Soil Properties Affecting Tread Condition Along the Baker Lake Trail
Angela Vaughan
Advisor: Darlene Zabowski
University of Washington, School of Environmental and Forest Sciences, Spring 2015
Introduction
Discussion
Trail construction and maintenance provides a means of reaching areas that are otherwise inaccessible and accommodates
peoples’ outdoor recreation desires. As the demand for these
recreation opportunities increases, hiking trails are subjected to
heightened levels of impact. Gaining an understanding of how soil
properties are affecting tread conditions along trails will provide
insight regarding better maintenance practices for existing trails
and how to locate the most optimal trail sites in the future.
 Gradual sections of trail tended toward having higher overall
organic matter content and were generally wider, although the
difference was not statistically significant (Figure 7 and Table 2).
Purpose
This study determined soil properties associated with muddy
tread conditions along the Baker Lake Trail and compared
locations with and without mud across sites with either steep or
gradual hillside slope.
 It could be that a true difference exists between steep and
gradual sites (Figures 1, 2, and 3) but this study design failed to
detect it. Likewise, it may be that the occurrence of mud is more
dependent on other factors as suggested by the comparison of
soil properties between tread with and without mud (Table 1).
Figure 1. Steeply sloped
site with mud.
Figure 2. Steeply sloped
site without mud.
Figure 3. Gradually
sloped site with mud.
Figure 4. Gradually
sloped site without mud.
Results
Hypothesis 1
 The plant species present were greatly overlapped across the
two landscape types and tread conditions making it so that
strong conclusions could not be drawn. Two observations can be
noted: 1) steep sites with mud tended toward having more moss
and denser understory vegetation compared to the sites without
mud, and 2) gradual sites without mud tended toward having a
higher frequency of evergreen species intermixed with the
deciduous species compared to the sites with mud (Table 3).
 When people go off-trail to avoid mud, it impacts the surrounding
soil and plant communities. The results from this study show that
these muddy conditions lead to an average increase in tread
width of 18cm (Figure 8 and Table 1).
Sites with mud will have a lower mean bulk density, higher
mean organic matter content, and greater mean penetrometer
depth compared to sites without mud.
Hypothesis 2
The relationship between these properties will differ for gradual
and steep sloped sites.
Methods
Figure 5. Significant difference
between average bulk density for sites
with mud and the control without mud
for both landscape types.
Study Area
The Baker Lake Trail is a
heavily used, 14 mile long,
unsurfaced trail in Mt. BakerSnoqualmie National Forest
that is accessible to hikers and
equestrians year round. The
trail runs along the eastern bank
of Baker Lake (Figure 9),
traversing steep slopes farther
away from shore and dropping
down to more gradual terrain
closer to the lake and the Baker River flood plains.
Field Methods
Figure 8. Average tread width
shown for tread conditions with and
without mud compared between
gradual and steep locations.
Figure 6. Significant difference
between average penetrometer
depth for sites with mud and the
control without mud for both
landscape types.
Figure 7. Significant difference
between organic matter content for
sites with mud and the control without
mud for both landscape types.
Future Considerations
 A study with a greater number of independent trail segments
sampled could evaluate the relationship between the length of a
muddy section and the tread width to see if there is a correlation.
Table 1. p-values resulting from t-tests comparing the means for sites with
and without mud indicate significant differences between all measurements
except for the tread width on gradual slopes.
 This study focused on gradual slope and steep slope. Given
these constraints, there may have been cases that lie in between
that were not sampled which could offer further insight into these
relationships when looking at samples across the entire
topographical gradient.
Table 2. p-values resulting from the t-tests comparing the means for steep and
gradual sites show that there was not a significant difference in soil bulk density,
percent organic matter, and tread width. The difference between penetrometer depth
was only significant for muddy tread conditions.
 There might be seasonality to the severity of mud; if conditions
are only prevalent in winter when usage is low, then the problem
areas would require less extreme measures for satisfactory
maintenance.
Recommendations
 Make sure that tread has appropriate out-sloping, doming, and
berm removal to prevent the accumulation of water and organic
debris.
Table 3. Site Characteristics.
In the field 72 soil samples were collected from 36 transect
points across 12 trail segments representing one of the four
different combinations of tread condition and landscape type
(Figures 1,2,3, and 4). At each transect plant species, tread
surface characteristics, and trail drainage features were recorded
and penetrometer depth and water displacement volume for soil
bulk density were measured.
 Construction of drainage dips and water bars may help to reduce
pooled water and saturated organic matter which creates mud.
 Appropriate methods will depend on landscape type, soil
properties, and the extent of the problem. More involved
strategies do not seem necessary for this trail, but puncheon
board and turnpikes are both possible solutions to combat issues
with extremely muddy trail tread.
Laboratory
Soil samples were hand textured, bulk densities were calculated by drying and weighing a known volume of soil, and carbon
concentration was analyzed to determine the organic matter
content of the samples.
Conclusions
Figure 9. Overview of baker lake
from the trail.
Acknowledgements
Thank you to Darlene Zabowski for her guidance and to the SEFS
Capstone Fund for their generous award which allowed me to
complete the carbon/nitrogen analysis on my samples.