INTRODUCTION
Forests are vital for human life, offering essential products and ecological benefits However, recent disturbances such as over-exploitation, urbanization, and poor management have led to a decline in forest resources in Vietnam In 1945, Vietnam had 14.3 million hectares of forest, covering 43% of its land, primarily consisting of high-quality primary forests By 1990, this area plummeted to 9.3 million hectares, with only 28.4% forest cover and significantly reduced quality Thanks to societal efforts in protection and afforestation, by 2010, the total forest area rose to 13.95 million hectares, including 10.4 million hectares of primary forest and 3.08 million hectares of plantations, increasing the forest cover to 39.5% Despite this recovery, the overall forest quality remained low, with a predominance of fast-growing trees of little economic value, failing to meet current and future production needs (Ministry of Agriculture and Rural Development, 2011).
Phu Tho province, situated in northern Vietnam, is bordered by Tuyen Quang and Yen Bai to the north, Son La and Hoa Binh to the west, Ha Noi to the south, and Ha Giang and Vinh Phuc to the east Covering an area of 353,294.93 hectares, as reported by the Ministry of Agriculture and Rural Development (MARD) in 2015, the province includes 64,097 hectares of natural forest and 121,703 hectares of plantations, resulting in a forest cover of 50.6% Despite the extensive forestry land, the quality of the forests remains low, predominantly consisting of small timber species This situation raises the critical challenge of sustainably developing forest tree species in the region.
For over 40 years, extensive research and experimentation with native species for afforestation have yielded significant results and identified certain limitations A key success has been the selection of 50 to 52 native species for large timber production, alongside smaller timber and non-timber forest products, as outlined in decision number 16/2005 by MARD Systematic studies have focused on approximately 28 species, including 11 large timber varieties.
Fifty timber species were planted across a thousand hectares, yet only 22 large timber species were utilized, with just 18 actually thriving The main challenges included a diverse range of planning tree types and a lack of focus on spearheaded species Species selection was primarily based on experience rather than research-backed studies, hindering effective development To address these issues, a systematic study concentrating on key spearheaded species is essential While many native species have been identified for reforestation by MARD, most lack comprehensive research on their biological characteristics.
Lithocarpus fissus is known as native and useful species which has wide distribution
Lithocarpus fissus is a valuable species known for its large, sturdy wood, suitable for constructing houses, creating household items, and manufacturing agricultural tools With advantages such as rapid growth, high resistance, and excellent natural regeneration, this species holds significant potential for developing forest resources and boosting the country's economy (Nguyen, 1999).
Despite numerous studies on Lithocarpus fissus, there is a lack of research focused on its biological characteristics in Doan Hung district, Phu Tho province Consequently, the graduation thesis titled "Some Biological Characteristics of Lithocarpus fissus for Large Timber Production in Doan Hung District, Phu Tho Province" was selected to address this gap.
LITERATURE REVIEW
Over the world
Lithocarpus fissus, a large timber tree from the Fagaceae family, is known by several scientific names, including Quercus fissa Champ ex Benth, Pasania fissa (Champ ex Benth.) Oerst, and Castanopsis fissa (Champ ex Benth.) Rehd & Wils.
Fagaceae has historically been viewed as part of the Cupuliferae group, as noted by Bentham and Hooker (1862 – 1883) However, many experts argue for its recognition as an independent family, encompassing 7 to 9 genera and subdivided into 2 to 5 subfamilies, as seen in classifications by Milchior (1964), Menisky (1984), Takhtajan A.L (1987), and Soepadmo (1972) In 1996, Takhtajan A.L proposed a classification system similar to Kupriantova's (1962), which excluded the Nothofagus genus from Fagaceae.
In 2008, some botanists arranged Nothofagus genus into Nothofagaceae family (Judd, 2008)
Huang Chengjiu et al (1999) describe Lithocarpus fissuss species as follows:
Trees exhibit distinctive features such as yellowish-brown, puberulent bud scales, shoot apexes, and young leaf blades, which are covered with rust-colored, waxy scalelike trichomes The branchlets are red-purple and prominently angular Leaves are spirally arranged, varying in color from yellowish-brown to gray, with a petiole length of 1–2.5 cm and oblong to obovate-elliptic leaf blades measuring 15–25 × 5–9 cm These leaves are thickly papery with a cuneate base, undulate and crenate margins, and acute, acuminate, or rounded apices The midvein is raised on the adaxial side, with 20 to 28 secondary veins on each side The infructescence measures 8–18 cm with a glabrous rachis, while the cupule is 1–1.5 cm in diameter, irregularly 2- to 4-valved, and covered with dark reddish-brown mealy waxy scalelike trichomes The nut is globose to elliptic, measuring 1.3–1.8 × 1.1–1.6 cm, with a brown-red tomentose apex and a basal scar that is 4–7 mm in diameter.
