Totholzvolumen und -qualität in ausgewählten Schweizer Naturwaldreservaten

Abstract

Deadwood volume and quality in selected swiss natural forest reserves Deadwood is structurally and functionally important for forest ecosystems. To date, there are hardly any data on the amount of deadwood in Swiss natural forests which can serve as reference value for deadwood management in managed forests. In this study, deadwood volumes and qualities (sizes, broadleaf/conifer ratios, decomposition stages) from six natural forest reserves were analysed and compared with data from managed forests as well as from natural and virgin forests. An average of 69 m3/ha with a broadleaf proportion of 66% was calculated for the six reserves. Deadwood volume in relation to the total volume was 12% on average. Overall the volume of lying deadwood was double the volume of standing deadwood. The average proportion of large deadwood (diameter >30 cm) was 48% and was higher in snags (52%) than in lying deadwood (46%). Advanced stages of decomposition made up 53% of the lying deadwood. The volumes, sizes and decomposition stages varied greatly within the reserves. In comparison, in the Swiss forests altogether, there is less deadwood (21.5 m3/ha, 5% of total volume), the deadwood is thinner (35% large deadwood proportion) and less decayed (proportion of advanced stages of decomposition 10%). However, deadwood volumes in the reserves are considerably lower than those in European natural beech forests and beech virgin forests. The investigated reserves are therefore, 40 to 92 years after the last silvicultural intervention, only at the beginning of the process of acquiring a virgin forest character.