MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAM NATIONAL UNIVERSITY OF FORESTRY

THESIS
SOLUTIONS FORSTUDENT
TRANSFERING
SMALL TIMBER INTO
LARGE TIMBER PRODUCTION
OF ACACIA HYBIRD
IN QUANG BINH PROVINCE
Major: Natural Resources Management
Faculty: Forest Resources and Environmental Management

Student: Nguyen Ngoc Thanh Huyen
Student ID: 145 309 0588
Class: K59A - Natural Resources Management
Course: 2014 - 2019

Advanced Education Program
Developed in collaboration with Colorado State University, USA
Supervisor: Assoc.Prof. Dr. Pham Minh Toai

Ha Noi, October/2018


TABLE OF CONTENTS
ABSTRACT ........................................................................................................................................1
1. INTRODUCTION ..........................................................................................................................2
1.1 OVERVIEW OF RESEARCH IN THE WORLD ....................................................................3
1.1.1 Research on forest structure ................................................................................................3
1.1.2 Simulation research some basic forest structure laws .........................................................4

1.1.3 Research on technical elements related to forest transformation .......................................5
1.1.4 Research on cutiting and nurturing the forest .....................................................................6
1.2 OVERVIEW OF RESEARCH IN VIETNAM ..........................................................................7
1.2.1 Research on forest structure ................................................................................................7
1.2.2 Simulation research some basic forest structure laws .........................................................8
1.2.3 Research on technical elements related to forest transformation .......................................8
1.2.4 Research on cutiting and nurturing the forest .....................................................................9
1.2.5 Research on Acacia hybrid ................................................................................................10
2. GOALS AND SPECIFIC OBJECTIVES ..................................................................................11
2.1 GOALS ........................................................................................................................................11
2.2 SPECIFIC OBJECTIVES .........................................................................................................11
3. STUDY AREA AND METHODS ...............................................................................................11
3.1 SELECTION OF THE STUDY AREA ....................................................................................11
3.2 NATURAL AND SOCIO-ECONOMIC CONDITIONS OF THE STUDY AREA .............12
3.2.1 Natural conditions .............................................................................................................12
3.2.2 Social and economic conditions.........................................................................................13
3.3 HISTORY OF ACACIA HYBRID PLANTATION ...............................................................14
3.4 RESEARCH METHODS ..........................................................................................................15
3.4.1 Semi-quantitative interview methods .................................................................................15
3.4.2 Data collection methods for the experimental area ...........................................................15
3.5 METHODS OF DATA ANALYSIS .........................................................................................19
3.5.1 Market analysis of wood materials ....................................................................................19
3.5.2 Study on the structure of Acacia hybrid stands .................................................................19
4. STUDY RESULTS AND DISCUSSIONS ..................................................................................26
4.1 THE STRUCTURE OF ACACIA HYBRID STANDS ..........................................................26
4.1.1 Age and trees density .........................................................................................................26
4.1.2 Trees distribution by diameter at breast height (

).................................................28


4.1.4 Determine the main exploitation age .................................................................................32
4.1.5 Market analysis of Acacia hybrid wood materials in Quang Binh province .....................34


4.1.6 Evaluating economic efficiency .........................................................................................35
4.2 DETERMINING TECHNIQUE CRITERIA FOR TRANSFERING ACACIA HYBRID
PLANTATION AND BUILDING TRANSFORMATION THEORY MODELS ......................36
4.2.1. Identifying the methods of transformation cutting ............................................................36
4.2.2. Identifying the time to begin cutting transformation ........................................................36
4.2.3. Identifying the phase between 2 cutting times ..................................................................38
4.2.4. Identifying the cutting times ..............................................................................................40
4.2.5 Identifying the intensity of cutting times ............................................................................40
4.2.6. Identifying the cutting intensity based on the number of trees .........................................41
4.2.7 Identifying the intensity of cutting depend on the stock (

) ............................................41

4.2.8 Identifying the trees that need to be cutting .......................................................................42
4.2.9 Creating theory models of transformation .........................................................................43
4.3 VERIFYING THE THEORY MODELS FOR TRANSFORMATION................................44
4.3.1 The transformation of stand structure ..............................................................................44
4.3.2 The transformation of average diameter of stands ............................................................49
4.3.3 Comparing between transformation and comparison plot. ...............................................50
4.4 PROPOSE TECHNICAL GUIDELINES FOR TRANSFERING ACACIA HYBRID
PLANTATION .................................................................................................................................53
4.4.1 Identification of specific factors of Acacia hybrid stands ..................................................53
4.4.2 Determing technical criteria of cutting..............................................................................53
4.4.3 Designing cutting for transformation ................................................................................54
5. CONCLUSIONS...........................................................................................................................54
6. LIMITATIONS & RECOMMENDATIONS ............................................................................56

6.1 LIMITATIONS ..........................................................................................................................56
6.2 RECOMMENDATIONS ...........................................................................................................56
APPENDIX .......................................................................................................................................61


List of tables

Table 3.1 Age class, site class and density level in the study area.....................................................17
Table 4.1: Statistics of standard cells based on site class, age class of Acacia hybrid in the study
area .....................................................................................................................................................27
Table 4.2: Results of N/

distribution on Acacia hybrid plantation stands age class III and IV ..28

Table 4.3: Results of the correlation between
Table 4.4: Results of of

-

-

on stands age level III ................................30

correlation of each stands at age class III ....................................30

