LITERATURE REVIEW
In The World
The study of forest rehabilitation in the world has started early In 1930, Richards P.W was the first author to study forest rehabilitation According to his research regenerated species in each plot are distributed in cluster for rehabilitation Scientific research on forest rehabilitation has been more developed since 1950 For example, both researches from Barnard (1950) and Smith (1952) in Malaysia, and Lampreht in Venezuela (1954) indicated the need of using the existing vegetation with different side conditions to maintain the natural regeneration and additional planting to restore the forest structure similar to be the original structure.[2] While other researches by Weidelt (1968) on the upland abandoned forests in Brazil indicated the development of secondary forests would move towards the initial condition of primary forest in the number of species and species composition.[8]
In 1975, Whitimore studied on development of secondary vegetation and found that the time needed to regenerate forests by seedling to reach to the initial state can take hundreds of years In 1996, Fedmaner found that the main factors affecting the process of forest rehabilitation are site conditions, component types and genetic resources.
In Vietnam
Since the 1950s, Vietnam has been actively researching forest rehabilitation, with significant expansion of study areas beginning in 1961 Throughout the 1990s, in-depth studies on forest rehabilitation and forest succession gained momentum, strengthening Vietnam's efforts in sustainable forest management and ecological restoration.
In 1993, Thai Van Trung proposed a two-step approach for rehabilitating forest ecosystems in southern Vietnam affected by Agent Orange First, he emphasized planting species capable of synthesizing natural nitrogen to restore soil fertility Second, he recommended cutting the planted species to allow regeneration by other species that offer greater ecological and economic benefits, ensuring sustainable forest recovery.
Nguyen Ngoc Lung (1995) stated on his research that, effective rehabilitation depended on many factors such as site conditions, characteristics of that species and social economic conditions of that region.[5]
Almost all studies have focused on understanding the law of succession process of forest rehabilitation These results serve as scientific basis for solutions of forest rehabilitation.
Characteristics of Castanopsis boisii
Castanopsis boisii has the average height is 10 – 15 m and average diameter range of
This species features a straight, round stem ranging from 30 to 40 cm in height, with grey, thick, fissured bark exhibiting small vertical cracks Young branches are smooth and elongated, with patches and long growths It has a well-developed mixed root system comprising both tap roots and lateral roots The leaves are simple, alternate, and measure 9–16 cm in length and 4–7 cm in width, with blades that are narrowly elliptic, ovate-oblong, or lanceolate-elliptic; they have slightly pointed heads and asymmetric shapes The adaxial surface of the leaves is dark green and smooth, while the abaxial surface features scales with a light pink hue Venation is pinnate, with 10–14 pairs of lateral veins The petiole is thin, measuring 1.5–1.8 cm long, and stipules are present.
Flowers are unisexual catkins with male inflorescences that are slender and measure 5 to 12 cm in length The calybium resembles a pointed acorn, featuring a hard cupule similar to beechnuts and spiny like chestnuts Three thickened ridges run along the length of the calybium’s shell, adding to its distinctive appearance.
Castanopsis boisii flowers from September till November, fruit ripes from August to
Castanopsis boisii typically flowers and produces seeds every one to two years, with seed ripening occurring biennially (Le Mong Chan, 2000; Nguyen Tien Ban, 2003) According to Dang Ngoc Anh (1996), the species begins flowering and seed harvesting at ages 4 to 5, with stable seed production starting from age 10 and continuing for 40-50 years The most productive period for Castanopsis boisii occurs between 20 and 35 years of age, making it valuable for sustainable forestry and seed collection efforts.
Castanopsis boisii is evergreen tree, lucipetal, growth and develop well on sandstone
Castanopsis boisii is a pioneer tree species that naturally grows in hillside and foothill environments It regenerates vigorously on bare soil or beneath woodlands, making it an important species for forest succession after clear-cutting Studies by Le Mong Chan (2000) and Nguyen Tien Ban (2003) highlight its strong regenerative capacity in disturbed habitats, emphasizing its role in restoring forest ecosystems.
