Context, tests and considerations for field measurements WP I

1
Context, tests and considerations for field
measurements (WP I)
RECIPE
2
Long term objectives

• Establishment of the carbon balance in Le Russey
  for two different stages of vegetation
• - recent with a lot of Eriophorum
  angustifolium and few Sphagnum.
• - advanced with mainly Sphagnum.
• Comparison with La Chaux dAbel ( full light and
  biophysical variables recorded) and part of the
  pots of WP II)
• Compartimentation of the fluxes for a better
  comprehension.

3
For the establishment of carbon balance in Le
Russey

• Tests done this summer
• Trial period for the new IRGA in order to know
  its properties, the time requirred for the
  equilibration in the chamber and the range of
  possible samples
• With full light measurement between
• 10 am to 3 pm.
• 20 of measurement per collar (62)
  before chamber stabilization 6 for the net
  ecosystem exchange and 6 for total respiration (
  with measurement recorded every 10 and averaged
  every minute.

12 to 14 collars
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Prelimanary results, trial period of the IRGA
NEE and Rtot for collar 6 stage recent
regeneration (21 August 2003)
Respiration of bare peat (5 august 2003)
CO2 concentration (um/m2/s)
CO2 concentration (um/m2/s)
5
For the establishment of carbon balance in Le
Russey

• Dispatching of the collars
• Stage of advanced regeneration 4 collars
• Stage of recent regeneration 4 collars
• Bare peat 3 collars
• ?Rehabilitated zone 3 collars if its seems
• to be OK next spring.
• Choice of their positioning for each stage of
  regeneration, inventory of the possible position
  of collars and after that random selection.

6
For the establishment of carbon balance in Le
Russey

• Leaf area index
• indirect measurement based on calibration
• relation between leaf length and area. Scan of
  75 leaves per species
• Eriophorum angustifolium
• Eriophorum vaginatum
• Carex nigra.
• For Vaccinium oxycoccos, leaves scanned,
  recording of number of leaves in various size
  classes.
• For Sphagnum and Polytrichum, measurement of
  density and estimation of the photosynthesis
  height with a light sensor.

7
For the establishment of carbon balance in Le
Russey

• Leaf area index

Relation between leaf length (mm)/ leaf area
(mm2) for Eriophorum angustifolium
Y0,248X1,439 R20,953
Relation between leaf length (mm)/dry biomass (g)
for Carex nigra

• Leaf biomass

Y4e-0,6 X1,7124 R20,95
8
For the establishment of carbon balance in Le
Russey

• Biophysical variables
• Installation of the rain collector, light
  sensor, air and deep peat temperature sensor at
  the site. For the peat temperature at 5 and 30cm
  depth at each stage.
• Hobo sensors, measurements every 30 with a
  large autonomy.

9
For the establishment of carbon balance in Le
Russey

• Estimation of humidity
• For the peat, test with a thetaprob sensor
  the integration of the conductivity for a height
  of 6cm is too approximative for this kind of soil
• For the Sphagnum, test of the visual index
  already used
• 1 (Sphagnum completely dessicated)
• 2 (Sphagnum 1cm capitulum dessicated)
• 3 (Sphagnum just rehydrated)
• 4 (Sphagnum good humidified)
• 5 (Sphagnum gorged with water).
• In order to test it sampling of 20 plants of
  4cm and weight fresh and dry biomass. The
  difference between the index was statistically
  significant.

10
For the establishment of carbon balance in Le
Russey

• Measurement campaign
• Once a week (except with snow) for CO2
• Every two or three weeks for CH4 (incubation in
  a small chamber placed near each collar and
  analysis in the laboratory with the micro GC).

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For La Chaux dAbel

• Utilisation of the tests done in Le Russey.
• Installation of sensors in order to record
  biophysical variables.
• Measurement once a month for 12 collars with full
  light.

12
Field measurements
Light sensor
Chamber temperature
Leaf area index
Sphagnum humidity
CO2 analyser
(analysis in Lab.)
CH4 chamber
- 5 cm
- 30 cm