Dynamics of the dead wood resources in the Swinia Gora strict nature reserve

The aim of the study was to characterize the state and dynamics of dead wood resources in the stands of the Świnia Góra strict forest reserve, which was excluded from use for a longer period of time (from 1938/1953), and to compare the results with the state and dynamics of living trees resources. The reserve covers 51 hectares of an upland forest in the Świętokrzyska Forest (central Poland). Data was collected in 2000, 2007 and 2014 on 95 systematically distributed 500 m2 sample plots. The location and dimensions of living trees, standing dead trees (snags, including stumps) and downed trees (logs) on each sample plot were determined and measured. The decay stages of dead wood were estimated using a four−point scale classification. The average volume of dead wood was 198 ±32 m3/ha (43 ±8% of living trees) in 2000 and 138 ±17 m3/ha (24 ±3%) in 2014 (fig. 1). The ratio of the volume of snags to logs decreased from 30 ±5% in 2000 to 24 ±6% in 2014. Silver fir was the dominant species among both living and dead trees (fig. 2). The share of dead wood volume in decay stages 1 and 2 was the highest among snags, while in stages 2 and 3 – among logs. The number of highly decomposed wood increased in the period 2000−2014 (fig. 3). The decay rate of wood calculated over a 7−year period was more rapid for logs (fig. 4). In the period of 14 years, 119 ±23 m3/ha of dead wood underwent a complete decomposition. Volume of trees that died within that period was 59 ±10 m3/ha (fig. 5). The complete decomposition of snags amounted to 64 ±10% and logs to 58 ±5% of the initial dead wood volume. The dead wood resources in the investigated period were not balanced: the amount of decayed wood was larger than the amount of wood replenishing the resources. The lack of this balance was due to the lack of the balance of living trees – dead wood resources were insufficiently replenished by trees that had died during analysed 14 years. The dead wood resources at a level of approximately 200−230 m3/ha might be balanced via their continuous replenishment by newly died trees in the amount close to the current volume increment