STUDY GOAL, OBJECTIVES AND METHODLOGY
STUDY GOAL AND OBJECTIVES
Contributing some solutions to rehabilitate Castanopsis boisii in Hai Duong province for sustainable forest development
Determining the characteristic of stands of Castanopsis boisii Hickel et A Camus
Purposing some solutions to rehabilitate Castanopsis boisii in the study site.
METHODLOGY
By leveraging data from previous comprehensive studies on the natural conditions, climate, hydrology, soil, natural resources, and socio-economic context of the study site, valuable insights are gained to inform effective strategies for the rehabilitation of Castanopsis boisii This integrated information is crucial for developing sustainable conservation and restoration solutions for this species.
2.2.2.1 Investigating mature trees, shrubs and regenerated trees
In Hoang Hoa Tham and Bac An communes, Setting up 4 sample plots with plot size of 1000 m 2 (40 m in length and 25 m in width) In each sample plot, establishing 5 sub-plots;
4 sub-plots at the 4 corners and 1 sub-plot at the center The shape of sub-plot is square (2 m x
In each sample plot, measurements of height, under canopy height, canopy diameter, and diameter at breast height are conducted to assess tree growth Additionally, within each sub-plot, shrubs and regenerated plants with heights ranging from 30 cm to 1.3 meters are identified and recorded The study also examines regenerated plants originating from seeds or buds to evaluate successful regeneration processes in the area.
To measure tree height accurately, use the Blume-Leiss device, which determines the elevation angle between the operator and specific points on the tree The operator should stand still at a horizontal distance of 15, 20, 30, or 40 meters from the tree's base, ensuring clear visibility of the targeted points on the vertical trunk This method provides precise height measurements by combining angle readings with known distances.
To accurately measure tree diameter, use calipers by placing the fixed arm along one side of the trunk at approximately 1.3 meters above the ground, known as breast height Position the moveable arm flush against the opposite side of the tree, ensuring the calipers are perpendicular to the stem's axis for precise readings Read the scale directly to determine the tree's diameter, which is essential for forestry assessments and growth monitoring.
- Measuring crown diameter: using fiberglass tape to measure crown diameter by sketching the tape to both ends of the crown and read the value, by N-S and E-W axis
- Investigating growth quality by observation
- Investigating shrub vegetation in each transect line by establish plots with area 4 m2 (2m x 2m)
- The height of shrub vegetation is measured by fiberglass tape
- Measuring height: Using fiberglass tape with accuracy of 1 cm
- Measuring diameter: Using fiberglass tape The tape is wrapped around the tree to measure circumference This value is divided by PI (3.1415…) to estimate diameter
The origin of regeneration can be identified by examining the plant's stem: a straight stem indicates regeneration from seed, while a curved stem suggests regeneration from a bud.
No Name H H under D 1.3 Crown D Quality Note
2.2.2.2 Investigating climate condition: determining temperature, moisture, rainfall
The study took the weather data from Chi Linh Hydrometeorology forecast station
Weather criteria Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
2.2.2.3 Investigating the lighting conditions of regeneration plant through canopy coverage and statistic to process data result
This study investigates canopy coverage using a 100-point sampling method within a designated plot Each point is assigned a value of 0, 0.5, or 1, representing the presence or absence of canopy cover The estimated canopy coverage is determined by calculating the mean value across all 100 points, providing an accurate measure of overall canopy density Additionally, shrub coverage in each sub-plot is assessed by estimating the percentage of area occupied by shrubs relative to the total area of the cell types, allowing for detailed analysis of vegetation distribution.
