Modelling dominant height and site index in different edaphoclimatic zones of Nothofagus dombeyi secondary forest in the Andes of south-central Chile

Nothofagus dombeyi grows in a wide variety of sites. The information about its productivity is still scarce, which makes it difficult for foresters and landowners to take decisions about the best practices to maintain and/or improve the goods and services derived from the forest. The aim of this study was to construct dominant tree height functions and site index curves for secondary forests of Nothofagus dombeyi (coihue) in south-central Chile. We measured 100 sample units throughout three edaphoclimatic zones, and 300 dominant trees (three per plot) were used for stem analysis. Three non-linear growth models (Chapman-Richards, Weibull and Logistic) were fitted, and the best model for each edaphoclimatic zone corresponded to Chapman-Richards. In addition, it was determined that for each zone it was necessary to obtain a given growth model given the high variability of sites. The best tree height growth corresponded with zone 2, followed by zone 1 and zone 3. In zone 2 trees reach 31 m at age 60, 29 m in zone 1, and 24 m in zone 3, indicating variation in growth patterns and differences between zones. We recommend using the models for a range of ages between 10 and 60 years (base age 35 years). This is the first large-scale study describing growth of N. dombeyi for the southern part of South America in secondary forests where they occur as one of the most important, but least managed, forest resources in the region