Rose gum (Eucalyptus grandis) is the most important commercial hardwood species in Argentina with 130,000 ha of plantations concentrated on the Mesopotamia region. Typical planting sites include alluvial sands with low organic matter contents and mineral reserves and are located along the Uruguay river on a 1030 km wide region. Eucalypts have been planted because of their high productivity rate, adaptability to diverse sites, ability to coppice and diversity of uses for their wood. They typically grow on 1012 yr rotation, with two additional rotations before replanting.
Over the past two decades, growth and yield of rose gum have been significantly increased by genetic improvement. Successive genetic trials demonstrated that stands established with south african clonal seed orchard seed yielded 20% more on average than when local seed sources were used. Surprisingly, few studies have evaluated the effects of intensive silviculture on productivity (i.e. bedding, fertilization, spacing, thinning).
According to soil depth, mean annual increment ranges from 20 to 50 m3 ha1. In mature plantations around Concordia, aboveground net primary production varies from 25 t ha1 yr1 for deep loamy sands (Inceptisols) to 15 t ha1 yr1 for deep sands (Entisols). Nitrogen + phosphorus fertilization accelerates early stand development and application of diammonium phosphate at planting increases stemwood volume by 30% at harvest.
The number of trees per ha at planting ranges from 1,000 to 1,600, although there is a tendency to reduce stand density. With less than 1000 trees ha1, total volume is reduced but trees are larger, increasing sawmill efficiency.
The importance of climate, soil and other silvicultural treatments on eucalypt productivity are also discussed.
Key words: Eucalyptus grandis, stand density, fertilization, site, northeastern Argentina.
Correspondence: Fernando Dalla Tea, INTA Concordia, C.C. 34, 3200-Concordia, Argentina
Telefax: +54-45-210363