The Fagaceae family comprises approximately 900 species found globally, predominantly in the temperate zones of the Northern Hemisphere as well as subtropical and tropical regions Notably, Asia, particularly Vietnam, serves as the most significant area for the distribution of Fagaceae species.
216 species The Africa and the Mediterranean are two places that contain the least species of
Lithocarpus fissuss, as noted by Paul C F Tam and D A Griffiths (1993), thrives at high elevations between 700m and 1700m, predominantly in evergreen forests characterized by moist soil conditions and a deep loamy layer with a pH range of 4.5 to 5 This species can withstand temperatures as low as -5°C and flourishes in areas with annual precipitation between 1000 mm and 2000 mm, making these conditions ideal for its growth.
Lithocarpus fissus thrives in ridge areas with a thick soil layer and demonstrates shade tolerance in its younger stages, while mature trees require full sunlight for optimal growth Known for their impressive regeneration capacity, these trees can grow rapidly, reaching heights of 22 meters and diameters of 300 cm by the age of 23 in secondary forests In plantation settings, they can achieve a diameter of 15 cm after 15 years However, growth slows significantly after 30 years Lithocarpus fissus begins producing seeds at 7 to 8 years old, yielding approximately 50 kg of seeds annually during peak periods, with seeds needing processing within 24 hours at a specific temperature for viability.
80 o C They will germinate after 4 weeks.
In Vietnam
Research on the Lithocarpus fissus species in Vietnam is limited, primarily concentrating on its biological characteristics, distribution, and certain planting techniques Additionally, there are discussions on seed selection and propagation methods that warrant further exploration.
According to Chan LM, Huyen LT (2000), the scientific name of this species is
Castanopsis cerebrina is a member of the Fagaceae family, which encompasses around 7 genera and 600 species globally In Vietnam, there are 5 genera comprising approximately 120 species Notably, the scientific name for this species is Lithocarpus fissus, which is the most widely recognized name in scientific literature.
Hoang et al (2004) describe the morphological characteristics of Lithocarpus fissuss species as follows:
“Trees up to 25 m high, up to 90 cm diameter Trunk straight, young branches covered with dense reddish brown, simple and stellate hairs Leaves distichous, obovate, 12–20 by 4 –
The leaf measures 8 cm with a cuneate base and features a margin that is acutely and regularly serrate for three-quarters of its length towards the apex, which is acuminate The upper surface is green, while the underside is reddish-brown and tomentose; however, mature leaves may appear almost glabrous The venation is pinnate, with 10 to 20 pairs of lateral veins that curve at the margin and are prominent on the lower surface.
Petiole 1 – 2 cm long, slightly tomentose Male catkins 4 – 9 cm long, in branched panicles, usually terminal Perianth puberulous Anthers small, filament slender Pistillode small, styles
3, divergent Female inflorescences 5 – 11 cm long Cupule cup-shaped, 1.8 – 2.5 cm long,
1.6 – 2.2 cm diam., enclosing about 1/2 the seed, densely hairy inside, slightly tomentose outside, scales acute, flat, arranged into many irregular bands, pedicel 4 – 5 mm long, solitary
Nut narrowly conical, 2 – 2.5 by 1.4 –1.8 cm, tomentose, apex sometimes 3-angled”
The study by Hoang et al (2004) reveals that Lithocarpus fissus is naturally distributed across Southeast Yunnan in China, Indochina, northern Thailand, and Louang Namtha in Laos, as well as in several provinces of Vietnam, including Ha Tinh, Nghe An, Thanh Hoa, Yen Bai, Tuyen Quang, Quang Ninh, Ha Bac, and Ha Tay This light-demanding tree thrives on low hills or forest edges at altitudes below 400 meters, exhibiting excellent natural regeneration and a high germination rate both in the wild and in nurseries Lithocarpus fissus flowers between February and April, as well as in October and November, with fruiting occurring from March to June and again from October to December.
