Basically
the model needs three kinds of information to estimate tree biomass:
information of tree size and branching pattern, information of woody components
and information of the final structure of the tree.

Tree size and branching pattern

Field
data of link (i.e. branch or root segment) diameter and length have to be collected
and the diameter is ideally measured twice, cross-wise, at three positions on each
link (describe in the figure below): proximal, middle, and distal. Link number
and its parent number should be recorded as follow: the main stem is given link
number 1, its offspring are number 2 and 3 (i.e. if it has two offspring). The
parent number of main stem is zero (described in the table below). The number
of leaves (single or compound leaves) of each link should be also recorded. For
reliable estimates of the fractal branching parameters, minimum number of 100
branching points should be collected for each tree sample.

Positions to measure diameter of each link (Dproximal,
Dmiddle, and Ddistal). The diameter measurement should be done perpendicular to
branch angle. At each position, the diameter is ideally measured twice, cross
wise, to consider a non-circular branch shape

            

fba1

Field data required to measure tree size and branching
pattern for the FBA model. Dprox, Dmid, and Ddist
are the average diameter at proximal, middle, and distal position of each link
respectively

Link no

Link length

Dprox

Ddist

Dmid

Parent no

N of leaves

1

L1

Dp1

Dd1

Dm1

0

n1

2

L2

Dp2

Dd2

Dm2

1

n2

3

L3

Dp3

Dd3

Dm3

1

n3

4

L4

Dp4

Dd4

Dm4

2

n4

...

 

 

 

 

 

 

Woody components

The model classifies the
woody part of the tree into three categories: wood, branch and twig. The classification
follows the diameter of the link. The dry weight per volume of wood (wood
density) should be measured for each of the three woody components.

Final structure of the tree

The length of bare tip on
final links (see Figure 2), the average surface area (one side only) of a
single leaf, and specific leaf area (SLA) defined as the surface area of leaves
per unit dry weight (cm2/g) are to be measured. For belowground, the
required parameters are the average of fine root (usually defined as those with
D < 2 cm) length and specific root length (SRL) defined as fine root length
per unit fine root dry weight (cm/g).