The effects of shade from trees on plants below

The basis of my prediction is the fact that plants need sunlight in order to produce food. Hence my theory that there would be less plants growing on the wooldand floor meaning that there would be more bareground.

The equasion for photosynthesis (shown below) demonstrates to us that not only do plants need sunlight to make food but they also need Carbon Dioxide and Oxygen.

CO2 + H2O C6 H12 O6 + O2

Apart from the fact that plants on the woodland floor will be exposed to less sunlight, plants growing on the woodland floor will also have to compete with the trees surounding them for water and carbon dioxide.

The equasion of respiration is:

Glucose + Oxygen Carbon Dioxide + Water + Energy

Plants oxidise part of the glucose to release energy during respiration, so this therefore means that if plants receive less glucose through having to compete with tress then plants will not be able to respirate quite as easily, therefore not flourishing as well as they would in an open air environment.

However some plants could survive underneath trees because there will be less wind, so the plants will lose less water through transpiration and will not have to take up as much water via the roots. If the plants need to take up less water then there would be less competition for water between the plants and the trees.

Another reasion why some plants could possibly survive underneath the trees is because some plants may have big leaves and therefore would be able to absorb sunlight easier then if the plant had small leaves.

Because I feel that there will be less plants in the woodland than there will be in the open ground, I predict that when I produce graphs to show my results the graph which will show the amount of bareground there is going from woodland to open ground will be a downward slope because the amount of bareground that there will be will go down.

The graph I will produce that will show the amount of plant growth going from woodland to open ground will be an upward slope because the amount of plants that will be growing from woodland to open ground will increase.

Examples of graphs

Plan

In order for me to test my theory I will be going to the devonshire road nature reserve, Forest Hill. Whilst there I will be using the 'Belt transect' method to test my theory that the amount of sunlight a plant recieves effects its growth.

At the nature reserve there will be ample enough resources for me to test my theory, due to the fact that there is a vast amount of wooldland and openground.

The continuous quadrat method is way in which I will be testing the amount of plant growth within a section of the woodland/ openground it involves using a metal frame divided into four sections using string. When placed on the ground the quadrat make it easier to estimate how much of the ground is covered by the plants and how much of it is open ground. Each section of the quadrat is worth 25%, so by working out how much of the square is covered by a specific plant you can estimate how much more or less than 25% is covered by the plant

Equipment that I will need

* 1 Quadrat (half a square metre)

* Tape

* Two pegs

* Identification sheet

* Metre rules

* Light metres

* Temperature probe

* PH Kit

I will firstly start off by choosing the area in which I will be carrying out my investigation, then I will reel out the tape and then use the two pegs to fasten the tape at both ends. One end of the tape will be under some trees in the woodland, the other end of the tape will be fastened in bareground.

Then I will place the quadrat along the edge of the tape and take various readings.

The readings that I will be taking are:

* Amount of area a specific plant takes up.

* The amount of bareground there is.

* The hight of the tallest plant

* The greenness of its leaf

* Size of its broadest leaf

* Temparature

* Intensity of light

* PH of soil

Although the Belt transect method is an effective way of taking a fairly accurate results, overlapping may occur, leading to the results being less accurate. I will have to ensure this does not happen by marking where each quadrat is placed.

Once I have gathered the results required from the testing I may then repeat the procedure and then work out the average results. This may enable me to get even more accurate results.

Although I would like to repeat the procedure, the time factor is an issue and I may not be able to completely repeat the process with the time I have available to me.

Discussion/ Conclusion

My prediction stated that there would be less plant growth in the woodland, therefore increasing the amount of bare ground. I predicted this because my theory was that because plants need sunlight for photosynthesis; if the canopy of the trees restricted access of sunlight getting to the plants there would therefore be less plant growth.

My results proved my prediction to be right because by looking at the results that I had gathered using the Belt transect method I was able to produce suitable graphs to show general trend between the woodland and open area plant growth.

The graphs that I produced were vary informative and enabled me to come to a suitable conclusion based on the line of best fit.

On the graph that I produced showing the amount of plant growth going from woodland to open ground. The line of best fit went in the same direction as I stated that it would in my prediction. The graph showed that the amount of plant growth increased as the quadrat was moved more and more into the open ground. Apart from the reason stated in my prediction, I feel that there may be other factors that contributed to the increase in the growth of plants.

One of these reasons could have been that there was more CO2 that was available for the plant to use, instead of having to be in competition with the trees for it.

CO2 is needed for the plant to make food and therefore if there were a more supply of it then plant growth would therefore thrive.

The graph I produced to show the amount of bare ground their was going from woodland to open ground it showed that their was a steady decrease in the amount of bare ground present, thus confirming the results shown in the plant growth chart.

In order for me to test to see if lack of sunlight affected all plant life I produced a third graph which showed the amount of bramble present in the woodland and open ground.

The reason that I chose this plant was because it is one of the most commonly found plants in woodland; I was interested to find out just how common it was.

This line of best fit for this plants graph showed a slight decrease in the amount of growth going from Woodland to open ground. This was quite surprising because it contradicted my prediction and did not follow the usual pattern of growth that occurred with the other plants.

In conclusion, I found out that in order for plants to grow adequately they need to have the right conditions to live in e.g. sunlight.

Sunlight is important because it is needed not only for making food but also for producing glucose that is used during respiration. Glucose is broken down for energy and growth, so lack of it could limit the healthy living of plants.

Evaluation

In order for me to test my theory that the amount of plant life growing underneath the canopy of the woodland would be decreased compared to the amount of plant growth occurring in the open ground. I used the belt transect method.

I found this method not to be that accurate. If someone was performing the same experiment as I did in order for them to find a fairly general view of how plant life is effected by trees then the belt transect method would be acceptable. However I feel that I someone more professional was performing this experiment to find out important information then I would suggest using either a different method or changing the way in which the experiment was done. The experiment could be changed in two ways. These ways are:

* By changing the amount of squares the quadrat is divided into, e.g. instead of using four squares like I did they could use 8 squares or possible more. However this way would take more time.

* They could also try taking the readings more than once. I performed the experiment only once because of time restrictions, however if more time was allocated then I feel that the experiment should be performed more than once to improve accuracy.

There were also problems with identification of the plants. It would probably be a good idea to have a fairly comprehensive overview of the types of plants you would find in woodland and what they look like. This would help when it came to writing down which plants were taking up the room in the quadrat. I found identifying some of the plants fairly difficult, and would prefer it if I had a clear description and photograph of the plants before beginning the experiment. Improving the accuracy of identifying the plants could improve the accuracy of the results.

Trampling of the plants was also an issue when it came to estimating how much room specific plants took up. If a plant were trampled then it would give an inaccurate reading. Although the trampling of some of the plants was unavoidable due to the position of the quadrat and other pieces of equipment.

Another problem was the overlapping of some of the plants, this made the task of estimating how much room a specific plant took up even more difficult and could lead to inaccurate results.

When looking at the graphs produced based on my results, it was clear to see that there were some anomalous results. These were possibly produced by a number reasons. One of these reasons could have been that the canopy was not as dense in some parts of the woodland as it was in others.

Although there were some anomalous results the general trend could still be seen.

As further work, or possibly to check accuracy, it might be a good idea to perform the experiment in other parts of the woodland, this could then determine whether or not similar results could be found elsewhere.

Science Coursework

Tony Capon 10E Biology