Reviews of the studies
Research on Lithocarpus fissuss is limited, primarily focusing on its classification and morphological and biological traits These studies highlight the economic value of this species, suggesting that it should be cultivated more extensively in various countries.
Research on Lithocarpus fissus in Vietnam has primarily concentrated on its classification, morphological traits, and distribution However, there has been a lack of focus on its biological characteristics, particularly species composition and height-based distribution Thus, the study titled "Some Biological Characteristics of Lithocarpus fissus for Large Timber Production in Doan Hung District, Phu Tho Province" is essential to fill this gap.
Natural and socio – economic conditions of the study area
Doan Hung is a rural district located in Phu Tho province, part of Vietnam's Northeast region Covering an area of 302.4 square kilometers, the district comprises 27 communes and one town, as reported by the electronic communication website of Doan Hung district.
According to the Central Northern Center of Forest Sciences, Doan Hung features a diverse topography characterized by deep gorges and dense streams, primarily classified into two main types.
The central district features low mountains characterized by gentle topography, with an average elevation of 350 meters and a slope of approximately 20 degrees.
The district features a variety of hills, both separated and connected, with an average slope of 15 degrees This topography is ideal for cultivating industrial plants, fruit trees, and long-term crops Additionally, the small valleys nestled between the hills provide suitable conditions for growing rice and short-term crops.
In general, both types of topography are suitable for afforestation and planning long – term industrial trees
The study area features a straightforward geological background predominantly composed of sedimentary and metamorphic rocks, resulting in the formation of Oxisols on mica schist, clay schist, and gneiss Notably, the weathered layer exceeds 2 meters in thickness, and the region also exhibits intermediate soil types where slopes converge.
The land features a mechanical composition that ranges from clay silt to silt, characterized by high soil porosity It exhibits excellent permeability and water retention capabilities, with a pH level between 3.9 and 5.4, and a relatively high organic matter content.
Phu Tho province's Doan Hung district exhibits a tropical monsoon climate, characterized by two distinct seasons: a long, dry winter and a hot, humid summer marked by heavy rainfall.
The annual average temperature in the region is 23.1°C, with a dry season lasting from November to April, where December experiences the lowest temperatures The hot season, which spans from May to October, sees average temperatures rise to 28°C, with maximum temperatures reaching up to 41°C.
The region experiences an annual average precipitation of 1,878 mm, with the majority of rainfall occurring in July, August, and September, particularly peaking in August at an average of 322 mm Conversely, January records the least rainfall, averaging only 31 mm Additionally, the annual average humidity stands at 85%, reaching its highest level in March at 92% and its lowest in December at 77%.
The northeast monsoon, spanning from October to March, brings cool weather and light drizzles, while the southeast monsoon, occurring from April to September, is characterized by humid breezes that result in significant rainfall.
The climate in Doan Hung district is conducive to the growth of Lithocarpus fissus; however, the area's topography, along with its annual rainfall patterns, often leads to cyclones and hail that can adversely impact the plants.
Doan Hung district has two rivers: Lo river and Chay river Besides, the study area has dense canal and stream systems which are favorable for transportation and irrigation
In recent years, Doan Hung district has made significant investments in harnessing natural water resources for irrigation and reservoir projects However, the limited area of natural forests and the reliance on single-species plantation forests have resulted in unstable water flow in streams, failing to meet the agricultural and forestry water demands Consequently, recurring drought years have led to substantial damage in forestry production.
Doan Hung district, situated in the northern forestry region between the northwest and northeast production areas, is home to an impressive diversity of 780 plant species across 477 genera and 120 families Notable valuable timber species include Erythrophloeum fordii, Dipterocarpus retusus, Amoors gigantea, and various Fagaceae family members, alongside several bamboo species Additionally, the district hosts herb species such as Gynochthodes officinalis and Homalomena occulta, contributing to its rich botanical landscape.
Arecaceae presented like Elaeis guineensis, Calamus armarus Lour
Due to exploitation and the practice of shifting cultivation, many forests have been degraded into poor secondary growth, hindering forest restoration efforts This situation has put numerous rare native species at risk of extinction.
In recent years, Doan Hung district has successfully recovered substantial forest areas through regeneration, rehabilitation, and afforestation efforts led by authorities and research agencies Currently, numerous forest stands classified as IIIa1, IIIa2, IIa, and IIb are under protection, showcasing the district's commitment to environmental conservation.
