ABSTRACT The objective of this study was to assess the effects of planting density on nutrient use efficiency (NUE) in the production of biomass of a hybrid of Eucalyptus urophylla × Eucalyptus grandis. Twelve planting densities were evaluated at 36 months of age, ranging from 498 to 2564 plants ha−1. Three trees were harvested in each treatment to determine biomass production and allocation (per plant and per area), concentration (g kg−1), amount (kg ha−1), and NUE of N, P, K, Ca, Mg and S in the biomass of leaves, branches, bark and wood. In summary, the increase in planting density resulted in: higher biomass production per area; a reduction in biomass production per plant; a reduction in homogeneity; an increase in the concentration of N, P and K in leaves, of N, Ca, Mg and S in bark, and of N, P and K in wood; a higher amount of nutrients exported by harvesting; and a higher NUE for wood production. The increase in NUE indicates a possible nutritional deficit in trees at higher stocking rates at the age of three years. The higher the planting density, the sooner the site will require re-fertilisation.

中文翻译：

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桉树无性系生物量生产的养分利用效率与短轮作种植密度的函数关系

摘要 本研究的目的是评估种植密度对尾叶桉 x 巨桉杂交种生物质生产中养分利用效率 (NUE) 的影响。在 36 个月大时评估了 12 种种植密度，范围为 498 至 2564 株植物 ha-1。在每个处理中收获三棵树以确定生物量生产和分配（每株植物和每面积）、浓度 (g kg−1)、数量 (kg ha−1) 和 NUE 的 N、P、K、Ca、Mg 和S 在树叶、树枝、树皮和木材的生物量中。总之，种植密度的增加导致： 单位面积生物量产量增加；每株植物的生物质产量减少；同质性降低；叶子中的 N、P 和 K 的浓度增加，树皮中 N、Ca、Mg 和 S 的浓度以及木材中的 N、P 和 K 的浓度增加；通过收获输出更多的养分；和更高的木材生产 NUE。NUE 的增加表明，在三年龄时，放养率较高的树木可能存在营养不足。种植密度越高，场地需要重新施肥的速度就越快。