The Effect of Type of Vegetation on Soil pH in Tsuga canadensis & Juniperus sabina “broadmore”

Kristen Campbell & Dionetta Piazzo

Abstract

We tested whether type of vegetation caused a decrease in soil pH in Tsuga canadensis & Juniperus sabina “broadmore”. We found that T. canadensis decreased soil pH (P=0.033).

Keywords: Type of vegetation, soil pH, Tsuga canadensis, Juniperus sabina “braodmore”

Introduction

Boreal forests are made up of spruces, firs, conifers, and deciduous trees (Runesson, 2011). Soils in the boreal forests are typically called podzols and podzolization results from acidic soil which is a product of the needles from the trees (Runesson, 2011). Certain evergreens will drop their needles yearly, every three to five years, or every seven years (Nuss, 2007). Hemlocks will lose their foliage every three to five years where junipers will lose them every seven years (Nuss, 2007). Tsuga canadensis (Eastern Hemlock) prefer moist soil conditions but can live in varying soil types (Nuss, 2007). It can live in highly shaded areas. Some can live up to 900 years after reaching maturity around 250 years (Nesom, 2002). Juniperus sabina “broadmore” are evergreen shrubs and small trees that are dioecious (McKinley, 2005). Soil pH can vary from 0-6 being acidic, 7 being neutral, and 8-14 being alkaline. Soil pH determines the availability of nutrients in the soil for plant growth (Foth, 1970). We hypothesized that that the soil pH of Tsuga canadensis samples would be more acidic than that of Juniperus sabina “broadmore” because it drops its needles more frequently.

Materials and Methods

On October 8, 2011 at 1200 we conducted our study at McCarty Park located at 78^th and Arthur Ave., in West Allis, Wisconsin. On this day it was sunny and 26˚C. We went to McCarty Park to collect 24 soil samples from two different types of trees, Tsuga canadensis & Juniperus sabina “broadmore”. While walking through the park we chose evergreens that fit our species descriptions and that is how we randomly chose them. Once we randomly selected a plant that we wanted to gather a sample from because it fit the description of either a Tsuga canadensis or a Juniperus sabina “broadmore”, we took a zip lock plastic bag and labeled in with a number. We then gathered a soil sample with the use of a Stanly hand shovel, and we did this by collecting a scoop of soil that was 1 m away from the base of the plant. We repeated this process for the 23 remaining plants. Once we gathered all of the samples we desired, we began to test the soil for its pH. We did this by following the instructions in the LaMotte soil test kit beginning on page 15. We followed this procedure for all 24 of the soil samples we collected. We analyzed the data using a 1 tail type 3 T-test on Excel^© for Windows 2007^©.

Results

The soil pH of Juniperus sabina “broadmore” was significantly greater than the soil pH of Tsuga canadensis (Fig. 1, P =0.033).

The mean of the soil pH for Tsuga canadensis was 7.29 with a standard deviation of 0.40. The mean of the soil pH for Juniperus sabina “broadmore” was 7.67 with a standard deviation of 0.54.

Figure 1. Mean (+/- S.D.) of soil pH in Tsuga canadensis & Juniperus sabina “broadmore”.

Discussion

Our data supported the hypothesis that the soil pH of Tsuga canadensis samples would be more acidic than that of Juniperus sabina “broadmore” because it has drops it’s needles more frequently. This may be because all of the samples that we gathered were from the same park. Another reason for our findings may be we gathered our samples in early fall so the needles that did fall off the trees had a small amount of time to be in the soil and affect the pH.

There were some limitations to our study such as we gathered our soil samples from a park is landscaped, verses an area that is natural and unaffected. If we were to repeat this study we would try to gather soil samples from a natural unattended area because we feel that would get a more representative sample of how soil pH is in nature.

It would also be interesting to study the soil pH of hemlock trees compared to maple trees to find out which plant has a higher soil pH.

LITERATURE CITED

Foth, H.D. (1970). A study of soil science. Charleston, Maryland: LaMotte Company.

McKinley, D. W. (2005). Influence of Interacting Factors on the Growth and Mortality of Juniperus Seedlings. American Midland Naturalist, 154(2), 320.

Nesom, G. (2002). Plant Guide. United States Department of Agriculture. Retrieved on November 2, 2011 at http://plants.usda.gov/plantguide/pdf/cs_tsca.pdf

Nuss, J.R. (2007). Evergreen shrubs and trees for Pennsylvania. The Pennsylvania State University. Retrieved on December 4, 2011 at http://pubs.cas.psu.edu/FreePubs/pdfs/sc229.pdf

Runesson, U.T. (2011). Overview. Borealforest.org. Retrieved on November 2, 2011 at http://www.borealforest.org/index.php?category=world_boreal_forest&page=overview#