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Sie sind hier: Startseite Forschung abstracts Mackensen J. and Bauhus J. (2003): Density loss and respiration rates of coarse woody debris of Pinus radiata, Eucalyptus regnans and Eucalyptus maculata.
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Mackensen J. and Bauhus J. (2003): Density loss and respiration rates of coarse woody debris of Pinus radiata, Eucalyptus regnans and Eucalyptus maculata.

Soil Biology and Biochemistry 35, 177-186.

This study compared field and laboratory decomposition rates of coarse woody debris (CWD) (>10 cm diameter) from three tree species: Pinus radiata, Eucalyptus regnans, and Eucalyptus maculata. For this purpose, the density loss of logs on the ground sampled from chronosequences of sites following harvesting was determined using the water replacement technique. Pinus radiata logs were sampled 1, 2.5, 6, and 9 years following harvesting, and logs of E. regnans and E. maculata were collected from sites that were harvested 1, 3.5, 6.5, and 12 and 1.5, 6.5, and 11.5 years ago, respectively. In addition, the C/N ratio of wood was determined and current respiration rates of logs from these different age classes were measured through laboratory incubation. The times for loss of 95% of material (t0.95) determined from density loss for these species were 24 years for Pinus radiata, 43 years for E. regnans, and 62 years for E. maculata. The decomposition rates of CWD derived from laboratory respiration were 6.1 times, 5.9 times and 11.9 times higher than the decay rates from density loss in Pinus radiata, E. regnans, and E. maculata, respectively. This points to severe constraints of decomposition through adverse conditions in the field. The changes in respiration rates and C/N ratio with age of decaying logs indicated that the single component, negative exponential decay model could be applied satisfactorily only to Pinus radiata. In the case of the eucalypt species, substrate quality (expressed through respiration rates) declined in the oldest samples. This may be explained by the loss of rapidly decomposing sapwood and the retention of more decay-resistant heartwood. In these cases, a two-component model will be more suitable to describe the density loss of decaying wood.

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