摘要
为研究木本种群的密度与生长的关系,从1984年到1986年,在苗圃地内进行了日本落叶松(Larix leptolepis)种群模拟试验。结果表明,在高密度种群中,自然稀疏显著,其过程遵从3/2乘则;试验初期和中期的同一生长阶段而不同密度的种群系列中,单株平均重与种群密度的关系满足竞争密度效应的倒数方程或幂方程,但随着种群的进一步生长,这种关系逐渐变成满足3/2乘则。单位面积直径断面积合计和树高生长随种群密度的变化是导致这种转变的根本原因。文中还讨论了在3/2乘则系统中树高与种群密度的数学关系,这种关系可用h=ap^(-1/2)表达(其中h和p分别表示树高与密度,a为常数)。
One year-old Japanese larch (Larix leptolepis) seedlings were planted in a nursery from 1984 to 1986 at four density levels with four replicates in order to investigate the relationships between plant growth and density of survivors.As the results shown,self-thinning occured severely in populations growing at high densities.The rate of the self-thinning followed a trajectory defined by the 3/2 power law.The relationship between mean dry weight per tree and population density at a given stage of growth followed the reciprocal equation and power equation at early experimental stages,but changed gradually to follow the 3/2 power law as plants grew further.Shch a change was mainly caused by the constant basal area per m^2 and decreased growth of tree height along a gradient of the density.The relationship between tree height (h) and density (p) also be discussed and in the 3/2 power law system it could be described by an equation consisting of h = αp^(-1/2) where a is a constant.
关键词
日本落叶松
种群
生长
密度
Basal area of diameter per m^2
Larix leptolepis
Reciprocal equation
Population density
3/2 power law
Tree height
