Card Project Progress Report:"Sustainable and profitable development of acacia plantations for sawlog production in Vietnam " MS3 doc

CARD Project Progress Report

032/05VIE
Sustainable and profitable development of acacia
plantations for sawlog production in Vietnam

MS3
Review of Acacia genetic resources and
propagation methods to support sawlog
production in Vietnam
C.E. Harwood1 Le Dinh Kha2, , Ha Huy Thinh2 and Phi Hong Hai2
1

Ensis Genetics, Private Bag 12, Hobart 7001 Australia

2

Research Centre for Forest Tree Improvement, Forest Science Institute of Vietnam
Chem, Hanoi, Vietnam


Abstract
Study of the processing of acacia logs in Vietnam’s sawmills indicates that to improve
profitability of acacia sawlog production for tree growers, the following essential tree and
log criteria need to be improved through a combination of species selection, genetic
improvement and silviculture.
Survival - high rates of survival are important for stand uniformity and wood yield
Rapid growth - ability to produce a sawlog in the shortest possible rotation (logs as
small as 2 m in length and 15 cm small-end diameter are routinely sawn)
Good stem form – reasonably straight main stem, minimum forking, and light branching
will maximize the proportion of the tree’s production that can be sold as sawlog

Defect-free wood - sawlogs must be free of heart-rot, loose knots and other defects that
cause visible defects in the sawn boards.
The history of species and provenance testing and genetic improvement in Vietnam, and
the development of selected acacia hybrid clones, is reviewed. From this review, the best
planting materials for sawlog plantations and the best propagation methods have been
identified. Selected clones of the acacia hybrid (A. mangium x A. auriculiformis) and the
best improved planting material of A. auriculiformis (selected clones and improved seed)
and A. mangium (improved seed) are the best suited acacia varieties for sawlog
production, and are already proven in this role in lowland regions of Vietnam receiving at
least 1000 mm annual rainfall. Details of superior germplasm of these species are
provided in the report. A. crassicarpa is also promising for sawlog production in these
environments in Vietnam but is not yet proven. Improved seed of this species is not yet
available. Computer software for climate matching is available to display regions of
Vietnam which have suitable climates for the growth of these species, and the 3-PG stand
growth model has been parameterized for A. mangium in Vietnam.
A. auriculiformis grows too slowly in northern Vietnam to be considered as a profitable
sawlog-producing species, so acacia hybrid and A. mangium are preferred for sawlog
production there. A. mangium is not favoured in the south of Vietnam because its wood
quality is seen to be inferior, and production enterprises there prefer to plant A.
auriculiformis and acacia hybrid.
Although performance of A. mearnsii and some provenances of A. melanoxylon is
promising in trials at Da Lat, it is too early to recommend acacia species adapted to
Vietnam’s highland regions as being suitable for sawlog production. Dry-zone acacia
species adapted to lowland dry zone environments receiving less than 1000 mm annual
rainfall are not suitable for sawlog production because their growth rates are too slow and
log quality is too poor.
These conclusions have been reached primarily from review of survival and growth data
from many trials in Vietnam. Less information is available on stem form traits (forking,
taper, bark thickness, branch size and stem straightness) of acacias. However,

2


quantitative assessment of stem form traits in clonal trials of acacia hybrid and A.
auriculiformis, and some progeny trials of A. auriculiformis, shows that these traits are
under moderate to strong genetic control and thus susceptible to genetic improvement,
particularly through deployment of selected clones with outstanding stem form.
Significant improvement in stem form is also achievable through use of improved
seedling stock of A. auriculiformis and A. mangium.
Little information is available on wood properties relating to sawlog production. A.
auriculiformis has higher wood density than A. mangium and is favoured for high-value
appearance products such as fine furniture and flooring. One study indicates that acacia
hybrid clones had higher wood density than A. auriculiformis at age 5 years. Further
information on wood properties is currently being collected by FSIV from clone trials and
progeny trials of A. auriculiformis and A. mangium, and clone trials of acacia hybrid
clones. No quantitative information is yet available on genetic rankings for susceptibility
to pests and diseases such as heart rot and stem cankers that might affect wood quality.
When ranking alternative germplasm sources (individual clones and seedlots) for their
suitability for sawlog plantations, it is not possible to be precise because the relative
economic weights for growth traits, stem form traits and wood properties to maximize
plantation and sawmill profitability have not yet been determined. The CARD project
will formulate economic weights that will enable better rankings of candidate varieties.
For now, we note that log shape and size, and wood defects, are strongly influenced by
silviculture (site selection, initial spacing, thinning and pruning, nutrition management
and control of competing vegetation) as well as by species choice and genetic
improvement, so silviculture and genetics must be considered together when efforts are
made to improve the profitability of sawlog plantations in Vietnam.

3

Table of Contents
Abstract ......................................................................................................................................................2
Table of Contents .................................................................................................................................4
1. Purpose of this review ..................................................................................................................5
2. Required tree characteristics for acacia sawlog plantations ..........................................5
2.1

Experience with processing acacia sawlogs in Vietnam .....................................5

2.2

Overseas experience in growing and using sawlogs of tropical acacia

species.................................................................................................................................................8
2.3

Summary of essential tree and log characteristics for acacia sawlog

production ........................................................................................................................................10
3. Acacia genetic resources and species-site matching ......................................................10
4. Species and provenance testing of Acacia species with sawlog potential ..............13
4.1 Species-site matching..........................................................................................................13
4.2 Species and provenance testing in lowland regions with moderate to high
rainfall................................................................................................................................................13
4.3 Species-provenance trials of temperate Acacia species at Dalat........................18
5. Genetic improvement of Acacia species in Vietnam........................................................21
5.1 Establishment of seed production areas and seedling seed orchards of
tropical Acacia species for lowland planting regions in Vietnam.................................21
5.2 Clonal testing and clonal seed orchards of A. auriculiformis and A. mangium

.............................................................................................................................................................22
5.3 Development of acacia hybrid clones ............................................................................25
5.4 Genetic gain trials of acacia species and acacia hybrids........................................28
6. Summary of recommended acacia species and varieties for sawlog plantations
in Vietnam.............................................................................................................................................30
7. Recommended propagation methods ...................................................................................31
8. References.......................................................................................................................................33

4


1. Purpose of this review
This review has been carried out as Activity 1 of CARD Project 032/05 “Sustainable and
profitable development of acacia plantations for sawlog production in Vietnam”. It
examines the currently available genetic material for acacia sawlog plantations in
Vietnam and recommends the best currently available germplasm suitable for sawlog
production. Appropriate propagation techniques for the recommended germplasm are
also reviewed. Much information is available from within Vietnam on species and
provenance testing, genetic improvement programs, propagation methods and
development of acacia hybrid clones for clonal forestry. Where this information has
already been published, reference is made to these earlier publications, rather than representing the original detail. Where local information is lacking in depth, experience
from other countries is examined.
Recommended strategies for future genetic improvement will be developed as Activity
4.5 of the project, so are not covered here.

