MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAM NATIONAL UNIVERSITY OF FORESTRY

STUDENT THESIS
EVALUATE THE GROWTH CAPACITY OF SOME INDIGENOUS
TREE AFFORESTATION MODELS AT THE CENTER OF
ENVIRONMENTAL RESEARCH IN HOA BINH PROVINCE

Major : Natural Resources Management
Code : D850101

Faculty

: Forest Resources and Environmental Management

Student

: Dao Duy Duc

Student ID

: 1453091252

Class

: K59A – Natural Resources Management

Course

: 2014-2018

Advanced Education Program Developed in collaboration with
Colorado State University, USA
Supervisor: Dr. Ha Quang Anh

Hanoi, October, 2018


ACKNOWLEDGEMENT
To accomplish and complete this thesis, I have received a great deal of support from
organizations and individuals. First of all, I would like to send my sincere thanks to the
School Management Board, teachers in the Forest Resource and Environmental Management
Faculty for helping me with my studies and training at the school.
In particular, I would like to express my deep gratitude to Dr. Ha Quang Anh for his
great guidance in the process of implementing this thesis.
Besides, this thesis could not be completed without help of the officers, especially Mr.
Tran Trung Thanh – director of the Center of Environmental Research Hoa Binh city who
helped me in the process of surveying, collecting data and assessing the afforestation situation
at the research center.
Finally, I would like to send my most sincere thanks to my family, relatives and
friends who have encouraged and helped me through the process of completing this thesis.
Although there have been a range of attempts to complete the project, due to the
limited time and knowledge, the thesis is inevitable shortcomings. So, I hope that I could
receive the attention and comments of teachers and friends to complete the course.
Hanoi, September 1, 2018
Student

Dao Duy Duc

i



TABLE OF CONTENTS
ACKNOWLEDGEMENT ........................................................................................................ i
TABLE OF CONTENTS .........................................................................................................ii
ABSTRACT ............................................................................................................................vii
CHAPTER 1 GENERAL REVIEW OF THE RESEARCH ISSUE ................................... 1
I.

Introduction ....................................................................................................................... 1

II.

GENERAL REVIEW OF THE RESEARCH ISSUE ................................................ 3

2.1.

In the world .................................................................................................................... 3

2.1.1.

Indigenous plants in the world ................................................................................... 3

2.1.2.

Basis researches ......................................................................................................... 3

2.2.

In Vietnam ...................................................................................................................... 4


2.2.1.

Indigenous plants in Vietnam ..................................................................................... 4

2.2.2.

Basis researches ......................................................................................................... 5

2.2.3.

Practical researches ................................................................................................... 5

CHAPTER 2 OBJECTIVES, CONTENTS, RESEARCH SUBJECT, LIMITS AND
RESEARCH METHODS ........................................................................................................ 7
2.1.

Objective ......................................................................................................................... 7

2.2.

Contents .......................................................................................................................... 7

2.3.

Research subject ............................................................................................................ 7

2.4.

Limits .............................................................................................................................. 7


2.4.1.

Place ........................................................................................................................... 7

2.4.2.

Time ............................................................................................................................ 8

2.5.

Materials and methods .................................................................................................. 8

2.5.1.

Materials .................................................................................................................... 8

2.5.2.

Methods .................................................................................................................... 13

ii


CHAPTER 3 NATURAL, SOCIO-ECONOMIC CONDITIONS OF RESEARCH
AREA ....................................................................................................................................... 18
3.1.

Natural conditions ....................................................................................................... 19

3.1.1.


Geographical location .............................................................................................. 19

3.1.2.

Topographic ............................................................................................................. 19

3.1.3.

Climate ..................................................................................................................... 20

3.1.4.

Hydrological ............................................................................................................. 20

3.1.5.

Geology, soil ............................................................................................................. 21

3.1.6.

Forest resources ....................................................................................................... 21

3.2.

Social and economic conditions .................................................................................. 22

3.2.1.