GOAL, OBJECTIVES, AND METHODS OF THE STUDY
Goal
To provide some biological and ecological characteristics of a species of Lithocarpus fissus as the basic for large timber production in Doan Hung district, Phu Tho province.
Specific objectives
- To determine the biological and ecological characteristics of a species of Lithocarpus fissus
- To compare the different plantation models in study area
- To propose some suggestions to develop the species for large timber production
Methodology
3.3.1.1 Method for morphological characteristics study
The morphological characteristics of a species of Lithocarpus fissus are described directly through the representative objectives The results are then compared to the data sources
3.3.1.2 Species composition and regeneration study method
In a primary forest characterized by a concentrated distribution of Lithocarpus fissus, three representative plots were established, each measuring 2500 m² (50 m in length and 50 m in width) These plots were selected based on site conditions, slope direction, slope, and the density of Lithocarpus fissus Data collection within these sample plots is essential for understanding the species' ecological dynamics.
For mature trees with a diameter at breast height (D1.3) greater than 6 cm, it is essential to classify the species present in the plots and assess various growth indicators, including total height (Ht), crown diameter (D cr), and under canopy height (H b) Additionally, evaluating forest density and tree quality—categorized as good, average, or bad—is crucial Measurements for diameter can be obtained using a tape measure, while height data can be collected with a Blume-Leiss instrument.
In each sample plot for regenerated trees with a diameter at breast height (D 1.3) of less than 6 cm, five square sub-plots measuring 5 m x 5 m are established, with four located in the corners and one at the center Key data collected includes the species name, tree density, total height, and quality assessment (classified as good, average, or bad), as well as the origin of the regenerated trees, which may be from seeds or buds The total heights of the trees are accurately measured using a tape measure.
For the plantation forest, set up three plots (each plot has an area of 1000 m 2 – 40 m x
25 m) for mix plantation and the same for single species plantation Repeat all of measuring steps as primary forest
The mean annual increment (MAI):
According to West (2009), MAI is average rate of production (of wood, biomass, basal area, etc.) to any particular age of a stand
Figure 1: The plot sample of the primary forest
Figure 2: The plot sample of the plantation forest
Y (t) : yield at time t t: the age of species at a measuring time
The coefficient of variation was calculated using Forkman‟s method (2009) γ γ: coefficient of variation
: Standard deviation à: mean of investigated factor
N%: the percentage of trees based on quality level n: number of trees based on quality level
N: total number of investigated trees
N: density of species per one hectare n: number of trees in the plot (for mature trees) or the sub – plot for (regeneration trees)
Splot: the area of plot or the total area of all sub – plots in the plot (m 2 )
The composition proportion of tree species is calculated by method of Vu (1984) IV% =
IV%: the composition proportion (important value) of the species
N%: density of tree in the plot
G%: % by total basal area of such species in the forest community
According to Thai (1978), species with an Importance Value (IV) greater than 5% are considered significant ecological contributors within a community For a species to be included in the community's composition, its important value must exceed the average important value of all species present Additionally, a group consisting of fewer than 10 species with an important value of 40% or more can be classified as a dominant group, which plays a crucial role in defining the community structure.
Ki: the species composition coefficient of a species of i
Ni: the number of a species of i
N: the total number of investigated trees
RESULTS AND DISCUSSION
Some biological characteristics of a species of Lithocarpus fissus
The investigated results in Doan Hung district, Phu Tho province illustrates some morphological characteristics of study species as follows:
Lithocarpus fissus is medium – sized timber species; the length varies around 17
– 23 m; the diameter can reach to 80 cm
Their stumps have small buttress Their trunk is straight; young branches are covered with black – brown hairs The bark has light gray color; 3 – 5 mm thick
Flower unisexual, monoecious Male catkins 4 – 8 cm long Female inflorescences 5 – 10 cm long Anthers small, filament slender
Picture 3.1: Trunk of Lithocarpus fissus species
Picture 3.2: Flower of Lithocarpus fissus (source: http://www.fpcn.net/)
Leaves simple, oblanceolate, and alternate
The leaf blade measures 12 to 18 cm in length and 4 to 8 cm in width, featuring a serrated margin for three-quarters of its length towards the top It has an acuminate apex and a cuneate base, with a petiole that is 1.5 to 2 cm long and tomentose Notably, the coloration of the two sides of the blade contrasts sharply, as the upper side is green while the underside is adorned with dark brown hairs.
