Wood Quality of Planted Wood Quality of Planted Teak Outside Forests Teak Outside Forests

((ToFToF))P.K. Thulasidas

K. M. BhatE. J. Maria Florence

Kerala Forest Research Institute Peechi, India

ToF

Home gardens and farmlands plays a significant role.

Investment on short rotation teak plantation attracts worldwide attention as also there is growing concern regarding the quality of wood produced from fast-grown teak.

Recent investigations

• Fast –grown teak timber is not inferior in quality and durability than the traditional plantation teak though slightly different in color, grain and texture.

• Fast growth in the younger plantations with judicious fertilizer application is advantageous in terms of higher heartwood volume and strength

(Bhat 2000; Bhat et al. 2001)

In Kerala, India,In Kerala, India,of the total annual production of the total annual production of 11.7 million M3 of wood in of 11.7 million M3 of wood in the state in the year 2000the state in the year 2000--0101about 75 per cent was from about 75 per cent was from homesteadshomesteads (house (house compounds/farmlands) compounds/farmlands) including estates (plantations including estates (plantations of rubber, cardamom, coffee of rubber, cardamom, coffee and tea)and tea)and only about and only about 9.5 percent from 9.5 percent from forest areasforest areas ((KrishnankuttyKrishnankutty et et al. 2005) al. 2005)

In Kerala, growing teak in the homesteads is a common practice by the farmers.

Goal of the study

To evaluate the timber quality of 35-year-old teak

grown in homesteads representing wet and Drylocalities of Kerala in comparison with that grown

in forest plantation of Nilambur – widely reputed for Malabar Teak with regard to wood quality

Specific objectives - assess the teak timber value from homesteads in terms of poles/posts and grade/recovery of sawn wood

- wood property differences with regard to particularly figure (colour, grain, texture), dimensional stability, strength, heartwood and sapwood dimensions and durability

Environmental conditions of sampled trees

Factor Wet Dry Forest Plantation

Altitude (m.s.l) 20 40 60

North latitude 9o 59’ 10o 35’ 11o 15’

East longitude 76o 34’ 76o 35’ 76o 13’

Soil type Loamy sand Loamy sand Loamy sand

Annual rainfall –range mm

2500 - 3500 1500 – 2300 2500 – 3000

Temperature range oC

17 – 34 26 – 37 17 – 37

Relative humidity % Above 80 70 70

Tree age (year) 35 35 35

Mean tree height (m)

17.0 14.0 21.0

Mean, DBH (cm) 39.6 24.0 31.0

wet sites has larger diameter logs (39.6 cm)- comparable to Site Quality I. Dry localities has smaller dimensional logs 24.0 cm) with more pole sizes

Number of logs in each Grade*

Number of logs graded in the homesteads

A B C Wet Dry1 >150 >3 - - - -

4 315

IV 65-75 >3 6 10 9 5 2038

639

-II >100 – 149 >3 3 7III >76-99 >3 7 7

Total 19

Teak timber class

Girth limits (cm)

Length (m)

Classification and grading of teak logs from homesteads based as per Indian Standard. Total of 96 logs graded. 59% of logs belongs to timber classes and the rest pole sizes

Log grading

Grade A - Cumulative value of permissible visual defects up to 2.5 units Grade B - Cumulative value of permissible visual defects up to 5 units Grade C - Cumulative value of permissible visual defects up to 7.5 units Grade D - Cumulative value of permissible visual defects above 7.5 units

Classification of teak poles from homesteads after grading

Pole class

Girth limits (cm)

Number of poles in each Grade

Number of poles graded in the homesteads

A B C D Wet Dry

(65-75) - 1 2 3

2 7

5

12

6

33

-

12

12

3

5

-

-

1

-

-

-

(53-64)

(41-52)

(28-40)

(15-27)

-

1 - -

II 1 -

III - -

IV - -

V - 6

Total 6

Teak logs from home gardens

Comparison-sawn timber recovery

Sawn timber volume (M3) and recovery (%)

Location Log mid girth (m)

Log volume (m3)

Sawn timber volume (m3)

Sawn timber recovery %

Wet 1.33* 0.111* 0.084*0.028*

Plantation 1.05* 0.069* 0.054* 77.8ns

76.5ns

Dry 0.81* 0.041* 66.8*

Physical property comparison of home garden teakProperty Wet Dry Plantation Significance

DBH, cm 39.6 24.0 31.0 W D PBasic density,kg/m3

600 645 597 WDP

Vol. Shrinkage% 9.2 8.3 11.3 WD P

Wood Colour and Appearance

Wet sitePaler

Dry siteDark brown, black streaks Plantation

Less streaks

47

51

55

59

wet dry plantation

L* b

right

ness

5

6

7

8

wet dry plantation

a* re

dnes

s

20

22

24

wet dry plantation

b* y

ello

wne

ss

Color characterisation -CIE L*a*b* system (1976)

L* (Lightness/brightness)

a* (Redness)

b* (chromatic index:Yellowness)

Heartwood Proportion in Wet, Dry sites of home gardensin comparison with Forest Plantation site

70.62 64.10 72.83

0

20

40

60

80

HW %

Wet Dry Plantation

Heartwood proportion

No significant difference in heartwood % despite the differences in log size

Bending Strength of Home garden Teakcompared with Plantation

020406080

100120140

MOR N/mm2

Wet Dry Plantation

Modulus of Rupture

OuterMiddleInner

0

5000

10000

15000

MOE N/mm2

Wet Dry Plantation

Young's Modulus

OuterMiddleInner

No significant variation

in Modulus of Elasticity

(MOE) and Modulus of

Rupture (MOR) with

respect to wet, dry and

plantation site

9102 9709.9 10045

109.9118.0 111.2

Compression stress and wood density (at 12% m.c).

400

600

Density kg/m3

Wet Plantation

Wood air-dry density

OuterMiddleInner

0

20

40

60

MCS N/mm2

Wet Dry Plantation

Maximum Crushing Stress

OuterMiddleInner

higher values obtained for

Maximum Compressive

Stress (MCS) parallel to

grain from dry site may be

due to the higher air-dry

density values recorded for

dry site

52.07 60.60 55.56

693

Wood durability –accelerated laboratory test (ASTM 1981)

Schematic illustration of test blocks from two opposite radii of the heartwood cylinder removed immediately above the breast height.

Timber grown in homesteads of wet sites has generally larger diameter logs than dry localities with smaller dimensional logs with more number pole sizes

Due to lack of standard silvicultural practices, log form is different in home garden teak with more severe defects like bends and knots which may lower the timber value

While the darker colour with black streaks of dry site heartwood from homesteads is more attractive and often similar to that of forest plantation sample, wood from wet site displays paler colour which may adversely affect the price of the timber

Timber from homesteads of wet sites is more susceptible to brown rot fungi although no significant differences exist with respect to white rot fungi among the home garden and plantation grown timbers

Higher natural durability of teak wood from drier home gardens and forest plantations is reflected in higher extractive contents with darker colour than wet site teak which has faster growth

It is the Naphthoquinone, the single major compound that offer high decay resistance of teak wood from dry site and supports the view that individual chemical composition, even if present in small amounts is more vital than total extractives in determining the durability of teak wood.

Teak wood of home garden forestry is however not inferior to that of forest plantation in its strength properties and heartwood proportion of the stem volume

The farmers at farm level should be oriented towards the market for quality production of teak wood.

Thanks