Population, ethnicity and labor ................................................................................ 22


3.2.2.

Infrastructure ............................................................................................................ 23

CHAPTER 4 RESULTS AND DISCUSSION ..................................................................... 24
4.1.

Growth criteria ............................................................................................................ 24

4.1.1.

Height growth (Hvn) .................................................................................................. 24

4.1.2.

Diameter at breast height – DBH (D1.3) ................................................................... 27

4.1.3.

Canopy diameter (Dt) ............................................................................................... 30

4.2.

Trees’ quality ............................................................................................................... 32

4.3.

Survival rate ................................................................................................................. 36


4.4.

Vegetation cover and shrubs ...................................................................................... 37

4.4.1.

Vegetation cover and shrubs in Acacia mangium model ......................................... 38

4.4.2.

Vegetation cover and shrubs in Acacia auriculiformis model ................................. 39

CHAPTER 5 CONCLUSION, DRAWBACKS AND PROPOSAL ................................... 41
5.1.
5.1.1.

Conclusion .................................................................................................................... 41
Some growth criteria ................................................................................................ 41

iii


5.1.2.

Trees’ quality ............................................................................................................ 42

5.1.3.

Survival rate ............................................................................................................. 42


5.1.4.

Vegetation cover and shrubs .................................................................................... 43

5.2.

Drawbacks .................................................................................................................... 43

5.3.

Proposal ........................................................................................................................ 43

REFERENCES
APPENDIX

iv


LIST OF TABLE
Table 4.1: Average height growth of the investigated species ................................................. 24
Table 4.2: Diameter at breast height growth – DBH of the investigated species ..................... 27
Table 4.3: Canopy diameter growth of the investigated species .............................................. 30
Table 4.4: Trees quality in different time period ...................................................................... 32
Table 4.5: Average quality of each species in all period .......................................................... 33
Table 4.6: The survival rate of tree species by age .................................................................. 36
Table 4.7: Vegetation cover and shrubs in Acacia mangium model ........................................ 38
Table 4.8: Vegetation cover and shrubs in Acacia auriculiformis model ................................ 39

v



LIST OF FIGURES
Figure 2.1: Overview of the project approaching method ........................................................ 14
Figure 4.1: Average height (Hvn) among different species ....................................................... 25
Figure 4.2: Annual height increase (Hvn) among different species ....................................... 26
Figure 4.3: Erythrophleum fordii ............................................................................................. 26
Figure 4.4: Peltophorum pterocarpum ...................................................................................... 26
Figure 4.5: Diameter at breast height (∆D1.3) among different species .................................... 28
Figure 4.6: Annual DBH (D1.3) increase among different species ........................................... 29
Figure 4.7: Cinnamomum obtusifolium ................................................................................... 29
Figure 4.8: Lithocarpus ducampii ............................................................................................. 29
Figure 4.9: Canopy diameter (Dt) among different species ...................................................... 31
Figure 4.10: Annual canopy diameter increase (∆Dt) among diferent species......................... 32
Figure 4.11: Quality of each species in different periods ......................................................... 35
Figure 4.12: Quality of each species in all periods .................................................................. 35
Figure 4.13: Survival rate of species at 1-year and 6-years of age in Acacia mangium model 37
Figure 4.14: Forest vegetation and shrubs ................................................................................ 40

vi


ABSTRACT
In recent years, the government has launched programs to promote the reforestation of
bare hills and economic forests with relatively good initial effects. However, due to the trend
of economic development, investment capital is limited. Therefore, the plantation programs in
our country focus on fast growing species such as Acacia, Eucalyptus and Bodhi. These
species only meet the economic objectives but not the requirements of protecting the
ecological environment due to the low sustainability. In the forestry development strategy,
forestry has focused on the conservation and development of indigenous tree species. Today,
it is known that the great benefits that indigenous tree species provide are not merely the

