LITERATURE REVIEW
In The World
The study of forest rehabilitation began in the early 20th century, with Richards P.W being the first to explore this field in 1930, highlighting the clustered distribution of regenerated species for effective rehabilitation Significant advancements in scientific research on forest rehabilitation emerged post-1950, as demonstrated by Barnard (1950) and Smith (1952) in Malaysia, along with Lampreht (1954) in Venezuela, who emphasized the importance of utilizing existing vegetation and additional planting to restore forests to their original structure Furthermore, Weidelt's research (1968) on abandoned upland forests in Brazil suggested that secondary forests could evolve towards the conditions of primary forests in terms of species diversity and composition.
In 1975, Whitimore's research revealed that forest regeneration from seedlings to their original state can require hundreds of years Later, in 1996, Fedmaner identified key factors influencing forest rehabilitation, including site conditions, component types, and genetic resources.
In Vietnam
Forest rehabilitation research in Vietnam began in the 1950s and expanded significantly in 1961 By the 1990s, the focus shifted towards more in-depth studies on forest rehabilitation and forest succession, highlighting the country's commitment to understanding and restoring its forest ecosystems.
In 1993, Thai Van Trung identified a two-step approach for rehabilitating forest ecosystems affected by Agent Orange in Southern Vietnam The first step involves planting species capable of synthesizing natural nitrogen, followed by cutting these species to allow for the regeneration of more valuable and beneficial plants.
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
The species grows to a height of 30 to 40 cm, featuring a straight, round stem with thick, grey bark that exhibits fissures and small vertical cracks Young branches are smooth and elongated, while the root system is a mix of well-developed tap and lateral roots The leaves are simple, alternate, and measure 9 to 16 cm in length and 4 to 7 cm in width, with a narrowly elliptic to ovate-oblong or lanceolate-elliptic shape The leaf blade is slightly pointed and asymmetric, displaying a dark green, smooth adaxial surface and a light pink-scaled abaxial surface The venation is pinnate, featuring 10 to 14 pairs of lateral veins, and the thin petiole measures 1.5 to 1.8 cm in length, with stipules present.
Flowers are unisexual catkins characterized by slender male inflorescences measuring 5 to 12 cm The calybium has a pointed acorn shape with a hard cupule similar to beechnuts and spiny like chestnuts, featuring three thickened ridges along its shell.
Castanopsis boisii flowers from September till November, fruit ripes from August to
According to Dang Ngoc Anh (1996), Castanopsis boisii begins flowering and seed harvesting at the age of 4 to 5 years, with stable seed production starting around 10 years and lasting for 40-50 years The most productive period occurs between the ages of 20 and 35, highlighting the importance of this tree species in sustainable forestry practices.
Castanopsis boisii is evergreen tree, lucipetal, growth and develop well on sandstone
Castanopsis boisii is a pioneer tree species that thrives in hillside and foothill populations, exhibiting strong regeneration on bare soil or beneath woodlands, particularly following clear-cutting.
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
Leveraging valuable insights from previous research on natural conditions, climate, hydrology, soil, natural resources, and the socio-economic context of the study site provides essential information for developing effective rehabilitation strategies for Castanopsis boisii.
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, we measure key metrics such as height, under canopy height, canopy diameter, and diameter at breast height Additionally, within each sub-plot, we assess the presence of shrubs and the quantity of regenerated plants that range in height from 30 cm to 1.3 m Furthermore, we also evaluate regenerated plants originating from either seeds or buds.
To accurately measure tree height, the Blume-Leiss device is utilized, which calculates the elevation angle between the operator and specific points on the tree The operator must remain stationary at a horizontal distance of 15, 20, 30, or 40 meters from the base of the vertical tree, ensuring that the required points are clearly visible for precise measurement.
To accurately measure a tree's diameter, use calipers by positioning the fixed arm along one side of the tree at a height of 1.3 meters from the base Next, place the movable arm flush against the opposite side of the tree and read the measurement directly from the scale It is essential to ensure that the calipers are aligned perpendicularly to the stem axis for precise results.
- 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 determined by examining the stem; a straight stem indicates regeneration from seed, while a curved stem signifies 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 method that involves assessing 100 points within a designated plot The estimated canopy cover values range from 0, 0.5, to 1, with the mean value calculated from these points Additionally, the coverage of shrubs in each sub-plot is measured by estimating the percentage of area occupied by the shrubs relative to the total area of the different cell types.
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 bordered by Nam Sach and Kinh Mon districts to the south, Luc Nam district in Bac Giang province to the north, Que Vo and Gia Binh districts in 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, which include 8 wards and 12 communes.
With these geographical location features, the town has advantages in business, agriculture and forestry production
Chi Linh features a diverse landscape that includes mountains, hills, and delta regions The northern and northeastern areas are characterized by the mountainous Dong Trieu range, while the hills along Highway 18 rise to heights of 50-60 meters with slopes of 10-15 degrees This unique topography presents significant opportunities for the economic development of agriculture and forestry, particularly through the implementation of hill garden 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 experiences an annual rainfall of 1,480 mm, predominantly during the months of June, July, and August, which account for 78% of the total precipitation The average humidity level is 85%, with November recording the lowest humidity at 33.5% Conversely, April is noted as the month with the highest humidity levels.
