In order to develop species-specific allometric equations , the biomass of four species (species pool 1) used by SP5 were measured in parallel with our 15N labelling campaigns (summer and autum 2009, winter and spring 2010). The allometric equations will be used to link 15N uptake to indivual tree biomass. 20 individuals per species were harvested in each season and dry weight of leaves, aboveground woody parts (stem and twigs) and roots were measured.

Tree saplings of four species (Castanea henryi, Quercus serrata, Schima suberba and Elaeocarpus decipiens) were harvested in the Pilot Experiment on plots used by SP5. Harvesting was performed at the end of each 15N labelling campaing in four seasons: Summer 2009 (beginning of September), autum 2009 ( mid November), winter 2010 (beginning of March) and spring 2010 (mid May). In every season, 20 indivuals per species were harvested and stem diameter (at about 2 cm), height (uppermost leaf bud) and rooting depth were recorded. Roots, aboveground woody parts (stem and twigs) and leaves were cut, dried to constant mass and weighed. 10 of the 20 tree samplings per species were harvested in the monocultures and the other 10 in the four species mixtures. Sampling was distributed more or less equally among the four blocks of the experiment and plots were selected randomly. Only one indivual per monoculture was selected whereas in mixtures up to four sapling of different species were sampled in one plot. Exceptions from the random sampling have been done when mortality rate in the plot was high or the selected tree sapling was heavily damaged by herbivores or pathogens. In the mixtures, the central plant individuals were already harvested for 15N samples so that for biomass determination only marginal plants were available. Whereas in monocultures, plants were selected randomly from the centre and the edges. In spring 2010, young leaves (from 2010) and old leaves (from 2009 or older) were collected separately for the evergreen species.

Pilot Experiment, Xingangshan, China 29°06'29''N 117°55'28''

Four seasons: Summer 2009 (beginning of September), autum 2009 ( mid November), winter 2010 (beginning of March) and spring 2010 (mid May)

Castanea henryi, Quercus serrata, Schima suberba and Elaeocarpus decipiens

species-specific allometric equations