Transcript Disturbia: The Real Dirt on Palos Verdes Peninsula Victoria Zamora , 1Long Kimberly Boyd , Jade Dean , Fenderson , KarryssaLora Stevens Marylynn Roun , Christine M. Rodrigue , Paul Laris , Beach Polytechnic High School,2

Disturbia: The Real Dirt on Palos Verdes Peninsula
Victoria
1
Zamora ,
1Long
Kimberly
1
Boyd ,
Jade
2
Dean ,
3
Fenderson ,
Karryssa
4
Lora Stevens
Marylynn
3
Roun ,
Christine M.
4
Rodrigue ,
Paul
4
Laris ,
Beach Polytechnic High School,2 Long Beach City College,3Woodrow Wilson Classical High School,4CSU-Long Beach
Introduction
Results
Coastal Sage Scrub (CSS) is a unique plant community
because it is found only in Southern California and it
supports several endangered species. CSS plants survive
in nutrient poor soils. It is usually found along Southern
California’s Coast including the Palos Verdes Peninsula.
Over the last century, however, invasive species have
been able to thrive and out-compete natives on the
peninsula. The reasons for their success remain a
mystery. This project is the preliminary assessment of
differences in edaphic properties of disturbed and
undisturbed areas. Samples were taken from two sites
which contain both mechanically disturbed and
undisturbed areas: Three Sisters and Portuguese Bend
(Figures 1-3). Soil properties studied included pH, salinity,
grain size, and organic/inorganic carbon content. We
hypothesize that soils within disturbed areas have been
altered so that they are no longer able to support native
vegetation.
Methods
In the field we used 3 m x 3 m quadrats to sample plant
diversity and soil characteristics of our study area.
Quadrat locations were chosen using aerial
photography to determine disturbance history of the
area. Both plowed and intact areas were sampled.
Discussion
Conductivity/ Salinity
•Grain size of undisturbed is characterized as clay
loam and disturbed as clay (see figure)
We hypothesized there would be a difference in the soil
properties of disturbed and undisturbed sites. We found
organic matter and grain size showed the greatest
difference. Undisturbed sites had much higher levels of
organic carbon than disturbed sites (27;2%). There was a
much higher percent of clay in the disturbed sites and a
higher percent of silt in the undisturbed. Its not surprising
that there is more organic carbon in the undisturbed,
because of the high leaf litter from CSS. The finding that
disturbed sites have higher clay percentages is in
agreement with finding from the other study group, and
reflects the fact that plowed areas tended to be more
level and have deeper, finer soils. These finer soils were
also dominated by non-native grasses.
According to the USDA, one would expect to find
calcium in areas with high pH. We found that many of
our neutral to basic soils had recognizable amounts of
calcite. Its not surprising to find the undisturbed to have
higher conductivity, which one expects in a semi-arid
environment. Perhaps the disturbed sites have lower
values due to farming and irrigation.
•Undisturbed sites have a higher percentage of total
carbon than disturbed areas (see figure)
Conclusion
A summary of the results is shown below. We found that
pH values were slightly high in the undisturbed sites.
Conductivity was also higher in the undisturbed sites.
Organic matter and especially organic carbon was
much higher in the undisturbed plots while disturbed
plots were found to have higher percentage clay
content. In terms of minerals, quartz was the most
abundant and found on all plots. Calcite was found in
most of the undisturbed plots, while magarite was
found mostly in disturbed sites. Geothite and whitlockite
were only found in the disturbed mustard site.
Undisturbed
Disturbed
pH
Summary of Results
•pH in undisturbed sites ranges from 6.7 to 8.15 and
disturbed sites from 7.2 to 7.9 (see figure)
•Conductivity in undisturbed sites : 113 -1529 mS;
disturbed sites 547.9-1451 mS(see figure)
In the lab we used several techniques to test soil
properties (figure 4). Inorganic and organic carbon
content was determined using a UIC Inc.® coulometer.
Mineral identification was done using X-ray diffraction
(XRD); soil samples were crushed, mixed with alcohol,
and spread onto glass slides (Engleman et al., 1985).
Next using the Lewis and McConchie technique (1994),
we found the percentage of the different grain sizes in
the sediment samples. Lastly, samples were turned into
a mixture using nanopure water in a 2:1 ratio and then
tested with a YSI™ meter to determine both the pH and
conductivity of the solutions.
This study concludes that mechanically disturbed sites
are more likely to have low organic carbon, more clay
content, and lower salinity (conductivity). We did not find
any obvious differences in soil minerals or pH levels
between disturbed and undisturbed sites. Furthermore,
the differences in soil texture are likely a function of
topography and not a result of the mechanical
disturbance itself, whereas the high carbon levels found
on CSS plots is probably due to the higher leaf litter
associated with this plant community. Further research
should explore the differences in nitrogen content
between the two types as nitrogen has been known to
favor invasive grasses over CSS (Talluto, M.V. and Suding
2008).
Minerals
Study Sites
Organic Matter
References
Grain Size
Engleman, E.E., Jackson, L.L., Norton, D.R., Fisher, A.G., 1985.
Determination of carbonate carbon in geologic materials by
coulometric titration. Chemical Geology 53, 125-128.
Lewis, D.W. & McConchie, D. 1994. Analytical Sedimentology.
Chapman and Hall, New York, pp. 94-108.
Talluto, M.V. and Suding, K.N. 2008. Historical change in coastal
sage scrub in southern California, USA in relation to fire frequency
and air pollution. Landscape Ecology, 23:803-815.
Soulé, Michael E.; Alberts, Allison C.; and Bolger, Douglas T. 1992.
Oikos 63, 1: 39-47.
Figure 1
Acknowledgements
Figure 2
Figure 4: Photo credit
Kim Boyd
Figure 3
I would like to thank: The National Science Foundation Award
#0703798 for funding GDEP Track 2, the Palos Verdes Peninsula
Land Conservancy for allowing us to use their land, Brian Nagy
for technical support, Jason Manack and Hazel for the support
and help Drs. Paul Laris and Chrys Rodrigue for helping and
guiding me with my project along with Daniel Cardoza, Karryssa
Fenderson, Marylynn Roun, and Jade Dean for their continued
help and support. Thanks to the everyone in the “Rock the
Water” group who helped me including Lizbeth Rodriguez,
Valerie De Jesus, Yoshi Maezumi, and of course Lora Stevens.
And always thanks to my Mommy.