provision of specialty forestry products, but also the long-standing evolution of plants should
be highly adaptable to the growing conditions and have high sustainability, therefore, planting
them would have many benefits. For that reason, I undertake this research: “Evaluate the
growth capacity of some indigenous tree afforestation models at the center of the
environmental research in Hoa Binh province”. The research was conducted by examining
the area which indigenous trees are planted at the center. After preliminary evaluation, two
standard sample plots of 500 m2 were established on two different supporting species which
are Acacia mangium and Acacia auriculiformis. The results illustrate that 5 species in two
models grow well under the assistance of supporting plants. However, most of the trees
Acacia mangium model were better than that of Acacia auriculiformis in terms of diameter
growth at breast height (D1.3), height growth (Hvn), canopy diameter (Dt), quality and survival
rate. After investigating and analyzing the data, some conclusions have been drawn and
hopefully they could be used to contribute to the elaboration of the scientific foundations,
which shall serve as a basis for proposing solutions for optimizing indigenous trees planting
efficiency.

vii


CHAPTER 1
GENERAL REVIEW OF THE RESEARCH ISSUE
I. Introduction
Forest is a precious resource with multiple benefits for community and society. Forest
is an irreplaceable part of the ecosystem which plays an extremely vital role in human life. At
present, the government restricts the exploitation of natural forests and many regions have
shifted to forest plantation. Provinces and enterprises determine the purpose of speeding up
the economic afforestation in terms of volume and quantity to meet the demand of goods for
society, first of all supplying raw materials for industrial parks and houses. machine, ...
Apart from providing timber, firewood and other forest products, forests play a crucial
role in protecting and maintaining habitats such as regulating climate, regulating water

resources, limiting erosion, mitigating the effects of floods, the absorption of carbon dioxide,
the maintenance and conservation of biodiversity.
Indigenous plants have formed symbiotic relationships with native wildlife over
thousands of years, therefore offered the most sustainable habitat for wild animals. A species
is considered as indigenous if it exists naturally in a particular region, ecosystem, or habitat
without human intervention.
It is challenging for some indigenous plants to adapt to the environment such as harsh
climates or special soil conditions. Although those plants only exist within a very limited
range (endemism), others can live in diverse areas or by adaptation to different surroundings.
Research has found that insects depend on indigenous plants.
An alternative but potentially conflicting usage is to describe plants (and animals) that
are indigenous to a geographical area, even if they are known to have self-introduced in
historical times.

1


Indigenous plants help the environment the most when planted in places that match
their growing requirements. They could thrive in the soils, moisture and weather of your
region. That means less supplemental watering, which can be wasteful, and pest problems that
require toxic chemicals. Indigenous plants also assist in managing rain water runoff and
maintain healthy soil as their root systems are deep and keep soil from being compacted.
If planting indigenous species (over 10-years production cycle) instead of other timber
trees such as acacia hybrid, the time for the product longer but the value will be larger. It is
possible to compare the three acacia crops that will take between 23 and 25 years. In the
meantime, if we invest in the planting of indigenous timber species in Group 3 (common
wood for home furniture) Teak, mucilage, hymenoptera ..., the trees have a diameter of about
20 - 25cm and can be harvested with a stock equal to or greater than the acacia hybrids of 7-8
years old. In addition, if the planting of multi-species trees such as pine, black, white fill ...,
the producer will harvest from non-timber forest products for example resin. It is higher than

that of timber in terms of benefit.
Thus, in terms of economic growth of large trees, indigenous trees are at least twice as
good as acacia hybrid. In terms of the area of afforestation of indigenous trees throughout 25
years, the land is continuously covered by vegetation cover and forest canopy; the forest
ecosystem is stable; Acacia hybrid plantation forest is interrupted by two mining operations,
equivalent to 5-6 years of land without sufficient cover, which not only eroded soil but also
affected climate change.