Cupule is cup – shaped; 1.7 – 1.8 cm in diameter, embracing 1/2 – 2/3 the seed; hairy inside; tomentose outside There are some unevenly distributed scales in the cupule The nut is conical – shaped; 2.5 –
3 cm long; 1.5 – 1.8 cm in diameter; easy to be detached from cupule
The community structure encompasses the silvicultural characteristics of a stand, including species composition, forest structure, and the distribution of trees based on diameter or height These elements are crucial for evaluating the bio-ecological stability of the ecosystem.
Picture 3.4: Cupule and seed of Lithocarpus fissus species (source: the Central Northern
The study conducted by the Center of Forest Sciences focused on the species composition and forest structure of Lithocarpus fissus The findings highlight potential strategies to enhance productivity and promote sustainable development within forest ecosystems.
Species composition serves as a crucial indicator of plant community dynamics, reflecting the contribution of each species to the overall ecosystem This metric helps assess forest sustainability, stability, and biodiversity, highlighting the resilience of the ecosystem against environmental challenges A more complex species composition correlates with enhanced sustainability and balance within the forest To quantify species participation, the study employed the Important Value (IV%) method, expressing species composition as a percentage that totals 100% Higher IV% values indicate greater importance of specific species within the community The findings regarding species composition in a natural forest featuring Lithocarpus fissus are detailed in Tables 3.1 and 3.2.
Table 3.1: The species composition of the mature trees in Doan Hung district, Phu Tho province
Number of trees per plot ̅̅̅̅̅
Table 3.2: The species composition’s formula of the mature trees in the study area
Plot Species composition Total number of species
Plot 1 58.05 Lf + 7.25 Ef + 6.65 Lc + 5.95 Gs + 22.1 Os (20 species) 24
Plot 2 28.0 Lf + 19.6 Ob + 10.8 Gs + 9.2 Ef + 8.7 Ld + 6.8 Sp4
Plot 3 18.7 Lf + 12.9 Ob + 9.2 Qp + 9.2 Ef + 8.0 Gc + 6.1 Sl + 5.3 Ed +
Lithocarpus fissus (Lf), Gironniera subaequalis (Gs), and Erythrophloeum fordii (Ef) are notable species in the region, alongside Lithocarpus corneus (Lc) and Garcinia cambogia (Gc) Additionally, Quercus platycalyx (Qp), Ormosia balansae (Ob), and Symplocos laurina (Sl) contribute to the area's biodiversity Elaeocarpus dubius (Ed) and Lithocarpus ducampii (Ld) further enrich the ecosystem, along with various other species (Os) that play significant roles in maintaining ecological balance.
The study reveals that the natural forests in the area are secondary forests, exhibiting a species composition ranging from 14 to 26 species as they recover from previous exploitation Notably, Lithocarpus fissus demonstrates a significant important value (IV%) across three plots, recorded at 58.05%, 28.0%, and 18.7% The dominant species contributing to the forest composition in Doan Hung district, Phu Tho province include Lithocarpus fissus, Gironniera subaequalis, Erythrophloeum fordii, Lithocarpus corneus, Garcinia cambogia, Quercus platycalyx, Ormosia balansae, Symplocos laurina, Elaeocarpus dubius, and Lithocarpus ducampii.
4.1.2.2 The plant's distribution of stand based on the tree’s height
Table 3.3: The distribution of the plants based on the trees' height
Figure 3.1: The distribution of the plants based on the tree’s height
The study categorizes forest height into three layers: A1 (over 20 m), A2 (10 to 20 m), and A3 (under 10 m) In plot 1, the average height ranged from 7.7 m to 14.6 m, with no trees in A1 and 396 trees/ha in A2 and 272 trees/ha in A3 Plot 2 showed a height variation from 7.7 m to 21.6 m, where A2 had the highest tree count at 516, while A1 and A3 contained 32 and 176 trees, respectively Plot 3's average height ranged from 8.2 m to 21.9 m, with A2 hosting 404 trees, compared to 68 trees in A1 and 160 in A3.
