Dead wood research in forest reserves of Northwest-Germany: methodology and results

Results and methodology of deadwood assessment in 7 forest reserves in Low er Saxony are presented and suggestions for a deadwood concept in managed forests are derived. The results are based on time series data of approximately 1 ha core areas in unmanaged forest reserves. The monitoring pert od comprises 19 to 25 years. For the third inventory the methodology was changed considerably in order to optimize deadwood assessment. This methodology is described in detail. The volume calculation for deadwood is comparable to the volume calculation for the living stand. Calculations are based on the measurement of dimensions at specific points of a certain object. Therefore, decay of the inner section and of parts between measured points are the biggest sources of error for volume estimation. Deadwood volume in 1996 varies between 9 and 79 m(3)/ha in the examined stands. The main portion are objects on the ground and deadwood with a diameter above 20 cm. Exogenously caused tree mortality is the most important source for deadwood formation. An efficient habitat strategy for deadwood in managed forests should therefore include disturbance mortality.