2. Required tree characteristics for acacia sawlog plantations
First, it is necessary to consider the log quality requirements for acacia sawlog plantations
in Vietnam. Use of acacia sawlogs in Vietnam and overseas is considered in this section

2.1

Experience with processing acacia sawlogs in Vietnam

A number of small and medium-sized sawmills sawing acacia logs were inspected in the
course of developing the CARD project, and discussions held with sawmill managers.
The largest sawmill visited was the Huong Giang sawmill and wood processing facility in
Hue. This plant saws about 2500 m3 of logs per year, mostly acacia, and employs about
300 staff, most of them in downstream processing of furniture based on acacia wood.
Several smaller sawmills in Ha Tay, Dong Nai, Quang Tri and Quang Binh provinces that
use plantation acacia sawlogs were also inspected. The sawmills are generally labourintensive with low-technology hand-controlled log milling systems. Sawmill managers
have clear understanding of their log requirements. Mills such as Huong Giang which
have small vertical bandsaws (Figure 2) can saw acacia logs down to a small-end
diameter (s.e.d.) of 15 cm under bark. Mills with horizontal bandsaws, such as the
sawmill of Mr Nguyen Si at Dong Ha, saw logs of at least 20 cm s.e.d., because recovery
from smaller logs is too low for profitable operation using this sawing system. All the
mills studied prefer logs with larger s.e.d. (over 20 cm) to achieve higher recovery and
productivity.
Mills around Hue pay at least 600-800,000 dong m-3 over bark (delivered to mill, volume
calculated from s.e.d. and log length) for logs of acacia hybrid and A. mangium (small
end diameter under bark down to 15 cm), and rather higher prices for similarly sized logs

5


of A. auriculiformis. Some mills pay 1 million dong m-3, at the roadside in the plantation,
for good-quality logs of A. auriculiformis and acacia hybrid with s.e.d. greater than 20
cm. These prices are substantially higher than the prices paid for acacia pulpwood, about
400-500,000 dong per “stere” (= 2 m3 of stacked wood, or about 1.2 m3 solid volume,
equivalent to a price of 330-420,000 dong m-3 solid volume) at the roadside adjacent to
the plantation at Dong Ha.

Most mills concentrate on producing relatively small-sized sawn lumber such as furniture
components, seldom exceeding final dimensions of 1000 x 100 x 25 mm. Logs are
usually cross-cut into lengths of 2 m or shorter, prior to sawing.
If larger logs are unavailable, some sawmills with vertical bandsaws will even use logs
with a small end diameter of as little as 10 cm under bark to meet production demands,
but this reduces recoveries and increases sawing costs. Small size of logs (leading to
higher cost of milling and lower recovery), and knots, particularly dead knots associated
with unpruned stems, causing defects in the sawn wood, are the most important defects in
acacia sawlogs under present conditions. Sawmills will usually avoid purchasing logs
with significant visible defects such as heart-rot or large dead branch stubs.

Figure 1. Acacia logs awaiting sawing at Huong Giang sawmill, Hue

6


Figure 2. Sawing furniture components from small acacia logs using a vertical
bandsaw at Huong Giang sawmill, Hue

Figure 3. Sawing trial of acacia hybrid sawlogs at sawmill of Mr Nguyen Si, Dong
Ha, using horizontal bandsaw and rail-mounted log carriage.

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After sawing, boards are racked and air-dried for 2-3 weeks, which is sufficient time for
the small piece sizes typically produced. Larger boards up to 40 mm thick may be dried
for longer periods, sometimes in kilns, and then re-sawn. Mills report few problems of
drying degrade with acacia hybrid and A. auriculiformis, but some problems (cupping,
excessive shrinkage, unacceptably low wood density and checking) with A. mangium,

particularly in the south of Vietnam.
Wood of A. auriculiformis, acacia hybrid and sound wood of A. mangium is acceptable
for manufacture of mass-produced furniture (such as component pieces for indoor and
outdoor furniture) for local and export use. It appears acceptable for these components to
have a mix of sapwood and heartwood, despite the strong sapwood-heartwood colour
difference in acacia wood. Furniture is typically stained or painted in the final assembly
process.
Acacia auriculiformis wood is regarded by the sawmillers as denser and harder than the
wood of acacia hybrid and A. mangium, and is considered to have more attractive colour
and grain. The higher wood density of A. auriculiformis compared to A. mangium of the
same age is confirmed by empirical studies in Vietnam (Le Dinh Kha 2001) and
elsewhere (CAB 2003). Large A. auriculiformis logs are especially favoured by sawmills,
because large boards of this species can be used for high-value “appearance” applications
including flooring and fine furniture. It is not yet clear whether and to what extent A.
mangium and acacia hybrid can substitute for A. auriculiformis in these higher-value
applications.
Small quantities of Acacia crassicarpa logs are now available from the first plantations of
this species in Vietnam, but sawmills are not yet familiar with this species. Experience in
Australia and other countries is that A. crassicarpa can produce good-quality sawn timber
(Doran and Turnbull 1997).
All sawmills visited to date confirmed that they would take more acacia sawlog timber
from local growers, if it was available at the prices they currently pay. During 2004-2005,
large sawmills around Ho Chi Minh City imported A. mangium sawlogs from Malaysia
for processing. The log specifications required by these sawmills have not yet been
studied, and no firms importing A. mangium logs could be located in 2006.