Table 4.5: Results of calculating maturity age for Acacia hybrid of age level III .............................32
Table 4.6: Analysis of Acacia hybrid wood materials in the market ...................................................0
Table 4.7: Average price of Acacia hybrid wood depend on

at present (


) ..................35

Table 4.8: Economic efficiency of Acacia hybrid planted forest .......................................................35
Table 4.9: Economic efficiency of Acacia hybrid planted forest .......................................................36
Table 4.10: Average diamter and horizontal cross section growth of Acacia hybrid stands .............37
Table 4.11: Results of calculating average growth of the stand canopy’s diameter and determine the
time for second cutting of age class III ..............................................................................................38
Table 4.12: Regulations on thinning techniques for growing Acacia hybrid plantations according to
TCVN 11567-1: 2016.........................................................................................................................39
Table 4.13: Time and cutting times for transfering of Acacia hybrid plantation ...............................40
Table 4.14: Intensity of cutting for transformation of Acacia hybrid based on the number of trees of
age class III.........................................................................................................................................41
Table 4.15: Intensity of cutting for transformation of Acacia hybrid depend the stock of age class
III (

...............................................................................................................................................42

Table 4.16: Transformation of average diameter of Acacia hybrid stands in transformation plots ..49
Table 4.17: Transformation of average diameter of Acacia hybrid stands in comparison plots.......49
Table 4.18: Comparing ̅ of Acacia hybrid stands between transformation and comparison plots
............................................................................................................................................................51
Table 4.19: Testing homogeneity of ̅ in 2 years bet transformation and comparison plots. ........51


List of figures
Figure 3.1: The map of transformation and comparison plots distribution ........................................18
Figure 3.2: Diameter of timber technology ........................................................................................21
Figure 3.3: Horizontal cross section of stand belongs age class III ...................................................22
Figure 4.1: Results of N/


distribution at stand plot 3E and 4D ...................................................28

Figure 4.2: Results of

-

correlation at stand plot 3A and 3B ................................................30

Figure 4.3: Results of

-

correlation at stand plot 3A and 3B.................................................31

Figure 4.4: The chain of wood material products ..............................................................................34
Figure 4.5: Determining cutting trees for transformation in horizontal cross section ......................40
Figure 4.6: Horizontal cross section of Acacia hybrid plantation after cutting for transformation ...43
Figure 4.7: Results of comparing

distribution at before cutting transformation (in 2016) and

after cutting transformation (2018) ....................................................................................................46
Figure 4.8: Results of comparing
Figure 4.9: Comparing between

distribution in 2016 and 2018 in comparison plots .........48
distribution of the stands in transformation plots and

comparison plots ................................................................................................................................50



List of Abbreviations

TSFE

Truong Son Forest Enterprise

PRA

Rapid Rural Appraisal

RRA

Participatory Rural Appraisal

MONRE

Ministry of Natural Resources and Environment

MARD

Ministry of Agriculture and Rural Development

FD

Forest Department

DARD


Department of Agriculture and Rural Development

LDFI co., Ltd

Long Dai Forestry-Industry one member co., Ltd

SPs

Sample plots

FSC

Forest Stewardship Council
The height of trees
Diameter at breast height

D

Diameter

N/

Diameter distribution follows the number of trees
The correlation between the height and diameter of the trees
The correlation between the canopy and diameter of the trees


ACKNOWLEDGEMENT

This thesis was completed at the Vietnam National University of Forestry follows

undergraduate training programs in this course 2014-2019, natural resources management major
(Advanced Education Program). This major was developed in collaboration with Colorado State
University, USA. During the implementation and completion of the thesis, the author has received
the support of the School-Board of University, Faculty of Silviculture, Faculty of Forestty and
Environmental Management that precious and effective help.
The author expresses the sincere and deepest gratitude to Assoc. Prof. Dr. Pham Minh Toai
is an instructor who has spent a lot of time for instructing and giving full attention and providing
valuable materials that related to the thesis for helping the author complete this thesis.
The author would like to thank the leaders of Long Dai Forestry-Industry one member co.,
Ltd, Forestry Department of Quang Binh province to created conditions for the author to study and
complete the thesis.
Finally, the author would like to express sincere gratitude to family members, friends, and
supporters during the years of studying as well as completion of this thesis.
Sincerely, thank you!

Hanoi, Octoberr

, 2018

Students

Nguyen Ngoc Thanh Huyen


ABSTRACT

The purpose of this research is study of the transformation from small timber to
large timber production of Acacia hybrid plantation. This thesis clarified the stand’s
structure of Acacia hybrid and built the models of transformation theories, after that
verificated those theory models. Besides, evaluated economic efficiency of the

transformation. From that, providing solutions to transfer Acacia hybrid plantation
including: transformation criteria; transformation techniques, etc…The research will help
forest owners who want to improve their timber production values as well as contributes to
the wood production industry in Vietnam.

