Essay, Pages 44 (10806 words)
One of the most familiar wild plants is the dandelion. It is, however, a troublesome plant that is a weed in lawns and gardens. The dandelion lives throughout the temperate zones. It is a perennial, surviving winter and re-growing in early spring. It blooms in spring and summer. The roots may be up to five feet (1. 5 meters) deep. The deeply lobed leaves grow out from center close to the ground. The best way to get rid of dandelions in a lawn is to use a weed killer.
They also may be pulled, but it is necessary to loosen the plant so that the entire root comes out.
Dandelions belong to the composite family of plants. The blossom is actually a bouquet of about 150 to 200 tiny flowers set in a solid head on a receptacle. Each flower is a perfect seed-producing floret. As the small, dry, one-seeded fruits mature, they push up a feathery structure called a pappus on a threadlike stalk.
All the pappi together make up the blow ball. The wind takes the seeds and scatters them far and wide. Dandelion greens are a delicacy in the spring when the leaves are tender and fresh. They can be boiled or eaten raw in salads.
The word dandelion comes from the French dent de lion, meaning ‘s tooth. The scientific name is Taraxacum officinale. Picture number one shows a fully blossomed dandelion, these are most likely to be seen in early spring. Picture number two represents a picture of a group of dandelions.
This picture is more precise as you can see the green leaves. They are easy to identify, as they resemble the holly leaf. To the suburban homeowner this deep-rooted wildflower may be nothing more than a pest, an unsightly blight in the lawn.
Yet nutritionists prize dandelion greens as a rich source of vitamins A and C, and in fact this brings $300,000 to $400,000 annually to the farmers of southern New Jersey, who supply dandelion greens to produce markets throughout the country. Dandelions increasingly irritate gardeners, as it is difficult to eradicate them totally. Therefore I will also research about ‘WEEDS’. Researching their desired habitats. Weed According to the common definition, a weed is any plant growing where it is not wanted.
Any tree, vine, shrub, or herb may qualify as a weed, depending on the situation; generally, however, the term is reserved for those plants whose vigorous, invasive habits of growth pose a serious threat to desirable, cultivated plants. A dandelion is often regarded as a weed. Through competition for light, moisture, minerals, and soil, a weed robs cultivated plants of vital resources. Weeds pose other threats as well. Halogeton (Halogeton glomeratus), a weed accidentally introduced into the Western states some 50 years ago, is highly toxic to sheep. A significant factor in the success of the common weeds is their fertility.
By blanketing an area with seed, they overwhelm less vigorous plants. One plant of pigweed, a common annual weed, may produce 117,400 seeds in a single year. As many as 1,147 seeds per square foot (12,342 seeds per square meter) may survive in the top inch of topsoil alone. Such seeds can retain their vitality for a remarkable length of time. In 1879, for example, botanist William Beal buried a pint bottle containing 1,000 seeds of 20 common weeds. Unearthed in 1980 the 101-year-old seeds still yielded a small but vigorous harvest of 26 seedlings. The dandelion has the ability to grow their roots up to 5 feet under the ground.
They also spread their seeds to reproduce by the force of the wind. A variety of ingenious adaptations assist weeds in dispersing their seeds, providing them with other advantages over less aggressive species. The seed capsules of the cocklebur (Xanthium pensylvanicum) use hooked prickles to attach themselves to the fur of passing animals and ride to new territory, while the seeds of the common plantain have a coating that turns sticky when moistened by a shower or heavy dew, enabling them to hitchhike on the shoes of unwitting pedestrians. As important to the success of weeds as their fertility is their adaptability. Read about test for presence of protein in food
Weeds flourish in conditions that would kill less hardy plants. Cultivated tomatoes are very sensitive to saline soil, yielding poorly if as few as 2,500 parts per million of salt are present in the soil. Such adaptability also makes weeds important members of the class of plants botanists call pioneers. These are the species that first colonize disturbed habitats, lands stripped bare by natural catastrophes or by human exploitation. The colorful perennial known as fireweed (Epilobium angustifolium), for example, earned its name for the speed with which it follows in the wake of forest fires.
Equipped with parachutes of fine hairs, the fireweed’s seeds float on the breeze to sow themselves throughout burned-over lands. Thriving on the nitrates they find in the ashes, the fireweeds assist the process of reforestation by stabilizing the soil, thus halting erosion. Weeds, in fact, may benefit the environment in a number of ways. They help to invigorate poor or exhausted soils, adding humus as they decompose. By sheltering the soil from the sun and wind, weeds actually promote the germination of other, less rugged plants. Birds, rodents, and many other kinds of wildlife depend on weeds for the berries and seeds they furnish.
Animals also find shelter in the cover provided by the weeds’ foliage. A promising area for future investigation is allelopathy, the phenomenon by which certain plants themselves control weeds by releasing toxins into the soil. Sorghum, sunflowers, and some strains of cucumbers have demonstrated an ability to curb weeds in croplands. Among the most effective allelopaths are the common weeds quack grass and Johnsongrass. This fact has led some scientists to theorize that the weeds of today may be the weed killers of tomorrow.
These pictures are just some of the many weeds that exist. Picture 1: is a picture of the ‘Queen’s Anne’s Lace’, or commonly known as wild carrot. * Picture 2: is a picture of the poison ivy. Interactions between plants affect their distribution and abundance. When a major resource, such as water or nitrogen, is in short supply, plants may compete with each other for use of the resource. Species that can use the resource more effectively are likely to grow faster and therefore to be more abundant. Such competition affects plant succession. Competition is also apparent in such ecosystems as agricultural fields.
Many weeds are better able to use water and minerals than are the crop plants with which they grow. Consequently, farmers must employ various methods of weed control in order to check the spread of weeds. Changes in the community during secondary succession are rapid, because every living thing contributes to its alteration. For instance, the weeds that grow on a vacant lot produce shade and increase the soil’s ability to absorb and store water. They also attract insects and birds and enrich the soil when they die and decay. The bare ground of the vacant lot is the best possible place for the pioneer sun-loving weeds to grow.
