MICROBE ACTIVITY COMPARISON BETWEEN NORTH AND SOUTH FACING SLOPES Jake DePompolo CU Mountain Research Station 2015

INTRODUCTION  Sunlight  Moisture  Temperature  Snow coverage  Vegetation  Organic Matter (What we know) &bih=706&source=lnms&tbm=isch&sa=X&ei=aKfnVO- FACTORS :

COMPARISON (PREDICTION) North facing slopes: Wet **More snow cover **Colder More vegetation? More organic matter in soil South facing slopes: Dry **Less snow cover **Warmer Less vegetation Less organic matter in soil

RESEARCH  Class data from week 4 and the Biological Sciences, both concluded that temperature and CO2 respiration have a positive linear trend. Yet researching further it appears that soil water concentration was not a factor in soil respiration (Bolstad et al. 2004)  Temperature increases microbe activity  Soil water concentration doesn’t effect the microbe activity

 Temperature gradient snow (TG) keeping soils warmer (More snow cover on north facing slopes)  South facing slopes are warmer due to greater sunlight exposure.  Due to TG snow, warmer temperatures from snowpack may have significant effects on microbe activity and soil respiration. (Monson et al. 2006) RESEARCH

HYPOTHESIS & PREDICTION  Alternative Hypothesis  Due to variances in sunlight exposure in the winter, organic matter, etc., Soil respiration will be significantly different between north and north facing slopes.  Null Hypothesis  Soil respiration in the winter will not have a significant change between north and south facing slopes despite the fact that the south facing slope receives more sunlight.

METHODS  I have measured CO2 respiration at three sites on each slope. Sites have been chosen based on most abundant slope landscape (snow depth and vegetation density).  Tools:  CO2 respirator  Snow depth meter stick  Altimeter  Controls:  Vegetation density  Sunlight  Elevation

RESULTS NORTH FACING Average snow depth: 33.6 cm Organic matter: rich/dark brown Saturation: fully saturated / wet SOUTH FACING Average snow depth: 13 cm Organic matter: light/medium brown Saturation: not saturated / dry

DATA North facing slope maintain higher respiration per unit area. North facing Slope: Mean SE 2.79e-4 South facing slope Mean SE 3.063e-4

DISCUSSION  T-test p-value = = significant  Reject the null hypothesis and accept the hypothesis that soil respiration is significantly different between north and south facing slopes.  Due to graph we can determine: South facing CO2 respiration < North facing CO2 respiration Even though south facing slopes receive more sunlight, north facing slopes maintains greater CO2 respiration during the peak of the day. Organic matter due to vegetation density and snowpack coverage in north and south facing slopes might significantly impact soil respiration.

LIMITATIONS  Day time only  Shade  Different snow depth was not controlled for  Limit of three measurements on each slope at only one elevation

FURTHER RESEARCH  Other controls  Soil saturation  Organic matter  Night & Day flux  Type of vegetation Future hypothesis: Organic matter due to vegetation density and snowpack coverage in north and south facing slopes might significantly impact soil respiration. Soil respiration might be higher with increasing vegetation density and depth of snowpack

REFERENCES:  Bolstad PV, Davis KJ, Martin J, Cook BD, Wang W Component and whole-system respiration fluxes in northern deciduous forests. Tree Physiol 24:493–504. [accessed 2015 Feb 21]  Monson, Russell K. Winter forest soil respiration controlled by climate and microbial community composition: Nature. [accessed 2015 Feb 13].  l l

Appendix

DATA STATISTICS North slope: Mean:.0061 Variance: 2.347e-7 S.D. 4.84e-4 S.E. 2.79e-4 T-TEST (unpaired and two tailed) P-value = South slope: Mean:.0024 Variance: 2.815e-7 S.D. 5.3e-4 S.E e-4

ACKNOWLEDGEMENTS  David (helped with data collection)  Taylor (graphing and data collection)  Tim Kittel (graphing and over-all guidance)  Derek Sweeney (bringing supplies)  Azuraye Wycoff (assistant)  Family and Friends