1


1. INTRODUCTION
Along with the continuous growth of the Vietnamese economy in nearly 20 years
of renovation. Forestry sector has many positive changes, especially in the field of forest
plantation and forest product processing that had many positive changes. According to the
Vietnam Administration of Forestry, Ministry of Agriculture and Rural Development
(2018) [14], total of the main export value for forest products in the first 7 months reached
$ 5.025 billion, equivalent to nearly 56% of the year plan, accounting for 22.6% of total
value of the agricultural exports. The export value of forest products in 7 months was
estimated at 3.77 billion USD. Particularly, export value of wood and wood products
reached 3.52 billion USD. In 7 months, the main export value of forest products has kept
the average growth rate over 14% with the same period in 2017. Meanwhile, the total value
of wood and wood products imported reached 1.24 billion USD, only slightly increase
0.4% with the same period in 2017. The reason is that organizations and individuals have
prepared material forest areas to ensure production and quality to provide the wood
processing industry for export. In particular, the use of large timber production models is
important for this success.
Prior to that, Tran Van Khoi (2018) [39] affirmed "The development of large
timber forests not only brings high economic benefits to households but also reduces
erosion, contributing to protect the ecological environment and responding to climate
change". Therefore, planting of large timber forests is an indispensable trend of the forest
plantation business of the forestry sector in Vietnam.
Since 2008, the State has adopted policies to encourage farmers to grow large

timber production forests in accordance with Decision 147/2007/QD-TTg to increase
income for forestry workers, especially mountain people. It also contributes to protecting
the ecological environment (Tran Van Khoi, 2018) [39]. Up to now, after 10 years of
implementation, the movement of growing large timber production has been developing
widely, initially created jobs for tens of thousands of rural workers and bring income to
planters.
Typically for the application of this model are the provinces: Thanh Hoa, Yen Bai,
Tuyen Quang, Lao Cai, Quang Nam etc…For example, according to the Vietnam
agricultural news (2017) [38], Thanh Hoa province set a target to 2020. It will established
and developed stably 56,000 ha of large timber business area. This implementation
progress is very positive. Through the overall review, the province has expanded the area

2


to 40,500 hectares (39,300 hectares for newly planted and 1,200 hectares for
transformated).
In Quang Binh province, Pham Hong Thai, Leader of FPD (2018) [33], said: "To
improve the productivity, quality and value of planted forests. Scheme on restructuring of
agriculture in the forestry sector of Quang Binh that has provided many important
solutions, focused on the development of large timber plantations." Therefore, it is urgent
to set up a large supply of timber from plantations.
Acacia hybrid is a fast-growing species with great potential for timber supply in
Quang Binh province with a total area of 14,749.48 ha. Thus, if we proceed to transform
these areas from the target of supplying small timber into large timber supply forests
through the application of silvicultural techniques, then in a short time we will have an
important supply of timbers that meets the market’s demand. However, transformation can
not take place et all site class, age class but only at a given site and age class.The
identification of silvicultural measures for proper transformation that has important
implications for success or failure and efficiency of the transformation model. These issues

in Quang Binh are currently very little researched.
From this fact, the research on "Solutions for transfering small timber into large
timber production of acacia hybrid in quang binh province" is very necessary since its
results provide a theoretical as well as practical basis for forest transformation in Vietnam
as well as contribute to high economic efficiency, society, environment also improve
livelihoods and incomes of households involved Acacia hybrid plantation in Quang Binh
province's districts.
1.1 Overview of research in the World
1.1.1 Research on forest structure
Studies on the ecological structure of tropical rainforest were conducted by
Richards P.W [9], Baur. G (1976) [2], Odum (1971) [8],..etc. These studies have showed
the point of views, concepts and qualitative descriptions of the species composition, life
forms and forest layer. They are basic research works that are very important and the
system helps us to better understand the structure of forests, especially morphological and
spatial structures.
Baur G. (1976) [2] studied the problems of the ecological basis of the rain forest
business. In which, the author has studied the factors of forest structure, silvicultural
treatments applied to natural rainforest. From that the author has made abundance
summaries of silvicultural treatment principles to provide basic forest for even-aged,
3


uneven-aged forests as well as improve treatment methods for rain forest. Odum EP (1971)
[8] was a complete theory of ecosystem based on ecology term by A. Tansley in 1935. The
concept of the ecosystem is clarified as a basis for studying the forest structural factors that
related from the ecological perspectives.
Richards P.W (1959, 1970) [9] [10] studied morphological structure of tropical
rainforest. According to this author, a prominent feature of rainforest is most plants are
woody. Rainforests often have many layers (most commonly, there are 3 layers, except for
scrub and grassy vegetation). In the tropical rainforest, beside the big trees, shrubs and