Later tree seedlings replace the weeds if the lot is in a forest climate, by native grasses if it is in a grasslands climate. Such changes occur until plants and animals that can make maximum use of the soil and climate are established. Dandelions, milkweeds, cattails, thistles, and asters have seeds with fluffy little parachutes. They drift through the air on the slightest breeze if the air is dry. On damp days, when the seed would not be able to travel far, the parachute stays closed. Seeds may travel many miles on their parachutes. For this assessment I will have to investigate the Dandelion within a grassland area.
I have decided to conduct this investigation due to the dandelions strong nature. Many botanists have researched the existence of the Dandelion and have made many theories on its living in nature. Gardeners and botanists have diverse opinions on the Dandelion. Some classifying it as a ‘weed’ and some consider it a benefit to their garden. However, the Dandelion is a very strong planate, and it would be interesting to see how abundant they are within these two areas. I will investigate my project within two different the grassland area and the chalk land area.
I have decided to use two different sites and make scientific comparisons. Due to the dandelions nature of being strong and sturdy. I have assumed that more will be present within the grassland area. (This maybe a part of my prediction). The grassland area is situated at Juniper Hall Field Centre, in Dorking in Surrey. My investigation will be investigated at this site. Our previous visit to this centre was very successful as we acquired much knowledge on that intense course. I can extract and use information which I attained from that specific AS course. My coursework title was ‘the abundance of large creeping mosses’.
To attain accurate and efficient results I will have to carry out an experiment, where I have to plan. I decided on how to implement my experiment. (I will justify in my method, which steps I took). There are many methods, which I can use to implement my investigation. Last year I used Random sampling to investigate the abundance of ‘Large Creeping Moss’, within a 40 square metre area; using gridded quadrates for accuracy. My techniques had improved a vast amount; hence have decided to adopt the same procedure for my A2 course, with minor adaptations, these will be explained and justified in my method.
I will try and repeat my investigation as many times as possible to attain accurate and efficient results. I have a vague idea of the method that I will use. This will be explained later on. I may include the results that I used last year to show how I presented my results. There are many risks and safety precautions in which I took. I had to make sure that I dress up appropriately according to the weather. It was not raining heavily, however it was very cold. Therefore, making sure that I dressed up warm is vital, as there is huge risk of catching hypothermia.
I will also make sure that I wear gloves protecting my hands from catching diseases. There are many diseases linked to unhygienic substances related to animals. Wearing gloves will not only affect my health, but also distort my results; our skins pH level is 5. 5. Therefore if I perspire I may affect the results of the soil pH. There are many factors, which may distort my results. For example, whether or not the pH levels effect the dandelions, or if the soil depth effects the stability of the dandelion. Many questions will arise during the course of my investigation.
It is therefore my duty to assign as many as I can. I may not be able to respond to each one due to the time factor. I may decide to include more factors to my investigation, and therefore apply them to my investigation, regarding I have the time. I have, attained a vast amount of knowledge, from the biology course I am studying; hence I will apply it to my investigation. For example I will discuss the population size of dandelions, competition and adaptation of the dandelion. Also, the dandelion may be a vital food supply for a certain organism, which will affect the amount of dandelions, which are present.
The season, as I implemented my investigation in September, the light intensity has decreased, which may have effected how the dandelion photosynthesis. All these factors will be considered when I write my conclusion. My background knowledge will also help me in my investigation. From the research that I have attained, I have acquired a sufficient amount of knowledge to address any inaccurate results. I feel that this investigation has not only been a part of an assessment, it has given me the chance to broaden my horizons in Ecology, and Zoology.
My aim from my A/S biology coursework was very similar to my experiment, which I have decided to implement for my A2 level coursework. However, the aim of this investigation was in depth, with justified scientific knowledge. I feel that I did not conduct my experiment to my fullest potential during my A/S course, however I have recognised this. Therefore I will implement my experiment making sure that I have covered everything that I did not include in my A/S level coursework. The aim was to actually to investigate the abundance of Dandelions (Taraxacum officinale. ), in two different sites.
The lawns, which I used, were present at Juniper Hall Centre, established in Dorking, Surrey. The lawns, which I used to implement my experiment, are called Templeton Lawn (see Appendix), and Lower Lawn (see Appendix). These are two trampled areas, which are used for recreational activities. Templeton lawn has a large tree (see appendix), which provides shade to the species on the lawn, whereas the Lower lawn does not. You can also predict the appearance of the lawns, however this is not relevant. My aim was to investigate where the abundance of the dandelion is situated.
I also have to consider the factors, which may affect the abundance of the dandelion. During my A/S course I felt that I did not investigate a sufficient amount of factors, which may have affected the abundance of ‘large creeping moss’. I have decided the factors in which I will investigate these factors are: > Air Temperature – ? c > Soil depth – mm > Frequency of the specie > PH level > Light intensity – (This factor was not intended to be used, however, it was needed to make it a fair test, this will be justified on my variables page). These factors will be described and explained in my variables section.
I implemented all these factors, at both sites, making sure I took into consideration the key factors. I tried my hardest making sure my experiment is fair, and that I measured everything accurately and precisely. For example, if I were to take the readings of the light intensity, I would round up the figures to 2 decimal places. Stating that I have used two decimal places. The fair testing will apply to all my factors. Fair testing will help me to attain accurate results, to make my experiment successful. I also aim that I repeat my experiment, at least twice. This is vital in my experiment.
With the secondary results I can compare the both to see whether or not my results are similar. This will help me by recognising if I conducted my method well enough. I must make sure that I check the air temperature at regular intervals. The air temperature may fluctuate during the day. The season in which I am going to implement my experiment may also affect the abundance of dandelions, the quotation below justifies this. ‘The dandelion lives throughout the temperate zones. It is a perennial, surviving winter and re-growing in early spring. It blooms in spring and summer’…
Quoted from Compton’s Encarta CD version 1997. I would also like to extend my aim. Regarding I have the time I would like to measure the nitrate levels in the soil. These are used to make proteins in plants. This factor may affect the abundance of dandelions. It is my duty to assign each factor, which may arise. This may be an extended investigation regarding I have the time to complete it. I will make sure that my actual experiment, which I conduct, is implemented with precision. I will plan a fully detailed method, which I will read before I implement the experiment.
