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Discussion:

the leaf size is also affected by canopy cover (find a paper)

leaf size also constrained by plant species

Limitations:

It was not possible for the transect location to be randomised as there was no access to an

accurate map of the ecological park including cliff and incline height which would have aided

in finding possible transect locations

The terrain constraints limited the areas that we could place the transects therefore the

transects may not be completely representative of the patterns that occur in the system as a

whole

Future studies:

analyse the effect of canopy cover as it alters the light availability and leaf temperature

analyse the results/construct the experiment to include analysis of species separately to allow

for better comparisons

Intro:Plants are sedentary organisms and therefore need to be able to alter their

morphology to suit their environment (Poorter & Rozendaal, 2008). Leaves play an

essential role in the growth and development of a plant as they are the main area for

photosynthesis and control other important functions such as gas exchange and

transpiration (Parkhurst & Loucks, 1972 and Geng et al., 2006). Heredity is the main

factor deciding plant morphology, but abiotic pressures from the surrounding

environment such as temperature, amount of sunlight and water and nutrient

availability have been shown to impact on plant morphology (Parkhurst & Loucks,

1972, Cookson, et al., 2005 and Geng et al., 2006). Water availability is important to

plants as it is an essential component of photosynthesis and assists with the structure

of the plant as it maintains turgidity within its cells (Parkhurst & Loucks, 1972 and

Zimmerman & Husken, 1979). Leaf size and overall morphology has been found to

correlate with the amount of available resources, with plants developing different

area, vein patterns, teeth and elongation to cope with environmental stresses (Xu, et

al., 2009).

In Australia, climate change is predicted to increase the occurrence of

droughts and the information of leaf size in relation to water availability may help


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identify plant species that may be more susceptible (Mushtaq, et al., 2013).In this

study, we aim to investigate the correlation between distance from a water source and

leaf area. We hypothesise that leaves closer to a water source (Macquarie Ecological

Park creek) will have a greater area than leaves farther from it. This study aims to

assist with plant models in relation to water availability which is becoming an

increasingly important field due to climate change concerns.

Materials and Methods:

The study site used in this study was the Macquarie University Ecological Park in NSW,

Australia. This site was chosen due to the abundance of plant life and the presence of a creek

running along the length of the park. A 50 metre wind up tape measure was used to plot three

transects with a minimum of 15 metres in between each to prevent pseudo-replication. Then

three sites along each transect were chosen, with 10 metre intervals between them; beginning

from the creek. The three transects were named T1, T2 and T3 and the sites within each were

labelled A, B and C respectively. At each site, a radius of 1 metre and a height of 1.5 metres

was marked using chalk and four leaves from each tree within this radius, at this height were

taken and placed into a clear plastic bag labelled with the transect and site number. These

leaves were then traced onto 1mm graph paper, clearly labelled with the transect and site

number and the area calculated by counting the number of squares within the traced leaves.

The average leaf area for each site was calculated and noted and these averages were used in

the statistical analyses conducted using Minitab.

Statistical analyses:

The program, Minitab was used to complete all the statistical analyses of the study. The box-

cox transformation was used to transform the raw data collected as it was inconsistent with

the assumptions of an ANOVA. This transformed data was then used in a one way ANOVA

with an 0.05 significance level to analyse the variance in leaf area in respect to distance from

the water source.

A Tukey post-hoc test was used to analyse the differences between each data set in order to

determine the specific interval where the average leaf size plants differed from the average

leaf size of plants from the other intervals.


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discussion notes:

the increasing trend of leaf area from dry to wet may also be the result of a reduction in

sunlight as leaf size changes in sun or shade to maximise the efficiency of water use

(Parkhurst & Loucks, 1972 and Poorter & Rozendaal, 2008)

the climate that these plants reside in also has an effect on their morphology and their inter-

and intra-specific interactions - if they live in rainforests or deserts, they have different

shapes and sizes to exploit the available resources with the least cost to them (Poorter &

Rozendaal, 2008)

With this information in mind, we hypothesised that

Materials and Methods.

