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The growth and yield of mixed-species stands has become an important topic of research since there are certain advantages of this type of forest as regards functions and services. However, the concepts and methods used to characterize mixed stands need to be understood, as well as harmonized and standardized. In this review we have compiled a set of measures, indices, and methods at stand level to characterize the structure, dynamics, and productivity of mixed stands, and we discuss the pros and cons of their application in growth and yield studies. Parameters for the characterization of mixed stand structure such as stand density, species composition, horizontal (intermingling) and vertical tree distribution pattern, tree size distribution, and age composition are described, detailing the potential as well as the constraints of these parameters for understanding resource capture, use, and efficiency in mixed stands. Furthermore, a set of stand-level parameters was evaluated to characterize the dynamics of mixed stands, e.g. height growth and space partitioning, self- and alien-thinning, and growth partitioning among trees. The deviations and changes in the behaviour of the analysed parameters in comparison with pure stand conditions due to inter-specific interactions are of particular interest. As regards stand productivity, we reviewed site productivity indices, the growth–density relationship in mixed stands as well as methods to compare productivity in mixed versus monospecific stands. Finally, we discuss the main problems associated with the methodology such as up-scaling from tree to stand level as well as the relevance of standardized measures and methods for improving forest growth and yield research in mixed stands. The main challenges are also outlined, especially the need for qualitatively sound data. © 2015, Springer-Verlag Berlin Heidelberg.

To support forest management decisions on converting stands from even-aged to uneven-aged management, tree models are needed that can simulate both options. Therefore, an individual tree model for Pinus halepensis Mill. is compared with the respective yield table. The individual tree model is built from data of two Spanish forest inventories in this province and evaluated with published yield tables, which have been built from permanent observational plots. The individual tree model consists of a basal area increment model and a height increment model, both based on two measurements of about 4,000 trees from single species stands of Aleppo pine. The R² values of 0.362 and 0.107 for the basal area increment model and the height increment model, respectively, are within the range of other published models of this type. Comparing the model with the yield tables for different site indices, we find that our model matches the yield table well. Only in higher ages where the database for the yield table was poor, our model indicates higher basal area growth rates than the yield table.

The shape of the diameter distribution is one of the important elements characterising forest stand structure. In this work we present the application of the method of moments for the estimation of the parameters of a 2-parameter Weibull function. Due to its properties, this function is often used for the description of the diameter distribution in forestry. The work analyses the properties of the Weibull function and its application to a data set representing natural (virgin forest Babia hora) and managed forests (Litschau and Forest School Enterprise of Technical University Zvolen). The parameters of the Weibull function are simply and reliably estimated from the basic stand variables, namely the mean diameter and the coefficient of variation of the diameters. The method is general and does not require specific parameterisation, e.g. for the individual tree species. The work also presents a new algorithm for the estimation of parameters in cases, where tree diameters are measured from a certain minimum recording limit. Based on this study, we suggest using the Weibull function in forest stands only for uni-modal diameter distribution with a mean diameter above 7 cm.