Aim: To investigate how light intensity affects leaf thickness of Ivy ( Hedera helix ) in shaded and exposed areas within a field located at Juniper Hall, Dorking, Surrey (TQ1725052707)

RESEARCH & RATIONALE:

(Abstract)This field study’s main purpose was to explore any form of relationship between light intensity and how it may affect physical properties such as thickness of Ivy leaf (Hedera helix). The investigation consisted of two different conditions; a shaded area (downfield- limited exposure to sunlight) and an area receiving greater exposure to sunlight (up field). The study was primarily conducted on the grounds of Juniper Hall field centre as the location provided both easy access to necessary equipment and was of convenience due to naturally occurring Ivy plantation. This location was also used to analyse other variables so that all significant influences on thickness could be taken in to consideration. These variables include atmospheric temperature, humidity, soil pH and soil depth. These factors did have an effect on the overall results.

EXPERIMENTAL HYPOTHESIS: There will be significant difference in the thickness between the leaves in the light area and the dark area

NULL HYPOTHESIS: There will be no significant difference in thickness between the leaves in the light area and the dark area; the sun leaf would only be slightly thicker

(Introduction)(i) Ivy also known as Common Ivy/ English Ivy, is a native species to Europe and temperate

Asia that’s Classification is as follows: Domain: Eukarya, Kingdom: Plantae, Phylum: Anthophta, Division: Magnoliophyta (flowering plants), Class: Magnoliopsida (Dicotyledons), Order: Fabales, Family: Araliacecae, Genus: Hedera L., Species: Hedera Helix. [1]

(ii) Ivy is a woody, evergreen that displays differences in infant and adult form which is uncommon in other plants.[ Diedrich and Swearingen (2000)] During its early (rapid growth) stages, plant is most likely to expand outwards and upwards with branched out aerial roots and lobed leaves from main stem (can reach 30m high with stems up to 25cm in diameter). The main stem itself is coated with hair-like roots that act as an adhesive to enable the plant to climb hard surfaces. [2] During later stages in contrast, plant loses its roots, developing dependence on stem for support. Additionally the leaves on creeping or climbing stems (have blades with 3 to 5 triangular lobes) change to oval or rhombic blades, without lobes and plant begins to flower although, this only occurs in full sunlight. The overall change through maturity results in plant developing appearance of shrub. Flowering period for Ivy occurs between September-December, whilst fruit ripening period begins in spring. [2] The Ivy leaves that I examined were hairless and glossy very dark green above with a paler back.

(iii) In a similar study conducted by Yang et al. (2007) it was found that decrease in light intensity resulted in leaf thickness amongst many other things. This study may apply to my investigation as this study observed the morphological and physiological characteristics displayed in tobacco seedlings according to light intensity and so can portray a more detailed account of the relationship.

(iv) Juniper Hall is recorded as a Grade 2 British listed building since 1951 and is the property of the National Trust, though as of 1947 has been occupied by the Field Studies Residential

Centre. [3] This centre has unimproved chalk grassland, coppiced woodlands, heath land and freshwater sites as environments and habitats for study. [4]

(Rationale)In 1988 Physiologia Plantarum, published a study conducted by Bauer and Thöni (1987) on photosynthetic light acclimation of fully developed leaves in the two different stages of common Ivy. Their results indicate that that in the adult life phase of ivy light acclimation occurs mainly during leaf development, while in the early plants phase; fully expanded leaves still possess rather wide changes in flexibility of acclimation. It could be argued that due to their study being a laboratory study it lacks ecological validity as results may not generalised to what actually happens in natural environment. However as the observations for my study will be carried out in the natural environment of where Common Ivy grows, so results from my study will then gain stronger ecological validity. The results from this investigation should be of interest to biologist and others working in the field as common Ivy leaves are used as herbs to help alleviate pain for disorders of the liver, spleen, and gallbladder; including muscle spasms, gout, joint pain (rheumatism), chronic bronchitis, and tuberculosis. [10]

Common Ivy can withstand an average soil pH minimum of 5.2 and a maximum of 7.8.according to a US plant database. So by recording soil pH we can be sure to observe whether differences in soil pH may affect the thickness of Common Ivy leaves. The same database found that Ivy required fine soil type which had a medium tolerance to calcium carbonate (CaCOᶾ). If soil type does not meet up to norm requirement of common Ivy than this in turn may have effect to leaf thickness, therefore soil type needs to be taken in to consideration. A factsheet by Diedrich and Swearingen (2000) state that Hedera helix requires some soil moisture to be present. It also claimed that English Ivy prefers damp soils, and a moist, cool environment. Therefore it is essential to take humidity and atmospheric temperature in to account as favourable conditions may indicate to greater thickening of leaves.

