Short communication: Variation of deadwood density by decay class in Douglas fir (Pseudotsuga menziesii (Mirbel) Franco) stands in Italy

Aim of the study: To estimate fresh and basic density values of Douglas fir deadwood for the five decay classes used in the National Forest Inventories (NFIs). Area of study: Rincine forest in Tuscany region (Italy). Material and methods: 140 samples of Douglas fir deadwood (28 for each decay class; 14 of which were collected in summer and 14 in winter) were collected and analysed in the laboratory. The samples were weighed fresh, then placed in the oven for 3 days at 60°C. Afterwards the samples were weighed dried. The laboratory data were used to estimate moisture content (%), fresh and basic density by decay class. Main results: The results showed that the trend of basal density decreased from 1st to 5th decay class (0.43 g cm-3, 0.39 g cm-3, 0.37 g cm-3, 0.29 g cm-3 and 0.20 g cm-3). An average basic density of 0.34 g cm-3 could be used in future studies concerning the estimation of C-stock in Douglas fir deadwood. Research highlights: The moisture content of all decay classes of lying deadwood is influenced by the season (winter vs. summer) and consistent with the local climate regime.