Forest Mensuration Formulas

(Some important formulae related to forest mensuration are listed below.You can also download it as pdf.)

1.Measurement of forms

a.Form Factor

F=actual volume/(reference basal area×height)

b.Form quotient

FQ=mid diameter/ diametre at breast height.

2.Bark Measurement

a.Measurement of bark thickness

Bark%=(Vob-Vub)×100/Vob
                  Vob= Volume over bark
                  Vub= Volume under bark

3.Crown Measurements

a.Crown Surface area

Ac= πdL/2
        Ac=Crown Surface area (m^2)
        d= diameter at base of crown (m)
        L= Length from tip to crown     margin(m)
  As L is difficult to measure,it can be replaced by,
√(d/2)^2+h^2
= πr √rb^2+h^2
   Where rb= radius at base of crown (m).

b.Crown Volume

Vc= πdb^2h/12  
    Where,
    Vc= crown volume
    db= diameter at base of crown(m)
    h= crown depth= (tree height-crown height)

4.Tree Volume

a.Estimation of Volume of tree

V= ghf (m^3)
= πd^2/4×hfm^3
          d= diameter at breast height
          g= basal area at breast height
          h= total area
          f= form factor

b.Measurement of Standing trees

Basal area=(reference diameter)^2 × π/4
        =(ref. girth)^2 ×1/4 π

c.Log volume by direct measurement

a.Smalian formula
V= πL(d1^2+d2^2)/8 ,
          d1&d2 are diametres at both end of logs.
         L= length of log,
        s1&s2 ars cross sectional area of log

        =L(s1+s2)/2

b.Huber's formula
V= πLdm^2/4
=Lgm,          dm= diameter at middle of log.
                     gm=cross sectional area at  middle of log.

c.Newton's formula
V= π(d1^2+4dm^2+d2^2)×L/24
      =L(s1+4sm+s2)/6
             d1& d2diameter at base and top of log resp.
              S1&S2 are cross sectional at base and top of log resp.
            dm= diameter at mid-length of log.
             L=log length
             V= volume of log

5.Cubic Volume of Logs

B= π D^2/4
  = 0.7854D^2

6.Cubic Volume of squared timbers

V=(g/4)^2 × L

7.Stacked Volume

L×B×H
For actual vol.
π/4=0.7854 (piling cofficient) is used.

8.Current method of estimating standing vol. of a coupe in Nepal:

Quarter girth formula

Volume= (Girth)^2/16× length
      is used to calculate the volume.

To download,Click here.

    
              By:Supushpa Regmi

IOF Hetauda Campus, Hetauda, Nepal

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