PLANNING:

(Independent and Dependent variables):

SI Units (of Measurements):

Number of Samples:

How variable will be manipulated:

Independent Variable (IV):Light intensity

(lx)/ Lux 10-20 It will be manipulated through taking random reading in sample area.

Dependent Variable (DV):Thickness of

the leaf

mm/ millimetres10-20 - - -

(Other variables):

Other Variables :

SI Units (of Measurements):

Number of Samples:

Why variable is needed to be taken in to account:

How it will be taken into account:

Humidity (%) / Percentage 10-20 Effects on results: the more humid it is, the higher of the water content of the atmosphere and soil, this will increase germination of Ivy.

Measured using a

Moisture Pin

Soil pH(pH)

10-20 Effect on results: lower pH (more acidic= lower number Ivy plants) higher pH (more alkali = higher number of Ivy)

Measured using Digital

pH Meter

Soil Temperature

(oC)/ Degrees Celsius

10-20 Effect on results: low- average (10-21 oC) it will increase the growth of Ivy.

Measured using a Temp

probe

Soil Type None- using description of

soil

10-20 Affect on clover: Well drained, dry, chalky and alkaline is favourable in growth of Ivy

Description of soil type

It is important to consider these inessential variables as they can influence the outcomes of this field study causing it to lack internal validity.

(Risk Assessment):

Hazard/Outcome:

L ikelihood : S everity : Risk Score:

Control:

1 Very rarely

2 Rarel

y

3 Infreque

ntly

4 Sometim

es

5 Often

1 Minor

2 Injury

3 Major

4 Cripplin

g

5 Fatalit

y

(L x S)

Low branches/ falling

8 Visual assessment for low branches and

Insect bite, stung by wasp

8 Visual assessment in case of disturbance to insects during

Steep Slopes 8 Wear footwear that is suitable for activities (grip).Looking

directly at the sun for a long period of time

16 Wear sunglasses that polarises and filters out UV rays, don’t look at it directly. Getting pocked

by temp probe1 Handle the all pins with

care and store in safe container if it is not in

The highest ranked risk score was 16 out of 25 for risk assessment. This risk score indicates that it is safe enough to proceed with this investigation.

A non-parametric Statistical Test used in this study to avoid making assumptions over parameter. To be more specific Mann-Whitney U test was used as it discusses basic differences between assumptions of population distributions and skewed data.

Anna LyMETHOD:

(Initial Trial Phase)

List of equipment:

Calculator Hygrometer Meter stick Light meter Soil temperature probe Soil pH- pH probe and distilled water Soil pots x 10 Micrometer

Steps: A sample size of 5m by 5m was chosen because it was big enough to cover a large

percentage of the Ivy plantation on the grounds of Juniper hall. Using two 5m measuring tape, an x-axis and y-axis were made and a scientific calculator was used to generate random numbers for co-ordinates.

An Ivy leaf was picked at each co-ordinate and in total I picked 5 from each area for my trial. The same sampling technique and sample size was used when carrying out the experiment downfield and up field will increase reliability.

Each Ivy leaf thickness was measured using a micrometer in 3 different sections and taken and average.

Humidity was measured using a hygrometer; this was placed on the ground and left for one minute to allow enough time for it to adjust to the surroundings for a more precise reading.

The temperature of the soil was collected using a temperature probe; it was placed in three different areas within the 5m by 5m sample.

Ten samples of soil was collected using a clean spatula and a sterile soil pots to avoid any contamination, distilled water and a pH meter were then used to work out pH of the soil. Each reading was taken twice for each sample.

The light intensity in the trial was measured at 2pm using a light meter; twenty readings were taken in each area with the light meter facing upwards.

The Sampling TechniqueRandom Sampling in its simplest form was the sampling technique used for my investigation as it is ideal for conducting experiment on a large scale within a short space of time. Co-ordinates were generated using “Ran” function on a scientific calculator; this reduces the chance of a biased sample and enables more samples to be taken. Therefore a large percentage of the population will be researched.

(Amendments):The overall method used in the trial was almost identical to the main investigation in terms of sample size and technique. The only alterations made for the main method was to use two light meters for synchronised readings.The trial helped rule out factors that stayed constant, readings did not vary as much factors such as soil pH and soil temperature, is due to the grounds of Juniper Hall, Surrey is above

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Anna Lysedimentary rock, calcium carbonate which dissociates and causes the soil to become alkaline. Soil temperature readings also didn’t vary as much.

