Experiments on functional amounts of individual tree and their dipendency on its size

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Photosynthetic production of a hinoki in standing conditionA rather sophiscated appratus for measuing photosynthetic production of a hinoki (Chamaecyparis obtusa, 11-year-old as of 1986) was constructed. In October 1986, daily changes in dark respiration per tree were sgown by an exponential function of air temperaure whose thermal coefficient was 2.55; daily gross photosynthesis P_g was approximated by 1/P_g = A/I + B, where I is daily summed illuminance at the top of tree, and A and B are constant. The equation enables us to predict P_g from I with moderate accuracy.(2) Size dependency of litterfall in sugiAnnual litterfall 1 in five sugi (Cryptomeria japonica, 15-year-oldas of 1985)was nearly related to their size x (dbh o diamter at the clear length) as 1 = a x ^b, where a and b are constant. A similar relationship was approximately realized between 1 and top dry weight of the five trees w_T by 1 = A w_T^B, where A and B are constant.Four-year- record on litterfall of a medium-sized tree(No.16) in the five trees showed that 1 = A' w_T ^<B'>, where A' and B' are constant , and that this relationship was clearly different from the former relationship obtained for the five trees.(3) Growth curve of tree sizeIt was emphasized that the basis of the Bertalanffy growth model in tree should be established with experimental evidence that individual tree functions are allometrically related to its size with the progress of time, and that we still lack such evidence as obtained from our litterfall study mentioned in (2).