Spring recovery of Scots pines based on dark-adapted fluorescence and canopy scale CO2 fluxes at Sodankyl during SIFLEX-2002
Abstract
Measurements of dark-adapted fluorescence and CO2 fluxes were made in Sodankyl during the SIFLEX campaign. The objective was to study the spring recovery of a Scots pine forest and the response of photosynthesis to light and temperature. Here we describe the measurements and show some preliminary results. The dark-adapted fluorescence Fv/Fm, i.e. the maximum efficiency of photosystem II, was measured daily at three different sites during the campaign. The time used for dark-adaptation was at least 30 minutes. The measurements were made using a Hansatech Fluorometer. The CO2 assimilation and respiration of Scots pine shoots were measured with a static cuvette system, which contains a LICOR 6262 CO2/H2O analyzer. Some shoot measurements were made with a LICOR 6400 Portable Photosynthesis system using a conifer chamber. A parallel measurement for comparison between the two cuvettes was also made. The results of these cuvette measurements were compared with the CO2 flux values from the micrometeorological tower. In figure 1 we show the average daily temperature, the CO2 assimilation from the cuvette measurements with LICOR 6262, and the fluorescence values at three different sites. The CO2 assimilation values are shown for only five days. The results indicate that the Fv/Fm values and the CO2 assimilation values follow the trend set by the temperature, with some lag behind the temperature. As for the other results the micrometeorological CO2 flux was observed to follow the same trend with the cuvette CO2 assimilation measurements. The respiration values appeared to rise with higher temperatures.
- Publication:
-
Remote Sensing of Solar-Induced Vegetation
- Pub Date:
- 2002
- Bibcode:
- 2002ESASP.527E..18T