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Anna Ly Alternative Data that has been taken into account, shaded and exposed area of Juniper hall (TQ1725052707)

(Trial)Sample 1 2 3 4 5 6 7 8 9 10 Mean

Temperature (°c) 18 17.8 18.2 18.1 17.5 18.0 17.6 18.2 18.3 17.8 17.95

Soil pH * 8 7.5 7 8.1 7.2 7.3 7.1 7 8 7.9 7.51

Humidity (%) 76 75 75 79 72 73 76 78 75 73 75.2Soil Temperature (°c) 13.8 14.1 13.9 14.1 14 13.7 13.9 14.3 14.1 14.4 14.03

Exposed sunlight area

Shaded areaSample 1 2 3 4 5 6 7 8 9 10 Mean

Temperature (°c) 17.8 18 18.2 18.3 17.2 17.9 17.5 18 18.2 17.7 17.88Soil pH * 7.4 7.1 8 7 7.2 7.4 7.2 7 8.1 7.7 7.41

Humidity (%) 75 76 74 79 73 72 74 77 74 75 74.9Soil Temperature (°c) * 13.7 14 13.8 14.3 14 13.5 13.8 14.2 14.2 14.1 13.96

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(Trial)

Average Leaf thickness- shade (mm)

Average leaf thickness-full sunlight (mm)

0.332 0.3210.252 0.3050.275 0.3040.273 0.3000.280 0.290 Lux readings/ light intensity- shade Lux readings / Light intensity- full

sunlight6170 173205730 175606320 189009360 273006340 17300

(Main)Sample number Average thickness

Shade mmAverage thickness Sunlight mm

1 0.287 0.3212 0.286 0.3043 0.273 0.3014 0.338 0.3215 0.253 0.3636 0.276 0.3067 0.250 0.3228 0.317 0.2979 0.349 0.26710 0.335 0.305

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Box plots comparing light intensity in Exposed and Shaded area (Lux)

(Main)

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Mann- Whitney ‘U’ Calculation Sheet

EXPERIMENTAL HYPOTHESIS: There will be significant difference in the thickness between the leaves in the light area and the dark area

NULL HYPOTHESIS: There will be no significant difference in thickness between the leaves in the light area and the dark area; the sun leaf would only be slightly thicker

Ranking A

7 5 2.5 6 18 2.5 1 14 19 17 Ra=92

Data A 0.287

0.273

0.253

0.286

0.338

0.253

0.250

0.317

0.349

0.335

na=10

Data B 0.320

0.304

0.301

0.321

0.363

0.306

0.322

0.297

0.267

0.305

nb=10

Ranking B

15 10 9 13 20 12 16 8 4 11 Rb=118

Ra+ Rb= 20 x 21 /2 =210

Ua=100 +55-118=37

Ub=100+55-92=63

Critical=23 (critical value table)

Conclusion: 95% confidence level for difference in leaf thickness in sun and shade area. My U value is smaller less than the Critical value (23); therefore you can reject the null hypothesis and accept the experimental hypothesis. Therefore there is a significant difference between the thickness in leaves exposed to the sun and shaded leaves.

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Anna LyINTERPRETING & EVALUATING:

Discussion: This section will discuss any limitations of findings and improvements made.The general trend of my dataset shows that in common Ivy plantation as light intensity increases the thickness of leaves increases, indicating that there may be a correlation between the two variables.The statistical test used to analyse the findings was Mann Whitney U test, this is ideal for comparing two different sets of data, and in this case it was to find and compared the thickness of common Ivy leaves in an area of greater exposure to sunlight and a shaded area. The results showed a positive correlation between light intensity and thickness.

Nonetheless there were fluctuations in the results most likely due to equipment used in the experiment such as the micrometer, which was used because it is accurate to 0.01 of a millimetre; therefore it would have a very low percentage error compared to using a ruler which is accurate to 1mm, giving it a larger percentage error. For example a leaf is 0.4mm thick (say it is less than 0.5 mm) would only have a percentage error of 0.01 in 0.4; 2.5%. Whereas, using a ruler accurate to 1mm to measure would give a 200% error. Due having a 2.5% percentage error, it is not guaranteed that the readings of the thickness is 100% accurate, so repeating the readings will not eliminate this error in any way as it is a systematic error. The micrometer used was manual so it could have been easier to miscount compared to using a digital micrometer increasing likelihood of random error. This might be the cause of the anomalous result of 0.363mm as the micrometer might have clicked too soon giving a thicker reading than expected. Fortunately the equipment was quick and easy to use, measurements taken were repeatable, large samples were easily taken and gave enough to calculate an average to support the conclusion, excluding anomalous results in the calculations. Despite the systematic and random errors in equipment and method, the results were reliable because it was controlled environment, the same micrometer and light meter was use throughout the whole experiment.