No Canopy cover Coverage of shrubs Note
Interviewing to have information about Castanopsis boisii forest such as how they are managed, harvested, and also the conditions to plant this species
1 Have you ever planted Castanopsis boisii specie?
2 Do you know about the condition to plant Castanopsis boisii specie?
3 Is there any factor that effect to the growth rate of Castanopsis boisii specie?
4 How much does it cost for 1 kg seeds?
5 How many kg seeds you can harvest per year?
6 Do governments support people to plant Castanopsis boisii specie?
7 How long is this specie harvested after planting?
8 Do people in here care about this specie?
9 Do you know about the current state of Castanopsis boisii specie?
10 Besides harvesting Castanopsis boisii, what do you do to increase income?
11 If you are supported by government, do you want to plant this species as your main source of income?
Using EXCEL software to analyze and measure data.
OVERVIEW OF NATURAL AND SOCIAL - ECONOMIC CONDITIONSS
NATURAL CONDITION
Chi Linh town is located in the Northeast of Hai Duong province The geographical coordinates:
Chi Linh is strategically positioned, sharing borders with Nam Sach and Kinh Mon districts to the south, Luc Nam district of Bac Giang province to the north, Que Vo and Gia Binh districts of Bac Ninh province to the west, and Dong Trieu district in Quang Ninh province to the east Covering a total area of 282 km², Chi Linh comprises 20 administrative units, including 8 wards and 12 communes, making it a diverse and well-connected region in northern Vietnam.
With these geographical location features, the town has advantages in business, agriculture and forestry production
Chi Linh features diverse terrain, including mountains, hills, and delta regions The northern and northeastern parts of the town are mountainous, part of the bow-shaped Dong Trieu mountain range Hills along Highway 18 stand at 50-60 meters high with slopes of 10-15 degrees, providing ideal conditions for agricultural and forestry development through hill garden farming models.
The annual average temperature is 23 o C The months which have the highest temperature are June and July (36 o C to 38 o C) January and February have the lowest temperature (10 o C to 12 o C)
The region receives an annual rainfall of 1,480 mm, with the majority occurring during June, July, and August, accounting for 78% of the total rainfall The average humidity is high at 85%, with the lowest humidity level of 33.5% observed in November Conversely, April experiences the highest humidity, making this period particularly humid and ideal for understanding the area's climatic patterns.
Two main wind directions are north-eastern monsoon and southeastern North-eastern wind is more harmful to agricultural products and forestry products
In general, Chi Linh’s climate is suitable for planting agroforestry species, including
Chi Linh is shaped by the powerful flows of the Pha Lai and Thuong rivers, with an average water current of 286 m³/s and a minimum flow of 181 m³/s The town is endowed with 33 natural dams and significant groundwater reserves, ensuring a reliable water supply for residents' daily needs and local production activities.
The total area of Chi Linh is 28.202,8 ha (01/01/2011) Including:
Agricultural land covers 20,700.77 hectares, representing 73.4% of the total area, with 51.2% allocated for agricultural production, 46% for forestry, and 2.8% dedicated to aquaculture Non-agricultural land comprises 7,360.2 hectares, making up 26.1% of the total area This land distribution highlights the region's emphasis on agriculture and forestry as key land uses.
Unused land is 141,8 ha, accounting for 0.5 % of total area.
SOCIAL ECONOMIC CONDITIONS
As of 2015, Chi Linh Town has a population of approximately 175,000 residents, with a population density of 584 persons per square kilometer, exhibiting uneven distribution across the area The town is ethnically diverse, comprising 15 different ethnic groups, with the Kinh ethnicity representing the majority at 95.1% Other notable ethnic communities include Man, Hoa, Kho Me, Tay, Nung, and San Diu, contributing to the town’s rich multicultural environment.
The town's workforce comprises 79,167 laborers, representing 55% of the total population A significant 75.4% of these workers are engaged in agroforestry and fishery sectors, highlighting their importance to the local economy Additionally, construction industry employment accounts for 12.5%, while service sector workers make up 12.1%, reflecting the diverse employment landscape of the town.
