Aim of study: We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) review the research perspectives in mixed forests.Area of study: The definition is developed in Europe but can be tested worldwide.Material and Methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests.Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used for specific objectives. A variety of structures and patterns of mixtures can occur, and the interactions between the component species and their relative proportions may change over time.The research perspectives identified are (i) species interactions and responses to hazards, (ii) the concept of maximum density in mixed forests, (iii) conversion of monocultures to mixed-species forest and (iv) economic valuation of ecosystem services provided by mixed forests.Research highlights: The definition is considered a high-level one which encompasses previous attempts to define mixed forests. Current fields of research indicate that gradient studies, experimental design approaches, and model simulations are key topics providing new research opportunities.Keywords: COST Action; EuMIXFOR; mixed-species forests; admixtures of species.

A total of 214 permanent and temporary plots from roble (Nothofagus obliqua), raulí (N. alpina) and coigüe (N. dombeyi) pure and mixed second growth forests located between 37°30' and 42°00' south latitude in Chile were used to fit an average size-density model. This model was then modified to obtain maximum density curves, and to construct stocking management charts with the aim to support planning of thinning, and to help the application of CONAF´s second growth forests management guidelines. The final size-density model considered a common slope and specific intercepts for three different compositions: raulí mixed, roble and coigüe. Comparisons of these models with others reported in the literature showed an acceptable level of similarity. Concerning load site capacity, the lowest levels were found for the composition roble, and the highest for coigüe. The following reference lines are suggested for the use of the presented stocking charts: 100% (line A or maximum density), 60% (line B or beginning of self-thinning), 30% (line C or load site capacity inferior limit), and 20% (line D or minimum density). Additionally, applications and methodology for the construction of these stocking charts are fully described together with concepts related to each of the reference lines.

No abstract

Conifer afforestation in the northwestern Patagonian provinces of Neuquén, Río Negro and Chubut has increased over the last few years, largely owing to federal and state government promotional policies. However, there is not enough information available on the profitability of this investment to support private or social decisions. In this study, we calculated and analyzed the expected benefits for ponderosa pine (Pinus ponderosa (Dougl.) Laws) plantations under different production models, which were structured as operation and cash flows using regional growth models. The models considered are based on preliminary growth prediction functions for the species in this region. By means of computer spreadsheets, we analyzed 12 economic models that combine three site qualities and four management systems, using primary and secondary information on costs, prices and products. Results indicate that the models have a positive internal rate of return (IRR), although not all of them have a positive soil expected value (SEV) at a discount level of 7% annual rate. Among all the economically viable models, the intensive-very apt site and the intensive-apt site models remained the most stable after sensitivity analysis. We also discussed the subsidies utilization, the investment on land combined with plantation and other producing alternatives.