Biol 301 Lab
Community Ecology Worksheet
Figure 1. Average pH levels of Varying Tree Species in W. Gordon Belser Arboretum.
Soil samples were taken at the base of the different tree species and were measured for their pH levels. This graph represents the average soil pH levels of 5 groups that took different samples around the same tree type. Two slightly acidic trees are the Tupelo and the Pines. The Tupelo is common in wet soils and the soil around the Pines is more acidic because of their needles that fall on the ground.
1. The first site we took samples from was at the base of a popular tree. We expected the pH of the soil taken from this site to be low because they inhabit well-drained, upland areas. The next site we took samples from was at the base of a Tupelo tree. Tupelos are found in poorly drained bottomlands and the soil surrounding these trees is assumed to have a low pH value. The soil surrounding a Chestnut tree is expected to have a higher pH because it is found growing on higher land. Both pines are expected to have a low pH because their pine needles lower the soil pH. The older pines will have an overall lower pH.
Table 1. pH differences between sites. This single factor ANOVA will tell if there is a difference in pH between any sites but it will not tell you which sites are different from one another.
Anova: Single Factor
Source of Variation
3. The presence of the Tupelo in the arboretum in an area of low soil pH shows that there is not a low of manganese in the soil because manganese inhibits its growth. The difference in the pH of the soil around the different aged pine trees is a result of age The older pines have dropped more needles to the floor which have resulted in a low pH than the young pines which still have a strong hold on their needles and have not dropped as many to the floor.