Big Walnut Creek ForestA study of soil and tree species

Brett Bohlander

Brittany Mohrman

Tory Pavlovich

Introduction

• How does human land use affect a forest ecosystem?

• Specifically, how has the DePauw Nature Park been affected by its history of degradation? – Mining, clear-cutting, contamination,

recreational abuse, etc.

Objectives

• Measure any differences in soil quality and vegetation composition in forested areas along Big Walnut Creek

• Provide baseline data for future research in the Nature Park concerning forest health and stability

Location along Big Walnut Creek

• GIS map imposed on an aerial photograph

Plots

• Set up transect along Big Walnut Creek

• 50m between the centers of each plot

• 15m from the creek• 11.3m radius per plot• Recorded GPS point at center

of plot• Total of 18 plots• Divided into 3 sectors due to

natural divisions• Sectors labeled North to South

as A, B, and C

15m

50m

11.3m

Soil Testing

• Nutrient Testing of Phosphorus and Nitrogen with Hanna Soil Kit

• Percent water• pH using pH meter from Hanna Soil Kit

Tree Sampling

• Based size on three diameter categories

Small: 8-23 cm diameter

Medium: 23-38 cmdiameter

Large: > 38 cm diameter

• Identified species

Comparison of Nutrient Levels

012345678

# P

lots

Trace Trace-Low

Low Low-Med

Med Med-High

High

NitrogenPhosphorus

pH Comparison

7

7.2

7.4

7.6

7.8

8

8.2

8.4

8.6

A B C

Sector

pH

Averages and errors calculated by an ANOVA

Difference between sectors is significant (p= 0.004)

Percent Water Comparison

0

5

10

15

20

25

30

35

40

Sector A Sector B Sector C

Per

cen

t W

ater

Averages and errors as calculated by an ANOVA

Variance between groups is not significant

Tree Species Diversity

Sector A

Sector B Sector C

Comparison of Tree Densities

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

# o

f T

ree

s p

er

m2

Sector A Sector B Sector C

SmallMediumLarge

Discussion

• Results show no conclusive data• The forest does exhibit signs of degradation and

low overall health• Sector C shows the most similarity to Eastern

Deciduous Forests in tree species composition• Soil quality may be low as indicated by low

nutrient levels and high pH levels

Soil pH

• pH plays major role in availability of minerals and nutrients– Phosphorus only readily available in soil with

pH around 6.5– Nitrogen is affected by influence of pH on

activity of microorganisms necessary for plant growth, specifically bacteria involved in decomposition of organic matter

Eastern Deciduous Forests

• Most Common Species:– American Beech– Sugar Maple– Lady Fern– Northern Arrowwood– Pecan– Shagbark Hickory– White Birch– White Oak

• In DePauw’s Nature Park:– American Beech– Shagbark Hickory– White Oak

Future Research

• Include research on the understory vegetation, shrubs, and saplings

• Conduct longitudinal study to monitor improvement or stagnation of the riparian forest

• Compare data gathered in the DePauw Nature Park to an area of low human impact such as the Big Walnut Nature Preserve

References• State University of New York, College of Environmental

Science and Forestry. www.usf.edu/PUBPROG/brochure/soilph/soilph.htm

• www.nearctica.com/biomes/edf/edfintro.htm• Helm, B. and L. Howard. 2005. Presentation to SAB.

Acknowledgments • Prof. Dudle• Prof. Artman• Park Ranger Brian Holsapple