2.2 Overseas experience in growing and using sawlogs of tropical
acacia species
Growing of tropical acacia species specifically for solid-wood uses is expanding rapidly
in several other countries in South East Asia, most noticeably in Indonesia and Malaysia

(Midgley and Beadle 2006, S.J. Midgley pers. comm. 2006). A. mangium is the most
important acacia species in these two countries. To date, silvicultural inputs into acacia
plantations managed for solid wood have seldom included pruning and thinning, though

8


the potential of these practices for a species like A. mangium has been recognised for
some time (Srivastava 1993). Persistent branches have led to the development of liftpruning regimes with the intention of converting the bottom log to clear or knot-free
wood. Form pruning that removes large branches and branches forming an acute angle
with the stem has been shown to significantly improve stem form (Beadle 2006). As the
plantations are established at around 1000 stems ha–1, thinning is also required to develop
large log diameters (Figure 4). In Indonesia, it is anticipated that final-crop stocking will
be around 300 stems ha–1 for crops being harvested when tree dbhob is 30 cm (Beadle
2006). Heart-rot and root-rot are significant problems for A. mangium plantations in
Indonesia (Potter et al. 2006)

Figure 4.
A 10-y-old-thinned stand of Acacia mangium in Merbau, South
Sumatra. Average dbhob and height and total stem volume were 36.6 cm, 26 m and
228.7 m3 ha–1 respectively (after Hardyanto 2006)
Malaysia, which has a long history of planting A. mangium (Pinyopusarerk 1993) is a
major exporter of A. mangium wood. Several companies actively export both logs and
sawn timber that has been processed to a greater or lesser extent. For example, log prices
in 2005were around $US 50 m–3 and finger-jointed timber $US 900 m–3 FOB (Midgley
and Beadle 2006). In 2003, Vietnamese furniture manufacturers were importing A.
mangium sawlogs from Malaysia at a landed price of up to $US 85 m-3.
A considerable body of published information is available on the properties processing
characteristics of A. mangium wood (Abdul-Kader and Sahri 1993, CAB 2003,
Hardiyanto 2006, Kumar et al. 2006). In summary, the wood is of medium density

(typically 420-480 kg m-3) and is relatively easy to dry and saw, and process into finished
furniture components. Shrinkage is moderate (typically about 6% tangential and 3%
radial shrinkage from green to air dry), and the wood can be cut, sanded, glued, stained
and painted easily. “Acacia” furniture, manufactured from the wood of tropical acacia

9


species, mainly A. mangium, is now a recognized international product type marketed by
global companies such as IKEA.

2.3 Summary of essential tree and log characteristics for acacia
sawlog production
In summary, acacia wood from at least A. auriculiformis, acacia hybrid and A. mangium
can be used by Vietnam’s sawmills to produce sawn boards for furniture components.
Individual sawlogs purchased are generally at least 2 m in length, with small end
diameter under bark of at least 15 cm, reasonably straight and without obvious defects
such as heart rot, cracks and loose knots. When plantations are harvested, small and
crooked trees and upper logs which do not meet these specifications are usually sold
separately to pulpwood and fuelwood markets. Using the best genetic resources and
optimizing silviculture will enable growers to maximize the proportion of log volume
which can be sold, at higher price, as sawlogs.
It follows that for acacia sawlog plantations, the following essential tree and log criteria
need to be improved through a combination of genetic selection and silviculture:
Survival - high rates of survival are important for stand uniformity and wood yield
Rapid growth - ability to produce a sawlog in the shortest possible rotation
Good stem form – reasonably straight main stem, minimum forking, and light branching
will maximise the proportion of the tree’s production that can be sold as sawlog
Defect-free wood - sawlogs must be free of heart-rot, loose knots and other defects that
would cause visible defects in sawn boards and lead to them being rejected for further

processing.

3. Acacia genetic resources and species-site matching
Acacia species have become important plantation species in Vietnam over the last two
decades. They display rapid growth even on degraded soils, and form symbiotic
associations with nitrogen-fixing bacteria, thus reducing the requirement for fertilizer
inputs. Acacia wood can be used for both pulpwood and sawn timber. In Vietnam, there
are about 15 native Acacia species (Nguyen Tien Ban et al., 2003), but these are small
and shrubby and of no economic value for wood production in plantations. The Acacia
species now planted in Vietnam are native to Australia and in some cases the adjacent
regions of Papua New Guinea (PNG) and West Papua, Indonesia (Nguyen Hoang Nghia
and Le Dinh Kha, 1998). There are many hundreds of Acacia species occurring in
Australia and adjacent countries. The identification of suitable candidate species,
collection of genetic resources of these species and their introduction to Vietnam has not
occurred in isolation, but as part of an international testing program supported by the

10


Australian Government, FAO and CSIRO that has operated since the 1970s (Turnbull et
al. 1998).
Climates vary greatly within Vietnam. The wide range of altitude and latitude, and the
effects of mountain ranges on monsoon systems, result in substantial differences in
rainfall and temperature regimes. As a result the Acacia species planted in Vietnam can
be considered in three groups:
Species adapted to tropical lowland environments with medium to high rainfall
The best-performing of these species are A auriculiformis, A. crassicarpa and A.
mangium, which are all native to northern Queensland (Qld), Australia and adjacent PNG
and West Papua, Indonesia. A. auriculiformis also occurs naturally in Australia’s
Northern Territory (NT). A. auriculiformis, A. mangium and selected clones of the

interspecific hybrid A. mangium x A. auriculiformis are the most widely planted acacia
species in Vietnam (Nghia and Kha 1998, Centre for International Economics 2004).
Species suited to low-rainfall tropical lowland environments
Coastal areas of Binh Thuan and Ninh Thuan provinces in the south of the country in
have a dry climate, receiving mean annual rainfalls lower than 1000 mm per year. Sandy
soils are prevalent in flat terrain near the sea coast. In the 1980s it was found that A.
auriculiformis and A. mangium perform poorly in these environments, being prone to
drought death in dry years. Dry-zone acacias from northern Australia were tested at Tuy
Phong in Binh Thuan Province in the 1990s (Harwood et al. 1998). The best-performing
species were A. difficilis, A. tumida and A. torulosa. Subsequently, A. difficilis was also
found to have a valuable role in establishing vegetation cover on extremely eroded
shallow soils of bare hills in central and northern Vietnam, and the dry-zone species were
also planted for stabilizing moving coastal sands in other provinces with higher rainfall
such as Quang Binh province. However, none of these dry-zone species attain maximum
heights greater than 10-12 m, and they fork and branch heavily from a low height, so they
cannot produce straight sawlogs. Their growth rates in low-rainfall environments are
slow. In the species trial at Tuy Phong mean maximum height at age 6 years was only 7.5
m and mean maximum diameter at breast height 15 cm for A. difficilis, the fastestgrowing of these species. In wetter lowland environments they are out-performed by A.
auriculiformis, A. crassicarpa and A. mangium. This makes them unsuited for sawlog
production, and they are not considered further in this review.
Species suited to highland environments in Vietnam
There are large areas of land in the north and centre of Vietnam where elevation exceeds
1000 m and the climate is cooler than optimum for the tropical acacias, with mean annual
temperature below 21oC (Nghia 1996). Species and provenance trials were carried out in
the 1990s to identify the best-performing temperate acacias for these cooler
environments. A. mearnsii and A. melanoxylon have been found to be the best performing
species in highland Vietnam, which is consistent with their good performance in tropical
highland regions in other countries. A. mearnsii is now widely used for planting in
tropical highland areas in India, China, South America and Africa (CAB 2003). A.