Alternative factors were also measured such as humidity; pH and soil temperature had an effect on the thickness. Humidity the shaded area had, 74.9% and the exposed area, 75.2%. The thickness may have been due to the moisture in the air, the sunlight exposed area may have had higher water intake due to the surrounding atmosphere, and therefore it would have higher water content in the cells.

Soil pH sample was taken ten times and each reading was given at least one minute for the ions to dissociate with the distilled water before it was taken. There was barely any difference, it can be concluded that it is generally alkaline due to the grounds being on Calcium Carbonate.

Soil temperature may have had an effect on the size of the leaves, the shaded area Ivy leaves appeared larger than the sunlight exposed leaves, Ivy grows better in colder temperatures which is why they are most abundant in September-December. The Shaded area was slightly colder (13.96°c) than the sunlight exposed area (14.03°c). [9]

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Anna LyFluctuation in light intensity readings was probably due to reaction timing of my assistant and I, the fluctuations might be due to taking readings and being out of sync. It could be also due to a cloud going by and affecting the results, which is why 30 readings were taken to increase reliability. Computer generated box plots where used to compare results because the results were too close together to plot manually on graph paper.

Overall the investigation has shown a positive correlation between higher light intensity has an effect on the leaf thickness. To improve results this experiment could be replicated on a larger scale to identify the accurate effects of light intensity on leaf thickness.

BIBLIOGRAPHY:

[1]- Website: - http://bioweb.uwlax.edu/bio203/s2009/hitchins_abby/classification.htm – English Ivy Classification (Copyright 2006)[2]- Website: - http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/economic-impact/hedera-helix/index.html – Natural History Museum (Copyright 2012)[3]- Website: - http://www.britishlistedbuildings.co.uk/en-289953-juniper-hall-mickleham-surrey - British Listed Buildings, Juniper Hall, Mickleham [4]- Website: - http://en.wikipedia.org/wiki/Juniper_Hall - Wikipedia, Juniper Hall (2012)[5]- Journal: -Yang, X.Y. & Ye, X.F. & Liu, G.S. & Wei, H.Q. & Wang, Y. (2007), Effects of light intensity on morphological and physiological characteristics of tobacco seedlings, Ying Yong Sheng Tai Xue Bao, 18(11):2642-5. [6]- Journal: - Seong, B. and MITSUO, K. (2003), The Cold Resistance of Hedera helix L., based on the Interrelations between Plant Surface Temperature and Cultivation Environments, Journal of Agricultural Science, 47(NO.4) 252-259. [7]- Journal: - Bauer, H. and Thöni, W. (1988), Photosynthetic light acclimation in fully developed leaves of the juvenile and adult life phases of Hedera helix. Physiologia Plantarum, 73: 31–37. doi: 10.1111/j.1399-3054.1988.tb09189.x [8]-Factsheet: - http://www.nps.gov/plants/alien/fact/pdf/hehe1.pdf -- Conservation Alliance’s (PCA) Alien Plant Working Group, Factsheet: English Ivy (Copyright 2006)[9]-Website: - http://houseplants.about.com/od/foliageplants/p/Ivy-How-To-Grow-English-Ivy.htm (Copyright 2013)[10]-Website: - http://www.webmd.com/vitamins-supplements/ingredientmono-465-ENGLISH%20IVY.aspx?activeIngredientId=465&activeIngredientName=ENGLISH%20IVY(Copyright 2009)

EVALUATION OF SOURCES:

[2] This source can be viewed as having very high reliability; as it is a concurrent website for Natural History Museum and it is always up to the date with new scientific guidelines. This source is an electronic outlet of information from a well known institution based in the UK.

[7]This article was published in 1988 therefore the reliability can be questioned for this source, as the study can be considered out dated and new findings could disprove the content of this research. Although, study was based in Austria, it is part of Europe where common Ivy is native to. This article was also published in a journal that is still publishing ecological scientific work to date.

[8]This fact sheet has a variety of references of other journals that date to 2005 and this fact sheet itself is considered current (2006) however this fact sheet focuses

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Anna Lyprimarily based in the US so credibility would be questioned due to environmental differences.

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