GDP of the town reaches 22.2 million VND / person / year Agroforestry and fishery make up 23 %, construction industry make up 45.6 % and service make up 31.4 %
Cultural, informational, and sporting activities continue to expand, enriching community life Progress in business training, employment opportunities, and social security initiatives has contributed to a significant reduction in the poverty rate, now at 3.5% The province maintains political stability, public order, and safety, with notable declines in social issues Ongoing inspection efforts, effective resolution of complaints and denunciations, and judicial reforms have further strengthened governance and social cohesion.
The local electric power system comprehensively supplies all households in the town, ensuring 100% access for both daily living and industrial use The irrigation infrastructure is well-developed and effectively managed, with solid flood and storm prevention plans in place Additionally, the transportation network has been upgraded to enhance safety and reduce accidents on highways, improving overall travel safety and convenience for residents.
RESULTS AND DISCUSSION
Characteristics of the study site
Terrain significantly influences the survival and development of forests by affecting key ecological factors such as rainfall, temperature, humidity, light, and wind These environmental elements directly impact forest growth, regeneration, and overall health, making terrain a crucial factor in forest conservation and management efforts Understanding how terrain shapes these ecological conditions is essential for promoting sustainable forest development.
Using the inheritance method, the study site consists of hills approximately 50–60 meters high with a slope of 10–15 degrees According to the "Manual on Land Evaluation for Reforestation," gentle slopes are favorable for regeneration because they help reduce surface erosion The low absolute elevation further benefits reforestation efforts, forest management, and protection.
Climate significantly influences the growth and development of forest trees and vegetation by affecting key environmental factors such as light, temperature, and humidity Changes in climate patterns can lead to shifts in vegetation classes and overall forest ecosystems Data from the Chi Linh Hydrometeorology Forecast Station provides valuable insights into local weather conditions, essential for understanding and predicting the impacts of climate change on forest health and composition.
Table 4.1: Weather data in Chi Linh Hydrometeorology forecast station (2014)
Weather criteria Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
The study site experiences moderate climate conditions, with an average temperature of 23.8°C, reaching its peak in June at 29.5°C and dropping to its lowest in December at 16.5°C Humidity levels are lowest in January and December at around 70-73%, while March records the highest humidity at 93% Annually, the area receives a total rainfall of 1,097.7 mm, with August experiencing the highest rainfall at 274.9 mm and January the least with just 1 mm The total annual evaporation amounts to 881.3 mm, peaking in December at 130 mm and lowest in March at 23.8 mm The region features mild weather with no occurrences of disasters such as floods or droughts Thunderstorm activity is minimal and mainly occurs from June to September Sunshine exposure totals 1,457.9 hours per year, with May receiving the highest sunshine hours at 192.3 hours, while February has the fewest at 24.4 hours.
Figure 4.1: Comparison precipitation and evaporation in Chi Linh 2014
From October to February, evaporation exceeds precipitation, resulting in a water shortage that impacts plant growth This period's low soil moisture hinders seed germination and bud development, making seedling regeneration difficult Adequate moisture is essential for optimal plant growth and successful regeneration during these months.
Characteristics of Castanopsis boisii stand
Mature trees play a crucial role in forest plant communities by regulating regeneration and guiding forest succession The diversity and abundance of species are influenced by various factors, including soil conditions, terrain, exposure, temperature, humidity, and human activities Forest rehabilitation primarily aims to restore the woody tree layer, making the study of mature trees essential for classification and developing effective rehabilitation strategies The characteristics of mature trees at the study site are detailed in Table 5.2.1.
