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Plant size and density

Kyoji Yoda's -3/2 power rule of self-thinning

Average dry weight per plant = Species coefficient X plant density (n/m2)^-3/2

Stand density and stocking​

Stand density:​

  • In general, amount of tree vegetation per unit of land
  • In silviculture most often defined as stems/ha

Stocking​

Relative measure of stand density What we find in a stand vs. what we expect Usually as percentages e.g., 70% of volume, 90% of basal area Crown competition factor Stand density index

Stand density index​

Developed in 1933 by Reinecke

  • Size-density relationships for 14 forest types
  • Plot of:
    • Log of quadratic mean diameter (QMD)
    • Log of No. of trees/acres (TPA)

Maximum density line

LogN = -1.605logD+K

Interpretation​

  • Index value is the number of trees in a stand with QMD of 10 in.
  • Comparison with max SDI for species
    • On the same site
    • Same provenance
  • Each point on the diagram represents a stand

S1: 300 S2: ?

Stand density management diagrams​

  • Represent stand development
  • Show the relationship of density with QMD, top height, & Volume
  • Good for even-aged single species stands