Competition in forest plantations: Empirical and process-based modelling in pine and eucalypt plantations

Competition for resources among trees, shrubs and weeds in forest plantations is an important factor that directly interferes with the growth and production of forests. Understanding the ways in which plantation trees compete for resources during their development helps to more accurately estimate tree growth and wood production in models. Growth and production models are classified as empirical or process-based models. For both types of models, competition is added either directly as a numerical variable or indirectly through submodels that quantify the use of available resources for growth among plants. The first part of this article is a contextualization of how competition is embedded in empirical (G&YM) and process-based (PBM) growth and production models. The second part is a systematic review between the years 1999–2021 that seeks to answer the questions “Which species in Brazil has the highest number of publications on competition in G&YM and PBM? Which competition assessment methods are used in studies on G&YM and PBM in Pinus and Eucalyptus plantations in Brazil? What were the advances in studies on competition in G&YM and PBM in Pinus and Eucalyptus plantations?” The largest number of articles published during the period studied was in Eucalyptus plantations, which is because there is a larger area of these plantations in Brazil compared to Pinus plantations. The review showed that competition in most articles is treated indirectly using basal area, number of trees, density, and Beer-Lambert law. Competition is a complex process to assess, however, not neglected by the models. The contrary, studies have advanced and shown direct ways to competition by incorporating processes and indices in either G&YM and PBM.