Table 4.2: Characteristics of mature trees in study site
The table above shown that, total height is 8.2 – 9.8 m; under canopy height is 3.9 – 5.0 m; diameter at breast height is 13.8 – 19.8 cm This data presented trees reach the age of
Overall, the quality of tree in study site is quite good Good quality tree ranging from 82% - 89%, average quality tree ranging from 6% - 13%, bad quality tree only ranging from 3% - 10%
Table 4.3: Standard deviation and coefficient of variation of H vn
Standard deviation of Hvn is ranging from 1.31 – 1.93 and coefficient of variation ranging from 15% - 21% These values can be acceptable and show a divergence of the height in study site
Table 4.4: Standard deviation and coefficient of variation of D 1.3
Plot Mean(cm) SE(cm) SD(cm) S(%)
The standard deviation of D1.3 ranges from 4.58 to 6.94, with a coefficient of variation between 24% and 38%, indicating notable variability in tree diameter at the study site Particularly, plots BA2 and HHT1 exhibit higher variability, with coefficients of variation reaching 35% and 38%, respectively, highlighting significant divergence in diameter measurements across different plots.
4.2.2 Distribution of mature tree layer bases on the height and diameter
Figure 4.2: Distribution of mature tree layer bases on the height
The practice survey indicates that most trees range in height from 8 to 12 meters, with some trees reaching up to 14 meters under favorable conditions Conversely, trees that only grow to about 6 meters are typically of poorer quality or are still young.
Figure 4.3: Distribution of mature tree layer bases on diameter
4.2.3 Distribution of regenerated trees bases on the height
Tree height is a critical factor for selecting potential regenerated trees, as it reflects growth and development status The quantity and quality of regenerated trees serve as essential indicators for assessing forest health and regeneration success The distribution of regenerated trees based on height is influenced by various factors, primarily competition for nutrients, space, and light among regenerated trees and between regenerated trees and surrounding shrub vegetation.
Table 4.5: Distribution of regeneration plant bases on the height
Regenerated trees with heights below 1 meter—specifically less than 0.5 meters and between 0.5 to 1 meter—constitute the majority of the regeneration, indicating vigorous early-stage growth In contrast, taller regenerated trees exceeding 1 meter are less common, reflecting the gradual development process The high regeneration density is supported by local community actions, as residents regularly clear shrub vegetation to create space that promotes healthy nutrient cycling and allows young trees to grow effectively.
The proportion of good quality regenerated trees is very high ranging from 87.3% - 91.2%, average quality regenerated trees accounting for 3.1% - 8.5% and bad quality regenerated trees only ranging from 2.9% - 6.7%
Castanopsis boisii regenerates through two primary methods: by bud and seed The regeneration process is influenced by site conditions, land characteristics, weather patterns, and particularly human activities These factors determine the origin of regeneration, shaping the growth and sustainability of Castanopsis boisii in the study area.
Table 4.6: Origin of regeneration trees in study site
Regeneration trees primarily originate from seeds, often leftover from the previous year's harvest, which find favorable conditions for growth However, field surveys and local interviews reveal that the growth strength of seed-originated trees is generally low, mostly consisting of seedlings and some stunted trees, with minimal impact from human activities In contrast, bud-derived regeneration benefits from nutrient transfer from the parent plant, leading to healthier and more vigorous growth The majority of potential regeneration comes from bud-derived trees, with a density ranging from 7,500 to 12,000 trees per hectare The spatial distribution and origin of these regenerated trees can be clearly identified in Figure 4.4.
Figure 4.4: The distribution of origin of regenerated trees in study site
Shrubs play a crucial role in influencing the density, distribution, growth, and quality of regeneration plants by competing for nutrients and light under the canopy When the canopy of mature trees diminishes, shrub vegetation flourishes, promoting favorable growth conditions for regeneration plants However, the reduction in canopy can also create adverse conditions that may hinder the successful growth of young regeneration plants.
Table 4.7: Characteristics of shrub vegetation in study site
Plot Number Name H vn (m) Cover (%)
Microsorum pteropus, Phyllanthus emblica, Ardisia crenata, Aporosa tetrapleura,
Ardisia crenata, Microsorum pteropus, Rourea microphylla, Aporosa tetrapleura
Phyllanthus emblica, Gardenia jasminoides, Rourea microphylla, Bauhinia purpurea,
Microsorum pteropus, Ardisia crenata, táo xanh
Shrub vegetation coverage in the study area ranges from 33% to 47.5%, with heights between 0.46 and 0.55 meters, primarily due to human activities such as shrub removal and annual harvesting in forest areas While shrub layers help maintain soil moisture, reduce wind impact, and create favorable conditions for seedling and sapling growth, they can also compete for light and other resources, potentially hindering regeneration Additionally, dense shrub growth can reduce seed grounding ability, limit sunlight reaching the ground, and slow down seed germination processes.