11


melanoxylon is a favoured species for production of sawn timber from natural forests in
its native range in Australia (CAB 2003, Doran and Turnbull 1997).
Climatic requirements of the most important candidate species for sawlog production are
summarized in Table 1 below. A climatic mapping program was produced by Dr T.H.
Booth of CSIRO Forestry and Forest Products which enables display of areas in Vietnam
satisfying any set of climatic requirements such as those shown in Table 1. This software
has been used by the Forest Science Institute of Vietnam (Nghia, 1996) to display areas
climatically suitable for planting of A. auriculiformis and A. mangium.
Table 1. Climatic requirements for most important candidate Acacia species
for sawlog production in Vietnam
Acacia species suited to lowlands of Vietnam
auriculiformis1 crassicarpa2
mangium1
22-30
22-28
22-28

Acacia species suited to highlands
mearnsii3
melanoxylon4
10-20
Not available

Mean
maximum
temperature of hottest
month (oC)

25-37

25-35

25-35

21-30

Mean
minimum
temperature of coldest
month (oC)

10-22

10-22

8-22

0-15

Mean annual rainfall
(mm)

1000-2500

1000-2500

1300-2500

700-2300

Length of dry season
(consecutive
months
receiving less than 40
mm)

0-6

0-6

0-5

0-6

Climatic factor
Mean
annual
temperature (oC)

1

modified from Nghia (1996). In northern Vietnam A. mangium can tolerate slightly lower
winter temperatures than can A. auriculiformis. It can be grown at elevations up to about
300 m in the northernmost provinces of Vietnam, whereas A. auriculiformis can only be
grown at elevations up to 100 m there. The climatic range for acacia hybrid clones is
probably intermediate between those of A. auriculiformis and A. mangium
2

T. Jovanovic pers. comm. 2006

3

Jovanovic and Booth (2002)

4

natural provenances of A. melanoxylon occur over wide geographic range from Tasmania
to Queensland, so climatic requirements of specific provenances will differ.

Subsequently, with funding support from the International Greenhouse Partnerships
Program of the Australian Government, the 3-PG process-based forest growth model was
calibrated for A. mangium in Vietnam, enabling growth and carbon sequestration of A.
mangium to be predicted at example locations in different regions across Vietnam, taking
into account climate and local soil conditions (Booth et al. 2001)
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4. Species and provenance testing of Acacia species with
sawlog potential
4.1 Species-site matching
In the early 1960s, A. auriculiformis was introduced for planting in south-eastern
Vietnam. From the 1980s, systematic trials of this and other Acacia species known to
have good potential for industrial plantations were carried out by the Forest Science
Institute of Vietnam and other research agencies, usually in collaboration with Australia’s
CSIRO, which supplied most of the seedlots under test. Species-provenance and
provenance trials have been carried out at many locations across Vietnam. The locations
of trials reviewed here are summarized in Table 2, below. Most of the results obtained to

2003 are summarized by Le Dinh Kha (2003).
Table 2. Site details of Acacia species-provenance and provenance trials in Vietnam
Trial
location
Da Chong

Province

Longitude
(S)
105o26

Altitude
(m)
60

Mean annual
rainfall (mm)
1680

Soil type

Ha Tay

Latitude
(N)
21o07

Cam Quy

Ha Tay

21o07

105o26

60

1680

yellow-red ferralitic soil
over
50
cm
deep
developed over sandstone.

Dai Lai

Vinh Phuc

21o10

105o17

Dong Ha

Quang Tri

16o50

107o05

Mangyang

Gia Lai

13o59

108o10

o

o

50

yellow-red ferralitic soil
over
50
cm
deep
developed over sandstone.

1500
2370

ferralitic soil developed
over schist.

800

2270

granite-derived soil

1640

grey soil developed from
alluvial deposits

Song May

Dong Nai

11 05'

107 06

50

Bau Bang

Binh
Duong

11o32

105o56

50

Da Lat

Lam Dong

11o57

108o26

1600

grey soil developed from
alluvial deposits
1730

yellow-red ferralitic soil
on magma acid rock, pH
4.5-5.0

4.2 Species and provenance testing in lowland regions with moderate
to high rainfall
Species-provenance trials
In the 1980s, A. auriculiformis, A. mangium, A. crassicarpa and A. aulacocarpa were
introduced to establish pilot plantations at Ba Vi (Ha Tay province), Hoa Thuong (Thai
Nguyen province) and Trang Bom (Dong Nai province). Assessment in 1991 of pilot

13

plantations established at Ba Vi in 1982 and at Hoa Thuong in 1984 showed that the most
promising species were A. auriculiformis, A. mangium and A. crassicarpa. A.
auriculiformis displayed the fastest early growth (Le Dinh Kha and Nguyen Hoang
Nghia, 1991).
From 1990 to 1991, under projects financed by UNDP, trials of 39 provenances of 5
tropical acacia species were established at Da Chong (Ba Vi, Ha Tay province, northern
Vietnam), Dong Ha (Quang Tri province, central Vietnam) and Dai Lai (Vinh Phuc
province, northern Vietnam).
The species/provenance trials established in 1990 at Da Chong and Dong Ha included 13
provenances of A. auriculiformis, 9 provenances of A. mangium, 9 provenances of A.
crassicarpa, 5 provenances of A. aulacocarpa and 5 provenances of A. cincinnata,
provided by CSIRO. All provenances came from Queensland (Qld) and Northern
Territory (NT) of Australia; Papua New Guinea (PNG) and Indonesia (Ind). Local
seedlots of A. auriculiformis and A. mangium from Dong Nai of A. were used as controls.
The trial at Da Chong used a randomized complete block design with 3 replications and
49 trees per plot. The trial in Dong Ha was established in 1991. This trial had only one
replication with 49 trees per plot. The trial at Dai Lai (Vinh Phuc) included all 13
provenances of A. auriculiformis.
The trial at Da Chong was measured in 1999 at age 9 years after planting at Da Chong.
Mean total stem volumes over bark of each species, in dm3/tree, (assuming a standard
stem form factor of 0.5) were as follows:
A. crassicarpa:
A. mangium:
A. auriculiformis:
A. aulacocarpa:
A. cincinnata:

221
191
192

103
94

Log volumes are only approximate, being strongly influenced by stocking, which in turn
is influenced by survival, so the mean volumes shown above should only be taken as an
indication. Nonetheless, this result demonstrates the substantial log size that can be
attained by the tropical acacias in nine years on a reasonably productive site in northern
Vietnam.
Another species/provenance trial of A. mangium, A. auriculiformis, A. crassicarpa, A.
aulacocarpa and A. cincinnata was established by Phu Ninh Forestry Research Centre in
in 1992 on granite-derived soil at Mangyang, Gia Lai province, central Vietnam (Mai
Dinh Hong et al. 1996). After 4 years A. crassicarpa, A. mangium and A. auriculiformis
were the best-performing species. Bloomfield (Qld) and Pongaki (PNG) provenances of
A. mangium, Coen River (Qld) and Kings Plain (Qld) provenances of A. auriculiformis
and some provenances of A. crassicarpa were the fastest growing and A. cincinnata was
the poorest species. These conclusions on promising species and provenances generally
agreed with other results (Le Dinh Kha 2003).

14


Generally, in the trials of tropical acacia species, A. crassicarpa, A. mangium and A.
auriculiformis have performed best. A. aulacocarpa and A. cincinnata are slower
growing species and hold little promise for plantation forestry in Vietnam (Le Dinh Kha
2003). The taxonomy of A. aulacocarpa is complex: the best-performing provenances of
this species, which occur naturally in Western Province, PNG and adjacent West Papua,
Indonesia, have been renamed A. peregrinalis (McDonald 2000).
Evaluation of the species-provenance trials established at Ba Vi, Dong Ha and Dai Lai
showed that after 912 years the best-performing tested provenances in northern and
central Vietnam were:

A. auriculiformis: Mibini (PNG), Coen River and Kings Plains (Qld) and Manton River
(NT)
A. mangium: Pongaki (PNG), Iron Range (Qld), Ingham (Qld) and Mossman (Qld).
A. crassicarpa: Mata (PNG), Gubam (PNG), Dimisisi (PNG) and Deri-Deri (PNG).
A. auriculiformis provenance trials
In 1990, a provenance trial of A. auriculiformis was established at Dai Lai. Nine years
after planting, Coen River (Qld) was the best provenance of those tested in this trial. Data
collected at Ba Vi and Dai Lai at age 12 years (Table 3) showed that Mibini (PNG),
Coen River (Qld) and Kings Plains (Qld) were promising provenances at both sites, while
Manton River (NT) was fast growing at Ba Vi but mid-ranked at Dai Lai.
A series of provenance trials of A. auriculiformis was established in Cam Quy (Ha Tay),
Dong Ha (Quang Tri) and Song May (Dong Nai) under the ACIAR project 9310. A local
seedlot from Dong Nai was included in these trials as a control. In the trial in Song May
at 5 years the best-performing provenances were Wenlock R. (Qld), Halroyed (Qld) and
Morehead (PNG), while at Cam Quy the best provenances were Halroyed (Qld) and Rifle
Creek (Qld). In these three trials the Dong Nai local race of A. auriculiformis displayed
intermediate to slow performance. The fastest growing provenances had volumes two
times greater than those of the slowest.
At Song May the mean stem volume of 16 provenances at age 5 years was 90.0 dm3 per
tree, while at Dong Ha it was 30.1 dm3, and at Ba Vi only 20.4 dm3. All trials used the
same spacing of 3m x 2m. This result shows that differences in climatic and soil
conditions in Vietnam have a major impact on the growth of A. auriculiformis.

15


Table 3. Growth of A. auriculiformis provenances at Dai Lai and Ba Vi
(1990-2002)
Seedlot

Provenance

16148
16106
16142
16485
16163
16152
16684
16158
16484
16683
16107
16154
16151

Manton R. NT
Mibini
PNG
Coen R.
Qld
Kings Plains Qld
Elizabeth R. NT
Alligator R. NT
Bensbach PNG
Gerowie Ck. NT
Morehead Qld
Morehead PNG
Old Tonda PNG
Goomadeer NT

Mary River NT

Ba Vi
Height
(m)
17.3
17.7
17.5
17.8
17.3
16.1
17.4
14.8
15.9
15.5
15.6
15.9
13.4

Dbh
(cm)
21.4
21.2
20.8
20. 6
19.6
19.4
19.4
18.0
18.0

17.6
17.3
16.2
13.9

Dai Lai
Height
(m)
12.9
13.6
14.1
13.4
10.5
13.2
12.7
10.4
13.3
*
10.9
13.2
12.4

Dbh
(cm)
14.3
14.2
14.8
14.4
12.6
14.8

12.5
10.4
14.5
*
10.8
14.3
13.6

A. mangium provenance trials
In 1989 - 1990, provenance trials of A. mangium were established at Bau Bang and Song
May by the south-eastern Forest Science and Production Centre. At age 8.5 years, there
were substantial differences in growth between the two sites (Table 4). Waterlogging at
Bau Bang appeared to be the cause of the slower growth there.
Only one provenance from PNG, Deri-Deri, was tested. This proved fastest-growing at
both sites. The Olive River and Pascoe River from the Far North Queensland region of
Queensland also performed well when tested at Song May. This is consistent with results
in other countries (Harwood and Williams 1992). Earlier Vietnamese provenance trials
of A. mangium did not test the PNG provenances of the species, so it is difficult to draw
useful conclusions from them.

