Maximum depth of fine roots of Eucalyptus urophylla across an edaphoclimatic gradient in Brazil

Climatic seasonality, coupled with rainfall availability, plays a fundamental role in determining the deep rooting patterns of Eucalyptus sp. plantations. In this research, we evaluated the distribution of fine roots of Eucalyptus urophylla 6 years after planting under four sites with contrasting edaphoclimatic conditions (annual rainfall ranging from 413 to 1920 mm, annual temperatures between 18.2°C and 25.2°C, and clay content between 40% and 77%) in Brazil when grown in systems with and without rain exclusion (33% reduction in rainfall was diverted through gutters, placed between the tree rows). Fine root density was assessed by collecting soil samples in triplicate using a mechanized probe, reaching the maximum rooting depth. Fine roots were detected at a depth of 15.4 m; however, high fine root densities (45%) were concentrated only within the top meter of the soil profile. Stocks of fine root biomass varied between 2.6 and 9.7 Mg ha−1 across the different sites, with the greatest amounts found in areas receiving <720 mm of rainfall per year. The results emphasize the importance of considering soil, climate, and physiological factors across different sites in the selection of species for planting, providing valuable insights to support decision-making by forest managers and environmental agencies.