This will help me get an idea of what is required from my skills. Once I have set-up up my experiment, I will get a second opinion to see whether or not I have set-up the experiment precisely. I aim to keep my investigation as ‘fair’ as possible. I will make sure that I wear gloves when collecting the soil pH level; our body pH level is 5. 5, and if I perspire it may affect the pH level. I will discuss my variables separately; these will be explained and justified with applied scientific knowledge. This is my aim for my experiment.
It was predicted that there would be more dandelions present at the Lower lawn, than Templeton Lawn. This will be due to several factors. The reason I think this is because the Lower lawn is used much more than Templeton lawn. There is much more ‘trampling’ on the lower lawn, than Templeton lawn. However, this is a variable that I cannot control. However, I feel that the effect of trampling will not affect the dandelions a vast amount. Dandelions are very strong specie, which are very competitive. ‘The roots may be up to five feet (1. 5 meters) deep. The deeply lobed leaves grow out from center close to the ground.
The best way to get rid of dandelions in a lawn is to use a weed killer’. Dandelions in nature, by J. B Bradley. The dandelions roots can be up to 1. 5 metres deep below the ground, this is a very deep root. This quotation describes how the leaves are spread out, and how they grow from the centre. Knowing that the dandelions are quite sturdy and strong there should many dandelions present at both lawns. If the roots can grow up to 1. 5 metres under the ground, the soil depth must be quite deep. ‘Weeds flourish in conditions that would kill less hardy plants’. Dandelions in nature by J.
B Bradley. This quotation suggest that the dandelion is actually a very strong plant, it describes how the dandelion can still flourish in conditions which may kill or harm other less competitive or strong plants. A good example would be moss. From my A/S course I researched that mosses are not fixed in position. It does not have a strong back to support it. The structure of the moss does not give the moss the ability to stay very strong, and the moss is easily pulled out. Unlike the dandelion. I also feel that the light intensity may affect the abundance of the dandelion.
I predict that there will be fewer dandelions present in the unshaded area (lower lawn). I predict this simply because all plants depend on light to photosynthesis. Light is a vital factor in the growth of a plant. The dandelion is autotrophic, an organism which uses inorganic forms of carbon, to make complex organic compounds. Therefore the light is important in the process of photosynthesis. Without the production of these organic compounds the dandelions may not exist. “Plants adapt themselves to obtain sunlight, two ways of doing so are leaves having a large surface area, and the leaves are thin”…
Toole and Toole, Understanding Biology Knowing the appearance of the dandelion, I feel that the above quotation fits in with the dandelion. The dandelion spreads outs its leaves close to the centre of the ground, and the leaves are generally quite thin. If the dandelion leaves were thicker, the upper layers would filter out all the light and the lower layers would not then photosynthesise. A larger surface area of the leaves helps the plant to capture more sunlight. From previous results from my A/S course, I researched that the soil pH was not acidic. It was actually alkali. I found that the pH level was 8. 5 (2 dp). These pH conditions are an ideal level which plants need to survive. Hence, the plants had the right conditions to survive in. I will not depend on these results; I will still investigate the pH levels of each soil sample. As the weather may affect the soil pH, for example ‘acid rain’. If the soil pH is acidic, this will destroy the dandelion, therefore affecting their abundance. ‘Each flower is a perfect seed-producing floret. As the small, dry, one-seeded fruits mature, they push up a feathery structure called a pappus on a threadlike stalk. All the pappi together make up the blow ball.
The wind takes the seeds and scatters them far and wide’. As I am implementing my experiment in September, the beginning of Autumn I feel that the wind would also affect the abundance of the dandelion. The wind helps the dandelions to reproduce by the seed dispersion. The wind will blow off the seeds and scatter them onto the surface, where they will grow to produce a full dandelion. Hence, I predict that there will be a vast amount of dandelions on both lawns. A quotation from the 2001 version of the encyclopedia, justifies this. ‘A significant factor in the success of the common weeds is their fertility.
By blanketing an area with seed, they overwhelm less vigorous plants. One plant of pigweed, a common annual weed, may produce 117,400 seeds in a single year’. This is my prediction for the abundance of dandelions. However, I still feel that there will be more dandelion present in the lower lawn. I have given justified reasons for each prediction that I have made, with applied scientific knowledge. I will summarize in bullet points the main predictions. Summary – My predictions > Dandelions are very strong and sturdy as their roots can grow up to 1. 5 meters in to the ground.
Therefore the effects of trampling may not affect the abundance of dandelion. > Light intensity will affect the abundance of dandelions. > Dandelions will adapt to capture more sunlight. > Soil pH will affect the abundance of dandelions, if to acidic, will destroy plant. > Wind will help the reproduction of the dandelions, hence there should be more dandelion present. > Dandelions are very competitive, and will outgrow any other specie. Where I will be implementing my experiement Lower Lawn Templeton Lawn Method The method, which was chosen for my experiment was similar to the method, which I used for my A/S course.
However, minor adaptations were made. Last year I used ‘RANDOM SAMPLING’. I felt that this would be the fairest possible way to attain accurate results. The reason for this is because I felt that it would not be biased. If I had attained biased results my results would not be accurate and reliable. However, my techniques had improved from last year. I adopted many new skills, which I will be applying to my experiment on dandelions. Random sampling is a simple technique, which is used to investigate the abundance of certain specie. This is the best method to use compared to any other.
After researching the best sampling method to use, I decided to use random sampling. Random sampling however, can be as simple as throwing a quadrat over your shoulder and counting the species within it wherever it falls. Even with the best intentions it is difficult not to introduce an element of personal bias using this method. However, I would then generate numbers between 1 to 15 to produce my co-ordinates. ‘Quadrat are used for sampling in relatively uniform terrestrial habitats such as grassland. Random sampling is ideal to knowing the abundance of a particular specie’… Biology 2, endorsed by Cambridge.