2


II. GENERAL REVIEW OF THE RESEARCH ISSUE
2.1. In the world
2.1.1. Indigenous plants in the world
Indigenous plants are planted to a certain area during geological time. This includes
plants that have developed, naturally occur, or persisted for many years in an area (plants,
flowers, grass and other plants).
Some countries are given good farming conditions, and with it, a number of fruitful
trees, while others are less fortunate. For example, Peru has over 25,000 native plant species.
The country has a wide variety of climates and terrains, ranging from coastal lowlands to the
Amazon rainforest or the Andes Mountains. In the 15th century, the Inca planted over 70
different crops and used a complex of terraces and canals to irrigate saplings.
In contrast, a small island nation of the United Kingdom has a barren native
vegetation. Even the trees planted here at the end of the Ice Age still taste unpleasant. A list of
wild vegetables, fruits and nuts is available for hunting British hunters including chestnut,
blueberry and plum.
2.1.2. Basis researches
E.P.ODUM has many research studies on ecology as the basis for researching forest
ecosystems. This is a very important theoretical basis for the research and development of
silvicultural techniques for tropical forest in the world.

Geoge N Baur (1952, 1964, 1976) has made extensive ecological studies in the forest
business, restoration and management of tropical forests. The author summarizes silvicultural
treatments to bring the same age and unequal forests to tropical forest business in different
continents of the world.
Richards PW (1952), Cantinot (1965) explored the morphology of the forest structure
by describing structural elements that are described in detail, living, slate, stratum.

3


Parde (1961), bottam (1972), Rollet (1979) applied statistical mathematics to study the
structure of forest growth, quantify the rules and at the same time to propose forest measures
development techniques.
2.1.3. Practical researches
The study of the application of techniques for regeneration of indigenous tree species
by different planting methods, adding to poor forests, poorly regenerated forests, etc., to
improve the quality and quantity has been used in many countries such as Nigeria, Congo,
Cameroon, Gabon, ....
In Japan: Kasama Forest Technology Center has established a series of multi-tiered
forest models comprising many different species of forest trees and at different ages, at
different heights in the Tsucuba region (876m high with sea squirts) for both the Japanese
Cedar tree species and the interactions between plant species as well as the environmental
impact of each species has found.
In Taiwan and some Asian countries have developed indigenous plants grown in bare
hills after being planted with coniferous trees, resulting in sustainable mixed forest models
with high productivity and positive effect in protecting the natural environment of the forest
and preventing soil erosion.
2.2. In Vietnam
2.2.1. Indigenous plants in Vietnam
Since the 1970s, our nation has spent more than 40 years researching and using

indigenous trees for afforestation and forestry development throughout the country. We have
obtained valuable results including preliminary selection of nearly 100 plant species,
including 30 internal species, initially meeting the objectives of afforestation and protection
forest plantation (Decision No. 680/1986 of the Ministry of Forestry).
Subsequently, 50-52 indigenous plant species were selected for plantation forest
production that provides large timber, small timber and non-timber forest products (Decision

4


16/2005 of the Ministry of Agriculture and Rural Development). 28 species have been studied
relatively systematically and 50 species have been put into production on different scales.
Nearly 22 species of wood are planted on hundreds to thousands of hectares.
However, according to a World Bank report in 2005, nearly 700 species of globally
threatened plant and animal species in Vietnam are "extremely critical".
The report also points out that the introduction of new plant varieties, especially highyielding hybrids, has reduced both the area and genetic resources of indigenous plant
varieties. More than 80% of indigenous plant varieties are lost in the field after the
modernization movement.
2.2.2. Basis researches
 On forest structure: Many authors have used the mathematical statistics function to
study the structure:
Nguyen Si Tuat (1974), Nguyen Hai Tuat (1986, 1990), Vu Tien Hinh (1990) used
regression and statistical functions to describe the current forest structure in both natural and
planted forests.
Nguyen Van Truong (1983), Phung Ngoc Lan (1986) and Vu Tien Hinh (1987,1988)
studied and found the results to be based on the model of forest with stable yields (on some
key factors).
 On the classification of forest status: there are works by Tran Ngu Phuong (1963),
Thai Van Trung (1978), Vu Biet Linh (1984), and many important achievements. forest
development.

