Microbial Respiration in Soil Surrounding Aspen Trees Maria Rocco EBIO 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
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.