The Estimation of the Standjng Crop of
the Forest in Northeastern Thailand
Kazuhiko OGINO
Sanga SABHASRI
Tsunahide SHIDEIINTRODUCTION

An accurete and detailed knowledge of thestanding crop of a plant community is the neces-were 20.1°C (68.2°F) and 28.5°C (83.3°F). The
temperature continued to drop so that it reached a minimum of 11.7°C (53.1°F) and a maximum of 20.8°C (69.4OF). Nevertheless leaffall
did not occur in those stands during the period of our work.

sary biological basis of any attempt to control
the productivity of that plant community. However, available information about standing
crops of forests is not very detailed so far.
Recently Japanese ecologists have used allometric relations in estimating standing cropsof plant communities. Several attempts in thisdirection have been made in Thailand by the
Osaka City University Biological Expedition

In that area we can see two types of forest:
Dry Dipterocarp Forest and Dry Evergreen
Forest. As to the notation of the forest types,
we think another discussion would be necessary
from the point of view of the plant sociologist;
however, in the present work we will take

1957-58 and the Thai-Japanse Biological Expe-tentatively the practical nomenclature which

dition 1961-62.
Our present work is also an attempt along

was devised by the Royal Thai Forest Department.

these same lines, that is to say, to examine
the possibility of using allometric relations
in estimating standing crops in tropical areas.

Field work was carried out from the 22nd of
October to the 11th of December, 1962 at Wang-

As is already well known, Dry Dipterocarp
Forest has a rather sparse forest crown of
about 15m in height, is a scarcely stocked
stand and consists mainly of Shorea obtusa,
Shorea floribunda, Pentacme siamensis andother kinds of Dipterocarpaceae. The open
forest floor is covered with abundant grasses.

namkhiow, Pakthongchai, Nakornrachasima.
This area is situated about 60 km south ofOccasionally younger trees, dwarf shrubs andcycads are scattered around. A soil survey

the town of Korat in northeastern Thailand.
The season in which the work was done wasaround the end of the rainy season and theshows very shallow dry sandy soil with muchgravel and many pebbles.

A BRIEF DESCRIPTION OF THE STAND

beginning of the cool season in the area. It
was getting cooler day by day. The averageminimum and maximum temperatures during
the first week when the work was carried out-

On the other hand, Dry Evergreen Forest
which is adjacent to the Dry Dipterocarp Forest is taller and has a much denser forest
crown. The stand is packed with five stratified tree layers. Lofty gigantic trees more than89-

20m in height make up the prominent arboreal
layer. The tall arboreal layer 15-20m in heightforms a continuous forest crown. The shortarboreal layer 5-15m in height comes next to
it. The tall shrubbery layer is I-5m in height.
The short shrubbery layer is less than 1m inheight. Many kinds of climbers grow up and37 sample trees in Dry Evergreen Forest were
cut for individual tree measurements. Thesesample trees were selected carefully so thatevery species which occurred in the plot would
be included. More sample trees were cut of
those species which occurred more frequently.
The trees which had a better tree form weredown, in and out these stratified layers.
The number of species which constitute theselected. Sample trees were taken from a wide
range of the diameter distribution in order tostands is large. More than 90 species werecounted, including trees, shrubs, climbers andreduce the error of interpretation as far as
possible. The following items of each sample
tree were measured:

grasses. Soil observation shows that the soil isdeeper than that of a Dry Dipterocarp Forest
stand and holds more organic matter.

H: height of the tree

Hb

THE METHOD ADOPTED FOR THE
SURVEY

Do.oheight of the trunk up to the lowest
living branchdiameter at ground level

As mentioned above two types of forest were
found in the area. Two sample plots of 10 x 50

DO• 3
D1 • 3

diameter at a.3m in height
diameter at 1.3m in height, which isanalogous to diameter at breast height(DBH)

m in size were placed in each forest type after
a preliminary look around so that the plot
would represent each forest type.
In order to know the floristic compositionof the forest, the local name of every tree

D3 •3which occurred in the plot was recorded, using
the names as given by a local worker whocame from a neighbouring village. The manuals of Royal Forest Department was used for

Do.m

:

diameter at 3.3m in height, from 3.3m
in height upward
height of every 2mdiameteratthediameter at the height of one-tenth of
the tree height

life form of all trees higher than 1m were
measured and recorded.

: diameter at the height of the lowest
living branchR: crown diameterW 8 : stem weightW b : branch weight
W 1 : leaf weight

Other measurements were taken of subordi-

If the sample tree was too big to weigh, anate species and these measurements were kept

sample part or sometimes several parts wereseparate from those of the dominant species.
Ten subplots of 5 x Sm were taken in sample
plots for this purpose. The subordinate species
were gathered according to their life form into
several groups, seedlings of the dominant trees,
climbers, herbs, grasses and cycads. The
local names, leaf weight and stem weight ofeach group were recorded.

taken, and the ratio of weight to volume wascalculated. Exploiting the weight to volume
ratio, the weight of the remaining part of thetree was calcul::lted.

