Sabeen Ahmed

Lauren Nisely


Respiration of Bacteria in Soil and Leaf Litter of Coniferous Under Deciduous Trees

Balanced soil is vital for healthy plant life. Plants depend on a nutrient full environment to grow. Without bacteria and fungi to break down organic materials on the surface, the soil would lack the nutrients needed for a healthy environment. Bactria plays a key role in the decomposition process. In one gram of soil, populations of bacteria can range from about 100 million to 3 billion. Soil bacteria thrive in the soil water. The majority of the soil dwelling bacteria is aerobic and goes through cellular respiration to produce energy.

The purpose of our experiment was to determine the rates of the respiration of bacteria in leaf litter and ground soil under different types of trees. We hypothesized that bacteria will respire more in leaf litter than in ground soil. Our methods to perform this experiment were to first collect leaf litter and ground soil under both coniferous and deciduous trees. We collected soil under each type to maintain an experimental control. Using the CO2 probe we tested each soil for output levels of CO2. We did this by taking a sample of each soil and enclosing it in a jar. We ran the test for about eight to ten minutes, graphing the results. Our results showed that CO2 levels were much higher in leaf litter compared to ground soil under both types of trees. This means that more bacteria was present in the leaf litter. This conclusion makes sense because leaf litter contains so much organic material that needs to be decomposed, so more bacteria are present.

When testing our data we found that the P value was insignificant because of a small number of samples. Overall, our results were partially consistent with our hypothesis because there were higher numbers of CO2 output in leaf litter. However, our P-value of 0.23645 shows us that the difference of the means of the two variables (21.59 and 2.79) was insignificant. The main problem of our experiment is that we didnŐt collect enough samples to find a big difference in respiration levels of leaf litter and ground soil.

After reviewing our results, we found that the levels of respiration in soil under deciduous trees were generally higher than in soil under coniferous trees. This is most likely because deciduous trees are losing their leaves in the fall season. More leaf litter is present for the bacteria to decompose. This was interesting to us because we did not realize the effects that seasons would have on bacteria. It would be fascinating to see how the amount of bacteria changes due to the difference in seasons. More bacteria would need to be present when more organic material needs to be decomposed.


Works Cited

Soil Life. Wikipedia, The Free Encylopedia. 30 November 2007.