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CARBOTATRA 2006-2007

CARBOTATRA 2006-2007. Measurement Campaign of eddy fluxes in the High Tatra (Vysoke Tatry)-Slovacchia. Partecipanti al progetto UNITUS – Viterbo MPI-BGC – Jena IBIMET-CNR – Firenze CEALP – Trento Parco Nazionle dei Tatra (TANAP) – Tatranska Lomnica (SK). CARBOTATRA-Sites description.

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CARBOTATRA 2006-2007

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  1. CARBOTATRA2006-2007 Measurement Campaign of eddy fluxes in the High Tatra (Vysoke Tatry)-Slovacchia • Partecipanti al progetto • UNITUS – Viterbo • MPI-BGC – Jena • IBIMET-CNR – Firenze • CEALP – Trento • Parco Nazionle dei Tatra (TANAP) – Tatranska Lomnica (SK)

  2. CARBOTATRA-Sites description • Three eddy covariance towers for NEE and ET measurement • Intact Forest (IF) • Extracted (EX) • Non-extracted (NEX) NEX IF EX

  3. CARBOTATRA-Sites description Annual course of temperature and precipitation Winter 2007 was sensibly warmer than 2006. No difference in total precipitation during growing season Tair – daily course 2007 Tair – daily course 2006 Mean Tair

  4. CARBOTATRA-Sites description Soil Water Content (daily avarage) And Net Radiation (weekly sums) Seasonal trend of SWC shows maximum content in early spring at snow melting in 2006. Maximum in REF site occurs also in June (peak precipitation). The forested site (REF) has, on avarage, lower SWC possibly due to higher transpiration (see later). SWC in EX site starts diverging from NEX starting from June: coupling with net radiation? Increased water requirement to sustain the higher growth of vegetation? The net radiation trend at NEX site shows a visible divergence from EX in mid June 2006 (peak level of radiation): due to the presence of logs and the consequent lower vegetation cover, the pattern of net radiation doesn’t respond to the phenologic change like in the other two sites. Frequent sensor failing in 2007 at NEX site

  5. CARBOTATRA-CO2 Fluxes The marked difference in the pattern of NEE during 2006 between the wind throw sites (EX and NEX) and the reference forested site (REF) is almost offset in 2007. A rapid change in the vegetation composition of EX site is mainly responsible for this behaviour. EX: respiration rate increased as well: higher substrate availability? NEX: Effects of vegetation regrowth on assimilation, which were lowered in the 1st year, were visible in 2007. (Waiting for new elaboration from CNR-IBIMT*)

  6. CARBOTATRA-CO2 Fluxes month • Monthly mean diurnal variation better marks the interannual change of NEE in the two wind throw sites. • A general increase in both assimilation and respiration in EX-site. In 2007 the vegetatoin period was longer because of higher winter temperatures and earlier snow melting (doy 73 in 2007 and doy 90 in 2006, see before). The efflux peak in March 2007 may be biased by the low number of data points at night (high u* threshold). • NEX site shows an increase in assimilation at the beginning of the season and an apparently stable efflux rate. A failure of the analyzer in the period May-July 2007 compromised the calculation of NEE (because of Webb correction of LE on Fc). Recovery of data may be possible.

  7. CARBOTATRA-CO2 Fluxes Carbon balance NEP 4 AUG- 31 DEC 2006 Missing data were filled using non linear regressions. Equations and parameters are shown in the next slides.

  8. CARBOTATRA-CO2 Fluxes Carbon balance divided by the three components NEP, TER, and GPP

  9. CARBOTATRA-CO2 Fluxes Ecosystem Respiration response to soil temperature. Night respiration was modelled with a non linear regression using a sigmoid equation (Falge et al., 2001). Dataset was diveded in 4 periods, 3 months each. FRE,night = FRE,Tref e[E0*(1/(Tref−T0)−1/(TK−T0))] FRE,Tref is the respiration at temperature Tref (283 K). E0 is the activation energy of the biochemical reactions of microbial decomposition. Tk is the soil temperature. T0 was set at 227.14 K.

  10. CARBOTATRA-CO2 Fluxes NEE response to radiation. NEE was modelled with a non linear regression using a Michaelis-Menten equation (Falge et al., 2001). Dataset was diveded in 24 bi-weekly periods. NEE = Km*Amax*PPFD/(Km*PPFD+Amax)-R0 Km is the “quantum yeald”, Amax is assimilation at saturating levels of PPFD (Photosysnthetic Photon Flux Density), R0 is base respiration. 15-30 June 2006 PPFD(mmol*m-2*s-1) 1-15 Aug 2006 PPFD(mmol*m-2*s-1)

  11. CARBOTATRA- H2O Fluxes Evapotranspiration: weekly sums. The period indicated in the tables starts from the doy assumed as the beginning of snow melting as indicated in slide 6. Data were gapfilled using MDV method applied to periods of one month.

  12. CARBOTATRA- Heat Fluxes Sensible heat: weekly sums. Data were gapfilled using MDV method applied to periods of one month.

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