The results of a census survey of the stands
are summarized in Table 1.

25 sample trees in Dry Dipterocarp Forest andAs is easily understood, the figures for standfurther checking.
The diameters at breast height, height and-Db

RESULTS AND DISCUSSIONS

90-

Table 1.

Summarized Figures of the Census Survey of the Stands
Dry Dipterocarp Forest

Sam pIe plot
Nos. of trees in theplot
Stan d density
tree nos./haBasa I area m 2 /ha

P-1

PP-1

P-2

PP-2

57

68

135

114

1140

1360

2700

2280

11.18

19.34

26.34

42.55

density, numbers of species of dominant trees
and basal area of Dry Evergreen Forest arelarger than those of Dry Dipterocarp Forest.
In permanent plot No.1 (PP-1) and permanent
plot No. 2 (PP-2),

some trees

bigger than

average happened to occur in the plot so thatthe size of the basal area was affected.
The allometric relations: The allometric relations was first foumulated by J.S. Huxley(1932), Teissier (1934) as

y=Axh

(1)

or log y= log A + hlog x(2)where y, x are any quantity of two parts ofan individual, A, h are specific constants.
Although the allometric relation was foundin the study of relative growth of animals, italso seems to fit plant growth satisfactorily.
Equation (2) shows a linear regression between log x and log y. The linearity of thesetwo variables enables us to compute the specific constants A and h easily, and to verify
whether the two variables follow the allometric
relation or not.
If we take a diameter as the independent

variable and volume or weight for the dependent variable of the equation (2), the equation
will be written as follows:log Vl=log AVI+hvl log Dj
log Wl=log AWi + hWi log Dj

Dry Evergreen Forest

(3)
(4)

where Vi and Wi stands for a volume or weightof any kind, log AVI, log AWl, hVI and hWI

for the specific constants for VI, WI and Dj
concerned, and Dj for diameter of any kindwhich is taken into account. Usually for thesake of convenience of utilization of these equations, the value of the diameter is preferably
taken for x, the value of volume or weightfor y.
Checking of allometric relations: The data ofstem weight, branch weight and leaf weight
were plotted on logarithmic paper, in order
to examine their linearity. For instance stem
weight was taken for y, and DBH for x. As
shown in Fig. 1 these plotted dots seem tofollow the linear regression, the regression
equation of stem weight on diameter at breast
height (DBH) was decided by means of theleast square method.
We were primarily interested in finding out
which of a large number of variables weremore closer related to a given dependent variable, e.g. stem weight.

The coefficients ofdeterminations were computed in order to know
the strength of the relationship. The 95%
confidence intervals were also calculated. The
calculated values of the specific constants handlog A, the 95% confidence intervals, the coefficients of determinations r 2 , are shown in Tables 2,3 and 4.
'h' shows the slope of the regression line
and log A shows the y interception of the line,
in other words the value of y when x=1. Needless to say, log A is not an ordinary numerical-91-

Table 2.
Allometric relations of stem weight on several kinds ofdiameter (Data based on those from Dry Dipterocarp Forest)

h
log A
c. i.
r2

I

Do.o

DO• 1 H

DBH

2.95448-1. 76246
0.30288
0.949

2.93538-1.48659
0.28416
0.955

2.50913-0.94402
0.212280.974

2.34410-0.60247
0.45071
0.874

Table 3.
Allometric relations of stem weight on several kinds ofsquare of diameter (Data based on those from Dry Dipterocarp
Forest)Th>2
1. 46547
4.12497
0.31627
0.943

h
log A
c. i.

r2

1. 46457
4.378400.28538
0.954

I

1. 25235
4.06969
0.212670.974

1.14886
4.02945
0.483310.867

value but a logarithmic value.
The value of r 2 shows that the variables of
all regression equations based on the productof the square of diameter and height of thetree have thebest relationship. We can explain
this fact easily.
Weight is a three demensional quantity; therefore if we take a three
dimensional value for x, the slope of the reo
gression line becomes nearly 1, and consequent.
ly various error of the interpretation would be
minimized.

