Above- and belowground biomass and net primary productivity of a Larix gmelinii stand near Tura, central Siberia

We assessed above- and belowground biomass and net primary production (NPP) of a mature Larix gmelinii (Rupr.) Rupr. forest (240-280 years old) establ ished on permafrost soils in central Siberia. Specifically, we investigated annual carbon budgets in roots in relation to root system development and availability of soil resources. Total stand biomass estimated by allometry was about 39 Mg ha(-1). Root biomass (17 Mg ha(-1)) comprised about 43% of total biomass. Coarse root (greater than or equal to 5 mm in diameter) biom ass was about twice that of fine roots (< 5 mm). The aboveground biomass/ro ot biomass ratio (T/R) of the larch stand was about unity, which is much le ss than that of other boreal and subalpine conifer forests. The proportion of fine roots in total root biomass (35%) was relatively high compared with other cold-climate evergreen conifer forests. Total NPP, defined as the su m of annual biomass increment of woody parts and needle biomass, was estima ted to be 1.8 Mg ha(-1) year(-1). Allocation of total NPP to needle product ion was 56%. The proportion of total NPP in belowground production (27%) wa s less than for evergreen taiga forests. However, belowground NPP was proba blyunderestimatedbecauserootmortalitywasexcluded.We conclude that L. gmelin ii trees invested annual carbon gains largely into needle production or roo ts, or both, at the expense of growth of aboveground woody parts. This carb on allocation pattern, which resulted in the construction of exploitative r oot networks, appeared to be a positive growth response to the nutrient-poo r permafrost soil of central Siberia.