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 significantly influenced by the tides of the Pha Lai and Thuong rivers, with an average water current of 286 m³/s, and a minimum of 181 m³/s The town boasts 33 natural dams and a substantial groundwater reserve, providing ample resources to support both the local population and various 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% dedicated to agricultural production, 46% to forestry, and 2.8% to aquaculture In contrast, non-agricultural land encompasses 7,360.2 hectares, making up 26.1% of the overall area.
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 175,000, resulting in a density of 584 people per square kilometer, characterized by uneven distribution The town is home to 15 ethnic groups, with the Kinh ethnic group comprising 95.1% of the population, alongside smaller communities including the Man, Hoa, Kho Me, Tay, Nung, and San Diu.
The town's workforce comprises 79,167 individuals, representing 55% of its total population A significant portion, 75.4%, is engaged in agroforestry and fishery, while the construction industry employs 12.5% of the labor force Additionally, 12.1% of the workforce is involved in the service sector.
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 are on the rise, contributing to significant advancements in business training, employment, and social security, with the poverty rate now at 3.5% The province maintains political security, public order, and safety, leading to a reduction in social evils Additionally, efforts in inspection, complaint resolution, and judicial reform have shown notable progress.
The electric power system fully covers the town, ensuring that 100% of households utilize electricity for both daily living and production The irrigation system is well-developed, with effective plans in place for flood and storm prevention Additionally, the transportation system has been enhanced, addressing unqualified roads that frequently cause accidents, thereby ensuring safe and uninterrupted travel for residents.
RESULTS AND DISCUSSION
Characteristics of the study site
The terrain significantly influences the survival and development of forests by affecting key ecological factors such as rainfall, temperature, humidity, light, and wind These factors play a crucial role in the growth and regeneration of forest ecosystems.
The study site, characterized by hills reaching heights of 50 to 60 meters and slopes of 10 to 15 degrees, is conducive to reforestation efforts As outlined in the "Manual on Land Evaluation for Reforestation," these slopes are beneficial for the regeneration process as they help minimize surface erosion The relatively low elevation also supports effective forest management and protection activities.
Climate significantly impacts the growth and development of forest trees and vegetation by affecting light, temperature, and humidity Consequently, climate change can alter the types of vegetation present in an area Below is a table displaying the weather data from the Chi Linh Hydrometeorology forecast station.
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 average temperature at the study site is a moderate 23.8 °C, with June recording the highest temperature of 29.5 °C and December the lowest at 16.5 °C Humidity levels are lowest in January and December at 70% and 73%, respectively, while March experiences the highest humidity at 93% Annual rainfall totals 1,097.7 mm, peaking in August with 274.9 mm and dropping to just 1 mm in January The site has an annual evaporation rate of 881.3 mm, with December seeing the highest evaporation at 130 mm and March the lowest at 23.8 mm The area enjoys a mild climate, free from disasters like floods or droughts, and experiences a low number of thunderstorms primarily from June to September Additionally, the total annual sunshine hours reach 1,457.9, with May having the most hours at 192.3, while February has the least at 24.4 hours.
Figure 4.1: Comparison precipitation and evaporation in Chi Linh 2014
From October to February, the study site experiences higher evaporation rates than precipitation, resulting in water scarcity during these months This lack of moisture adversely affects seed germination and bud development, making it challenging for seedlings to regenerate, as plants require adequate moisture for growth and development during this critical period.
Characteristics of Castanopsis boisii stand
Mature trees play a crucial role in forest ecosystems by regulating regeneration and influencing forest succession The diversity and abundance of species within these communities are shaped by various factors, including soil conditions, terrain, exposure, temperature, humidity, and human activities Effective forest rehabilitation focuses on restoring the woody tree layer, making the study of mature trees essential for developing classification systems and 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 varies between 4.58 and 6.94, with a coefficient of variation ranging from 24% to 38% These figures indicate a notable variability in diameter across the study site, particularly in plots BA2 and HHT1, which exhibit coefficients of variation of 35% and 38%, respectively.
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
Survey results indicate that the majority of trees range in height from 8 to 12 meters, with some reaching up to 14 meters under favorable conditions Conversely, trees that are of lower quality or still young may only attain heights of around 6 meters.
Figure 4.3: Distribution of mature tree layer bases on diameter
4.2.3 Distribution of regenerated trees bases on the height
The height of regenerated trees is a crucial criterion for selecting potential candidates for forest regeneration The quantity and quality of these trees serve as fundamental indicators for assessing their growth, development, and overall forest quality The distribution of regenerated trees, influenced by various factors, primarily hinges on competition for nutrients and light, whether among regenerated trees themselves or between these trees and surrounding shrub vegetation.
