Soil and vegetation components

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Soil and vegetation components
Ecophysiology Group - Mica Creek
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Soil Respiration
Dr. John Marshall Erin Berryman (Graduate student)

• Soil CO2 flux measurements near tower at Mica
  Creek
• Automated Carbon Efflux System (ACES)
• Allows 16 simultaneous chamber flux measurements
  using one IRGA sensor
• Constructed by Forest Service scientists
• Objectives
• Measure soil respiration at high temporal
  resolution in Northern Rockies
• Estimate belowground contribution of ecosystem
  respiration

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Estimating Total Belowground Carbon Allocation
(TBCA)

• Soil CO2 flux measurements
• LI-6400 - IRGA
• Soil surface flux using chambers
• Subtract litterfall C from total C removal
  (respiration) to estimate TBCA (Raich and
  Nadelhoffer 1989)
• Mica Creek - tentative
• Can do this with ACES - requires installation of
  litterfall traps near tower
• Priest River Experimental Forest (PREF)
• Strong landscape component to soil respiration
• Measure CO2 flux variation by
• Altitude
• Slope aspect (solar radiation load)

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• Dissolved Organic Carbon (Blecker, Gravelle, et
  al.)
• Seasonal DOC mass balance across the mgmt
  gradient (inputs precip, stemflow, throughfall,
  outputs stream water, internal transformations
  litter soil)
• Quality measures of DOC through exchange resins
  (humic vs. non-humic) and spectrophotometry
  (aquatic vs. terrestrial source based on relative
  measure of lignin)

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• Nocturnal Cold Air Drainage (Blecker, Kavanagh
  et al.)
• Begins when vertical temp gradient becomes
  isothermal
• iButton temp measurements for thickness of cold
  air layer
• Proposed study Measure diurnal variation in
  quantity and isotopic signature of CO2, in
  conjunction with vertical profile of temperature,
  
• wind speed direction.

How Tethered balloon (rise above cold air lake,
capture greater of nocturnal CO2 drainage),
portable mast, tall trees) Possibly use SF6
release upstream to determine footprint
(figure taken from Pypker et al. 2005 HJ
Andrews)
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As the evening progresses, the cold air lake
forces air from the upper portions of the
watershed over the tower. Thus, the tower
footprint shrinks and the quantity of CO2 passing
the tower declines (approx 30 to 60 of the CO2
respired in the watershed)

(Pypker et al. 2005 HJ Andrews)
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Effects of canopy density and slope position on
transpiration rates per unit leaf area in conifer
forests of northern Idaho.

• Kathleen Kavanagh
• Peter Gag

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Radial Sap Flow Meter (Granier 1985, 1987)

• Method for measuring whole-tree transpiration
• Measures a temperature difference between
  heated and reference probe.
• Sapwood flux creates temperature differences.
• Measure transpiration rates (E) and stomatal
  conductance (Gs)

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Methods

• Two transects
• 3 sites demonstrating variation in slope
  postion/elevational gradient
• 2 sites same elevation, varied canopy structure
• One shared site between transects
• Measured at each site
• 5 trees of dominant and codominant crown position
• All Douglas-fir (Pseudotsuga menziesii)
• Soil Moisture
• Temperature and humidity

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Hypotheses

• 1) Increased rates of transpiration per unit leaf
  area in thinned stands.
• 2) Increased rates of transpiration per unit leaf
  as elevation increases away from riparian areas.

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Remote data mgmt

• Telemetry working with Senior ECE majors to
  design and install telemetry system for remote
  data access.

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Water fluxes

• Katy Kavanagh, Pete Gag, Steve Blecker
• Transpiration study sap flux setup in 2005,
  volumetric soil moisture and soil water potential
  monitoring planned for 2006