THE INFLUENCE OF EXPOSURE TIME ON THE MAG NITUDE OF SOIL RESPIRATION UNDER EMPLOYMENT OF THE LUNDEGARDH PROCEDURE

To assess the role of carbon-rich soils under a potential climate chan ge much more data are needed then currently available. These have to b e collected also under conditions, where only limited technical and pe rsonal resources are available. Therefore the easy to be accomplished Lundegardh-procedure, which is accepted as a standard procedure for ex posure times up to 24 hours (Anderson, 1982), was tested for its suita bility to longer periods of exposure. For this purpose six Lundegardh- traps were installed on seven consecutive days (treatment B), and the means of the six repetitions added to a weekly value. In the immediate vicinity to the former, six Lundegardh-traps were installed for perio ds from one to seven days (treatment A). This was done during the warm season as well as in the winter. The comparison of the treatments A a nd B revealed a linear correlation, which allows to substitute cumulat ed daily values by values of traps, that have been installed for sever al days. However, the ''chamber-effect'', an overestimation of respira tion by the traps installed for more than 24 hours found by Tesarova a nd Gloser (1976) has to be considered. In the summer, the same degree of overestimation (16%) was found as reported by Tesarova and Gloser ( 1976). In the winter, far lower absolute values and therefore higher s tatistical importance of extremes led to an overestimation of 46%.