title: Evaluating the accuracy and generality of a hybrid patch model.
abstract: Forest patch models have been used extensively to simulate vegetation development under current and changing environmental conditions. However, their physiological foundation is subject to criticism and recent validation experiments against long-term growth and yield data have shown major deficiencies in reproducing observed growth patterns of mixed-species forests. Here we describe the modified forest patch model PICUS Version 1.3, a model variant that couples the structurally detailed three-dimensional patch model PICUS Version 1.2 and the physiologically based stand-level production module of the 3-PG (Physiological Principles in Predicting Growth) model. The approach attempts to combine the ability of PICUS v1.2 to simulate forest dynamics on time scales relevant to forest succession with a simplified but successful production model based on the concept of radiation-use efficiency. We evaluated the hybrid model in a series of simulation experiments. Results indicated a realistic response to a climate sensitivity experiment: the response to environmental gradients was well captured both in terms of productivity on time scales of a rotation length and of forest succession over several hundreds of years. Testing against independent long- term growth and yield data revealed good correspondence between observed and predicted values of volume production and stand structure. Further model development should include a dynamic soil component to consider effects of nutrient cycling.
authors.affiliation: University of Natural Resources and Applied Life Sciences (BOKU) Vienna, Department of Forest and Soil Sciences, Institute of Silviculture, Peter Jordan Strasse 82, 1190 Vienna, Austria.
authors.forename: Rupert
authors.initials: R
authors.lastname: Seidl
authors.forename: Manfred J
authors.initials: MJ
authors.lastname: Lexer
authors.forename: Dietmar
authors.initials: D
authors.lastname: Jäger
authors.forename: Karl
authors.initials: K
authors.lastname: Hönninger
mesh_terms: D002980:Climate; D003198:Computer Simulation; D017753:Ecosystem; D008954:Models, Biological; D011156:Population Density; D015203:Reproducibility of Results; D014197:Trees / Q000254:growth & development*