Eucalyptus benthamii Maiden et Cambage growth and wood density in integrated crop-livestock systems in Brazilian subtropic

Abstract

Integrating trees in agricultural landscapes is a great option to sustainably provide goods for society while increasing biodiversity, securing animal welfare, and generating profitability for stakeholders. The choice of the tree species is fundamentally important once it will affect resources partitioning among agricultural components. Knowing how timber quality is affected when trees are integrated to crop and/or livestock enterprises can provide additional insights into the usefulness of timber after harvest, and wood density is one of the most important properties in this regard. The present study aimed to evaluate how Eucalyptus benthamii growth and wood density are affected in integrated crop-livestock systems when compared to monoculture forestry 74 months after planting in subtropical environments. The integrated systems were in alley cropping design where crop and/or grazed pasture were temporally rotated in between tree lines (14 x 2 m trees spacing), and those systems were compared to monoculture forestry (3 x 2 m spacing). Tree trunks (n=60) were sampled in five diametric classes of each treatment by cutting disks in six positions of the trunk (0.1 m, 1.30 m, 25%, 50%, 75% and 90% of the total height) (n = 360). The wood density was calculated as a function of the shelled volume of the logs. Trees growing in integrated systems increased trunk diameter at breast height by 24.7% and produced wood 9.0% less dense than in the monoculture forestry system. Wood density along the trunk decreased from the base until 1.30 m, followed by an increase up to between 50 or 75% of the tree height, depending on the analyzed production system, with subsequent decline in all treatments until tree top. Monoculture forestry increased tree height and there was no difference of trunk volume among the production systems. These results suggest that integrated systems can produce timber with lower wood density and faster individual growth than in forestry monocultures. Such a system can promote sustainable intensification of agricultural production complementarily with other ecosystem services.