Self-thinning exponents based on the allometric model in Chinese pine (Pinus tabulaeformis Carr.) and Prince Rupprecht's larch (Larix principis-rupprechtii Mayr) stands

The allometric power relationships of mean tree height H(proportional to nu (theta)) and stem volume packing d(proportional to nu(delta)) to mean stem volume nu were investigated in 182 Chinese pine (Pinus tabulaeformis Carr.) stands and 56 Prince Rupprecht's larch (Larix principisrupprechtii Mayr) s tands. According to Weller's allometric model, the slope of the self-thinni ng boundary line, i.e. -1/[1-(theta+delta)], was calculated from the expone nts of the allometric power relationships. The resulting slope was -1.79 fo r the larch and -1.72 for the pine, The self-thinning boundary lines corres ponded well with the combinations of mean stem volume and density in the ni ne densest stands of pine and larch. The steeper slope for larch was attrib uted to allocation of more resources to height growth and to greater stem v olume in space already occupied in the larch than in the pine, resulting in higher exponent values of theta and delta in the larch than in the pine. ( C) 1999 Elsevier Science B.V. All rights reserved.