grass species. It also have many species of vines with all shapes and sizes, as well as many
auxiliary plants attached to the tree trunk…etc. "Rainforest is actually the most complete
and most elaborate tribe in terms of structure and also the most abundant in terms of
species."
Odum E.P (1971) [8] is not consistent with the idea that there is a dense forest
stratification where the elevation is less than 600 m Puecto Rico and assume that there is
no concentrated clustering on a particular layer.
Li Yiqing (1992) [6] investigated and predicted the structural behavior of the Pinus
yunnaensis diameter on the sample plot and said: Growth conditions of individual trees are
divided into four categories such as growth of 2 cm per year, 1 cm per year, stagnant
growth and death. Two indexes of mean diameter deviation and density are used to model
the diameter distribution. The authors also modeled the diameter distribution of the species
with natural forest objects.
1.1.2 Simulation research some basic forest structure laws
Kraft (1884) [25] introduced in the first time about the hierarchy of forest trees.
The author divides the forest into 5 different levels based on the growth, size and quality of
the trees. Kraft's hierarchy reflects the differentation of forest trees. The advantage of this
hierarchy is that it is clearly decentralized, simple and easy to apply, but only suitable for
pure forest. Sampion Gripfit (1948) [25] in the study of Indian natural forests and moist
tropical forest in the West of Africa proposed the classification of forest trees into five
levels based on the size and quality of forest trees.
The law of diameter distribution follows the number of trees (N/ ) is the basic
and most important rule of the stand. There have been many authors describing this rule,
which may lead some authors to the following works:
Burkhart (1974) [12] used the Beta function, Bliss, and Reinker (1964) [3] used to
the standard logarithm function,...etc. Using this function or another function to represent
4


the structural rule depends on experiences of individual authors as well as the different

plant species and actual measurement data. Beacause the diameter of forest trees increases
with age, the diameter distribution of forest stands is also change with age.
The height and diameter of the stem are always closed. This is one of the fundamental and
important structural laws. Many authors have used mathematical methods to find these
rules: Naslund, M (1992) [26]; Prodan (1944) [26]; Assmann, E (1936) [26]; Meyer, H.A.
(1952) [7]. They proposed the following equations:
;
;

;

Forest canopy is a division decided on the growth of forest trees. Ionikas (1980) [26];
Lebedinski (1972) [26] used and measured foliage volume to study forest productivity.
Through the study, many authors have come to the conclusion that the canopy diameter
and stem diameter have a close relationship are same as Zieger's; Erich (1928) [26],
Comer, O.A.N; Depending on the species and the different conditions, this relationship is
expressed differently, but the most common is the linear equation:

Quantitative forest structure studies are strongly developed when mathematical
functions are used to simulate the forest stand structure. Rollet B. L (1971) [32]
demonstrated the relation between height and diameter by regression functions,
distribution of diameter at breast height, canopy diameter by probability distributions.
Balley (1973) [13] used to Weibull function to model the diameter structure of Pinus
species.
1.1.3 Research on technical elements related to forest transformation
 Growth and productivity
According to V.Bertalanfly (wenk, G.1990) [26] growth is an increase of some
quantity due to the result of the assimilation of a living thing. Thus, growth is associated
with time and is often referred to as the growth process. Burkhart (1982) [4] summarized
three research directions for growth for even-aged forest is the study of full stand, the size

and study of trees.
For research towards full stands will research the relationship between the growth
indicators such as stock/ha, yield/ha,…etc. The factors that make up it, such as the stand
age, the average diameter of the stand, total horizontal area/ha, density, land allocation
index...are a great interest. In the early XX century there was a set of graphical outputs

5


(Missulations Publication 50 - led by Burkhat, 1982) [4]. The first multiple-correlation
equation was used by Markiney and Chaiken (1959) [4] to estimate the yield of Lobelly
pine forest (cf. Burkhat, 1982).
⁄

(

Where: Y is the stock/ha; A forest stand age; SDI is the density; S is the land level
index and C is the horizontal group of pine forest.
Density is an important factor in the growth and productivity of forests. In the results of
Pinus patula, Alder (1980) [1] concludes that when the density decreases, the increase in
the diameter of the forest trees increases while the stock and horizontal forest cover
decreases.
 Structure of the stand
The rules of the structure are important and the authors focus on research is the law of
distribution of trees by diameter, the law of distribution of trees by height, correlation
, correlation

,…etc.

Study on the correlation between height and trunk diameter Tovstolesse, D.I (1958) [24]

study correlation

based on site class and age. To establish relationship

many authors have suggested the use of different types of math equations but the most
common form of linear equation is:

. Within the scope of the topic, the

author acknowledges the conclusions of the previous authors on the correlation law to
concretize the content of the study.
 Forest output
The study of the distribution of forest yields by size, usually applied to diameter
sizes. This research has flourished since the 1960s with such authors as Burkhat (1974)
[12],...etc. On each diameter sizes, take values for height, volume, number of trees,…etc
by the rules of correlation or median statistics or using pre-set forms. The core of this
research methodology is to determine the density distribution function for the diameter
classes during the forest's time-varying process.
1.1.4 Research on cutiting and nurturing the forest
Forest transformation is silvicultural impact on the current stand to transform it into
predefined stands to achieve business goals in the future. Thus, the actual forest
transformation is cutting and nurturing the forest. It’s applied to young and middle-aged
stands for the purpose of improving the stand growth and wood quality.

