Root respiration rate before and just after clear‐felling in a mature, deciduous, broad‐leaved forest

Abstract Soil respiration was measured throughout the year (June 1992 to May 1993) in a mature, deciduous, broad‐leaved forest and an adjacent, clear‐felled stand which was made in November 1991, in Hiroshima Prefecture, west Japan. The same soil temperature and soil moisture content as those in the forest stand were maintained in two frame boxes covered with sheets of white netting in the clear‐felled stand to observe soil respiration. A herbicide was applied to the cut end of all stumps in one of the two frame boxes in order to kill the root system. There was no significant difference in the aboveground biomass and soil environmental conditions between the forest and the frame boxes in the clear‐felled stands. The difference in soil respiration rate between the forest and the frame box, in which the root system was killed by the herbicide, was considered to be due largely to the contribution of root respiration. Taking into consideration CO 2 evolution due to the decomposition of roots killed and the change in A 0 layer respiration rate after clear‐felling, the proportion of root respiration to the total soil respiration before clear‐felling was estimated to be 51% annually, which coincides closely with those values estimated previously in mature forests by other methods. The difference in the soil respiration rate between the two frame boxes (one with killed roots and the other with undisturbed roots) suggested that the annual root respiration rate just after clear‐felling dropped to about two‐thirds (70%) of that before clear‐felling.