The single tree-based stand simulator SILVA: Construction, application and evaluation

Single tree forest growth simulators have proven to be very flexible tools for predicting forest growth. They are commonly applied in the United States but they are rarely used in European forest management yet. One of the few exceptions is the simulator SILVA, which is presented in this paper. The underlying equations of this simulator are developed from a set of more than 155,000 tree observations, including the species Norway spruce (Picea abies (L.) Karst.), Silver fir (Abies alba Mill.), Scots pine (Pinus sylvestris L.), Common beech (Fagus sylvatica L.) and Sessile oak (Quercus petraea (Mattuschka) Liebl.). These basic model equations are presented together with respective parameter values, derived from the aforesaid data set. The benefits of SILVA for forest practice, research, and education are demonstrated with three exemplary applications. Evaluation in terms of biological plausibility, validation, and practical use of the implemented software is presented, which shows that: (1) biological principles could be represented without explicitly being implemented, and (2) the simulation results are very close to independent observations as far as the range of parameterized site conditions is not exceeded. Furthermore, possible implications of changing conditions or an application of the model across a wider geographical range are discussed with special reference to the ongoing process of parameterization.