Average Height Of 10 Pneumetaphores example essay topic

Introduction: Plants when grow in areas of bad conditions such as waterlogged soils must be able to deal with environmental extremes not experienced by other plants. Mangroves live in the swamp, bathed twice a day by the sea and having their roots in waterlogged soils which are devoid of oxygen, poorly drained, rich in organic matter and anoxic. Because of the lack of oxygen in the soils, mangroves rely on numerous erect aerial roots called pneumetaphores, the mangrove's breathing roots, to obtain oxygen from the air by means of aerial roots that descend like buttresses from the trunk and lower branches for its extensive root system. The pneumetaphores have corky, water-resistant bark and a spongy interior stiffened by an axis of vascular tissue. Oxygen once taken up will be diffused through aeration tissue in the lateral roots and spread to the rest of the plant.

The height of pneumetaphores varies from one to another, is it related to the height of seawater level or it just happens to be like that? Is there any special strategy for pneumetaphores to get as more oxygen as the water level gets higher? Do they grow higher as they grow closer to the channel where the water level is the highest? If they are, why is it so? Aim: To find out if the height of pneumetaphores if related to the height of the water mark on the trees. Hypothesis: The pneumetaphores grow higher as the height of the watermark increases.

Equipment: A 10 m long stick, a meter ruler. Methods: 1. Imagine a transect line across the creek from the bank to the channel. 2. Use the 10 m stick to set out ten 10 m 2 (radius 1.75 m) quadrats from the bank to the channel along the transect line.

Each quadrats is equally spaced in between. 3. At each quadrat, use the meter ruler to measure: a) The height of watermark on the trees. b) The height of 10 random chosen pneumetaphores. 4. Use the t test to test the null hypothesis. Where XA = mean of the sample A (10 heights of pneumetaphores in the first quadrat closest to the bank), XB = mean of the sample B (another 10 heights of pneumetaphores in the last quadrats closest to the channel), S 2 A = sum of (XA-XA) 2 / n-1, S 2 B = sum of (XB-XB) 2/ n-1, n = number in each sample.

To use the formula n must be the same for sample 1 and 2. XB- XA T = S 2 A + S 2 B n n Variables: Controlled -- - Each quadrat need to be evenly spread ed out, and in each quadrat measure exactly 10 heights of pneumetaphores. Changed -- - Set the height of watermark as independent variables. -- - Set the height of pneumetaphores as dependent variables. Therefore the null hypothesis is rejected.

So any difference is not just due to chance, there are some facts that determine the distribution of different height of pneumetaphores. Conclusion: The null hypothesis is rejected. The pneumetaphores grow higher as the height of the watermark increases. Discussion: The result shows the trend that pneumetaphores grow higher as they get closer to the channel, where the watermark on the trees is the highest. As talked in the introduction, pneumetophores are used to obtain oxygen from the air by mangroves, as water level gets higher towards channel, the surface of pneumetaphores exposure in the air will reduce more and more if they remained the same height and eventually covered totally by the seawater. Thus, to adapt the bad living environment and to survive, the pneumetophores must grow higher as the water level rises, in order to get as much oxygen.

However although the line of trend of the distribution of pneumetaphores basically goes upwards, the specific number didn! |t show the exactly accurate trend as in quadrat 5 and 8, the average height of 10 pneumetaphores are both lower than the previous quadrats which have lower watermark. This may be because of insufficiency of samples, that is, only 10 pneumetaphores in each quadrat are not enough, number of samples should be as more as possible. Another reason for the inaccuracy could be the range of area that samples collected is not large enough. More transect lines should be set across the creek.

Samples should be collected more and in a large range of area, so the height of pneumetaphores will vary even more in each quadrat and being more accurate. Further more, the way of measuring pneumetaphores may not be as accurate. As we put the ruler down to the mud, it's always hard to say how deep to the mud should the ruler be put exactly. Therefore the height measured might not be what it really is. Other than those controllable errors, some causes might affect the result as well, which is hardly avoidable. When we measure the height of the watermark on the trees, a certain amount of watermark might have evaporated in the air already because of the strong sunlight.

Thus not 100% accurate the level of watermark is measured..