6


Thinning is one of the technical means of nurturing the forest. The objectives of
thinning are defined by business purposes to improve product quality, increase yields,
improve beneficial functions of the forest, and maintain a favorable ecological regime for

forest trees. and develop in the direction that business purpose poses.
The results showed that thinning improves tree growth (Harri Makinen and Antti Isomaki,
2004 [5]; Suzane et al, 2003 [11] ), however, depending on species and time pruning that
the stands have different responses after thinning.
US Foresters (1925) [26] argued that: Forest transformation is the process of
applying silvicultural principles and business methods to achieve business goals. They
have been tied up in five categories:
- Cutting off, cutting down trees, not used, secondary.
- Free cutting, cutting up the trees on the upper storey.
- Cutting thin pruning, like tight growth.
- Cutting revised, cut the tree weak, shape and poor growth.
- Cutting waste timber, cutting down the damaged trees.
1.2 Overview of research in Vietnam
1.2.1 Research on forest structure
According to Phung Ngoc Lan (1986) [38], the forest structure is a concept used to
describe the compositional arrangement of the components that make up the forest
vegetation community following to space and time. Forest structure includes ecological
structure, morphology and age structure.
Tran Ngu Phuong (1970) [40] has showedn the structural characteristics of forest
vegetation in Northern Vietnam based on the results of the Baseline Survey and Forest
Situation in North Vietnam, 1961-1965. The first structural element was studied is a
combination and through that a number of rules of forest ecosystem development are
discovered and applied to production practices.
Thai Van Trung (1963, 1970, 1978) [38] introduced a hierarchical model of the
structure, such as: the canopy spread (A1), the dominant layer (A20), understorey (A3),
shrub layer (B), grass layer (C). The author divides Vietnam forest vegetation types into 14
types. As such, forest structure factors are thoroughly employed in forest classification
from an ecological point of view of arising populations.
According to studies by Ho Viet Sac (1984) [18], there is no exploitation of growth
among the main species of Dipterocarp forests. Different growth patterns occur only in


7


different sites. Ho Viet Sac was based on the relationship ⁄

to distinguish four levels

of productivity of Dipterocarp forest including: good growth, good, medium and bad
growth.
1.2.2 Simulation research some basic forest structure laws
In recent decades, quantitative structure studies have been studied at different levels
by many Vietnamese scientists with the purpose of building the scientific basis for rational
silvicultural solutions. Tran Van Con (1990) [401] conducted the study some structural
characteristics and dynamics of the Central Highlands ecosystem. The author has come to
some conclusions: The structure of the Dipterocarp forest can be modeled by Stocker and
Bergmann (1977) [26] by

(

(

, from which the author divides the 16

common forest types Diphtheria; N/D structures of the Dipterocarp forest follow the
Weibull distribution rule.
Modeling of

diameter structures has been investigated by several authors and


presented in different probability distributions, highlighting the work of authors such as
Dong Si Hien (1974) [17] using the Meyer function and the Poisson curve system to
determine the empirical distribution of standing trees in Vietnam.
Tran Van Con (1990) [41] applied the Weibull function to simulate the diameter
structure of Dipterocarp forests in Dak Lak; Le Sau (1996) [23] used the Weibull function
to simulate the diameter distribution law, height in Kon Ha Nung, Tay Nguyen.
1.2.3 Research on technical elements related to forest transformation
 Growth and productivity
Research on growth and productivity is one of the most important field in Vietnam to
improve the economic efficiency of plantation production.
Le Hong Phuc (1992) [22], after studying the growth and yield of biomass of 3-leaf
pine plantation in Da Lat - Lam Dong, has introduced some rules of growth, biomass,
productivity of the Pinus kesiya plantation on some of the main land levels, with
continuous age classes in the area. On that basis proceed to make graphs of volume,
biomass and determine thinning for Pinus kesiya in Dalat.
Research on the growth of Pinus massoniana, Vu Nham (1988) [47] has set up a
land supply chart and a volume chart of two forest timber business elements to serve the
production schedule. Huynh Duc Nhan (1994) [19] evaluated "The growth and
development of four major plantation species in paper pulp areas 1989 - 1994" give some
conclusions: The fastest growing and most productive is Eucalyptus urophylla, followed

8


by Eucalyptus camaldulensis and Acacia mangium, the lowest is the Caribbean Pine. In
general, all four species have large annual growth.
 Structure of the stand
The law of distribution

⁄


is studied by many scientists. In the pure species

stand, both young and middle-aged, Trinh Duc Huy (1987, 1988) [26], Vu Nham (1988)
[47], Vu Tien Hinh (1990) [48], Pham Ngoc Giao (1989, 1995) [34] [35], etc...agree that
the curve of the distribution rule

⁄

is left-sided and can be used as a mathematical

function such as Weibull function, Scharlier function,...etc.
In the study of the relationship between height and tree diameter, Vu Nham (1988)
[47] constructed a model of the height curve for Pinus massoniana in the Northeast.
On the correlation between canopy diameter and diameter at breast height: Vu Dinh
Phuong (1985) [46] confirmed the intimate relationship between the canopy diameter and
diameter at breast height in the form of the first equation.
 Forest output
Nguyen Ngoc Lung, Dao Cong Khanh (1999) [31] conducted comprehensive and
comprehensive studies on the growth and yield of Pinus kesiya plantations in Vietnam. The
authors conclude that Pinus kesiya grows fast, strong at 3 to 9 years. Factors such as
diameter, height, canopy diameter are grow in sync. The general growth rule is the
individual is highly dependent on height and density.
Dang Van Thuyet et al (2010) [15] on the basis of applying the experimental
method studied about technological transformation of 5 major tree species in production
forests of

