Gauging the effects of climate variability on Eucalyptus plantations productivity across Brazil: A process-based modelling approach

Managing climatic variability is essential for dealing with current genotype x environment interactions and for adapting Eucalyptus plantations to future climate change. This study uses a process-based modelling approach to assess long-term effects of spatial and temporal climate variability on Eucalyptus productivity for 36 sites across Brazil. The attainable stem wood mean annual increment (MAI, m(3) ha(-1) yr(-1)) was simulated by the APSIM Next Generation Eucalyptus model, considering three soil types (clay, sandy-clay and sandy-loam) and twenty-seven rotations of seven years, using weather data from 1980 to 2013. Spatial and temporal (inter-annual and interseasonal) climate variability strongly affected Eucalyptus MAI across Brazilian regions. Average Eucalyptus MAI ranged from 38 m(3) ha(-1) yr(-1) (Imperatriz, MA, Northeast region) to 69 m(3) ha(-1) yr(-1) (Borebi, SP, Southeast region), while its coefficient of variation ranged from 3.2% (Antonio Olinto, PR, South region) to 17.2% (Bocaiuva, MG, Southeast region). Our results suggest an average increment of about 0.91 m(3) ha(-1) yr(-1) for each increase of one degree in latitude. Eucalyptus growth was mostly driven by water deficit combined with high temperatures at tropical sites, while the tree growth was more affected by low winter temperatures at subtropical sites. The results of the present study have value for understanding how Eucalyptus plantations change their growth in response to changing climate. Gauging the effects of climate variability on Eucalyptus growth may assist in forest planning by estimating the area to be cultivated, machinery sizing, climate risk, and guiding the tree breeders in choosing appropriate genotypes.