This quotation played a vital role in me choosing my sampling method. As it describes that random sampling would be the best technique to investigate the abundance of a certain plant. Apparatus > 1 divided quadrat (20 squares, 0. 25 m) – This was made from steel, and was actually quite strong. Hence, it is ideal to use if it was to rain. It would still be god enough to use. The grids which were present were quite reliable, and easy to use. You would place the quadrat on the ground and the species present within the frame are identified, and their abundance recorded. The quadrat was in the shape of a square.
Even though the quadrat is the best way to investigate the abundance of specie, you may make a mistake or error when counting the specie. For example, in one square your particular specie could be densely packed in one square than the others. I could also be bias when recording my results. However, I will try to be ‘fair’. > 2 Measuring tapes – This is used to plot my area in which I will implement my experiment. I had to choose a sensible area to work in, with sensible measurements. From secondary opinions, it was suggested to use 15m by 15m. This was the right area to use within the two sites.
I took out the measuring tape horizontally by 15m and brought it out by 15m vertically. Making sure that the origin is at 0. However, it is difficult not to introduce personal bias. Hence, I stood in the middle of the lawn, and implemented my experiment there. The measuring tape must be straight, to make the experiment a fair test. I held the measuring tapes in place with some weights. I made up the co-ordinates, by using a calculator, to make sure that there were no biased results. This was reliable piece of equipment. 0 15m 15m > 1 Metre Ruler – This was used to plot where your quadrat would be placed.
You would need this piece of equipment for accuracy and precision. You also want your results to be reliable. You would plot your co-ordinates. And however, far the plot was, you would count out how many metres you needed to go. So this was also reliable. > 40 Soil pots – These would be needed to place the soil samples. I would need 40 soil pots as I am implementing my investigation at two sites. I would take approximately a teaspoon amount of the soil, to test the pH level. These would help to collect and organise my samples. This was a reliable way of collecting my results. However, I could not make sure that the pots were sterilized.
If they were not then they may affect my soil samples, pH level. However, this was the best possible method for collecting my soil samples. > 1 Knitting needle – The knitting needle was used to measure the soil depth. Every time I placed the quadrat at the specific co-ordinate, I would also measure the soil depth. I placing the needle as far down as possible would do this. Then I would take it out and then measure how far it went down by measuring the mark with a ruler. This was efficient, however, it was not very reliable. The knitting needle was bent and dented in many places; therefore my results may not be accurate.
Because it is not straight, it will give the correct measurements. However, this was the only way to measure the soil depth. I tried my best to attain accurate results. > 1 Thermometer – Seasonal temperature variations occur during the day, therefore I also had to measure the temperature, at regular intervals. Every time place my quadrat, and recorded my results for the abundance of dandelion. I would also check the temperature at that time I collected the result. I measured these variations by using a mercury thermometer. This was the most accurate way of attaining the air temperature.
Even though this was a reliable way of collecting accurate results, I misread the thermometer. Therefore making an incorrect reading. > 1 PH meter – This was a device, which was very reliable and quite accurate. This was used to measure the acidity or alkalinity of the soil samples, which I took previously. The probe of the instrument is rinsed in distilled water (pH 7 – neutral) before placing it in the test solution. This is very reliable. However, this may distort results, sometimes the battery could be weak; therefore resulting in an inaccurate result, this is very unlikely.
This is maybe the best way to determine the pH level of the solution, as it gives you readings to 2 decimal places. > Photographic light meter – this was used to measure the light intensity. My investigation includes the abundance of dandelions within a shaded and unshaded area. This is the most accurate way of attaining data about the light intensity. This again is very reliable and the most precise way to measure light intensity. In comparison to the canopy metre. > Polythene bags and containers – These were used to help me organise my experiment and collect results.
It is important to organise yourself, especially whilst implementing an experiment. Containers where used to place my soil pots, separating them from the shaded and unshaded area. So I collect my results in a systematic way. > Spoon – this was used to dig out the soil samples. Was very useful. However, was not accurate. I may have got some more or less soil, in each pot. Method and Materials > A table was produced for collecting the results that you will attain. It was very organized and contains the write headings and titles. Once this was done you must have this checked. > Random coordinates were generated.
The co-ordinates that were needed to be produced must be random to make it a fair test. They need to be within the range of 1 to 15. They cannot exceed over 15. These can be done by choosing numbers off the top of your head, or using a calculator. > Once you have chosen your co-ordinates, you must assign them to each site. For example 20 for Templeton lawn, and 20 for the lower lawn. Therefore you should plot 40 co-ordinates altogether. > Two tape measurers were laid out, at right angles to one another. One tape measurer should be laid out horizontally, making sure that it is 15 metres across.
The other one should come out vertically by 15metres. 0 15 metres 15 metres > Within this area, you can plot your co-ordinates. When you plot your co-ordinates, you can use the metre ruler stick to go out. This will help for accuracy, and precision purposes. Then once you have reached your plot you can then place your quadrat on the ground. Making sure that you are not biased. > When you have placed the quadrat down on the ground, you have to collect your results. Check how many dandelions are present within each square. Make sure you spend a couple of minutes on analysing the plants, and that you have identified the correct specie.
Count the amount of squares, and then record your results. It is vital you count the correct specie, or your results will be affected. > You have to make sure you investigate your other factors. (In my case, light intensity, pH level of the soil, air temperature, and soil depth. ) > To measure the temperature a thermometer was used. Making sure that the thermometer was read correctly. You must make sure that you do this every time you collect results. Hence you must have 40 readings of air temperature altogether. > Soil samples were taken using a spoon and soil pot. This will be used to take the soil samples of the soil.
You only need a small amount of soil. Once you have retrieved this you may place them in their pots. Be sure to do this every time you place you quadrat on the ground. > Once the first 20 soil samples were collected all the pots were placed in a bag, and labelled. Where you have attained these samples. > Be sure to wear gloves when you are taking pH samples. Our body pH is 5. 5; therefore if you perspire you may distort your results. Remember this is apart of your control variable. > To measure soil depth you had to take your knitting needle and place it in the ground. Push as hard as you can.
