Vietnam Journal of Forest Science Number 4-2015

Từ khóa: Giâm hom, nhân giống vô tính, bạch đàn lai

Research on cutting propagation of new eucalyptus hybrid

Research on methods to create shoots, cutting and watering control for plus trees of hybrid combinations between E. urophylla and E. exserta (called UE), E. urophylla and E. grandis (UG), E. urophylla and E. camaldulensis (UC) indicated that: (1) All three methods to create shoots (re – barking around the bole, tree cutting and direct cutting of 6 month old trees) have their own advantages and disadvantages, so that base on real situation, one could apply one of the three said methods for experiment; (2) The method to plant selected clones on land with roofing when raining and limitted watering from the time when shoot lengths are from 2 – 3cm to the cutting time was the most effective method; (3) Cutting propagation of UC and UG were easier than that of UE. In addition, clones within a hybrid combination have different rooting rate and a hybrid, which has low rooting rate, also has low quantity of roots and the length of roots is short, too.

Keywords: Cutting, vegetative propagation, eucalyptus hybrid

Từ khóa: Xử lý hạt, che sáng, tỷ lệ nảy mầm, sinh trưởng, Mạy châu

Research on influence of treated water temperature to germination and shading to growth of Carya tonkinensis Lecomte, 1921 in nursery

Carya tonkinensis Lecomte, 1921 is a native and end endemic tree species, everage tree with high economic and conservation values, stenotopic, in Vietnam is only distributed in some districts and cities of Son La provinces. This is a species listed in the Red Book of Vietnam with an assessment “will endangered, level V”. However, the information on this species is very limited and there are no studies on silvicultural characteristics, propagation and planting. Therefore, it is essential to research on influence of water temperature processing to germination and shading to growth of Crarya tonkinensis Lecomte in nursery.

Research results showed that water temperature processing affect germination rate significantly, formula soaking seeds in water temperature 60^oC have the highest germination rate 82.79% and the lowest formula soaking seeds in water temperature 100^oC with 21.11% germination rate. About shading in the first 4 months after sowing, shading 75% is appropriate, survival and ability to grow in height at high shading reached similar values application is 92.67% and 23.03cm. However, from after the 4^th month to 8^th month, shading 50% is appropriate, with survival rates as well as the growth reached the highest heights with the corresponding value was 92.66% and 52.74cm, seedling 7 – 8 months old qualified planted forest planting.

Keywords: Seed processing, shading, germination, growth, Carya onkinensis Lecomte, 1921

Kết quả nghiên cứu chỉ ra rằng cây keo lai có thể sống trên các dạng bãi thải, với tỷ lệ sống dao động từ 60 – 90% sau 4 năm trồng. Đối với các mô hình hoàn thổ, keo lai có sinh trưởng về đường kính và chiều cao tốt hơn so với các mô hình nguyên trạng hay chưa hoàn thổ. Có sự khác biệt lớn về sinh trưởng của cây keo lai trong các mô hình hoàn thổ, theo đó lượng tăng trưởng đường kính gốc ở mô hình hoàn thổ đất mặt đạt 3,35 cm/năm lớn hơn nhiều so với 1,7 cm/năm của mô hình hoàn thổ bằng bùn thải, tương ứng với chiều cao vút ngọn là 1,6 m/năm so với 1,2 m/năm.

Từ khóa: Bãi thải, hoàn thổ, keo lai, mỏ bauxite, sinh trưởng.

Growth of A. mangium ´ A. auriculiformis in mine wasteland at Loc Phat, Bao Loc and Tan Rai, Bao Lam bauxite mine, Lam Dong province

The research was carried out at the bauxite – mined site of Loc Phat, Bao Loc and Tan Rai, Bao Lam. The end result for mining activities on the surface is mining waste and alteration of land forms. There are 3 types of mine wasteland, given that (i) “directly return” topsoil; (ii) “directly return” sludge and (iii) combined topsoil and sludge. The soil texture of mine wasteland was found to be from moderate to slight, with the soil pH to range of 4.8 – 6.5. The content of macronutrient such as nitrogen, phosphorus, potassium on the landfill of waste sludge factor is very poor compared to the one with topsoil.

Results show that A. mangium ´ A. auriculiformis could tolerate on the mining waste, with survival rates ranging from 60 – 90% after 4 years of planting. For the restoration models, A. mangium ´ A. auriculiformis had growth of diameter and height better than undisturbed or unrestored soil. There are major differences in growth of A. mangium ´ A. auriculiformis in restoration land, in which MAI of collar diameter growth in restoration of topsoil reaches at 3.35cm per year much greater than 1.7cm per year in restoration of using sludge, respectively MAI of height is 1.6m per year compared to 1.2m per year.