Figure 3.2: The distribution of Lithocarpus fissus species based on the tree’s height
The study on Lithocarpus fissus revealed that its distribution across different plots showed notable variations In plot 1, the majority of trees (66) were found in the A2 layer, with no trees in A1 and 23 in A3 Plot 2 had 41 trees in the A2 layer, alongside 3 in A1 and 5 in A3 Conversely, plot 3 exhibited a different trend, with the highest number of trees (8) in the A1 layer, while A2 and A3 contained 2 and 1 tree, respectively The mean height of Lithocarpus fissus varied across the plots, ranging from 8.2 m to 14.1 m in plot 1, 9.0 m to 21 m in plot 2, and 8 m to 22.5 m in plot 3.
4.1.3.1 The density of natural regeneration
The density of natural regeneration, measured as the number of regeneration trees per hectare, serves as a crucial indicator of a site's regeneration capacity and self-sowing ability Evaluating this density alongside species composition allows for the identification of appropriate silvicultural techniques, such as additional planting and enrichment, to enhance forest management practices.
Plot 1Plot 2Plot 3 planting, cutting down bushes, sowing can be applied to achieve the forestry business purpose The results of naturally regenerated trees‟ density in Doan Hung district, Phu Tho province were presented in table 3.4
Table 3.4: The density of naturally regenerated trees
Lithocarpus fissus ’s density (trees/ha)
The study area exhibited significant densities of regenerated trees, ranging from 21,280 to 26,000 trees per hectare Notably, the densities of Lithocarpus fissus across three plots were remarkable, varying between 4,400 and 8,960 trees per hectare.
4.1.3.2 The species composition of naturally regenerated trees in the study area:
The species composition of naturally regenerated trees reflects the stand's natural regeneration capacity, seed dispersal, and germination abilities This composition not only showcases community diversity but also highlights the forest's economic value, serving as a foundation for recommending effective silviculture techniques to boost forest productivity and quality Additionally, by analyzing this index, the species composition of mature trees can be enhanced through the removal of non-beneficial regenerated trees and the support of targeted regenerated trees for optimal growth.
Table 3.5: The species composition index of naturally regenerated trees
Table 3.5 shows a high diversity of naturally regenerated species in Doan Hung district, Phu Tho province, with approximately 19 to 22 species identified Only plants with a Ki index of 0.5 or higher contribute to species composition, as summarized in Table 3.6.
Table 3.6: The species composition formula of the naturally regenerated trees in the study area
No Plot Forest status Species composition
3.35Co + 2.07Lf + 0.94Am + 0.71Gs + 0.71Ob +
Note: Lf – Lithocarpus fissus, Co – Cinnamomum obtusifolium, Ob – Ormosia balansae, Am – Alphonsea monogyna, Gs – Gironniera subaequalis, Os – Other species
Table 3.6 reveals that out of the 19 to 22 species identified in the study area, only 3 to 5 species contributed to the species composition The restoration forests, which underwent rehabilitation after exploitation, predominantly featured naturally regenerated trees The key species involved in the composition of these regenerated trees were identified.
Lithocarpus fissu, Cinnamomum obtusifolium, Ormosia balansae, Alphonsea monogyna, and Gironniera subaequalis
4.1.3.3 The quality and the origin of the naturally regenerated trees
Table 3.7: The quality and the origin of the naturally regenerated trees in the study area
The results of table 3.7 could illustrate several reviews about the quality and the origin of the regenerated trees
In the study area, naturally regenerated trees originating from seeds dominated three plots, with percentages of 98.1%, 97.8%, and 94.7% Conversely, the proportion of naturally regenerated trees from buds was minimal, ranging from 1.9% to 5.3%.
Lithocarpus fissus, the results remained the same as that of plots The number of Lithocarpus fissus coming from seed in three plots was massively high, accounting for 95.5%, 95.5% and
96.4% of the total, correspondingly By contrast, the percentages of this species having origin from the bud in three plots were seriously flat, at 4.5%, 4.5%, and 3.5%, appropriately
Assessing the plantation models in Doan Hung district, Phu Tho province
The research gathered data from two plantation models: a 15-year-old single-species plantation and a 10-year-old mixed plantation located in Doan Hung district, Phu Tho province The findings from the data analysis are detailed in Tables 3.9 and 3.10.