When it does not go deeper into the ground, you now that this is the furthest that it will go. Then take it out, and measure how far the mud mark is on the needle. For accuracy reasons, it would be better to measure this in mm. > Then you must take the light intensity reading. All you need to do is stand where you took your co-ordinate and then take the reading. Record this on your table. > This method was repeated on the 2nd lawn, on the other desired site. Which will be the shaded or unshaded, depending on what ground you implemented your experiment first. Back at the lab, the soil samples were tested for pH. Collect all of your soil samples. They must be in two separate polythene bags, one for the shaded area and one for the unshaded area. > Take your first soil sample and place it in the beaker. > Add a small amount of distilled water, to the beaker, to convert it into a solution. Mix it with a stirrer. > Wash the probe with some distilled water, and then wipe it dry. > Place the pH metre in the beaker and record the results, which appear. > Repeat this procedure with the other 39 samples. Risks and Hazards There are many risks and safety precautions in which I took. I had to make sure that I was dressed up warm, as it was quite cold.
It did not rain heavily, however in case it was to rain I would be protected. There is a huge risk of contracting hypothermia. I also made sure that I wore gloves. This was not only to keep my hands warm, but also to protect my hands from contracting any other diseases. There are many diseases linked to unhygienic substances secreted by animals. Gloves are also worn to prevent results being affected. Our body pH level is 5. 5. If my hands were to perspire whilst I was taking a soil sample, I may affect the pH of the soil without realising. Even though I am not handling any sharp apparatus, I may cut my hand.
I must therefore need a first aid box to cover my cut. This is to prevent any harmful germs entering my body. I must be careful from any poisonous plants. For example, the poison ivy. I must be aware of its appearance. In case I come in contact with it. These are the basic risks and hazards for my investigation. Results Data collected. Lower Lawn: Quadrat number Air Temperature (? C) (1dp) Soil Depth (mm) Frequency of dandelion PH level (2dp) Light Intensity (lux) 1 15. 0 91 3 7. 91 6480 2 15. 0 141 9 7. 86 6600 3 15. 0 166 10 7. 82 6540 4 15. 5 161 2 7. 95 7260 5 15. 5 129 5 7. 90 7200 6 15. 5 155 9 . 86 6660 7 15. 0 101 12 7. 70 6300 8 15. 0 88 2 7. 89 6240 9 15. 0 172 14 7. 99 6360 10 15. 0 156 11 7. 86 6120 11 16. 0 76 9 7. 77 6780 12 16. 0 82 7 5. 74 7500 13 16. 0 95 8 2. 84 7140 14 16. 0 90 2 7. 86 7080 15 16. 0 192 5 7. 87 7020 16 16. 0 176 4 7. 67 6180 17 16. 0 182 16 7. 98 6540 18 15. 0 175 10 7. 92 6240 19 15. 0 110 14 7. 88 6120 20 15. 0 96 7 7. 91 6660
These are the results, which I attained from my first experiment. Templeton Lawn Quadrat number Air Temperature (? C)(1dp) Soil Depth (mm) Frequency pH level Light Intensity (lux) 1 19. 0 170 2 7. 21 2220 2 20. 0 125 7 7. 47 2100 3 19. 90 5 7. 58 2340 4 19. 0 110 1 7. 52 2280 5 19. 5 80 8 7. 68 2400 6 19. 5 112 1 7. 32 2280 7 19. 5 109 4 7. 47 2220 8 19. 5 85 0 7. 42 2340 9 19. 5 96 0 7. 47 2280 10 19. 5 107 2 7. 15 2040 11 20. 0 110 1 7. 30 2400 12 20. 0 105 6 7. 26 2460 13 19. 5 110 7 7. 42 2460 14 19. 5 111 6 7. 16 2520 15 19. 5 162 4 7. 52 2580 16 19. 5 154 4 7. 50 2400 17 19. 5 142 2 7. 64 2640 18 19. 5 132 7 7. 39 2100 19 19. 5 120 8 7. 82 2400 20 19. 5 102 6 7. 47 2940 For the readings of my air temperature, I could not read them up to 2 decimal places. Therefore, these were the most accurate readings that I could obtain.
Graphs. Lower Lawn Graph A: Graph B: Graph C: Graph D: Graph E: Templeton Lawn (shaded area) Graph F: Graph G: Graph H: Graph I: Graph J: Conclusion I have captured my data in different ways. I have used tables and graphs to represent my data. There are different types of graphs, which I have used. I have also used statistical tests. Air temperature – I conducted my experiment on the lower lawn approximately at 11. 30 am. The weather was quite windy, and there were slight spells of rain. The temperatures from my results show that they are quite consistent, although they do tend to fluctuate slightly.
The weather was very inconsistent; this may be the reason why the air temperature fluctuates. There could be many reasons as to why the air temperature fluctuates; I will list all theses reasons in my conclusion. I feel that these results are reliable. Soil Depth – As you can see from my results, the soil depth was quite inconsistent. The soil depth was deeper in some areas than in others. This could be due to the effects of trampling. As this lawn is used for recreational activities, it could be that the soil is more compact. This could be a possible reason for this inconsistency. However, they are still reliable.
PH level – From my results you can see that there are two anomalous results. Disregarding these two results, the pH levels seem to be quite consistent. The pH levels were taken from the soil samples of where I placed the quadrat. From my A/S course I did not take the pH level of every soil sample. I took one soil sample, and applied this to my investigation. This year I took a soil sample, every time I placed the quadrat on the ground. Hence, this would be more accurate. Light intensity – The light intensity is also consistent. I feel that these results are reliable. Although they do tend to fluctuate, I still feel that they are consistent.
