Lauri Palva 
,
Eero Garam,
Sari Palmroth,
Raimo Sepponen,
Pertti Hari
Utilizing a multipoint measuring system of photosynthetically active radiation in photosynthetic studies within canopies
Palva L., Garam E., Palmroth S., Sepponen R., Hari P. (1998). Utilizing a multipoint measuring system of photosynthetically active radiation in photosynthetic studies within canopies. Silva Fennica vol. 32 no. 4 article id 673. https://doi.org/10.14214/sf.673
Abstract
A novel multipoint measuring system of photosynthetically active radiation (PAR) has been constructed and operated within a Scots pine canopy. A regular grid of 800 measuring points has been incorporated into a cuvette to observe the spatial and temporal distribution of PAR incident on the needles of a twig along with simultaneous measurements of the CO2 exchange in order to determine the dependence of photosynthesis on PAR. It was shown that large errors can result if the photosynthetic rate is estimated using the mean value of PAR instead of the instantaneous values of PAR detected at given points in the region of the needles. The results demonstrate that the obtained regression between the CO2 exchange rate estimated using the multipoint PAR measuring system and the measured CO2 exchange rate is as good within a canopy as in unshaded conditions.
Keywords
carbon dioxide;
instrumentation;
measurement;
photosynthetically active radiation
-
Palva,
Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland
E-mail
lauri.palva@hut.fi
- Garam, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail eg@nn.fi
- Palmroth, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail sp@nn.fi
- Sepponen, Helsinki University of Technology, Applied Electronics Laboratory, P.O. Box 3000, FIN-02015 HUT, Finland E-mail rs@nn.fi
- Hari, University of Helsinki, Dept. of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland E-mail ph@nn.fi
Received 5 March 1998 Accepted 5 August 1998 Published 31 December 1998
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