Growth, biomass and nutrient stock in mixed-species planting of hybrid Eucalyptus urograndis and Acacia mearnsii in Southern Brazil

The stock of biomass and nutrients has been the basis of many studies in the forest area, mainly those that evaluate the nutritional sustainability of the system. The objective of the present work was to evaluate the biomass and nutrients for the hybrid Eucalyptus urograndis and Acacia mearnsii in monospecific and mixed-species stands at the age of 9 years. For this, the study was carried out in an experimental area in South of Brazil, with three treatments: 100% E. urograndis; 100% A. mearnsii; 50% E. urograndis + 50% A. mearnsii. The hybrid E. urograndis showed lower stemwood in mixed-species planting (105.8 Mg ha(-1)) when compared to monospecific planting (145.5 Mg ha(-1)), however A. mearnsii, which increased stemwood at planting (213.9 Mg ha(-1)) relating to its pure planting (143.6 Mg ha(-1)). The nitrogen concentration in the leaves and stembark (25 and 5 g kg(-1), respectively) of A. mearnsii was significantly higher than that found in the respective hybrid E. urograndis components (18 and 3 g kg(-1) for leaves and stembark, respectively). A. mearnsii had higher accumulation of biomass and nutrient accumulation in the mixed-species plantation when compared to its monoculture, and the inverse was observed for the hybrid E. urograndis, thus showing that mixed-species planting exerted a competition effect on eucalyptus.

Automated summary

The study evaluated the biomass and nutrient accumulation of hybrid Eucalyptus and Acacia in different planting methods, finding that Acacia had higher accumulation in mixed-species plantation while Eucalyptus showed the opposite, indicating a competition effect exerted by mixed-species planting on Eucalyptus.