How does sunlight affect the distribution of a specific type of plant specie in an area which has approximately the same temperature, soil pH, nutrients, soil salinity and water content?
Dependent variable: distribution of the chosen plant.
Independent variable: amount of sunlight in the area.
Constant variable: the amount of temperature, soil pH, nutrients, salinity and water content.
Some plants grow well under higher amount of sunlight while others grow well under less amount of sunlight. The plant which has been chosen is likely to grow well in an area which it is not exposed to high amount of sunlight. This is predicted after looking at the area where this type of plant is found and just observing the plant growth and distribution without ant practical work.
* Light sensor
* TI calculator
* CBL Cable
* Vanier LabPro (with batteries)
The light intensity being emitted from any light source can be measured by the light probe depending on the appropriate range of the light intensity.
~ 0-600 lux is used for low levels of illumination
~ 0-6000 lux is generally appropriate for indoor light levels
~ 0-150,000 lux is mainly used for measurements in sunlight.
Method for controlling variables:
* The investigation should take place only in a certain part of the area and it should not be carried out elsewhere from that selected area.
* The time of the day should remain the same whenever the investigation takes place so as to keep the amount of sunlight constant or similar.
* Only the chosen plant specie should be looked at and it should not be confused by similar looking plants.
* It is better to complete the investigation on the same day and once so as to get the most accurate distribution of the chosen plant.
Method for collecting data:
* Choose a plant type in an area that will be depended on sunlight to measure its distribution.
* By using the light probe, determine what parts of that area have different amounts of sunlight.
* Use a quadrat which is 50cm by 50cm and place it in the areas with different amounts of sunlight.
* Count how many grids (boxes) are filled by all the plant population on which the quadrat lies.
* Then count how many grids (boxes) are filled by the chosen plant type out of all the plant population.
* Repeat the same steps as many times as possible on different parts of the area where the amount of sunlight varies.
* Compare the numbers of chosen plants found under different amounts of sunlight and conclude whether there is a higher number of plant distribution of the chosen plant under high amount of sunlight or less amount of sunlight.
As it was hypothesized, the area with less amount of sunlight had a higher number of the chosen plant population then the area with more amount of sunlight. This can be noticed by looking at both the graph and the processed data table where by the highest percentage fill on the quadrat by the chosen plant specie was when the amount of sunlight was the least. Therefore, the distribution of the chosen plant specie is most where the amount of sunlight is less.
The highest amount, 64% of the grids in the quadrat were filled by the chosen plant specie when the sunlight was 50,700.8lux, and the lowest amount, 4% of the grids were filled by the chosen plant specie when the sunlight was 51,800.4lux.
The reason the results were quite accurate could be because the investigation or the experiment was not taken place in varies areas but was just taken in many parts of only one area. If the distribution of this chosen plant type was looked at in another area, the result would not necessarily be the same since other factors determining the plant distribution would differ, such as the water content, nutrients, soil pH and so on.
Evaluation of limitations and weaknesses:
* Some of the grids might not have been totally full by the plants and so the actual number of grids filled by all the plant population and also by the chosen plant specie could be less.
* The amount of sunlight would not have remained constant and therefore when the light intensity was measures, a higher amount or a less amount of sunlight would have been captured by the light sensor.
* Other factors such as temperature, soil pH, nutrients, soil salinity and water content that also determine the plant distribution would not be exactly the same in the whole area and therefore it could have also affect the distribution of the chosen plant type and not only the sunlight.
* Since the experiment was just done once, there could have been some errors and so the distribution obtained would not have been totally right.
* It would have been better if there would be another more accurate way to measure the distribution of a specific chosen plant since measuring it manually may not be as precise as measuring it by using some kind of an electronic instrument.
* If the other factors that determine the plant distribution were actually kept constant and not determined, then a more precise distribution of the chosen plant type could have been obtained.
* A more accurate result would have been obtained if the experiment would have been repeated more then once, and so an average could have been found.