16


Table 4. Growth of provenances of A. mangium in Bau Bang and Song May
Seedlot

Provenance

16591
0517

15700
0554
1667
0523
16589
0535
0579

Deri-Deri PNG
Herbert Valley Qld
Cardwell
Qld
Tully Region Qld
Bloomfield Qld
Gap Creek Qld
Olive River Qld
Pascoe River Qld
Innisfail Qld
Average

Bau Bang
(to 10.5 years)
Height
Dbh
(m)
(cm)
17.9
19.2
17.0
18.6

16.8
18.3
17.3
18.0
15.1
13.9
12.6
13.8
*
*
*
*
*
*
16.1
17.0

Song May 1
(to 10.5 years
Height
Dbh
(m)
(cm)
*
*
18.0
22.0
17.9
23.3
18.6

22.4
18.1
19.4
19.1
19.1
*
*
*
*
*
*
18.4
21.2

Song May 2
(to 9.5 years)
Height
Dbh
(m)
(cm)
18.0
24.6
*
*
17.0
21.5
*
*
17.8
20.3

*
*
18.0
23.3
18.0
23.0
15.3
18.5
17.4
21.9

A. crassicarpa provenance trials
In September 1991, a provenance trial of A. crassicarpa was established at Bau Bang,
where the site conditions are similar to those at Song May. After 8.5 years, the bestperforming provenances of A. crassicarpa at Bau Bang were Dimisisi, Deri -Deri,
Morehead and Bensbach, all from PNG (Table 5). The slowest-growing provenances
were those from Indonesia and Queensland. A. crassicarpa clearly out-performed a local
seedlot of A. auriculiformis in this trial.
Table 5. Growth of A. crassicarpa provenances at Bau Bang (1991-1999)
Seedlot
16602
16993
17869
17552
13682
13680
17561
16598
17944
17849
16128

Provenance
Dimisisi
Deri-Deri
Morehead
Bensbach
Oriomo
Wemenever
Limal
Bimadebum
Claudie R.
Samlenberr
Jardine R.
A. auriculiformis
Dong Nai

Country
PNG
PNG
PNG
PNG
PNG
PNG
PNG
PNG
Qld
Indo
Qld
Vietnam

Ht (m)
19.7
19.6
19.7
19.3
18.9
18.7
17.2
17.6
15.0
18.0
12.4
8.7

Dbh (cm)
21.4
21.4
21.0
20.8
19.6
19.0
19.3
19.2
18.6
17.6
16.6
8.4

A. crassicarpa has been observed to outperform other acacia species on the coastal white
sandy soils of central Vietnam, for example in Thua Thien Hue Province. These soils are

low in fertility and subject to seasonal waterlogging. There are many thousands of
hectares of these low-lying white sandy soils in coastal regions of central Vietnam, and
the area of A. crassicarpa plantations in these environments is expected to expand
rapidly. However, producing logs of sufficient size for sawing and achieving

17


sustainability of production will be particularly challenging on these difficult, infertile
sites.
Identification of superior acacia provenances by MARD
On the basis of species and provenance trials conducted in Vietnam, in 2000 the Ministry
of Agriculture and Rural Development issued Decision No. 4260/KHCN-NNTT to
approve the following provenances as Technological Advanced Germplasms for mass
planting in suitable ecological zones:
A. auriculiformis: Coen River (Qld), Morehead River (Qld) and Mibini (PNG).
A. crassicarpa: Mata province (PNG), Deri-Deri (PNG) and Dimisisi (PNG).
A. mangium: Iron Range (Qld), Cardwell (Qld) and Pongaki (PNG).
Results from other tropical countries support the superior ranking of most of these
provenances, with the exception of the Cardwell provenance of A. mangium. Provenance
and progeny trials of A. mangium in many countries including Australia, China, Indonesia
and Malaysia (Harwood and Williams 1992), and the Philippines (Arnold and Cuevas
2003) have confirmed that Cardwell is not a fast-growing provenance of this species,
when compared with most provenances from PNG, and provenances from the Far North
Queensland region (Claudie River/Iron Range, Olive River and Pascoe River). We
recommend that Cardwell should no longer be classed as a superior provenance of A.
mangium. It is also noted that there are other provenances of A. auriculiformis, A.
crassicarpa and A. mangium not tested in provenance trials in Vietnam which have
performed equally well as those identified by MARD. Some of these provenances are
represented in the seedlings seed orchards and seed production areas subsequently

established by FSIV.

4.3 Species-provenance trials of temperate Acacia species at Dalat
In 1996, through a project sponsored by ACIAR and in cooperation with CSIRO, the
Research Centre for Forest Tree Improvement (RCFTI) established a series of
species/provenance trials of temperate acacias at several highland sites, including Da Lat
(altitude 1600m), Tam Dao (1000m), Moc Chau (1000m) and Ba Vi (600m).
Preliminary assessments conducted in 1997 showed that survival and growth of these
species was best at Da Lat (Ha Huy Thinh et al., 1998), therefore evaluation in later ages
focused on the trial at Da Lat (Table 6).
Da Lat has a mean annual temperature 18.3oC, a mean maximum of the hottest month of
23.3oC, and a mean minimum of the coldest month of 14.3oC. The absolute minimum
temperature is -0.1oC (recorded in January 1932). Mean annual rainfall is 1730 mm/year,
and the rainy season is mostly from April to October, peaking in September - October
(Nguyen Trong Hieu, 1990).

18


Table 6. Survival and growth of temperate Acacia species at four years at Da Lat
Species

Provenances
tested
A. mearnsii natural provenances 6

Survival
(%)
67.9

Height
(m)
10.0

Dbh
(cm)
8.6

A. mearnsii Dalat land race

1

47.5

7.0

7.1

A. binervata

1

68.7

7.9

7.7

A. chrysotricha

1

21.3

6.6

5.2

A. cincinnata

4

13.1

3.5

2.2

A. dealbata

4

50.6

7.0

6.5

A. decurrens

2

15.0

6.0

4.7

A. elata

3

35.8

5.8

5.4

A. fulva

2

59.4

8.8

6.3

A. glaucocarpa

3

25.0

7.6

5.5

A. implexa

3

54.2

4.9

3.1

A. irrorata

3

66.5

7.3

7.5

A. melanoxylon

6

56.3

5.3

4.6

A. parramattensis

2

56.3

6.4

5.4

A. silvestris

1

46.3

8.6

7.6

The trial was established in May 1996 at Mang Linh, Da Lat, at an altitude about 1600 m,
on a yellow-red ferralitic soil on magma acid rock with pH 4.5 - 5.0. The trial included 42

provenances from 14 temperate acacia species provided by CSIRO, and used a
randomized complete block design with 4 replicates, 20 trees per plot and spacing of 2 x
1.5 m.
At 48 months, A. mearnsii (67.9%), A. binervata (68.7%), and A. irrorata (66.5%);
showed the best survival (Table 6). A. mearnsii was the best-performing species. Growth
rate and survival percentage of the 6 introduced provenances of this species was superior
to that of the Da Lat local race. Among other species, only some provenances of A.
melanoxylon, A. dealbata and A. irrorata performed well
Provenance rankings for A. mearnsii and A. melanoxylon at Da Lat
An assessment conducted in 2003 at age 7 years showed that growth rates and survivals
of all introduced A. mearnsii provenances were better than that of the Da Lat local race
used as control. Of the four A. melanoxylon provenances tested, Mt Mee (Queensland)
was clearly superior to more southerly provenances from New South Wales and
Tasmania (Table 7).

