The Effect of Sunlight on Soil BiodiversityINTRODUCTIONSoil: often an overlooked field in science. Because the microorganisms found in soil are so minute, scientists often do not choose to study this particular part of Earth. However, soils are the only place on earth where the four life-supporting realms come together: the atmosphere, lithosphere, hydrosphere, and biosphere making it an extremely important part of the Earth (Parker, S., 2010). It is important that we know where exactly can we predict trends in soil biodiversity for endeavors we encounter in our everyday lives. We need to know things like where to plant a garden, where to have a picnic, where to put our dog’s feeding bowl, where to hammock, or where to build a house. It is not only important to study these trends for our own sake, but for the sake of the soil as well. Human activities and development threaten soils all around the world (Parker, S., 2010).For our experiment, we isolated one factor that may have an effect on soil biodiversity. We wanted to know whether or not sunlight had any effect on biodiversity. If it does, we can determine biodiversity trends in soil just walking around outside. We based our hypothesis on theassumption that microorganisms tend to thrive more in darker environments.We hypothesized that if soil is exposed to more sunlight, then its biodiversity will be affected. Our null hypothesis was that sunlight has no effect on biodiversity of soil. We predict that soil exposed to less sunlight has a greater biodiversity, meaning it will have more richness and higher evenness than soil exposed to a greater amount of sunlight.METHODSIn our experiment we used two replicates of each type of soil tested, shade and light. We tested the samples using TSA plates and MacConkey plates. We used both types of plates to maximize visible biodiversity. TSA plates show general biodiversity, while MacConkey plates isolate certain types of bacteria maximizing the total visible biodiversity. Our independent variable was the amount of light the soil samples received. Our dependent variable was the richness and evenness of the soil samples. We then collected data and used Simpson’s Diversity Index (see formulas) to measure the evenness of the samples. We used Microsoft Excel to calculate our mean, standard deviation, standard error, and t-test. We used mean as out measure of central tendency and standard deviation for dispersion. In order to accept our hypothesis that sunlight affects soil biodiversity, then our experiment would have to result in a p-value of 0.05 or less for both richness and evenness with the soil in the shade having the greater numbers.RESULTSFigure 1 shows the relationship of species richness between the two soil samples and Figure 2 shows the relationship of soil evenness. As you can see in the figures, the sunlight soil sample produced larger numbers in both categories, contradictory to our hypothesis. DISCUSSIONOur experiment resulted in a p-value of 1 for the species richness test and .0695 for the evenness test. We rejected our alternative hypothesis and failed to reject the null hypothesis that sunlight has no effect on biodiversity because neither p-value was less than 0.05.Although there was no significant evidence that sunlight has an effect on soil biodiversity, the p-value calculated for evenness was pretty close to 0.05. Further studies could be conducted retesting our hypothesis, but changing the prediction.If we were to re-do the experiment, we would have many more replicates. Also we wouldcollect soil samples from areas with an even greater difference in the amount of sunlight received. We would also control for other variables, such as animal/human interaction because it has an effect on biodiversity. We could do this by testing soils from unpopulated areas or collect samples from lab/greenhouse soils. FORMULASSimpson’s Diversity Indexn is the total number of individuals in a particular speciesN is the total number of individuals of all speciesFigure 1- richness comparison between soils with different exposure to sunlightSunlight Shade0123456789Species RichnessFigure 2- comparison of soil evenness between soil samples exposed to different amounts of sunlightSunlight Shade00.050.10.150.20.250.3Soil EvvennessREFERENCESParker, Sophie S. (2010). Buried treasure: soil biodiversity and conservation. Biodivers Conserv, 19,