 On ecology: The works of Thai Van Trung (1948) on the characteristics of
mangrove formation in Ca Mau, vegetation cover on the hills in midland mountainous north
(1959).
2.2.3. Practical researches

5


Tran Nguyen Giang (1961-1963 and 1960-1962), Tran Xuan Tiep - Le Xuan Tam
(1963-1967), introduced technical measures for planting and restoration of indigenous trees in
order to be effective in the process of high-altitude tree regeneration. In these studies, Tran
Nguyen Giang has successfully built a model of planting many native species under the trees
and has a preliminary report on the growth of forest in the study area. However, there is no
assessment of the impact of ecological factors as well as the interrelationships between these
species.
In 1996, Tran Nguyen Giang was studying how to plant 10 indigenous species under
canopy of acacia auriculiformis and acacia mangium at Cat Ba National Park. The author
argues that these two species have the effect of improving the protection of forest soil,
supporting the native plant growing and developing should demonstrate how to do so is true.
But in 1998, the results were not as expected initially, indigenous trees planted under canopy
of acacia auriculiformis have very high survival rate, growth and development quite well,
while native plants under the canopy of acacia mangium has a relatively low survival rate,
growth and poor development. The author explains that this may be due to the large demand
for mango juice that makes the soil always dry, thus improving the soil environment.
The Northeast Forestry Science and Technology Center (Ngoc Thanh - Phuc Yen Vinh Yen) has experimented with indigenous plants under the canopy of acacia mangium in
2000 and 2001 on an area of 10 ha in Lung Dong Danh including 5 species indigenous
species: erythrophleum fordii, peltophorum pterocarpum, ormosia pinnata, re huong and de
Yen The. In addition, the center also built some plantation sectors of over 180 species of
indigenous plants together with acacia auriculiformis and acacia auriculiformis (1996 - 2001).


6


CHAPTER 2
OBJECTIVES, CONTENTS, RESEARCH SUBJECT, LIMITS AND RESEARCH
METHODS
2.1. Objective
Evaluating the growth capacity of some indigenous tree afforestation models to
contribute to the elaboration of the scientific foundations, which shall serve as a basis for
proposing solutions for optimizing indigenous trees afforestation efficiency.
2.2. Contents
2.2.1. Comparing some growth criteria among different indigenous trees planting
models (Hvn, D1.3, Dt)
2.2.2. Comparing trees’ quality among different planting models
2.2.3. Calculating survival rate of indigenous trees in Acacia mangium model
2.2.4. Investigating vegetation cover, shrubs
2.3. Research subject
Indigenous species planted under the canopy of acacia mangium and acacia
auriculiformis:
 For indigenous trees planted under canopy of acacia mangium: survey 5/10 species
that were planted according to the model.
 For indigenous species planted under the canopy of acacia auriculiformis, survey
5/180 species are planted according to the model.
2.4. Limits
2.4.1. Place
The study only performed at the center of environmental research which is located in
Binh Thanh commune, Cao Phong district, Hoa Binh city.

7



2.4.2. Time
Owing to the limited time and resources, the research only focus on some of the most
promising native species which grown on both standard plots (5/10 species in the acacia
mangium model and 5/180 species in the acacia auriculiformis model).
In this project, the investigation could not be performed on the whole area but only on
some sample plots representing the stands (each plot corresponds to a unit of experimental
layout).
This research identifies the relationship between the growth of indigenous plants and a
number of contextual factors such as light and vegetation among many factors that dominate
the growth of trees.
2.5. Materials and methods
2.5.1. Materials
2.5.1.1.

Brief introduction of indigenous species planted at the research center

At the research center, there are two models of native tree species under the forest
canopy of Acacia species and these are also two models of research subject of the project.
1.