The reason as to why they may fluctuate could be due to the inconsistency of the weather. As there were breaks of sunshine, and rain. The results for Templeton are listed in a second table, this was my second experiment which I implemented approximately at 1. 00 p. m Air temperature – Again I feel that these set of results are reliable. The air temperature was consistent, however tends to fluctuate slightly. This again, could be due to the inconsistency of the weather. However, there was no major decline in the temperature. Soil Depth – Soil depth in this area was consistent.
There was an even distribution of soil, and the soil was quite soft. I feel that they are reliable, however the apparatus I was using to investigate I the soil depth was not efficient. The knitting needle was not straight; therefore I could not take down an accurate reading. I tried my best to attain results. PH level – The pH level was consistent. There are no anomalous results; they tend to be similar to one another. I also feel that they are reliable because of the apparatus that I used to attain the pH level. Light intensity – I expected the light intensity to be much lower than the lower lawn, and it proved that it was.
The light intensity does vary slightly, however, I still feel that they are a reliable set of results. The wavelength is in between the range of 2000 and 3000. Graph A represents the air temperature at the lower lawn, throughout the duration of my first experiment. I spent approximately an hour on the lawn. Therefore, the average time spent on each quadrat would be three minutes. For the first three quadrates the temperature remained stationary. It then increased slightly to 15. 5 ? C, this could be due to the weather being inconsistent.
If you compare graph C with graph H you can clearly see that there is more dandelion present in the lower lawn. This is what I have found out. However, I will discuss what may affect the abundance of dandelions on the lawn. These are my results, which I attained from the experiments. From my results you can clearly see that there were more dandelion present at the lower lawn. I will prove this also by using statistical tests. The test that was best suited for my investigation is the Mann Whitney test, and the t-test. These will help me to justify my work and prediction I will also discuss all these factors in my final conclusion.
For my frequency factor I used the Mann Whitney, it proved that there was a significant difference of dandelions between the two different sites, those being trampled and untrampled areas. My critical value was 64 and my U value was 34. Therefore I rejected my null hypothesis, which meant that I could accept my alternative hypothesis. My soil depth results showed that there was a major difference between the two sites, therefore we can relate the difference of the dandelions within the 2 sites. For example from my background information I researched about the dandelions, were that the dandelions need at least 5 feet to grow their roots.
The soil depth at both sites was nowhere as deep as 5 feet. My calculated value for t = 3. 44, and the critical value for t = 2. 02. My calculated value of t was greater than my critical value of t, I therefore accepted my alternative hypothesis and rejected my null hypothesis. I do not feel that the air temperature had that much affect on the abundance of dandelions. There was a difference of temperature between the two sites, however I do not think that they would majorly affect the abundance of dandelions. To prove that there was a difference however, I calculated a t – test.
This test proved that there was a significant difference, my calculated value of t= 15. 613 which was greater than the critical value of t = 2. 02. Whenever the calculated value is greater than the critical value this means you can accept your alternative hypothesis. The light intensity I feel does have an effect on the abundance of dandelions, as light is vital for the process of photosynthesis. This is the process by which they produce their food. There was a significant difference of light intensity between the 2 sites.
The t-test, which I carried out, proves this. My calculated value of t = 40. 844 and my critical value of t= 2. 2. If you refer back to my results you can see that the lower lawn has a higher frequency of dandelions, it also has a higher intensity of light. The pH levels I felt were quite consistent, however there were some anomalies that occurred. I have discussed this in my evaluation. There was not that much of a difference in the pH levels, and my statistical test proves this. My U value was -106. 77 and my critical value were 127. I carried out a Mann-Whitney test for this. I therefore rejected my null hypothesis and accepted my alternative hypothesis, which was the fact that there was no significant difference of pH between the two sites.
I therefore come to the conclusion that there was a difference of the abundance of dandelions, between the two sites. The effects of trampling effect the abundance of dandelions. However there were some factors, which may have affected the abundance of dandelions as I have discussed. Results of statistical tests. Frequency – Mann Whitney: There is a significant difference of frequency of dandelions between the two sites. PH – Mann Whitney: There is no significant difference of pH between the two sites. Soil depth – t – test: There is a significant difference in soil depth between the two areas.
Light intensity – t-test – There is a significant difference in light intensity between the two areas. Air temperature – t – test: There is a significant difference in air temperature between the two areas. Interpretation Throughout my investigation there are certain variables or rather factors, which you must control, to keep the experiment a fair test. However there are some factors, which you cannot control. For example, the effects of trampling on each site. One would be more ‘trampled’ than the other. I have already discussed the factors, which I am investigating.
However, I have not discussed the variables, which apply to them. In my conclusion I have stated clearly what I have found out. These are just a list of facts, which I attained from my experiment. I will discuss the variables. In my prediction I predicted that there would be more dandelions present at the lower lawn. This was due to several factors. I thought that the soil depth might have affected the abundance. Dandelions grow their roots up to 1. 5 metres in the soil, and I thought because the lower lawn is used for recreational activities, the soil would be more compact and dense.
Variables were used to make sure that I attain accurate results. I will list the factors: > Air Temperature – ? c > Soil depth – mm > Frequency of the specie > PH level > Light intensity Soil pH and air temperature – these two factors were controlled. I took soil samples each time I threw the quadrat. Wherever the quadrat landed, I would take a soil sample. This was for accuracy and precision. I also checked the air temperature at half an hour intervals. If the temperature were very high, the dandelions enzymes would have been denatured, leaving the leaf to wilt. Therefore there would be fewer dandelions present.
This could be true for Templeton lawn, however the temperature was not very high. Therefore, this could not be a reason as to why there are fewer dandelions present in this lawn. This was an apart of my control variable also. These two variables were also used for my A/S investigation. Soil depth – The soil depth I could not control. The soil depth fluctuated throughout the whole experiment. However, this factor was vital part of my investigation, as the dandelions roots can dwell into the ground, up to 1. 5 metres. This was also measured each time the quadrat was thrown. However, the ground deepest depth was 192 mm.