19


Table 7. Growth of A. mearnsii and A. melanoxylon provenances to 7 years at Da
Lat
Seedlot

16246
16621
16380
18607
18979
18975

17263

15821
19001
19494

Species/
provenance

Height
(m)

Dbh
(cm

A. mearnsii
Nowra
NSW
Bodalla
NSW
Nowa Nowa VIC
Berrima
NSW
Blackhill VIC
Bungendore NSW
Da Lat
VN

13.5
13.6
12.3
12.6

12.5
11.7
10.4

12.2
12.1
11.3
10.5
11.0
10.6
10.8

A. melanoxylon
Mt. Mee Qld
Raveshoe Qld
Mt. Linsay NSW
Kannunah Tas

10.7
9.6
8.5
8.4

11.2
8.7
7.3
7.0

In 2000, the Ministry of Agriculture and Rural Development issued Decision No.
4260/KHCN- NNTT to recognize Bodalla and Nowa Nowa provenances of A. mearnsii

and Mount Mee provenance of A. melanoxylon as Technological Advanced
Germplasms for pilot plantations in high mountainous areas in Vietnam.
Growth rates achieved in the trial of temperate acacia species at Da Lat are generally
slower than those achieved for the tropical species A. mangium, A. auriculiformis and A.
crassicarpa. Tree size in this initial trial in Vietnam is still small (maximum stem
diameters are only around 15 cm), and large scale plantations of these species have not
yet been established. It is not yet possible to evaluate the potential for sawlog production
of temperate Acacia species suitable for Vietnam’s highland regions, and they are not
considered further in this review.

20


5. Genetic improvement of Acacia species in Vietnam
Following the identification of the best acacia species and provenances, the Forest
Science Institute of Vietnam, working with some other research agencies and with
support from CSIRO Forestry and Forest Products, has implemented a genetic
improvement program aimed at producing improved acacia planting stock. This program
is described under the following headings:

5.1 Establishment of seed production areas and seedling seed
orchards of tropical Acacia species for lowland planting regions in
Vietnam
From 1996 to 1998, under the UNDP FORTIP (Improved Productivity of Man-Made
Forests through Application of Technological Advances in Tree Breeding and
Propagation) Project operated by RCFTI in cooperation with CSIRO, and financially
supported by AusAID, seed production areas (SPAs) and seedling seed orchards (SSOs)
of A. auriculiformis and A. mangium were established at Cam Quy, Ba Vi, and at Chon
Thanh near Ho Chi Minh City. In the period 2000-2002, through cooperation with
CSIRO Forestry and Forest Products and with financial support from the International

Greenhouse Partnerships program of the Australian Government, seedling seed orchards
of A. crassicarpa were established at Dong Ha and at Ham Thuan Nam in Binh Thuan
province. In 2002, under the MARD project on forest tree improvement, a further 4 ha
seedling seed orchard of A. crassicarpa was established at Phong Dien in Thua Thien
Hue province.
Details of these seed production areas and seedling seed orchards are shown in Table 8,
overleaf. The SSOs were established using open pollinated progenies of trees from
previously identified superior natural provenances, or of superior trees from other SSOs
in Australia, China or Thailand. Most of the SSOs were established initially as progeny
trials testing 8 replicates of 4-tree family plots. SPAs were established using single bulk
seedlots either based on a single superior natural provenance of the species, or on a mix
of superior provenances together with superior families from SSOs obtained from other
countries. Thus, family identities are not retained in the SPAs.
The progeny trials were assessed at age three years, and selective thinning was done by
removing inferior trees and families. Trees were selected for retention using an informal
selection index that combined rapid growth rate and stem form (straight stems with light
branching being preferred). The weighting between stem form and growth was not
formally specified. The single best tree per plot was retained for most of the plots and
most of the families. This thinning converted the progeny trials into SSOs, to provide
seed for plantations and the next generation of the breeding population. The best
individuals from the best families of A. mangium and A. auriculiformis were also
selected to establish clonal tests to identify elite clones of high productivity and disease
resistance for breeding and possible use in clonal plantations.

21


Table 8. Seed production areas and seedling seed orchards of A. auriculiformis, A.
crassicarpa and A. mangium established by FSIV, 1993 to 2002
Species, SSO or

SPA1

Site

Province

Year
est.

Number
of
families
in
SPA or SSO

Area
(ha)

Status
in 20062

A. auriculiformis
SPA
Cam Quy
Ha Tay
1993
Coen R prov.
3
+
SPA

Dong Ha
Quang Tri
1996
>100
3
+
SSO
Cam Quy
Ha Tay
1997
139
4
++
SSO
Chon Thanh
Binh Phuoc
1997
185
4
Felled
A. crassicarpa
SSO
Dong Ha
Quang Tri
2000
105
3
+
SSO
Ham Thuan Nam Binh Thuan

2001
85
3
+
SSO
Phong Dien
Thua Thien Hue
2002
112
3
0
A. mangium
SPA
Cam Quy
Ha Tay
1993
Pongaki prov.
3
++
SPA
Dong Ha
Quang Tri
1996
>100
3
++
SSO
Cam Quy
Ha Tay
1997

84
3
+
SSO
Chon Thanh
Binh Phuoc
1996
168
3
Felled
1
SSO= seedling seed orchard, SPA = seed production area
2
++ = producing commercial quantities of seed (>5 kg/year), + producing small quantities of seed, 0 = no
seed

The SPAs were also selectively thinned, removing the individuals with poor vigour and
stem form so that only 200-300 phenotypically superior trees per hectare were retained
for seed production.