Indigenous tree species with Acacia mangium model
 In this model, there are 10 indigenous tree species which have high economic value

and capable to adapt to the conditions in the selected area by inheriting indigenous knowledge
and native materials published.
 However, when preliminary survey, it can only be only seen the following species:
Ormosia pinnata (ràng ràng xanh), Cinnamomum iners (re hương), Erythrophleum fordii (lim
xanh), Lithocarpus ducampii (dẻ đỏ), Peltophorum pterocarpum (lim xẹt), Cinnamomum
camphora (long não), Hopea odorata (sao đen) and Cinnamomum obtusifolium (re gừng). In

particular, the frequency of encountering Peltophorum pterocarpum, Michelia tonkinensis,

8


Cinnamomum camphora are very sparse, so the investigation will be performed on the growth
of 5 species.
2.

Indigenous tree species with Acacia auriculiformis model
 This model was designed to study the adaptation of many indigenous tree species

under the site conditions and also to create a valuable botanical garden for scientific research.
Therefore, the number of species planted in the center is quite large, including 180 species of
45 plant families.
 Owing to the total number of species in the area is tremendous, hence, only a
number of the most promising species have been selected to carry out a detail survey of the
topic covered.
 The model of the trees under the canopy of acacia auriculiformis: there are 180
indigenous species of 45 families were planted in the research center. However, according to
the preliminary survey report of the forest technical department, a number of the best grown
species have been selected. In order to ensure the suitability of the subject matter, 5 species
were selected in the list to investigate the growth capacity.
2.5.1.2.

The sketchy description about morphology and ecology of indigenous
species which are investigated

1. Erythrophleum fordii (Lim xanh)
-


Morphological characteristics: Erythrophloeum fordii is a large, evergreen tree
species which is capable of reaching a height of 37–45 m and a diameter of 200–250
cm. The stem is rounded with dark brown bark, which is square cracking, has many
conspicuous lenticels and can be peeled off in scales. The base of the stem has a small
buttress. The foliage is thick and green all year round. The leaves are bipinnate and
ovoid, with a rounded base and pointed tip. Their upper layer is dark green, whereas
the lower layer is pale green with conspicuous veins. The inflorescence is apical

9


racemose and 20–30 cm long with small, white flowers which open in March– April.
The fruit is an oblong-elliptic pod, 15–30 cm long, which contains 6–12 seeds. Fruits
ripen in December–January and are brown or greyish black. The seeds are large, flat
and square-shaped with a pointed tip, and grow at an obtuse angle. The seed coat is
hard and black (JICA 1996).
-

Ecological characteristics: Erythrophloeum fordii grows in many kinds of soil, and
can develop in various types of mother soil such as sandstone, shale, mica schist and
even soil with a mechanical composition ranging from light to heavy. It can tolerate
high humidity, an average to high acidic content, and site conditions which have a
humid and deep soil layer. It usually grows with many other broad leaved tree species
in a multistoreyed forest environment, where vegetation is rich (FSIV and JICA 2003).

-

The tree grows slow, the growth rate depends on age and distribution. Flowering
season from March to May, fruit ripen in October to November. Light-loving plants,

when small live under the canopy. The average ideal temperature for developement is
22.4 – 24.100C and average ideal rainfall is 1500 – 2859 mm. The ability to regenerate
seeds is good.
2. Peltophorum pterocarpum (Lim xẹt)

-

Peltophorum pterocarpum is a large tree species, 25 – 30 m in height, diameter (DBH)
could reach to 50 – 60 cm. Light brown skin, with many lines around the body.
Straight stem, small root. Branches have rusty feathers.

-

Double feather, dark green, with 7 – 16 pairs of secondary petiole. Each petiole has 5
– 15 pairs of oval-shaped leaves that are 1 cm length, 4 – 9 mm width. Young rusty
leaves, early fall.

10


-

In the natural forest, Peltophorum pterocarpum flowers start at the age of 7 – 8.
Flowering from April to May, fruit is in flat bean shape. When the fruit is ripe, the
fruit skin is dark brown, the fruit is sticky to its stem.