Overall there was a higher depth at the lower lawn; at it also appears that there were more dandelions present at this site. Light intensity – the light intensity was not apart of my initial factor. However, as I arrived to the sites, I realised that one area was particularly shady (Templeton), and the other site (lower lawn), was not shaded. If I had not taken this factor into consideration my investigation would not be accurate as light may affect the abundance of dandelions. Every time I threw the quadrat I would take the light measurer and stand where the quadrat was present, then take the reading.
Hence, this was a ‘varied’ variable. As I am varying the factors, by using shaded and unshaded. Specie frequency – The amount of dandelions were counted when the quadrat was thrown. Each grid, which contained a dandelion, was counted as 1. I could not control the amount of dandelions, which were present. Hence, this was also a dependent variable. Two different sites used – I have varied the sites, which I am going to use. I am using to sites, which are trampled on, however one is shaded and one is unshaded. This is a controlled variable, as the sites are the same.
I have not used two different sites. However, last year (A/S) I used two different sites, one for recreational activities, and one, which was not. For accurate results, I decided to throw the quadrat 20 times, at each site. I would therefore end up with two sets of results. 20 times was a sufficient amount, hence did not need repeating. This is more reliable as I am doing a vast amount of throws. These are my variables explained. There maybe more factors which could affect the abundance of the dandelion. However, I may not have the time to address all these points.
For example, if there were fewer dandelions than I expected, it could be due to a whole number of reasons. For example, predation, there could be animals who feed on the dandelion, which may be a vital part of their food diet. I am not investigating this factor, as it would require a long length of time, and precise observation skills. This can be discussed in the limitation section, in my evaluation. Humidity has a major bearing on the rate of transpiration in plants and so affects their distribution. To a lesser degree, it affects the distribution of some animals by affecting the rate of evaporation from their bodies.
However, this has no relevance to my investigation. Nitrate levels in the soil also affect the plant. Nitrates are vital in the production of making proteins. Nitrates are absorbed through the roots of the plant, and are used to make amino acids, which then make proteins. This may affect the abundance of the dandelion. My interpretation proves that my prediction was right. Evaluation I feel that overall my experiment and investigation was quite good. I had attained accurate efficient results that I could rely on. There are some areas of improvements that I feel could be improved on.
However, from experience from last year my A/S course I felt I had a good knowledge of some techniques that I implemented. For example the random sampling technique where you are meant to use a quadrat. The areas that I felt needed to be improved on was my timing skills, even though this may not apply to biology, I feel that it was a part of the implementation skills to have good timing skills. I feel that I used the equipment to its fullest potential. The weather overall was quite good, and was quite sunny which may have helped the plants to photosynthesis making them appear much stronger and tougher.
However, I also noticed that the grass and lawns was quite moist. I had done this by feeling it with my hand. From the results that I have obtained I feel that my results are quite accurate, as they have supported, by prediction correct, and the knowledge behind the results support my results significantly. From the results that I had obtained I found that there was a higher frequency of dandelion at the lower lawn, and this was proved by the Mann Whitney test, which I carried out with my data. The results that I had obtained from this statistical test backed up my prediction.
Even though my conclusion supported my prediction, I still feel that there was more that I could do. For example, I could have investigated more factors for my experiment. I had researched many factors for this experiment. For example, the pH, soil depth, air temperature, and light intensity. I also had done statistical tests to prove these factors. Therefore, all my factors were implemented. I felt there were a few limitations to my experiment. Firstly, I wanted to carry out an experiment to see if the nitrate levels affected the abundance of dandelion. However, as the equipment was not available I could not use it as a part of my variable.
This may have affected the abundance of the dandelion, as nitrates are used to make proteins, a deficiency in this mineral means that the dandelion won’t be as strong. From the results that I obtained, the overall conclusion did prove my hypothesis correct but I feel that there were several anomalies, in my results. Such as when I was carrying out my experiment, when I placed the quadrat on the ground, I noticed that some of the grids were more densely packed than others. There was one grid, which was extremely full, and could have counted as three grids.
The frequency results of the dandelion from the lower lawn were extremely high. Even though I predicted that the dandelion would be more abundant at the lower lawn, I found them surprisingly high. In quadrat, number 1 there was 19 grids filled with dandelion. I may have made a mistake whilst identifying the dandelion, however they are quite easy to identify. This could be due to human error. The limitations to the investigation were quite apparent. There were many factors, which I could not test as one of my variables due to lack of equipment; also, some factors were impossible to control.
Factors affecting the abundance of dandelion 1. Time – this was an impossible factor to control as my investigation was over a period of one day. 2. Spatial heterogeneity 3. Competition – organisms compete with each other for food, water, light, minerals shelter and a mate. They not only compete with members of other species – interspecific competition – but also with members of their own species – intraspecific competition. This factor is virtually impossible to control. The dandelion is very competitive towards other plants, unlike the moss, which I concluded in my A/S investigation; but may be competitive with its own kind. . Predation – the abundance of dandelion is determined by the presence or absence of its prey and predators. The predator – prey relationship is an important aspect in determining population size, but it is impossible to control. I found out in my research that many animals feed on dandeliones for a vital part of their diet. For example, predation, there could be animals who feed on the dandelion, which may be a vital part of their food diet. I did not investigate this factor, as it would require a long length of time, and precise observation skills. 5. Environmental stability – this is how stable the ecosystems are. 6.
Nitrate levels -I could not measure the nitrate levels due to the lack of equipment. Nitrates are used in plants to make amino acids, which in turn produces proteins. 7. Moistness of the soil – Again due to the lack of equipment I could not measure the moistness of the soil. However, I do not feel that this may have affected the abundance of dandelion as they can withstand extreme weather conditions, as it is classified as a weed. 8. Sulphur dioxide (SO2) – from my background knowledge I have found out that pollution affects plants, however again the dandelion is very strong, therefore may withstand the pollution levels.
However, there was no equipment available for me to check the sulphur dioxide levels. Most of the factors shown above I could not measure as my variables. Factors such as predation are impossible to control, which could have easily been the cause for my results. There are many external factors that I could not control that might have affected my results such as competition this is an interaction between two or more organisms, in which, for each growth rates are depressed and therefore the death rate increased by other organisms. The dandelion is very competitive, and will outgrow any other plant, for example the moss and plantain.