Table 3.9: The growth of Lithocarpus fissus in 10 – year - old mixed plantation model
The findings from Table 3.9 reveal that the growth of Lithocarpus fissus is comparable to that of Lithocarpus ducampii, with both species showing an identical mean annual height increment of 1.6 While Lithocarpus ducampii slightly outperformed Lithocarpus fissus in total height, bole height, diameter at breast height (DBH), density, and overall quality, both species maintained a quality percentage exceeding 90% The coefficient of variation for DBH and total height was 30.9% and 17.7% for Lithocarpus fissus, respectively, while Lithocarpus ducampii exhibited lower values of 27.8% and 14% Despite these differences, all coefficients of variation were below 1, indicating low variance in DBH and total height for both species Overall, the data suggest that neither species is dominant over the other, contributing to a stable mixed plantation.
Table 3.10: The growth of Lithocarpus fissus in 15 – year - old single species plantation model
The single species plantation model for Lithocarpus fissus indicates that the trees have nearly reached a size suitable for large timber production, with impressive average measurements: crown diameter at 6.7 m, bole height at 9.7 m, diameter at breast height (DBH) averaging 21.2 cm, and total height averaging 17.2 m Additionally, the low variance in DBH and total height contributes to a small coefficient of variation, reflecting the overall quality of the species.
Lithocarpus fissus exhibited a high quality rating of 96.2%, with only 3.8% considered average and 0% rated as bad However, the plantation density was notably low, with just over half of the initially planted trees remaining, primarily due to diseases and competition for nutrients.
A comparison of the mean annual increment (MAI) for Lithocarpus fissus reveals that mixed plantations outperform single-species plantations in both diameter at breast height (DBH) and total height MAI, with values of 1.5 vs 1.4 and 1.6 vs 1.1, respectively.
Lithocarpus fissus between two models are nearly the same, including around 95% of good quality trees while the average and bad quality trees were lower than 5%.
DISCUSSION
Review of the mature trees
- The morphological characteristics of a species of Lithocarpus fissus which were described in this study are not different comparing with those of other studies
Lithocarpus fissus is a promising species for single-species plantations, thanks to its significant IV% in species composition Additionally, it can be effectively paired with other key species for mixed plantation growth alongside Lithocarpus fissus.
The A2 layer of the forest exhibited the highest density of trees, indicating a stable ecosystem Notably, Lithocarpus fissus was the most prevalent species found in this layer.
A 1 layer and A 2 layer, which indicates that this species had ecological dominant in the community However, the number of Lithocarpus fissus trees occurring in the A3 layer of plot
3 was very low because the percentage of plants in other layer were very high lead to the lack of nutrient space for this species.
Reviews of the naturally regenerated trees
In Doan Hung district, Phu Tho province, the density of naturally regenerated trees is notably high, with Lithocarpus fissus comprising approximately one-third of the total This indicates a remarkable capacity for natural regeneration of this species By leveraging this regeneration alongside effective silvicultural techniques, the forest has the potential to recover rapidly.
The main species that took part in species composition were Lithocarpus fissus, Ormosia balansae, Alphonsea monogyna, and Gironniera subaequalis Lithocarpus fissus and
Cinnamomum obtusifolium emerged as the dominant species across the three plots, achieving the highest Ki index results By implementing appropriate support measures, these dominant regenerated trees could have ample space for growth.
The study area shows that approximately 95% of tree species, including Lithocarpus fissus, originate from seeds, highlighting the importance of preparing optimal site conditions for sowing and sapling growth Additionally, it is crucial to investigate the factors influencing seed germination The high percentage of quality trees, particularly Lithocarpus fissus, across three plots indicates strong natural regeneration capabilities in the area With positive influences, these trees are likely to grow sustainably and maintain stability.
In the study area, the number of regenerated trees, including Lithocarpus fisuss, decreased significantly as tree height increased, particularly in the 1–2 m and over 2 m height ranges This decline indicates intense competition for nutritional space, especially between regenerated trees and surrounding bushes Consequently, it is essential to enhance the growth conditions for regenerated trees.
Review of the plantation models
Mixed plantations offer greater advantages over single-species plantations due to their higher Mean Annual Increment (MAI) index, contributing to larger timber production Additionally, mixed plantations enhance disease resistance, protecting against threats to Lithocarpus fissus species Their biodiversity also promotes sustainability and stability, making them a more resilient choice for forestry.