-

Morphological characteristics: It is a deciduous tree growing to 15–25 m (sometimes
up to 50 m) tall, with a trunk diameter of up to 1 m belonging to Family Leguminosae

and sub-family Caesalpiniaceaea. The leaves are bipinnate, 30–60 cm long, with 16-20
pinnae, each pinna with 20-40 oval leaflets 8–25 mm long and 4–10 mm broad. The
flowers are yellow, 2.5–4 cm diameter, produced in large compound raceme up to 20
cm long. The fruit is a pod 5–10 cm long and 2.5 cm broad, red at first, ripening black,
and containing one to four seeds. Trees begin to flower after about four years.
3. Lithocarpus ducampii (dẻ đỏ)

-

A mature Lithocarpus ducampii is large tree species with approximately 50 – 60 cm in
diameter (DBH), up to 30m in height, with straight trunk; gray-brown casing, deep
cracks. Usually has wide canopy and green all year round.

-

Single leaf, early fall; mostly in spike shape which is about 10 – 12 cm in length, 3 – 4
cm in width, petiole 1 cm long; Leafy veins are prominent on the underside, the top of
the leave is star-shaped rust.

-

Unisexual flowers. Male flowers have 10 – 12 stamens which is long and slender.
Female flowers grow into cluster, each cluster has 2 to 5 flowers. The flower season in
from May to July. Fruits do not have stem, grow into clusters of 3, with many sharp
spikes, fruit is 1.5 – 2 cm in height, diameter is 1 – 1.5 cm. Fruit season from
November to December.

-

Lithocarpus ducampii is suitable for growing with tropical monsoon climate while the

average rainfall of 1500 – 2500 mm/year and the average temperature of 22 – 270C.

11


-

Reproductive capacity of seed under canopy condition is good. Light-loving plants,
requires lightly shade to grow in the early years. Business cycle is not too long (25 –
35 years) because Lithocarpus ducampii grows relatively fast. Lithocarpus ducampii
can be used for pure plantation, afforestation, enrichment and rehabilitation.
4. Cinnamomum obtusifolium (re gừng)

-

Cinnamomum obtusifolium is a large tree species which could reach up to 30 m in
height, diameter (DBH) can reach 50 cm. Brown or dark brown, smooth, shiny brown
or light yellow, crisp and fragrant. Young green shoots, when old brown.

-

Single leaf, grows upright or opposite, spike or oval, smooth which could reach 9 – 30
cm in length, 3.5 – 9 cm width. The stem is 12-20mm long.

-

Bisexual flowers have two forms: middle flowers are larger than the flowers. Each
flower has 6 pieces, oblong, hairy on both sides. Males reproduce 9, 3 times, 2
degenerate, 4 pollen. Flower pot is in egg-shaped, smooth, long tap with gourd.
Flower season in March.


-

The fruit is in egg-shaped, 1 cm in length. The fruit is green at first, at nine stage, the
fruit turns dark green, flesh is light purple color with a light brown seed, could be
harvest in February to March.
5. Hopea odorata (Sao đen)

-

Hopea odorata is a large tree species, mature species could reach 30 – 40 m in height,
straight cylindrical shape, diameter (DBH) up to 60 – 80 cm. Small pruning, good
pruning of branches so the branches under the branches long and straight. Blackbrown shell, longitudinal crevice. Young shoots and hairy petioles.

-

Single leaf in spear shape, is 9 – 11 cm length, the veins are clear. Leaf replacement in
the dry season but does not fall simultaneously as other trees.

12


-

Flowers are clustered with 11-12 small branches, each cluster has 4-6 flowers, hatched
in February to March. Fruits with two wings with 5 – 6 cm in length, ripen in April to
May. One kilogram of grain has about 3000 seeds.