Table 4.5: Distribution of regeneration plant bases on the height
A significant proportion of regenerated trees are less than 1 meter in height, with those under 0.5 meters and between 0.5 to 1 meter making up the majority In contrast, trees exceeding 1 meter in height represent a small fraction of the total The high regeneration density is attributed to local practices of regularly cutting shrub vegetation, which creates space and allows for optimal nutrient availability, facilitating the healthy growth of regeneration trees.
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%
The study site of Castanopsis boisii exhibits two forms of regeneration: bud and seed regeneration The origin of this regeneration is influenced by site conditions, land characteristics, weather patterns, and notably, human impact.
Table 4.6: Origin of regeneration trees in study site
Regeneration of trees primarily occurs from seeds, which are often remnants from the previous year's harvest that thrive under favorable conditions However, field surveys and local interviews indicate that the growth strength of these regenerated trees is low, predominantly consisting of seedlings and some stunted trees, largely unaffected by human activities In contrast, trees regenerated from buds benefit from nutrients supplied by the mother plant, resulting in better growth The density of regenerated trees ranges from 7,500 to 12,000 trees per hectare, with their origin distribution clearly illustrated in figure 4.4.
Figure 4.4: The distribution of origin of regenerated trees in study site
Shrub vegetation significantly influences the density, distribution, growth, and quality of regeneration plants due to competition for nutrients and light beneath the canopy As the canopy of mature trees diminishes, shrub growth becomes more favorable; however, this also creates unfavorable conditions for the growth of 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
The study site exhibits a low coverage of shrub vegetation, ranging from 33% to 47.5%, with heights between 0.46 and 0.55 meters This limited growth is attributed to human impacts, including the removal of shrubs and annual harvesting activities While shrub vegetation plays a dual role under the forest canopy, it offers benefits such as maintaining soil moisture, mitigating wind effects, and fostering favorable conditions for seedling development Conversely, it competes for light and other resources, which can hinder seed grounding ability, reduce ground radiation, and slow seed germination processes.
4.3.1 Economic value of Castanopsis boisii forest in study site
The Castanopsis boisii forest in Chi Linh primarily serves as a rehabilitation forest, with land allocated to local households for management Each household receives 200,000 VND per hectare per year from the government However, local residents primarily engage in traditional shifting cultivation, focusing on seed collection without reinvesting in forest care, which results in low seed yield and quality due to the over-exploitation of forest resources.
Interviews revealed that the quantity of Castanopsis boisii is approximately 3 to 4 dozen per hectare, with seeds priced between 20,000 and 25,000 VND per kilogram This results in an average annual income of 8,000,000 to 10,000,000 VND per hectare Additionally, locals utilize shade from these trees for chicken raising and bee breeding, providing supplementary income for households.
4.3.2 Environment value and other value of Castanopsis boisii forest in study site
The Castanopsis boisii forest plays a crucial role in enhancing local livelihoods while contributing to ecological balance and sustainability This forest supports essential ecological processes, including plant photosynthesis, erosion control, air quality improvement, and soil fertility enhancement.
In study site, Castanopsis boisii create the shade to reduce temperature in the summer
The Castanopsis boisii forest is crucial for protecting buffer zone ecosystems and preventing floods and droughts while maintaining water quality The forest canopy and layer of dried leaves help to mitigate the impact of raindrops, reducing flooding on the ground Additionally, the root systems regulate water flow on the surface Consequently, deforestation increases soil erosion and decreases soil fertility.
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 significantly benefited local communities by aiding in poverty reduction and enhancing the region's landscape To promote the regeneration and development of the Castanopsis boisii stand at the study site, I recommend implementing several strategic solutions.
Most fruit and nut trees, including Castanopsis boisii, are photophilic and require specific light levels at different growth stages Young seedlings thrive under appropriate canopy cover; however, excessive opening of the canopy can lead to increased temperature and light intensity at the forest floor, heightening transpiration rates This poses a risk for small regenerations with underdeveloped roots, making it challenging for them to maintain water balance and increasing their mortality risk Conversely, for larger regenerations, a high canopy cover restricts light availability, hindering their growth potential.
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 is between 20 to 30 years old, with total heights ranging from 8.2 m to 9.8 m and canopy heights between 3.9 m and 5 m The diameter of the trees varies from 13.8 cm to 19.8 cm, while the crown diameter spans from 3.8 m to 4.8 m, resulting in a canopy cover of 38.4% to 55.2% The majority of the trees are of good quality, with only 11% to 18% classified as medium or poor quality.
Shrub vegetation typically reaches heights between 0.46 m and 0.55 m, with coverage ranging from 33% to 47.5% Fieldwork identified eight species in this area: Microsorum pteropus, Phyllanthus emblica, Ardisia crenata, Aporosa tetrapleura, táo xanh, Rourea microphylla, Gardenia jasminoides, and Bauhinia purpurea.
The density of regenerated trees ranges from 7,500 to 12,000, with the majority of regeneration occurring through seeds, although seedlings constitute a significant portion Most potential trees regenerate via buds, while those that regenerate solely by seeds represent a small fraction.
- 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