Fig. 1-1 Allome~ric Relationof~. on DBH

(P-l)

l00r
5T-~+---~
j
~

OJ

:-

Comparion between the kinds of diameterI

10.0 --------,Hr-r----lf-------t--I

S.O -----I-~f+---4f-------t-resulted in the conclusion that whatever thedimension of x happens to be, that based on
the diameter at breast height is better thanother.
If we can find a proper way to measure theDBH(em)tree height, the use of the product of thesquare of the diameter at breast height andheight of the tree as an independent variable
would give most reliable estimation of theIstem weight. However, apart from the cut sample trees the measurement of tree height is--J..------..SO.O..--

1.0--+-.Ht..--........
5.0

10.0

-

92-

Table 4.
Allometric relations of stem weight on the products ofseveral kinds of diameters squared and the tree height (Databased on those from Dry Dipterocarp Forest)

0.868222.66352
0.35161
0.929

still quite difficult,especially insuch a forest stand where the topof the trees can hardly be seen. So
we have to use the next best, thatis to use the diameter at breast
100.0 - -height as the independent variables.

Fig. 1-2 Allometric Relation

The values of the constants, theof Ws on DBHf(p_l)
50.0-----1I-----t-------+--7'T-r-----:f----.f.----

95% confidence intervals and thecoefficients of determinations oftheregression equation

for

the

estimation of stem weight, branchweight and leaf
10.0 -----1f--~---+___,*_.."j,ol'---+-------.J--

weight onthediameter of breast height are shownin Tables 5 and 6.

5.0 ---r----i-r--;I'~+--+----+-------+--

Estimation of standing crop: Using
the regression equation the specificconstants of which have just decided, we can compute the averagevalue of the standing crops interms of weight. The calculation

l.0 -~'--~-...L...JL..---------'----+--_----+-0.0100

0.0500I I

I

0.0050Dmr ( ui2 )Table 5. Allometric relations used for theestimation of standing crops of Dry
Dipterocarp Forest

procedures oftheestimation ofstem weight are as follows:

Table 6. Allometric relations used for theestimation of standing crops of Dry
Evergreen Forest

Ws

Ws
I

h
log A
c. i.
r2

2.50913-0.94402
0.212280.974

2.93168-1.98034
0.29938
0.963

1. 81022

h
log A
c. i.
r2

-1. 41128

0.41922
0.835
-

93-

2.21604-0.57729
0.19661
0.965

2.32660-1. 34271

0.51804
0.816

1.33842-0.83584
0.581510.537

1oo.0I+-__+--+__-+_~,.""""'_":.-_+_--

Fig. 1-3 AllOMtric Re1&tion of W. on
DrH (P-1).

SO.o ------i----,~.-;....----_+-~_I;oo'~'7'_----+_--

10.0------+---h'-4l~r"7'~--+---+------+_--

I

5.0 ------+,.-I:......:~ho"~----_+--_+------_t_--1.0~:.-~---...L---.l-------~----I..-------+---

1

0.5

O.oosoI I

0.05000.0100Du2H (First we prepare the diameter frequency table.
The measurements of the diameter at breast
height are grouped into diameter steps using
the round number of every 2 cm. Next wecompute the average stem weight of every
diameter step substituting the value of thediameter for x. The stem weight of each diameter step is easily calculated by multiplication of the average stem weight by the numberof trees. The total of these values is the stem
weight of the sample plot. The branch weight
and the leaf weight are similary calculated.
Thus we have the estimation of the standing
crop of the dominant trees of the stand interms of weight.
For the standing crops of the subordinate
species another measurement was carried out.
The results were converted into the value forhectare, which are shown in Tables 7 and 8.
-mz )0.1000I I

0.5000I

The permanent plot No.1 in Dry Dipterocarp
Forest and the permanent plot No.2 in Dry
Evergreen Forest are kept undisturbed; therefore figures for the standing crops of subordinate species of the plots are not available.
However, the amount of the subordinate species
is comparatively so small that the standing
crops of the dominant trees would give approximate values for the plots.
We noticed that the magnitude of the standing crops varies from plot to plot even in thesame stand. In Dry Dipterocarp Forest thevalue of Wt for PP-1 250.48 ton/ha is morethan 2 times the value for P-l 91.37 ton/ha.
In Dry Evergreen Forest the value of Wt for
PP-2 403.77 ton/ha is a little less than 2 times
the value for P-2 220.94 ton/ha. Such a variability of the magnitude of the estimates may
be caused by unusually big sized trees which94-Fig. 2-2 Allometric Relationof Wb on DBH(P-l) -T---+--+--+---+--

100.0

1

5 O . 0 - - - - - - - ! - - - - + - - / - / - / - - _ - +_ _Fig.2-l100.0-

J

Fig. 2-1.
Relahon ofI

Allometric"s on DBH(P-l) •-+_50.0------1----ft++-

10.0-------!---f--jf-f------+--

I
10.0

I

5.0

I

5.0-------+--:l--I--If-------+---------7I--JH-+--------J.-----f--H-I---+--------I--

•
1.0

10.0

I

•

50.0
DBH

(em)

0.5
1.0

5.0

10.0
DBH

50 0

(em)

I
·0.1

I

Table 7.

