Modelling natural regeneration in SIBYLA tree growth simulator

Göttingen

2011

S. 5-10

Artikel aus einer Zeitschrift

200173580

Models of natural regeneration represent an important amendment to complex growth models. They allow making prognoses behind one production cycle of a forest, and also simulating the development of natural and virgin forests. This work deals with the modelling of natural regeneration density and of parameters of natural regeneration. The model consists of an empirical part, which simulates regeneration density (number per hectare) at a stand level, and of a process-based part, which simulates seed production and seedling germination at a tree level. The empirical part of the model is based on the data of the National Forest Inventory and Monitoring of the Slovak republic 2005-2006 and climatic rasters with the pixel size of 90 × 90 m, which capture the spatial distribution of important climatic characteristics. The model simulates regeneration density of individual tree species in relation to quadratic mean diameter of the parent stand and its crown closure. In addition, the model is site-specific. Weibull’s function is utilised for the generation of diameter distribution. Tree heights are modelled by Wolf’s function. The process-based part of the model is based on seeding functions and fuzzy logic. It is based on the prediction of seed yield of individual trees in relation to such characteristics as seed purity, seed quality, germination capacity, absolute weight of seeds, seed production per adult tree, etc. The production is further modified with the regulators and reduction factors, which describe other conditions necessary for the germination, survival, and the establishment of the next generation. In the next step, empirically derived regeneration density is reduced in relation to the ratio of individual tree species to the total production of all individuals estimated from the process-based model.