Vietnam include: Acacia hybrid, Acacia mangium, Acacia auriculiformis,

Eucalyptus, Caribbean pine for 3 ecoregions are North East, North Central and South East,

from the target of supplying small timber forest into large timber forest. Research results
showed that Acacia hybrid forest is transformed into large timber forest, it is necessary to
plant the initial density of 1,300 - 1,600 trees/ha. When trees reach the fifth year, should be
cut bad trees, poor quality and keep 600 - 700 trees per hectares. After that, application of
100- 200g NPK + 100-200g of microbiological fertilizer per tree will increase 18 - 25
/ha.
1.2.4 Research on cutiting and nurturing the forest
In pure plantation forests, there was Acacia hybrid in Binh Duong province. After
thinning, both the diameter and the height of the stand are better than no thinning. After 2

9


years of experiments, the highest intensity thinning (858 trees/ha) gave the best growth
compared to 1,333 trees/ha (Nguyen Huy Son et al, 2006) [28].
Nguyen Huy Son (2006) [28] reported that thinning affects the growth of Acacia
hybrid, between planting density and pruning techniques have had a clear mutual effect on
the diameter growth. Research results for Acacia hybrid after 1 year old showed that:
Planted forest with densities of 1,330-1,660 trees/ha tended to predominate at the density
of 2,500 trees/ha; Thinning tends to grow better than no thinning; Thinning ½ body down
grower than thinning from ¾ stem downward. Thus, for young Acacia hybrid, thinning
will reduce the growth of the trees.
1.2.5 Research on Acacia hybrid
In Vietnam, the natural hybrids between Acacia mangium and Acacia
auriculiformis. It was discovered in 1992. It appears sporadically in some places in the
South such as Tan Tao, Trang Bom, Song May, Tri An and Ba Vi in the North. From 1993
up to now there have been many studies on acacia hybrid. There is a lot of research on
forestry and silviculture.
Research on the natural hybrids between A. mangium and A. auriculiformis of Le
Dinh Kha, Nguyen Dinh Hai, Pham Van Tuan (1993) [20], Ho Quang Vinh, Tran Cu

(1995, 1997) [42]. Acacia hybrid is a form of natural breeding between A. mangium and A.
auriculiformis. It has many intermediate morphological features between A. mangium and
A. auriculiformis. Acacia hybrid has distinct advantages in terms of growth compared to A.
mangium and A. auriculiformis, the volume of Acacia hybrid wood can be 4.6 - 6.8 times
higher than A. mangium, 2.5 times higher than A. auriculiformis.
Research by Le Dinh Kha et al. (1997) [21] also suggests that seedlings of Acacia
hybrid should not be used for new plantations. F1 of Acacia hybrid has intermediate form
between A. mangium and A. auriculiformis and relatively homogeneous. At the same time,
there is a clear cross-fertilization effect on the growth of the parents and other
characteristics of superiority. In F2 generation of Acacia hybrid are manifested degenerate
and quite distinctly dissociate into different types of plants.
Silviculture and Forest Inventory have some typical researches:
Nguyen Trong Binh (2005) [32] "Establishing a temporary growth process for Acacia
hybrid forest", the author has studied the structure of Acacia hybrid growth in large
localities in the whole country and successfully gained step to meet the business of Acacia
hybrid plantation in Vietnam.

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Tran Xuan Duong (2007) [43] "Studying the structure and growth of forest stands,
as a basis for planning site class of Acacia hybrid forest in Quang Tri to serve forest
inventoring and forecasting", research on the structure, output as well as productivity and
set up the site class for Acacia hybrid forest in Quang Tri province.
Nguyen Duy Phong (2008) [42] has inherited the methodology of studying the
dynamics of plantation structures to describe the evolution of forests over time or with age
for acacia hybrid stands. Initially, a number of structural dynamics models have been
successfully constructed for the basic survey elements that represent the size of the tree.
The above is a brief introduction to the issues related to research content of the thesis.
They will be inherited during the collection process for research purposes.

2. GOALS AND SPECIFIC OBJECTIVES
2.1 Goals
To provide theoritical basics for transfering plantation forest from small to large
timber purposes in order to contribute to achieving the goal of improving economic
efficiency - environment towards sustainable forestry economy.
2.2 Specific objectives
(1) To study of stand structure of Acacia hybrid.
(2) To create and verify the theory models for plantation’s forest transformation.
(3) To evaluate economic efficiency of the transformation.
(4) To propose solutions for transformation Acacia hybrid plantation from small to large
timber forest.
3. STUDY AREA AND METHODS
3.1 Selection of the study area
The study area was selected based on the following criteria:
 Large Acacia hybrid plantations.
 Acacia hybrid is grown at different age class, distributed fairly evenly on good and
medium soil layers, suitable for transformation conditions.
 Forests are less affected, still retain the age structure, density appropriate.
 Having favorable market conditions.
 Forest owners are keen to transform acacia forests with the goal of supplying small
timber into large timber supply forests.
Based on the sources of information, the data collected showeds that Truong Son
Forest Enterprise belongs to Long Dai Forestry-Industry one member co., Ltd in Truong