The estimates of the standing crops of Dry Dipterocarp Forest

We

Ws
!

Dominant tree
Subordinate sp p.
Total

PP-l

Dominant tree
I 176.34
Subordinate sp p.
176.34
Total
-

:

18.62
0
18.62

65.78
2.07
67.85

P-1

--~

I

84.40
2.07
86.47

3.41
1. 49
4.90

87.81
3.56
91. 376.44

250.48

,

67.70

i --

67.70

95-

I
I

-

- - - - - --

-

!

-

244.04
-

-

244.0

6.44

- - I- - - - - --250.48~--

Table 8.

The estimates of the standing crops of Dry Evergreen ForestWe

P-2 Dominant tree
Subordinate spp.

We

151. 95
10.10

45.75
1. 33

197.70
11. 43

WI

I

8.26
3.55

205.9614.98~__.__1._62_._0_5~'_--47~.-0.8----c-_2_~9.13_L._11. 81 _ _220. 94_
PP-2 Dominant tree
313.3481.50
394.848.93
403.77_ _ _ _T_o_t_al

Subordinate spp.
Total

313.34

81.50

500.0

394.84403.77

8.93------j----.,I----f-+-r--+-Fig. 2-3 Allometric Relation

I

10.0of Wl. on DBH(P-l)

I

Fig. 3-1 Allometric Re1A tion

100.0_"_
5.0 ------+--++--.i';.........,~----1t__-of We on DBH(P-2)

SO.O
I

1.0----~~-+-!~--'~------t--

I---+--......+--f-+-------t--~.,I:r---+--------lf-

10.0 - - - - - - I -. .

I

0.5

5.0 - - - - f - , H t f - - - + - - - - - - - - - l f - -

0.1

5.0

10.0

50.0
DBH

(em)

1.0

I
happened to occur in the sample plot. This
fact may imply that the size of the sample
plot is still smaller than necessary. In otherwords, if the size of the sample plot is large
enough to cover the diversity of the stand, thevariability of any quantity of the stand will beminimized. The bigger the individual, the more
-

5.0
I

10.0
I

DBH

I

,

(em)

so

I

critically they will affect the value of thequantity estimated. However, as yet we do
not know the suitable size (or minimum area)of a sample plot for this purpose. But thesuitable size have to be fairly accurately determined, if we were to make a reliable quantitative study.
96-

Fig. 3-3 Allometric Relation of W1
on DBH(P-2)

I

100.0

-

50.0-------If----+---~~-l---

-

10. 0

-

5.0 -----..-1t.--=-tr+-'""7'---_--7Yf---

1.0 -~--__7LjiH---H'-------+--

Fig. 3-2 Allometric Re_l_at_i_on_-I-_-I-_---J.~­of W~ on DBH(P-2)

SO.O ------+---+-~-+-_J.-_+_-

I--'-_--+_---.t-+-J~-___f__J~

I
I

•

;t>I
10.0

I --------t't-----I'--++-------+--

I

I

5.0

- - 0.5 ---'""7'----+--..'---:

1.0 ---t--f~m~-nrln--------l-SO.O

ric relation have a little variability even in

DBH (em)the same forest

1

stand,

they

approximately

agree with those made in different localities
in a similar stand of forest type.
Recently T. Kira et al. read a paper at the

In 1957 a group of Japanese ecologists studied the estimation of standing crops in north-11th Congress of Japanese Ecological Society,in which they treated the relationship of leaf

ern Thailand. They estimated the total weightamount to the other elements of the individualof trees for the Dipterocarp savanna forest attree on the reciprocal expression base. The

49.6 ton/ha, and for the temperate ever green-leaf amount would reach at the saturation

forest at 177.9 ton/ha.

They worked out theirestimation thoroughly on the dry weight basis;
therefore direct comparison of our results with
theirs would have no meaning.

value sooner or later. The regressions presented
here would have to be examined again on thereciprocal expression base.

We have to

REFERENCE

take the difference of bases into account in
the comparison. If we do so, it seems that theirresults and ours agree with each other approximately.

1)

J.D. Ovington: "Dry-Matter Production by
Pinus sylvestris L." Ann. of Bot., NS vol. 21,
No. 82. 1957.
2) T. Shidei et al.: Studies on the Productz'v-

ity of the Forest. Part I. Essentz"al Needle
Leaved Forest of Hokkaido (in Japanese).

Thus we see a possibility of using allometric
relation in estimating standing crops of a for-3)

est stand. Though, the estimates of standing
crops by using regression equation of allomet-

97 -T. Kira et al.: "A Preliminary Survey on
the Vegetation of Thailand." Nature andLife in Southeast Asia, vol. 1. 1961.