4.3.1 Economic value of Castanopsis boisii forest in study site
The Castanopsis boisii forest in Chi Linh is primarily a rehabilitated area that has been allocated to households for management Local residents receive 200,000 VND per hectare annually from the government to support their efforts Traditionally, the community practices shifting cultivation by collecting seeds from the land, without reinvesting in forest care, which leads to low seed yield and poor quality This approach, driven by maximum exploitation for short-term gains, hampers the forest's productivity and long-term sustainability.
According to interview results, the density of Castanopsis boisii is approximately 3-4 dozen trees per hectare, with seeds priced at 20,000 to 25,000 VND per kilogram This can generate an average income of 8,000,000 to 10,000,000 VND per hectare annually Additionally, local residents utilize the shade provided by Castanopsis boisii for poultry raising and bee breeding, which offers supplementary income sources for households.
4.3.2 Environment value and other value of Castanopsis boisii forest in study site
Castanopsis boisii forests play a vital role in enhancing local livelihoods by increasing income and improving living conditions for nearby communities These forests also contribute significantly to maintaining ecological balance and fostering a stable, sustainable environment By supporting essential ecological processes like photosynthesis, reducing soil erosion, decreasing airborne dust, and enhancing soil fertility, Castanopsis boisii forests are essential for preserving ecosystem health and resilience.
In study site, Castanopsis boisii create the shade to reduce temperature in the summer
Castanopsis boisii forests play a crucial role in protecting buffer zone ecosystems, preventing floods and droughts, and maintaining water quality The forest canopy and dried leaf layer reduce the impact of raindrops, mitigating flooding risks, while the root system helps regulate surface water flow Deforestation in these areas accelerates soil erosion and decreases soil fertility, highlighting the importance of preserving these vital forests for environmental stability.
In addition, Castanopsis boisii forest is provide good trees that useful for scientific research Many researchers had research about Castanopsis boisii It is also bring beautiful landscape to region
4.4 Some solutions to rehabilitate Castanopsis boisii
The Castanopsis boisii stand has provided numerous benefits to local communities by helping households reduce poverty and enhancing the region's scenic landscape To promote sustainable regeneration and support the development of the Castanopsis boisii stand at the study site, I recommend implementation strategies that ensure its long-term growth and ecological health.
Most fruit and nut trees are photophilic, thriving under adequate sunlight, but their light requirements vary during different growth stages For seedlings and young trees, it is essential to adjust canopy cover to provide suitable light levels; excessive opening can raise ground temperature and light intensity, increasing transpiration and risking dehydration due to undeveloped roots Conversely, maintaining high canopy cover for larger regenerations can restrict light access, hindering growth and development Proper management of canopy cover based on regeneration size is crucial for optimizing forest health and ensuring successful tree development.
According to master thesis of Kieu Thi Duong (2013) was mentioned necessary for coverage in each height levels.[3]
Table 4.8: Necessary for coverage in each height levels
Name Age Height (cm) Coverage (%)
However, adjusting the canopy cover in this range of this thesis not mentioned, so can refer to the adjustment of canopy cover above to apply for regional regeneration research
4.4.2 Adjusting the distribution of regenerated trees
GENERAL CONCLUSION AND FUTURE STUDY
Conclusion
Through practice surveys, research has some conclusion:
- Study site has slope ranging from 10 o – 15 o at hill side It is favorable growth and development of Castanopsis boisii
- Climate condition: the study site has mild and cool climate, not storm or disaster natural
The mature tree layer at the study site consists of trees aged between 20 and 30 years, with total heights ranging from 8.2 to 9.8 meters The height within the canopy varies from 3.9 to 5 meters, and the trunk diameter ranges from 13.8 to 19.8 centimeters Crown diameters are between 3.8 and 4.8 meters, with canopy cover percentages ranging from 38.4% to 55.2% Most trees are of good quality, while medium and poor-quality trees constitute only about 11% to 18% of the total population.
