-To assess the level of diversity in different parts of the Menagesha National Forest, by using the Simpsons Diversity Index we can compare the diversity levels to each other.
-The size of the area being measured is very crucial because if this number varies the test will not be a fair one. In this case an area of 20 meters squared was measured. Another control was only measuring plants taller the one meter. This let us make the research more narrow and accurate. If we had to measure all the plants in the area not only would it have taken a lot of man power but also a lot more expertise.
-The diversity of the forest will alter in different parts of the forest. The older the area being assessed the more diverse the species will be.
* Old plantation (120 years old)
* Young Plantation (60 years old)
* Natural Forest A (500 years old)
* Natural Forest B (500 years old)
We looked at four different areas in the Menagesha forest. As mentioned before a twenty by twenty meter area was assessed in each case. One person stood at each corner of the square and the other people were made to count the different species that inhibit the area and the number of species. In all cases any plant species taller than one meter was used in the research.
Total number of species= 20
Simpsons Diversity Index for Menagesha
D= Diversity Index
N= Total number of all species at a given site.
n= Total number of a particular species at a given site.
1) Old Plantation
2) Young Plantation
3) Natural Forest
4) Natural Forest
Simpsons Diversity Index Graph
Analysis and Conclusion
Looking at the results we got its obvious that there is a difference in the number of plants and the variety depending on the area of the forest we sampled. In the young plantation there are 6 different plants but with one species of plant that is dominating the area in number. This is because when the forest was planted there was a specific species that was used. In the old plantation there is no dominant plant. The number of each plant has more or less evened out. This is because with time all the plants are given a chance to survive.
In the Natural Forests there is an irregular result. Although both the areas we measured were the same type of the forest, the results we got varied greatly. In Natural Area A there is one dominant plant with a high population and a few other types of plant around it, whereas in Natural Forest B there is a large variety of plant species, with a small population of each species. As seen in the Simpsons diversity index graph the diversity was much higher in the old plantation. This result confirms my hypothesis, that the older areas of the forest have higher species diversity. Another thing I noticed while at the forest was the fact that the older the forest the bigger the difference in the positioning of the canopies.
The results we got through this research were fairly accurate and depicted the results that are to be expected, except for Natural Forest B. This variation in our results shows that the research could be improved to give even more accurate results. One thing that could be done is measuring a bigger area for each type of forest. Another thing that has to be done is more research so the names for all the species are known. Also when we counted the plants, if there was a group of them together it was counted as one, instead of doing this I think if the size of the area it occupies would be a better measure. If there were more people I think it would have been better if we did more than one set of data for each type of forest so as to get more accurate results.