Microbial Respiration in Soil Surrounding Aspen Trees

Maria RoccoEBIO 4100: Winter Ecology: Spring 2012

"Mountain Research Station, University of Colorado, Boulder"

Outline Background Hypothesis Methods Results Analysis Conclusions

Future Research

Background Seasonal Changes in Alpine Soil Community1

Changing populations throughout year, larger populations of soil microbes during winter months

Not only are populations larger but species diversity changes seasonally due to changing environmental considerations Summer : Phototrophy Winter: cold tolerant and rely on cellulose

Macroinvertebrate Presence in Soil with increased litter and organic matter2

Seasonal fluctuations of microbial biomass and available Nitrogen3

Background Initial goal to examine presence of

macroinvertebrates in soil, specifically looking at their presence in relation to tree growth and temperature gradients

CO2 flux primarily relates information about soil microbes CO2 as a measure of soil respiration

Aspen trees Higher N rich litter in aspen leaves

Overall Research Goal: Begin to examine possible behavioral adaptations of soil biota to winter environments

Hypothesis Soil temperatures further from the base of the

tree will be colder than those closer to the trunk.

The rate of respiration decreases in soil further from an aspen tree.

Methods Measured 3

distances from Aspen Tree for five sites

Took measurements at ground level

Measured respiration rates and soil temperature using: Soil CO2 flux system

(X57/SRC1-CO2 FLUX)

Results Analyzing CO2 change as a function of time Convert CO2 change to CO2 flux Compare different trials looking for outlier

data sets Compare different distances from tree to see if

CO2 flux changes with distance

0 cm from Tree Trunk

10 cm from Tree Trunk

Results

Results

Analysis Appears to be no significant difference

between the distance from tree and soil respiration.

Analysis on a larger scale may be necessary as root systems may extend further from the tree than 1 m This may have been a large contributing factor as

aspen root systems are very extensive.

Conclusions/Future Questions What components of the soil

microbes/macroinvertebrates’ genome deal with extreme temperatures and cold tolerance?

The possibility that photosynthesis is and could be taking place in soil, under snow during winter months

What other factors play a role in macroinvertebrate and microbe presence in the winter? Tree type Root systems? Moisture levels? Aspect?

References 1Lipson, D. A., and S. K. Schmidt. "Seasonal

Changes in an Alpine Soil Bacterial Community in the Colorado Rocky Mountains." Applied and Environmental Microbiology 70.5 (2004): 2867-879. Print.

2Negrete-Yankelevich, Simoneta. "Integrating Soil Macroinvertebrate Diversity, Litter Decomposition and Secondary Succession in a Tropical Montane Cloud Forest in Mexico." Global Change Research Institute PhD Thesis Collection (2004).Edinburgh Research Archive. Web. 24 Feb. 2012. <http://www.era.lib.ed.ac.uk/handle/1842/592>.

3Schmidt, S.K. and D.A. Lipson. 2004. Microbial growth under the snow; Implications for nutrient and alleochemical availability in temperate soils. Plant and Soil 259: 1-7. 

Questions?