The ecology field reserve located at Macquarie UniversityNSW, Australia was chosen for the

sample site due to its diversity of vegetation, its proximity to the university and for the creek

that runs through the middle of the reserve. At the site, three transects were established at the

perimeter of the creek and were spaced apart at least 15 metres from each other in order to

maintain an independence of sampling and to avoid pseudo replication. For each of the threetransects,intervals were established every 10 metres starting from eachtransects point of

origin (the perimeter of the creek). Eachtransect had a maximum of three intervals

established. To determine if leaf area size differed in areas distanced further from the creek, 4

leaves were taken from every plant at each interval (in each transect) at a height of 1.5 metres

in the vicinity of a 1 metre radius. The collected leaves were stored in a plastic bag and

marked accordingly to be measured. The sample leaves were traced onto graph papers

measuring 17x25 cm squared and measurements were conducted which recorded the number

of 1mm square spaces which the area of the sample leaves occupied. Minitab was the

statistical package used in this experiment to correlate and analyse data.

Results

The average area size (cm2) of leaves in plants found further from the creek were shown to

be, on average, smaller in sizethan leaves from plants situated closer to the creek (fig.1). A

one way ANOVA analysis on the transformed data showed that there was a significant

difference (F=20.31, P=0.00) in the average leaf size between at least one of the groups of


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leaves collected at a specific interval, either the group ofleaves collected at the origin of the

creek (group A), 10 metresfrom the creek (group B), or 20 metres from the creek (group C)

(fig2). A Tukey post- hoc test on the transformed dataconfirmed that there was indeed a

significant difference in average leaf area size between group A and group C, and between

group A and group B. However, the test showed that there was not a significant difference

between the average leaf size of plants in group B compared to group C.

Discussion

Our report showed that leaf size in plants showed a significant decrease in size when faced

with restricted water availability in the environment. We found that there was a significant

difference between the sizes of leaves from plants situated next to the creek and the sizes of

leaves from plants located 20 metres from the creek. We also discovered that there is a

significant difference between the sizes of leaves from plants located 10 metres away from

the creek and the sizes of leaves from plants situated 20 metres away from the creek. These

results indicate that as the proximity of plants to a water source decreases, so does the leaf

sizes of those plants.

These findings are congruent with a number of studies which found that leaf sizes of many

plants were significantly reduced in stressful environments that lack sufficient nutrients

needed for the development of the plant body. One study in particular found that leaves of

plants located in dry and drought like environments had significantly reducedbiomasses and

leaf areas compared to leaves of plants situated in cooler environments with increased wateravailability.

The variations in leaf size between plants found in environments with high resource availably

and plants located in environments with low resource availability can be attributed to

adaptations that enable the plants to better survive and thrive in the environment they reside

in. Plants that are located in harsher environments with limited water and nutrients are found

to have smaller leaves because they are structurally and physiologically better suited to

survive in drier soils than larger leaves. Likewise plants, with small leaves can also limit

water loss in hot and dry environments, thus helping them survive in harsher conditions with

limited water availability.

The relationship between leaf size and water availability are found to be generally consistent

amongst all species of plantsbut there may be additional factors that influence the size and

morphology of the surface area of leaves other than resource availability. However, due to the

limitations of this study, wecould not adequately investigate any additional factors that may

influence the size and morphology of leaves. Therefore, this report recommends further

examination into leaf size of plants and their applications for survival in differing

environments.


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Agricultural systems. Volume 117, May 2013, pp. 78-89

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security though investments in modern irrigation technology

S. Mushtaq, T.N. Maraseni and K. Reardon-Smith

Progress in Natural Sciencevolume 19, 2009, pp. 1789-1798

Leaf morphology correlates with water and light availability: What consequences for simple

and compound leaves?

F. Xu, W. Guo, W. Xu, Y. Wei and R. Wang
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2005.01368.x/fullhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2005.01368.x/fullhttp://aob.oxfordjournals.org/content/78/1/61.full.pdfhttp://aob.oxfordjournals.org/content/78/1/61.full.pdfhttp://treephys.oxfordjournals.org/content/21/9/599.full.pdfhttp://treephys.oxfordjournals.org/content/21/9/599.full.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://cid-inc.com/docs/CI-203%20Leaf%20morphology%20correlates%20with%20water%20and%20light%20availability%20-%20What%20consequences%20for%20simple%20and%20compound%20leaves.pdfhttp://treephys.oxfordjournals.org/content/21/9/599.full.pdfhttp://aob.oxfordjournals.org/content/78/1/61.full.pdfhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-3040.2005.01368.x/full

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