Almost symmetrical vertical growth rates above and below ground in one of the world's most productive forests

Whilst the relationships between growth strategies and leaf traits are well established in functional plant ecology, little attention has been paid to root traits in very deep soil layers. The objective of our study was to compare the vertical velocity of the above- and belowground exploration of the environment for one of the fastest-growing tree species. Fine roots were studied in a chronosequence of intensively-managed Eucalyptus plantations established on highly weathered soils. Here we show that the root front depth was accurately predicted at 85% of mean tree height for stands <20 m in height, in the absence of any physical or chemical barrier. Tree height and root front growth velocities peaked at 0.59 and 0.55 m month(-1) respectively 9-10 months after planting, and decreased steadily thereafter. Fast root front displacement might provide a competitive advantage to fast-growing species in forests established on deep soils. Our study may contribute to the debate on the environmental impact of short-rotation plantation forests in the Tropics.