5.4 Proposing several viable suggestions to develop Lithocarpus fissus species
- It is advised that planters determine the area which has Lithocarpus fissus species, and they could apply some suitable silviculture techniques to support the regeneration such as:
+ Cutting down the vines, brushes and purposeless regenerated trees to increase the nutrient space for Lithocarpus fissus species
+ Cutting down the diseased trees as well as underdeveloped trees, planting the healthy trees in places where the seed could not germinate or the tree died
To enhance barren land exceeding 1,000 m², it is essential to sow significant seedlings, including Lithocarpus fissus and other species such as Gironniera subaequalis, Erythrophloeum fordii, Lithocarpus corneus, Garcinia cambogia, Quercus platycalyx, Ormosia balansae, Elaeocarpus dubius, and Lithocarpus ducampii.
+ Hilling and digging around the tree stump twice a year
+ Thinning trees in the place that has the dense density to generate more nutrient space for Lithocarpus fissus species
To safeguard the natural forests in the study area from wildfires, particularly during the dry season, it is crucial to enhance fire-fighting equipment and implement a ban on activities like campfires and smoking.
- Protecting the mother trees as well as significantly regenerated trees from logging and destroying
- Preventing people from grazing in the natural forest in order to protect the naturally regenerated trees
- Enhancing the propaganda and advising people to take part in protecting the natural forest
For optimal growth and forest stability, it is advisable to cultivate Lithocarpus fissus in mixed plantations rather than as a single species This approach not only enhances the mean annual increment but also reduces insect infestations Suitable companion species include Lithocarpus ducampii and Erythrophloeum fordii, which are naturally found in the same forest composition.
CONCLUSION AND RECOMMENDATION
Conclusion
Lithocarpus fissus is a medium-sized tree species, reaching heights of 17 to 23 meters and a diameter of up to 80 cm Characterized by a straight trunk and small buttress stumps, its young branches are covered in black-brown hairs, while the light gray bark is 3 to 5 mm thick The leaves are simple, oblanceolate, and alternate, measuring 12 to 18 cm in length and 4 to 8 cm in width, with a serrate margin for three-quarters of their length, an acuminate apex, and a cuneate base The petiole is tomentose and measures 1.5 to 2 cm long The upper leaf surface is green, while the underside is covered with dark-brown hairs Lithocarpus fissus features unisexual, monoecious flowers, with male catkins measuring 4 to 8 cm and female inflorescences 5 to 10 cm long The small anthers have slender filaments, and the cupule is cup-shaped, measuring 1.7 to 1.8 cm in diameter and embracing half to two-thirds of the seed, with a hairy interior and tomentose exterior The nut is conical-shaped, measuring 2.5 to 3 cm long and 1.5 to 1.8 cm in diameter, and is easily detached from the cupule.
Lithocarpus fissus significantly contributes to species composition in Doan Hung district, Phu Tho province, with an important value ranging from 18.7% to 58.05% This species predominantly inhabits the A1 and A2 layers of the natural forest within the study area.
Lithocarpus fissus is the dominant species in tree regeneration, with a Ki index ranging from 2.01 to 3.64, highlighting its impressive seed regeneration potential as a viable development solution Although the quality of naturally regenerated trees is high, intense competition for nutrients has led to a limited number of regenerated trees exceeding 1 meter in height.
The mixed-plantation model offers significant advantages over the single-species plantation model, leading to increased mean annual increments, improved quality, and enhanced density of the plants.
- The study has provided several viable suggestions to develop the growth of the
Lithocarpus fissus species including technical suggestions and social – economic suggestions.
Shortcomings
- The study could not cover other biological characteristics such as phenological characteristics, physio - biological and distributed features due to the lack of time
- Soil features were not mentioned in this study
- The comparison between two plantation models was only relative due to the lack of the assessment about site condition and other factors.
Recommendations 36 REFERENCES
- Study on the phenological characteristics and the distribution of Lithocarpus fissus species to have clearer information about the ecological characteristic of this species
- Assessing the site condition of the two plantation models to have more accuracy results of the comparison between those models
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Appendix 01: Table for collecting data from mature trees
Appendix 02: Table for collecting data from regenerated trees
Appendix 03: List of species in the study
No Scientific name Vietnamese name
3 Ormosia balansae Ràng rang mít
15 Cryptocarya concinna Mò quả vàng
26 Castanopsis indica Dẻ gai Ấn Độ
35 Holarrhena pubescens Mộc hoa trắng