5.2 Clonal testing and clonal seed orchards of A. auriculiformis and
A. mangium
Candidate trees displaying clearly superior growth and stem form were selected from
pilot plantations of the Coen River provenance of A. auriculiformis at Ba Vi. They were
clonally propagated from basal coppice, and clone trials were established at Ba Vi and
Dong Ha in 1998. Seedlings of Coen River provenance and a commercial seedlot from
Dong Nai were included in the trials as controls.
Table 9 shows data from the clonal test at Dong Ha in 2004. The best clones, numbers 84,
25, 30, 85 and 83, had mean stem volumes of 49.4 - 55.5 dm3. The original Coen River
seedlot and the commercial seedlot had stem volumes of only 30.3 dm3 and 23.9 dm3

respectively. Assessment of stem quality for selected clones showed that they possessed
high stem quality, especially clones 83, 84 (stem quality index 41.4 - 51.8 points),
followed by clones 28, 25 and 85 (stem quality index 28.0 - 34.1 points). These clones
were also little affected by pests and diseases. Clones 84, 25, 85, 83, 28 and 81 had mean
annual increment (MAI) of 10.5 - 13.1 m3/ha/year, while the controls (Coen River natural
provenance seedlings and commercial seedlot seedlings) were the worst with MAI was
only 7.2 and 5.7 m3/ha/year respectively.

22


Table 9. Growth of A. auriculiformis clones in trials at Dong Ha (1/2001-10/2004)

10.3

Stem
volume Productivity
(m3 ha-1 year-1
(dm3/tree)
55.5
13.1

12.2

10.1

51.5

30
11.6

85
11.8
83
11.6
28
11.3
81
12.1
35
11.2
50
11.1
51
10.3
82
11.0
18
10.1
Coen R seedlings 10.2
Seed Co. seedlings 9.1
F-probability
of
treatment
differences
Least significant
difference (P<.05) 0.9

10.1
10.1
10.0

9.8
9.5
9.4
8.7
9.0
8.7
8.3
8.5
7.7

50.4
50.4
49.4
45.2
44.3
42.5
36.0
34.6
34.2
29.2
30.3
23.9

Clone/
seedlot
84

Height
(m)
12.9

25

Dbh
cm)

<.001

<.001

1.0

12.2
11.9
11.9
11.4
10.7
10.5
10.1
8.5
8.2
8.1
6.9
7.2
5.7
<.001

11.5

Overall assessment indicated the best clones of A. auriculiformis at Dong Ha and Ba Vi

were clones 84, 25, 85, 83, 28 and 81, in terms of both productivity and stem quality.
From the results of the trials at Ba Vi and Dong Ha, the scientific committee of MARD
in 2005 designated A. auriculiformis clones BVlt28, BVlt83, BVlt84 and BVlt85 as
Technological-Advanced Germplasms in Vietnam.
In 1999, the progeny trials of A. auriculiformis and A. mangium established in Binh
Duong were scheduled for felling, following conversion of the land use to an industrial
zone. In order to retain the superior genetic resources identified, RCFTI, in cooperation
with the Centre of South Eastern Forest Science and Production and with support from
the ACIAR-funded Domestication of Australian Trees Project, selected 150 candidate
plus trees per species (the best three trees from each of the 50 best families of each
species). These selections were clonally propagated from basal coppice and multiplied
from hedge plants. Not all selections were successfully captured. An additional 15
superior clones from the previous A. auriculiformis trials in northern Vietnam, discussed
above, were included in these trials. Cloned ramets were used to establish clonal tests at
three sites in southern, central and northern Vietnam in 2001 and 2002 as shown in Table
10.
These clonal plantings were designed to function as clonal tests of A. auriculiformis to
identify clones of high productivity and good stem quality for production. It was
considered unlikely that they would yield production clones of A. mangium, because

23


FSIV’s experience has been that this species is less amenable to operational clonal
propagation. The trials were designed so that they could also be converted to clonal seed
orchards once clonal assessments had been conducted, by completely removing the
inferior clones and retaining the best 20-30 or so clones of a species. At each site the
clonal trial of A. auriculiformis was planted adjacent to the clonal trial of A. mangium to
with the intention of producing a proportion of open-pollinated F1 hybrid interspecific
seed from many superior parental combinations. The three A. auriculiformis clone trials

have been assessed for growth, stem form and wood density at age 3-4 years by Mr Phi
Hong Hai of RCFTI in the course of his PhD studies, and the A. mangium clone trials are
undergoing similar assessment.
Already, at age 4.5 years, very superior clones of A. auriculiformis have been identified
at the Bau Bang trial (Figure 5).
Table 10. Details of clonal tests of A. auriculiformis and A. mangium
Location

Ba Vi

Dong Hoi

Bau Bang

Province

Ha Tay

Quang Binh

Binh Duong

Latitude

21007'N

17028'N

11032'N

Longitude

105026'E

106059'E

105056'E

Altitude

60

40

50

Soil

ferralitic clay loam with
heavy lateritization

ferralitic clay loam

Sandy alluvium

1680

2370

1817

Mean annual temperature ( C)

23.2

24.8

26.2

Site preparation

Slashed,
ripped

Slashed, burned and
ripped

Slashed, burned and
ploughed

Planting time

August 2002

November 2002

August 2001

Fertilizer (per tree)

3kg cattle manure +
0.2kg NPK

3kg cattle manure +
0.2kg NPK

0.5kg micro-organic
fertilizer + 0.2 kg
NPK

Annual rainfall (mm)
0

burned

and

Design
•

Replicates

5

5

8

•

Trees per plot

2

2

2

•

Spacing

3 m x 3m

3 m x 3m

4 m x 2m

Number of clones
•

A. auriculiformis

102

114

120

•

A. mangium

not planted

100

100

24


Figure 5. Clone trial of A. auriculiformis clones at Bau Bang, age 4.5 years after
planting. Two-tree plot of a superior clone in the foreground (dbh 18 cm), two-tree plot
of a very poor clone behind the observer.

5.3 Development of acacia hybrid clones
The development of highly productive selected clones of the interspecific hybrid A.
mangium x A. auriculiformis is a well-documented and very important contribution to
plantation forestry in Vietnam. Development of the first set of production clones, up to
the year 2001, is described in detail by Le Dinh Kha (2001) and will not be repeated in
detail here. Over 130,000 ha of production plantations of these selected acacia hybrid
clones had been established in Vietnam by the year 2004 (van Bueren 2005).
Key features of the development of acacia hybrid clonal forestry in Vietnam are as
follows:
•

Most hybrid individuals are not suitable for production forestry and an intensive
testing program has been implemented to identify individual clones which are easy
to propagate, display outstanding growth and stem form, and good resistance to

pests and diseases. Only well-tested individual hybrid clones should be used in
plantation forestry.
25