ORIGINAL PAPER Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid (Eucalyptus grandis 3 E. urophylla) clones S. K. Sharma 1 • S. R. Shukla 1 • S. Shashikala 1 • V. Sri Poornima 1 Received: 27 November 2012 / Accepted: 27 March 2014 Ó Northeast Forestry University and Springer-Verlag Berlin Heidelberg 2015 Abstract We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis 9 E. urophylla), GR283 and GR330, grown in Tumkur district of Karnataka (India), and felled 5–6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 (37 %). Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications. Keywords Eucalypt urograndis hybrid (Eucalyptus grandis 9 E. urophylla) Á Fibre characteristics Á Vessel characteristics Á Wood density Á Bark density Introduction Eucalypt species, predominantly the Australian E. grandis Hill Ex. Maiden, have been planted extensively in the tropics. The fast growth of eucalypts and the increased demand for wood and wood products has led to steady increase in the extent of these plantations (Bennett 2010). The existing plantations are promising, growth is fast and the wood is of quality suitable for industrial use. With the introduction of a genetic improvement program, many other eucalypt species, their hybrids and clones, besides E. grandis, have been planted in provenance trials aimed at improving growth rate as well as pulp wood characters, including density and fibre characteristics (Loulidi et al. 2012). Recently, these hybrids are used extensively in commercial plantations, mostly in clonal forestry (Gom- inho et al. 2001). One hybrid E. grandis 9 E. urophylla, commercially known as Eucalypt urograndis, provides a significant share of global eucalypt pulpwood supply. This species aims at combining the growth characteristics of E. grandis with an increase in wood density and fibre prop- erties of E. urophylla (Quilho et al. 2006). Basic density is generally taken as one of the major wood quality parameters in tree improvement programs (Lima et al. 2000). Wood properties of different species are known to vary at different heights of a tree with no definite trend of variation (Gominho et al. 2001; Shashikala and Rao 2009). We evaluated vertical variation of different properties to observe the extent of variability in the prop- erties due to the juvenile nature of wood. Fibre character- istics of important eucalypt pulpwood species were reported by Jorge et al. (2000), Miranda et al. (2001a, 2003), and Rao et al. (2002). Variation in basic density and fibre characteristics of E. grandis and E. urophylla were also reported (Quilho and Pereira 2001; Quilho et al. 2006). The online version is available at http://www.springerlink.com Corresponding editor: Yu Lei & S. K. Sharma sksharma@icfre.org 1 Wood Properties and Engineered Wood Division, Institute of Wood Science and Technology, P.O. Malleswaram, Bangalore 560 003, India 123 J. For. Res. DOI 10.1007/s11676-015-0080-6