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Son commue, Quang Ninh district, Quang Binh province meets the above criteria, so the
author has chosen to serve the investigation.
3.2 Natural and socio-economic conditions of the study area

3.2.1 Natural conditions
3.2.1.1 Geographic location
The Truong Son Forest Enterprise is located in mountainous areas of Truong Son
commune of Quang Ninh district; Phu Dinh Commune and Viet Trung Farm Township of
Bo Trach District with 39 sub-zones. The geographic coordinates are as follows:
- Latitude: From 17°10'00'' N to 17°40'00'' N.
- Longtitude: From 106°00'00'' E to 107°00'00'' E.
In the East is bordered by Ba Ranh Protection Forest Board and Viet Trung Farmer
Village, Phu Dinh Commune, Bo Trach District. In the West borders with Phong Nha-Ke
Bang National Park and Lao PDR. In the South borders with Khe Giua Forest Enterprise,
Truong Son commune. In the North borders with Phong Nha - Ke Bang National Park.
3.2.1.2 Topography and soil
3.2.1.2.1 Topography
The whole area of the TSFE is in the North of Truong Son Mountain Range with
the characteristic features: The mountain runs in the direction of northwest to southeast,
high slope and rugged terrain, divide strongly, complex with many streams, waterfall, etc.
The forest area can be divided into two areas as follows:
 Mountain land
Mountainous terrain accounts for 64.6% of the area, including high mountains and
low mountains, most of them are natural forest land. This area consists of many high
mountain ranges of 400 to 600 m and an average slope of 250. This type of terrain is
mostly natural forest, which is the largest concentration of forest resources of the TSFE.
 Rocky mountains
Rocky mountains are concentrated in the South and Southwest of the TSFE. The terrain
here is quite complex with many high peaks and slopes interspersed with narrow valleys.
3.2.1.2.2 Soil
Land in the area of the TSFE is mainly formed by feralitization, with the material
being sandstone, granite. There are also sloping land, humus in limestone valleys and
alluvial soil along streams.


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The material in the area consists of four main types of rocks: granite, sandstone,
claystone and limestone. Based on the material foundation of the parent rocks, topography,
elevation,...etc. In the area can be divided into two main soil types:
 Lowland feralite soils develop on granite, sandstone, clay, limestone.
 Medium mountainous humus soils develop on granite, limestone.
3.2.1.3 Climate and hydrography
3.2.1.3.1 Climate
TSFE is influenced by tropical monsoon climate. The climate in the year is divided into 2
distinct seasons: dry season from March to August, rainy season from September to
February of the next year.
 Temperature: The annual average temperature is 23 - 24°C, the absolute maximum
temperature is 39°C - 40°C, the absolute minimum temperature is 9°C.
 Wind: In this area is affected by two major monsoons. North East monsoon operated
from October to March in the next year. Low air temperature, high humidity, often
accompanied by rain. Average wind speed is 2 - 4 m/s. Southwest monsoon operated
from April to September. Due to being obstructed by the Truong Son range, the
denaturation, making the air dry and hot, high temperature, low humidity.
 Precipitation, humidity: Total annual rainfall is from 2,500 to 3,000 mm, precipitation
rises with height. It is concentrated with high intensity. Railfall distribution is not
uniform in the year usually concentrated in October and November, accounting for
about 60 - 70% of annual rainfall. Air humidity: The average humidity is 86%, it is
lowest in southwesterly winds, sometimes below 70%.
3.1.1.3.2 Hydrography
This area is located in the watershed of the CoTang river, upstream of the Long Dai
river and upstream of the Dinh river, with a network of rivers and streams spread
throughout the region. Streams and ravines are generally characterized by short, steep and
narrow, with many rapids. Flow depends on the season, the ability to transport waterways

difficult.
3.2.2 Social and economic conditions
3.2.2.1 Population, ethnic
 Population: Total number of households: 4,047 households. Total number of people:
16,615 people in which: Male have 8,184 people that accounted for 49.2% of the
population and female 8,431 people accounted for 50.8% of the population.

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 Ethnic: There are two ethnic groups (Kinh and Van Kieu) living in the area. In which:
Kinh ethnic group: 3,596 households with 13,897 people, accounting for 83.6% of the
total population; Van Kieu ethnic group: 451 households with 2,718 people, accounting
for 16.4% of the total population.
3.2.2.2 Infrastructures and social services
 Infrastructures: Ho Chi Minh Highway, the western branch runs through the territory of
TSFE with the length of 40 km, the concrete road width of 6.0 m, good quality. The
provincial road 11 from Dong Hoi - Truong Son through the TSFE with the length of
21 km, the road bed width of 4.0 m, good quality. The fishbone road system in the
forestry area is 52.0 km in length, mainly the old transportation route, most of which
have been degraded and seriously damaged. All roads are dirt roads, only accessible
during the dry season.
 Social services: The quality of teaching and learning is renewed. They get to school at
the right age. Additional enrichment classes and advocacy for children in universal
education. Most of the distant ones have been universalized to grade 3, capable of
reading and writing proficiency. In the summer, after gaining general education,
students are supplemented with knowledge to graduate from primary school.
3.3 History of Acacia hybrid plantation
The total area of Acacia hybrid plantation of the Long Dai Co., Ltd is over 6,214.43
ha. The selection of the study area not only the area of the forest, but also ensures that there

are more areast distributed at different age class. Because this company has Acacia
plantation that were planted since 2004. Beside, planting method is pure plantation, only
have Acacia hybrid. So that meets the requirements of this study. Acacia hybrid density
was initially from 2,000 to 2,500 trees/ha. Because of most forest owners are households
who can not afford to pay for taking care and thinning. Thus, the take care and thinning are
not usual, only reached 300 ha that werw took care and thinning reached 4.8%. Because
there is no take care, most seedlings were eaten by deers or die by a lot the storms. This led
to the density at the beginning of this study was only 860 to 2,200 trees/ha. This thesis has
selected areas have relatively stable taking care to serve the survey.