Also, I feel that the nitrates in the soil could have affected the abundance of dandelions. I know ploughing accumulates large amounts of nitrates in the soil, however none of the sites had been ploughed. This factor could easily be controlled by the use of a nitrate meter, which could measure the level of the nitrate in the soil, so I could have been able to see if there was a significant difference between the two sites. Hence, I would have been able to prove my hypothesis right about nitrates affecting the abundance of dandelion.
The apparatus that I used was not efficient. When I was taking the measurements of the soil depth the knitting needle was not straight, and it was bent in many places. This may affect how deep it could go down in the soil, and then when I measured it with a ruler, it could be all curved and not straight. This may have slightly affected my soil depth results. Also if I had a piece of equipment to check the moisture of the soil, this would help me in my investigation, as it would tell me if the dandelions are receiving enough water for their roots and nourishment.
I feel that my results are not that reliable even though I have a lot of evidence that proves my hypothesis right, and not only this, when obtaining my data from the two sites it was obvious just from observing the two sites that lower lawn had more dandelion present. During my implementation, I felt that I had implemented the experiment quite well. I did not repeat my results as I put into practice 20 test for each site, leaving me with 40 results altogether. I did not repeat the experiment several times, therefore I cannot be a hundred percent sure that my results are reliable.
If I repeated my investigation, again I might have not obtained similar results, but could have obtained results, which were totally different from my first set of results. Hence, my results cannot be that reliable as there are not several investigations carried out on those two sites for the abundance of dandelion for me to compare with my results. I may have made errors by reading the thermometer wrong, or by not using it properly. The same could be said for the pH probe. As there was just 2 between whole groups of people, it may have affected my pH results.
I think I could have improved the reliability of my results as I could have used equipment that is more scientific. It also could be repeated more times to help iron out any anomalies. A better overall result would be obtained by repeating the experiment more times because any errors in one experiment should be compensated for by the other experiments. I also think that I could have controlled some factors that were not impossible to control such as nitrate levels in the soil, soil temperature, humidity, by using whirling hygrometer – this could have affected my results at the sites.
The sites were at slightly different levels; Templeton lawn was at a slightly higher altitude than the lower lawn. This would results in slightly different humidity levels; also, slightly different altitudes of the two sites might have affected the wind speed. The mineral ion concentration of the two sites could also have been controlled to improve my experiment. I feel that this is an important factor as the dandelion maybe affected by the mineral ion concentration, if there is a low mineral concentration the plant will wilt and die. Compton’s Encyclopedia, version 1996, Windows 95.
I think that main sources of error that have resulted in my results was that the two sites were not very large, in terms of the areas that I took my results from. Restricting any more dandelion to grow. However, I could have implemented my investigation in a different area on the same site. As there may be more dandelion in another area within the same site. I feel that I could have been more accurate when I was extracting the soil from the two sites. Although I used a spoon, I noticed that there was some difference in the amount of soil that was present in the pots.
This could have affected my pH results; because if there was more soil in one pot, and less in the other, the soil with the less soil would have had a lower pH. I could have used some scales to weigh the soil, and use the same amount throughout. However, due to the time constraints, this would have token a vast amount of my time. When I was investigating the light intensity, I used a canopy metre. There was another piece of equipment, which I could have used to obtain accurate results. However, this was not available to me.
It is used to obtain results for light intensity. This is the most accurate way of attaining data about the light intensity. This is one modification that I would have made to my experiment. To improve the experiment I could have taken more samples at each site but also at different areas at the sites and not confined to the area within one perimeter as both the of the lawns were on different levels. For example, the Lower lawn was on a slightly lower level, therefore, there might have been a difference in the temperature; this could have affected my results.
I feel that even though the data that I had obtained supported my hypothesis, and my conclusion; there were various factors linked to the abundance of the dandelion that I could not control mostly due to the fact that they were impossible to control. There was also another reason, the lack of scientific equipment that was not available to me whilst implementing my investigation. Due to me not investigating some of these variables, I feel that it has compensated with some abnormalities shown in my results. For example, as there was a lower frequency of dandelion at Templeton lawn, the nitrate levels could have affected this.
There was an inconsistency of dandelion frequency in both lawns. If we see both tables, the frequency of dandelions is not consistent. This is another anomaly, which I have spotted. When I implemented my experiment, I realised that the dandelions were not evenly distributed within the quadrat. There could be a number of reasons as to why this may have occurred. It could be caused by predation by animals, which feed on the dandelions or to inefficient conditions. The dandelions need up to 5 feet to grow their roots. And the soil depth did not meet the requirements.
When I was doing my experiment in Templeton Lawn I noticed that there was a large oak tree. When I researched oak trees I found out that there roots are very large, and compete with the entire dandelion population. Even though the dandelion is naturally competing species I do not think that it would compete against a large domineering oak tree. The oak tree must have affected the dandelions abundance slightly, as it must have been up taking all the nutrients by active transport. I felt that I could improve on my accuracy in certain areas. For example, I wanted to investigate the soil temperature.
However, this was a limitation as their was no type of equipment to investigate this, I had to investigate the air temperature and use this. I do not feel the external temperature was the same as the internal temperature. Therefore this is a limitation. I believe that my results are quite valid overall. As my background, knowledge did also support my results. But I think that my results are not very accurate, as I did not investigate some important factors, such as nitrate level in the soil, and the moistness of the soil, which I feel is quite important, and could affect the abundance of dandelion between the two sites that I was working on.
Appendix These arrows represent the dandelions that were present on the trampled area, on the lower lawn. This is a picture of the lower lawn. The arrow represents the unshaded area. This is where I implemented my first experiment. This picture represents two of my peers collecting soil samples. We used the spoon, and placed the soil sample in the vile. Then placed them in a polythene bag. When the wind blows the seeds away, they land on the ground, and then grow into dandelions. This was found on the Lower Lawn. These are often known as parachute seeds. This is a picture of a fully blossomed dandelion.