

Mouser, P.J., Hession, W.C., Rizzo, D.M., Gotelli, N.J. (2005) Hydrology and geostatistics of a Vermont, USA kettlehole peatland, Journal of Hydrology, 301 (1-4): 250-266

Phillips, R. (1994) Wild flowers of Britain, Macmillan, London

Usher, M.B. and Thompson, D.B.A. (1993) Variation in the upland heathlands of Great Britain, Biological conservation, 66 (1): 69-81

Vidyakir, A.I. (2001) Phenes of woody plants: Identification, scaling and use in population studies, Russian Journal of ecology, 32 (3): 179 -184

Smart, S.M., Bruce, R.G.H., Marrs, R., LeDuc, M. (2005) Large scale changes in the abundance of common higher plant species across Britain between 1978, 1990 and 1995 as a consequence of human activity, Biological conservation, 124 (3): 355-371.

Appendix 1

|Species |Location |

|Myosotis laxa |Stoney and grassy places up to 1600m |

|Tussalago farfura |Bear and waste ground, fields and banks up to 2800m |

|Hercleum austriacum |Fields and shrubs up to 2500m |

|Prunella vulgaris |Woods and dry meadows up to 2400m |

|Crepis palodosa |Damp grassy places and stream sides up to 2150m |

|Taraxacum fomtanum (crepis x) |Grassy and rocky meadows up to 2500m |

|Lychnis flos-cucali |Native perenial of marshes, fens, damp meadows and woods up to 2500m |

|Potemetilla erecta |Grasslands, mountains, heaths and bogs up to 2500m |

|Ductylarhiza fuchfii |Marshes and wet meadows, grassy slopes, woods and fens up to 2200m |

|Saxifiga stellaris |Damp places, steep sides and marshes up to 1900m |

|Cardamine amellu |Wet places, stream sides often in woods up to 2000m |

|Epilobium pulustre |Wet places up to 2300m |

|Pedicalaris sylvatica |Deep marshes and meadows on acid soil 1800m |

|Euphrasia officinalis |Grass at mountain bottom |

|Vaccinum vitrs-idaea |Coniferous woods and subalpine pastures 3050m |

|Epilobium amagullidifolium |Wet places and acid soils up to 3000m |

Appendix 2

Figure A Soil moisture, site 1

Figure B soil moisture site 2

Figure C pH site 1

Figure D pH site 2

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[pic]

11 m

26 m

16 m

8 m

27 m

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