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3.4 Research methods
3.4.1 Semi-quantitative interview methods
Use of participatory rural appraisal (RRA) and participatory rural appraisal (PRA)
methods, with the main tools being interviewing different stakeholders to collect and verify
information. The interviewees included:
 Technical and managerial staff of Department of Agriculture and Rural Development
(DARD), Forestry Department of Quang Binh province on Acacia hybrid plantation,
applied techniques, market, orientations of the province.
 Leaders and forestry staffs of Quang Ninh district on the current status of Acacia
hybrid plantation in the district, situation of growth, distribution, technique and use.
 Leaders and technical staffs of LDFI co., Ltd - Units directly implements this study
about characteristics of Acacia hybrid plantations in the area such as age, site class,
distribution, density, management, use, market,...etc.
 Local people involved in acacia plantation development of the area:
- Households with Acacia hybrid plantation area of 5 - 10 ha.
- Households with Acacia hybrid plantation area of 2 - 5 ha.
- Households with Acacia hybrid plantation area of less than 10 ha.

In addition to gathering and verifying information through interviews with
stakeholders, there is a need to understand the consensus in transfering Acacia hybrid from
the target of supplying small timber into large timber. This is the basis for implementation
and transfer of technology.
3.4.2 Data collection methods for the experimental area
3.4.2.1 Forest species selection
Acacia hybrid stands at 5-15 years of age; The current density is over 600 trees/ha;
The forest has not been impacted, but the forest stands still retain the basic structure of the
planted forest. The stands are relatively evenly distributed at different levels of soil,
including good and medium site class: Site class I, II and III.
3.4.2.2 Set up sample plots
Previous research results showed that the age of maturing large timber technology
provides the processing industry of Acacia hybrid is 10-15 years old. The survey results
showed that the current density of stands with different age ranges from 600 to 2,500
trees/ha. So the Acacia hybrid plantation was classified into 5 age class, 3 levels of density

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and on 3 site class for selecting data. The author has inherited the age and site class by
Nguyen Huu Thien (2012) [26].

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Table 3.1 Age class, site class and density level in the study area
Age class

Age


Site class

Density levels
(Trees/ha)
600 ÷ < 1,500

III

5÷<7

I - II - III

1,500 ÷ < 2,000
2,000 ÷ 2,500
600 ÷ < 1,500

IV

7÷<9

I - II - III

1,500 ÷ < 2,000
2,000 ÷ 2,500
600 ÷ < 1,500

V

9 ÷ < 11


I - II - III

1,500 ÷ < 2,000
2,000 ÷ 2,500
600 ÷ < 1,500

VI

11 ÷ < 13

I - II - III

1,500 ÷ < 2,000
2,000 ÷ 2,500
600 ÷ < 1,500

VII

13 ÷ < 15

I - II - III

1,500 ÷ < 2,000
2,000 ÷ 2,500

On that basis, the topic of setting up the system of temporary Sample plots and
plots of positioning criteria is specified as follows:
 Sample plots: Using to measure the investigative factors for the construction of
theoretical models. Area of one plots is 500 m², with 50 sample plots are arranged on 5
age, 3 site class and 3 levels of density. There are 10 sample plots for each age class

and divided on age and site class.
 Transformation and comparison plots: Using to measure survey data and set up
transformation models. There are 10 plots with 1000 m² of each plots.The time of
cutting for transformation are 2015 and 2016. The map for distributing transformation
and comparision plot are showed in figure 3.1

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Figure 3.1: The map of transformation and comparison plots distribution
In the Sample plots:
 Measuring the species growth indicators includes:
- Diameter at breast height (

), base diameter (

) with diameter glass clamp

with accuracy to cm.
- Determine the height of the tops (

), the height under the branches (

) with

high measurement Blumleiss.
- Determine the diameter of the canopy with the tape measure.
- Describe the characteristics of the experimental design area: Sharacteristics of
fresh shrubs, slope, elevation, canopy,...
 Identify standard trees for felling to analyze stem (using secondary data from forest

owner:
- From SPs data, divide into 3 levels with the same horizontal diameter. At each
diameter class, determine the average standard tree (tree diameter close to the
average diameter of each diameter class) and cut down the standard tree. Thus,
each SPs cutting down 3 trees, the total number of trees to cut down 3 trees x 50
SPs = 150 trees.
- Sampling of wood cutting boards to analyze stem:
For each standard tree, measuring the diameter of the bark and without the bark
according to the 1m segment location at different age class for Identifying the

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