Soil respiration rates are higher in urban forests compared to rural forests. Soil respiration is the process by which carbon dioxide is released into the atmosphere through roots, organisms, and litter decomposition. It depends on factors like temperature, moisture, root density, and soil organic matter. A study measured soil respiration monthly for 10 years in Baltimore parks and found higher rates in urban forests. The hypothesis is that higher earthworm abundance in urban forests causes increased soil mixing and respiration. Methods included analyzing soil samples for microbial and root biomass, earthworm collection, and using previous temperature, moisture, tree density and soil respiration data. Understanding differences in soil respiration between urban and rural forests can provide insight into future forest carbon dynamics and climate change mitigation

1. WHY ARE SOIL RESPIRATION
MEASUREMENTS HIGHER IN URBAN
FORESTS THAN RURAL FORESTS?FORESTS THAN RURAL FORESTS?
Russell D. Auwae and Peter M. Groffman

2. Introduction: Soil Respiration
The emitting of carbon dioxide into the atmosphere
through roots (rhizosphere), heterotrophic and
autotrophic organisms, and the decomposition of
litter fall (Hogberg and Read, 2006).
Dependent on: topography, root density, quantity
and quality of soil organic matter, microbial
biomass, vegetation characteristics, and distance
from trees and leaf litter amount (Chimner, 2004;
Ryan and Law, 2005).
Varies with temperature and moisture.

3. Mystery
Urban Rural
(Groffman et al., 2006)

4. Study Site: Baltimore, MD
The Baltimore LTER plots
Measured every month for the past 10 years using an
in situ flux chamber method:
Oregon Ridge Park (4) = Rural
Leakin Park (2) = Urban
Hillsdale Park (1) = Urban

5. Question
Why is soil respiration higher in urban forests
compared to rural forests?

6. Hypothesis
Earthworm abundance is the cause for higher soil respiration measurements in urban
forests compared to rural forests.
(Szlavecz et al., 2006)

7. Methods
3 soil cores per plot
Laboratory analysis of soil for microbial and root
biomass and soil organic matter
Acquire previous soil respiration, moisture, andAcquire previous soil respiration, moisture, and
temperature data
Acquire previous tree density data
Field collection of earthworms

8. Importance
Annual soil CO2 effluxes (via decomposition) are
roughly 10 times that which is derived from the
combustion of fossil fuels (Mooney et al., 1987).
There is potential in soils to mitigate climate change
and sequester carbon, or release carbon and
increase the amount of CO2 in the atmosphere (Tang
et al., 2009).
To help better understand the global carbon budget
and its effects on global climate change.
Urban forests in Baltimore provide a glimpse of
how future forests will look and behave.

9. Expectation
SoilRespirationSoilRespiration
Earthworm Abundance

10. References
Chimner, R. 2004. Soil Respiration Rates of Tropical Peatlands in Micronesia and Hawaii. The
Society of Wetland Scientists. 51-56.
Groffman, P. M., Pouyat, R. V., Cadenasso, M. L., Zipperer, W. C., Szlavecz, K., Yesilonis, I. D.,
Band, L. E., Brush, G. S. 2006. Land use context and natural soil controls on plant community
composition and soil nitrogen and carbon dynamics in urban and rural forests. Forest
Ecology and Management. 236: 177-192.
Hogberg, P., Read, D. 2006. Towards a more plant physiological perspective on soil ecology.Hogberg, P., Read, D. 2006. Towards a more plant physiological perspective on soil ecology.
TRENDS in Ecology and Evolution. 21: 548-554.
Mooney, H. A., Vitousek, P. M., Matson, P. A. 1987. Exchange of Materials between Terrestrial
Ecosystemes and the Atmosphere. Science, New Series, Vol. 238, No. 4829, pp. 926-932.
Ryan, M., Law B. 2005. Interpreting, measuring, and modeling soil respiration. Biogeochemistry.
73: 3-22.
Szlavecz, K., Placella, S. A., Pouyat, R. V., Groffman, P. M., Csuzdi, C., Yesilonis, I. 2006.
Invasive earthworm species and nitrogen cycling in remnant forest patches. Applied Soil
Ecology. 32: 54-62.
Tang, J., Bolstad, P. V., Martin, J. G. 2009. Soil carbon fluxes and stocks in a Great Lakes forest
chronosequence. Global Change Biology. 15: 145-155.