-


Hopea odorata is well-grown and well-developed in tropical climate where rainy and
dry seasons distinct with an average temperature of 24 – 250C and annual rainfall of
1800 – 2000 mm/year.
2.5.2. Methods

In forest trees’ life, the forests themselves are affected by environmental factors around
them. The sub-forest situation includes the sub-climate of the forest and forest land. It can
be seen that the present status of the indigenous plant layer reflects the resultant interaction
of the ecological environment where they grow.
Therefore:


When studying the growth of indigenous tree species, it requires the overall impact
of high tree layer and other factors. This means the status of supportive trees and
other factors ecology have to be assessed.



When assessing the relationship between the biomass and quality of indigenous tree
layers with supportive tree layers and other ecological factors, it is necessary to
assume that the remaining factors are homogeneous and that the variation in this
heterogeneity causes variation in the yield and quality of the indigenous tree.

13


General approaching method

Evaluate growth capacity of some indigenous tree
afforestation models


Measuring a number of
growth criteria
including Hvn, D1.3, Dt

Evaluating
trees’ quality

Calculating
survival rate

Investigating
vegetation cover,
shrubs

Synthetic, analyze and evaluate the data

Make conclusion and propose solutions to maximize plantation efficiency

Figure 2.1: Overview of the project approaching method

14


2.5.2.1.

Inheritance method

During the course of the investigation, some of the materials are available at the research unit
could be inherited:

 Data on natural conditions, people, socio-economic in the study area.
 Various types of designed maps planted in the study area.
Previous research results on research content of different topics.
2.5.2.2.

Field-work method

Establish standard plot: the plots are set up in an area of 500 m2 (25x20) with the length of
the plot parallel to the contour line, the width perpendicular to the contour line. Plots are
based on the Pythagorean theorem to form angular edges.
The trees are numbered in the course of the measurement and are observed for annual data
collection. The indicators including: growth rate (Hvn, D1.3, Dt), survival rate (%), trees’
quality, shrubs, vegetation cover and pests.


Trees height (Hvn): is measured by the Blumleiss with precision up to 0.1 (m) or using
a pole with carved, accurate to (cm).



Diameter at breast height – DBH (D1.3): First step is to measure the perimeter of all
trees with circumference greater than 18 (cm) by using a 2-meters tape with 0.1 (cm)
accuracy. The diameter is calculated by the following equation:
D1.3 = C/



Canopy diameter (Dt): is calculated by measuring the leaf shape in two directions
East-West, South-North with tape.




Survival rate was determined by counting dead trees in the plot.



Trees’ quality is determined by the classification of good, medium and poor trees. The
classification criteria are based on the growth and development patterns of the species
in the model. Good trees are fast grown and have a balanced development pattern, no

15


pests; Medium trees are medium growth with morphologically unbalanced; Poor trees
are poor growth and stunted.


Pests are identified through visual inspection in the forest by eyes and magnifying
glass.
2.5.2.3.

Data analyses method

After field-work survey, data processing on computer with the support of Exel 5.0 software
and SPSS software to process data and calculate mean value of the height, diameter at breast
height, canopy diameter.
Use statistical mathematical methods in forestry to handle the survey criteria. Specifically:
 Calculate sample characteristics according to each plot:
 Calculate sample characteristics:
-


Average sample X (mean values: D 1.3, H vn, D t)
X =fi.xi/n

-

Standard error sample

-

Coefficient of variation CV = (SD/ X ) * 100.

-

Sample variance S2

 Identification of specific distributions:
-

Distribution of trees by diameter N/ D 1.3

-

Distribution of trees by size of height N/ H vn

16


 Calculate average growth criteria of investigated indigenous species:



The average diameter at breast height (D1.3) growth per year:
Average diameter at beast height
D 1.3/ year =

Total tree age
 The average height (Hvn) growth per year:

Average height growth
H vn/year =

Total tree age



The average canopy diameter (Dt) growth per year:
Average canopy diameter
D t/ year =

Total tree age



Statistics the trees’ quality by percentage.

Status of vegetation cover, shrubs:
 Statistics on the number of major species, average height, average coverage, quality

per plot.



Make a comment about the qualitative relationship between the variation in these
indicators and the variation in the growth capacity of indigenous plants

17