Stand-Level Components of a Growth and Yield Model for Nothofagus Mixed Forests from Southern Chile

Abstract

Reliable information on stand dynamics and development is needed to improve management decisions on mixed forests, and essential tools for this purpose are forest growth and yield (G&Y) models. In this study, stand-level G&Y models were built for cohorts within the natural mixed second-growth Nothofagus-dominated forests in Chile. All currently available (but limited) data, consisting of a series of stratified temporary and permanent plots established in the complete range of this forest type, were used to fit and validate these models. Linear and nonlinear models were considered, where dominant stand age, number of trees, and the proportion of basal area of Nothofagus species resulted in significant predictors to project future values of stand basal area for the different cohorts (with R2 > 0.51 for the validation datasets). Mortality was successfully modeled (R2 = 0.79), based on a small set of permanent plots, using the concept of self-thinning with a proposed model defined by the idea that, as stands get closer to a maximum density, they experience higher levels of mortality. The evaluation of these models indicated that they adequately represent the current understanding of dynamics of basal area and mortality of Nothofagus and companion species in these forests. These are the first models fitted over a large geographical area that consider the dynamics of these mixed forests. It is suggested that the proposed models should constitute the main components of future implementations of G&Y model systems.

Prediction Comparison of Stand Parameters and Two Ecosystem Services through New Growth and Yield Model System for Mixed Nothofagus Forests in Southern Chile

“…Similar conclusions have been reported in other mixed-species forest G&Y models [32,33]. Additionally, it is possible that the accuracy of stand-level BA growth models is affected by the higher tree density (NHA) of companion species, adding not only more uncertainty in their BA growth but, as mentioned before, affecting mortality patterns [11]. In contrast to the T simulations, the poor BA estimation of the stand-level simulation models affected the compatibility simulation models as well, given that these are fixed to the stand-level BA estimation.…”

“…The second module incorporates a modification from Reineke's self-thinning models to estimate future stand density. Further details are presented in Palmas et al [11].…”

“…The stand-level mortality model is an annual projection of NHA based on the expression from Reineke [20] and defined by the following two parameters:α andk. The original model was presented by Palmas et al [11] and parameter estimates are shown in the Appendix A, and its expression is as follows:…”

“…Oerst.). The simulator Nothopack was built for those forests, specifically for second-growth stands, incorporating a stand-level basal area growth model [11], a tree individual-level diameter growth model [12], and two compatibility approaches. This is the first simulator system for the complete distribution area of this native second-growth forest that covers more than 1.4 million hectares (10.8% of total native forest of Chile; [13]).…”

An Analysis of the Factors Affecting Forest Mortality and Research on Forecasting Models in Southern China: A Case Study in Zhejiang Province

“…Previous investigations conducted by Hallinger et al and Moore et al have put forth evidence suggesting that elevated stand density correlates with an increased likelihood of tree mortality within a given age and stand structure [23,62]. In a parallel vein, Palmas et al's research on natural mixed forests in Chile established models demonstrating that, as stand density approaches maximum density, the stand experiences augmented levels of mortality [63]. In this current study, the significance of BA as a predictor variable was also prominently featured.…”