ORIGINAL ARTICLE Petteri Vanninen Hanna Ylitalo Risto Sieva ¨nen Annikki Ma ¨kela ¨ Received: 2 February 1995 / Accepted: 1 June 1995 AbstractmThe distribution of the above-ground and below- ground biomass of Scots pine in southern Finland were investigated in trees of different ages (18 – 212 years) from two types of growth site. Secondly, some structural regula- rities were tested for their independence of age and growth site. Trees were sampled from dominant trees which could be expected to have a comparable position in stands of all ages. All stands were on sorted sediments. The biomass of the sample trees (18 trees) was divided into needles, branch sapwood and heartwood, stem sapwood and heartwood, stem bark, stump, large roots (diameter 20 cm), coarse roots (five classes) and fine roots. The amount of sapwood and heartwood was also estimated from the below-ground compartments. Trees on both types of growth site followed the same pattern of development of the relative shares of biomass compartments, although the growth rates were faster on the more fertile site. The relative amount of sapwood peaked after canopy closure, coinciding with the start of considerable heartwood accumulation. The relative amount of needles and fine roots decreased with age. The same was true of branches but to a lesser degree. The relative share of the below-ground section was independent of tree age. Foliage biomass and sapwood cross-sectional area were linearly correlated, but there were differences between the growth sites. Needle biomass was linearly correlated with crown surface area. The fine root to foliage biomass ratio showed an increasing trend with tree age. Key wordsmScots pine Biomass Allocation Age Single tree There is a vast body of data about the development of tree and stand biomass over time but these data relate only to stem biomass. Recently, more and more stand growth and yield models are being developed in a carbon balance, process-oriented framework (Bossel 1986; Ma ¨kela ¨ 1988; Valentine 1988; Nikinmaa and Hari 1990; Sieva ¨nen 1993; West 1993; Nikolov and Fox 1994), and stand volume development has turned out to be insufficient for their stringent testing. Information is required about the temporal course of biomasses of all the functional parts of a tree, such as foliage, fine roots and sapwood. As most of the models operate on an individual-tree basis, and stand biomass development may differ drastically from that of individual trees, the ideal test material should concern individual trees from different positions in the stand. Some pioneering work on foliage and wood fractions in a number of Central European species was carried out by Burger as early as the 1920s (e.g. Burger 1929, 1941). More recently, the problem has been widely recognized, and some studies have already shed light on the typical tem- poral patterns of some of the functional biomass variables. Estimates of the stand-level foliage development have been presented for several species (Kira and Shidei 1967; Forrest and Ovington 1970; Marks 1974; Sprugel 1974; Mohler et al. 1978). Albrektson (1980) provides information about the development of foliage, branches, stems and the below- ground parts in Scots pine stands in Sweden. Cannell (1982) has reviewed the stand-level biomass development of a number of species in the world. As regards individual trees, equations have been developed for calculating the foliage, branch, and below-ground biomass from informa- tion about stem dimensions and growth site (Marklund 1988). In the light of these efforts, a valuable body of data is emerging about the development of foliage biomass and some other biomass compartments, especially at the stand level, while information is still largely missing about individual trees, and particularly, sapwood and fine roots. Trees (1996) 10: 231 – 238  Springer-Verlag 1996 P. Vanninen ( ) H. Ylitalo A. Ma ¨kela ¨ Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 Helsinki University, Finland R. Sieva ¨nen The Finnish Forest Research Institute,Vantaa Research Center, P.O. Box 18, FIN-01301 Vantaa, Finland