Different harvest systems of Eucalyptus clone plantations affect above and belowground biomass production and nutritional sustainability

Abstract

Forest residue, such as stump and coarse roots, can contribute to an increase in the raw material supply from fast-growing Eucalyptus plantations for industrial uses, such as power generation, process wood and biotechnology. However, the impact real on the nutritional sustainability of forest sites because to utilization of belowground biomass is not known. The present study aimed to evaluate the impact of utilization of above and belowground biomass components on the nutritional sustainability of Eucalyptus clonal plantation. To do so, we used Eucalyptus urophylla clones (AEC 0144); E. urophylla × E. grandis (AEC 0224), and E. urophylla × E. camaldulensis (VM01) aged 6.8, 6.6, and 6.3 years of age, respectively. Trees were felled, up-rooted, and separated into leaves, branches, bark, stem wood, stumps, crown root, and coarse roots. Biomass production, stock, and export of N, P, K, Ca, and Mg were analyzed. Moreover, the number of rotations required to export all soil nutrients, and nutrient use efficiency in different harvest systems were determined. The complete tree and full tree harvest systems exported the highest N, P, K, Ca, and Mg amounts, and showed the lowest nutrient use efficiency. This shows the importance of maintaining waste, such as leaves, branches, and bark, on the site. In harvest system debarked stem wood with belowground biomass, intermediate values were obtained in terms of export, use efficiency and number of rotations required to export N, P, K, Ca, and Mg, when compared to other harvest systems. These results showed that the belowground biomass use, taking into consideration Eucalyptus clone selection, and harvest systems can be an alternative source of biomass, without reducing the forest site sustainability and future productivity.