Yield gap of the eucalyptus crop in Brazil: causes, magnitudes and possible short-term solutions

Abstract

Among the forest species, the genus Eucalyptus is the most planted in the world. Brazil, with approximately 5.7 million hectares of area planted with eucalyptus, stands out in the forest sector, leading the world ranking of productivity in volume per unit area and year. In this way, a better knowledge and quantification of the factors that determine the growth and productivity of forests is important. Therefore, the objective of this project is to identify the causes and magnitude of yield losses (Yield Gap) in different producing regions of Brazil, as well as those for which the crop is expanding. Forest productivity is usually estimated through simulation models, which are a set of algorithms that describe the processes that govern the carbon balance and the partitioning of the carbon between the different organs of the plants, which must be properly calibrated and validated. . Among the models available for eucalyptus cultivation, the Agroecological Zone Model (AEZ-FAO), classified as a physiological-mathematical model and recently adapted for eucalyptus cultivation, estimates the potential productivity (PP), conditioned by genotype, solar radiation , photoperiod and air temperature, and attainable productivity (PA), which represents the PP penalized by the water deficit over the cycle. The difference between PP and PA indicates loss of productivity due to water deficit, while the difference between PA and real productivity (PR) indicates the productivity decrease due to silvicultural management failures. Therefore, the AEZ-FAO model will be applied to different Brazilian regions and their results compared to field yields to indicate the main causes (water deficit or management deficit) and magnitudes of productivity losses of this important crop for the Brazil. On-site surveys will help identify the management actions that may be responsible for the breaks in this regard.