Shrub vegetation covers approximately 33% to 47.5% of the area, with heights ranging from 0.46 to 0.55 meters Field studies identified eight shrub species, including Microsorum pteropus, Phyllanthus emblica, Ardisia crenata, Aporosa tetrapleura, Táo xanh, Rourea microphylla, Gardenia jasminoides, and Bauhinia purpurea This diverse shrub community contributes significantly to the overall vegetation structure and ecological health of the area.
The density of regenerated trees ranges from 7,500 to 12,000 per hectare, primarily achieved through seed-based regeneration, with seedlings constituting a significant proportion Most of the potential trees are regenerated via budding, while seed-based regeneration accounts for a smaller share.
- Distribution of regenerated trees is cluster and irregular
- Adjust the distribution of regenerated tree
- The impact depend on origin of regeneration
Shortcomings
Due to survey experience is limited, research still faces shortcomings in the process of investigation and data collection
The study is only research 4 temporary plots So, the result does not fully cover regeneration, growth and development of Castanopsis boisii in study site
Not yet research age of seed trees and regenerations to clarify the influence of age on the growth of the trees above.
Recommendations 31 REFERENCES
Expanding study site, conducted in a longer time, established more plots for more accurate results
Needing method determine age of regenerated tree exactly From that will define impact of factors on regenerated trees
Expanding comparing research of the Castanopsis boisii characteristics in different the site conditions, at different ages and at different stages in order to give better results
1 Dang Ngoc Anh, Ha Van Hoach (1998), “Natural regeneration and restoration of Castanopsis forest in Ha Bac”, The study results of forestry science and technology in the period 1990 – 1995, Agriculture Publisher 1996
2 Dang Xuan Quy (2005), Study of structural features as a basis for silvicultural solution for restoration of regeneration research forest in Xuan Son National Park - Thanh Son - Phu Tho, Student Thesis in Vietnam Forestry University, Hanoi
3 Kieu Thi Duong (2013), Research on light requirement of regeration Castaniosis boisii Hickel et A Camus under forest canopy in some communes in Luc Nam district, Bac Giang province, Master Thesis, Vietnam Forestry University
4 Le Mong Chan, Le Thi Huyen (2000), Forest plants, Curriculum of Vietnam Forestry University, Agriculture Publisher, Hanoi
5 Nguyen Ngoc Lung, 1995, Research and application of scientific basis, technical and economic solutions for planning and design protection areas, building water source protection forests, coastal forests State theses, KN03.09, 1991-1995
6 Nguyen Toan Thang (2011), Research for technical solutions of Castanopsis boisii hickel et Camus forest maintenance in Bac Giang, Vietnam Academy of Forest Sciences
7 Nguyen Tien Ban (2003), The list of plant species in Vietnam, Volume II, Institute of Ecology and Biological Resources, Agriculture Publisher, Hanoi
8 Nguyen Thi Thao (2003), Research on some business- technical solutions for forest
Some pictures in field work:
Appendix 1: Distribution of mature trees layer bases on the height
Appendix 2: Distribution of mature tree layer bases on diameter
Plot BA1 No.1 Name D 1.3 (cm) H vn (m) H under (m) Crown D.(m)
No.1 Name D 1.3 (cm) H vn (m) H under (m) Crown D.(m)
No.1 Name D 1.3 (cm) H vn (m) H under (m) Crown D.(m)
Plot HHT2 No.1 Name D 1.3 (cm) H vn (m) H under (m) Crown D.(m)
Appendix 4: Descriptive Statistic of mature trees in study site