winter soil respiration near dead and living lodgepole pines at niwot ridge, co justin d’atri...
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Winter Soil Respiration Near Dead and Living Lodgepole Pines at Niwot Ridge, CO
Justin D’AtriWinter Ecology Spring 2010
Mountain Research Station – University of Colorado, Boulder
INTRODUCTION
• According to United States Geographical Survey scientist Craig D. Allen, “many forest and woodlands today are at an increasing risk of climate-induced dieback (Allen 2009).”
Mountain Pine BeetleNative InsectOutbreaks have happened in the past but never at the
current scale.
Current Situation Caused By:Alteration of Temporal & Spatial disturbances (Seastedt 2010)
-More Benign Winters-Decades of Fire
Suppression
Current Situation• Social Effects (Allen 2009)
-Pose Fire Risk (1.5 million acres in CO)-Potential Loss of Tourism (hiking, skiing, fishing)-Loss of Timber Resource-Expensive Management Techniques (Thinning,
Burning, Pesticides)• Environmental Effects
-Change in Carbon source/sink? Global Implications-Change in ecosystem services? Local Implications
• Research is Necessary for Sucessful Forest Management
What We KnowSoil Respiration increases with Snow Depth
Soil Respiration increases with Soil Temp
Dead root decay
Fungal-dominatedMicrobes
Soil faunaexcretion
Inorganic N
CO2
Bacteria and fungi co-dominate
Rhizodeposition
Soil fauna
Watertranspiration
excretion
N uptake
DOCSOM
Response to Tree Death
Current Research • Seastedt T, Xiong Y, D’Atri J. Rapid Soil Organic Matter (SOM) Loss from
Forest Dieback in a Subalpine Coniferous Ecosystem. INSTAAR, University of Colorado Boulder, CO. [In Press 2010]
RESULTS• -Forest dieback results in rapid C
emissions from surface soil• -Total Carbon (C) decreased 38–49 % • -Total Nitrogen (N) decreased
26–45 %• -Increased soil pH near dead trees caused by
an accumulation of soil NH4+ and K+.
• A rapid reduction in surface soil SOM suggests that forest dieback caused the ecosystem to be a large C source.
Where did over 38% of the surface carbon go?
1. Lost through microbial respiration as CO2
2. Leaching of Dissolved organic Carbon (Runoff)
The increased loss of Carbon near dead lodgepole pines suggests an increase in soil respiration.
Question:Is there more soil respiration
occurring near dead lodgepole pines than living lodgepoles during the winter?
If there is more respiration occurring under a dead tree then we should measure an increase in CO2 being emitted from the soil.
Hypothesis There will be a difference in the rate of
respiration between the soil near living lodgepole pines compared with the soil near dead lodgepole pines because of the amount of dead tree material in the soil.
Null: There is no difference in soil respiration
Methods Choosing a site:
In order to minimize variation in geology and topography and I chose one micro site consisting of a matrix of living and dead trees in the same small forest area.
Criteria for Comparison: Controls-Deep snowpack ~50cm-Mature Tree-Not too close to other trees of different treatment-All from same micro site-Same Organic Matter Quality
MethodsCO2 Flux Measurements– Measured by CO2
analyzerTemperature Measurements- Thermometers
Data collection-Dig snowpit
-Record concentrations at 0s, 30s, 60s, 90s, & 120s
-Calculate Flux (120s –0s)-2 collection trails per tree-Average the two fluxes-Compare fluxes in excel-10 trees total
ResultsAverage Living CO2 Flux = 39.1Average Dead CO2 Flux = 32.9
Living Dead
P-value = 0.517195994
Discussion• Reject alternative hypothesis • Accept Null
–There is no difference in soil respiration• Study suggests that winter respiration is
not influenced by tree type. • Temperature seems to be the largest
control influencing under snowpack soil respiration.
If the loss of Carbon doesn’t happen during winter then when does it happen and where does the carbon go?
Further Research:-CO2 flux measured year round-full soil profile-stream chemistry
Problems with Project• CO2 analyzer battery• Breathing near snow pit• Finding a “controlled” site• Not enough samples• Maybe could find significant results
with more trials
Summary• Study suggests that winter
respiration is NOT influenced by tree type.
• For this site, temperature seems to be the largest control influencing under snowpack soil respiration.
Thanks to:Derek
Sarah
Chris
References•Seastedt T, Xiong Y, D’Atri J. Rapid Soil Organic Matter(SOM) Loss from Forest Dieback in a Subalpine Coniferous Ecosystem. INSTAAR, University of Colorado Boulder, CO. [In Press 2010]
Allen, C. D. "Climate-induced forest dieback: an escalating global phenomenon?" Unasylva 60 (2009): 43-49.
Kurz, W. A et al. "Mountain pine beetle and forest carbon feedback to climate change." Nature 452 (2008): 987-90.
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