Keywords: Bauxite, restoration, mining wasteland, growth, A. mangium ´ A. auriculiformis.

Từ khóa: Cây Chua khét, Nao, Quảng Bình, tên khoa học

Re – Identification of scientific name for the tree species “Chua khet” or “Nao” in Quang Binh province

The “Chua Khet” tree species, also locally called “Nao” in Vietnamese, naturally distributes in Quang Binh province. This indigenous species is a timber of high commercial value, used for housing construction and fine indoor furniture – its wood has a beautiful light red color. In Decision 2198/CNR of the Ministry of Forestry, dated 26 November 1977, on temporary classification of timber species being used in Vietnam, this indigenous species (“Chua Khet” or “Nao”) is classified as Chukrasia sp., belonging to Group III. Hence, the name Chukrasia sp. have been used for this tree species by forestry technical agencies, forestry consulting companies and state – owned forest enterprises in Quang Binh province as well as in the list of flora in Phong Nha – Ke Bang National Park. However, detailed study of the morphological characteristics, classification and structure of the “Chua khet” (or “Nao”) in Quang Binh province suggests that it has many different characteristics as compared to those of the species classified as Chukrasia sp. in the above – mentioned Decision 2198/CNR, and actually belongs to the Dysoxylum genus. Therefore, in this study, we analyzed some characteristics of this plant in Quang Binh, compared with the “Chua khet” (Chukrasia sp.) of the Chukrasia genus and then determined the scientific name of the Chua Khet (Nao) species found in Quang Binh to be Dysoxylum cyrtobotryum Miq., Fl. Ind. Bat. Suppl. 1 (1861).

Keywords: Chua khet, Nao species, Quang Binh, scientific name

Hoang Thanh Son, Trinh Ngoc Bon, Nguyen Quang Hung,
Pham Van Vinh and Nguyen Thi Van Anh
Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Vietnam

SUMMARY

Impatiens parvisepala S. X. Yu & Y. T. Hou, a previously known species only in China, is newly recorded from Vietnam. It is found in primary limestone forest in Na Hang Nature Reserve, Tuyen Quang Province, Vietnam.

Keywords: Balsaminaceae, Impatiens, Na Hang, Nature Reserve, Tuyen Quang

Impatiens parvisepala (Balsaminaceae): Một loài bóng nước mới cho khu hệ thực vật Việt Nam

Impatiens parvisepala S. X. Yu & Y. T. Hou, loài Bóng nước đài hoa nhỏ trước đây chỉ được biết phân bố ở Trung Quốc, nay là một loài mới cho khu hệ thực vật Việt Nam. Nó được tìm thấy trong các khu rừng nguyên sinh núi đá ở Khu bảo tồn thiên nhiên Na Hang, tỉnh Tuyên Quang.

Từ khóa: Họ Bóng nước, chi Bóng nước, huyện Na Hang, khu bảo tồn thiên nhiên, tỉnh Tuyên Quang

Từ khóa: Chi Riềng, Sa nhân, đa dạng, họ Gừng, Bắc Trung Bộ

Diversity of the genera Alpinia and Amomum (Zingiberaceae) in North Center Vietnam

The genus Alpinia about 230 species and Amomum about 150 species. They are distributed in the tropics and subtropics. In Vietnam genus Alpinia about 31 species and genus Amomum about 21 species. Study result of diversity of genera Alpinia and Amomum (Zingiberaceae) in North Centre of Viet Nam reported, 40 species among more than 51 reported species. There are 6 species new record for list of North center Vietnam (2011) and 2 species new record for flora of Vietnam. These plants are used to treat different diseases that we grouped into: 30 species for medicinal plants, 6 species edible, 36 species for essential oils plants, 10 species for spice. There are 5 major habitats: forest, light forest, subforest, along streams. The distribution of Alpinia and Amomum species in North Centre of Viet Nam are mainly comprised of the tropical Asia element (45.0%), temperate element (7.5%) and endemic element (45.0%).

Keywords: Alpinia, Amomum, diversity, Zingiberaceae, North Center Vietnam

Từ khóa: Bệnh thán thư, bệnh thối cổ rễ, sâu đo, xén tóc đục thân cành và xoan nhừ

Insect pests and diseaes of Choerospondias axillaris

Choerospondias axillarisis is a large fast growing tree that has many different uses as for wood in furniture, construction and bark, fruit and leaves used in medicine. But the cultivation and development of this species is difficult because of insect pests and diseases affecting its growth and development. The main insect and diseases of C. axillaris include 5 species pests of insect and 3 kinds of disease, in which, four major causative agents for C. axillaris are looper (Hyposidra talaca), longhorn beetle (Aeolesthes sp.) and anthracnose disease (Colletotrichum gloeosporioides) and damping off disease (Fusarium oxysporum). Some main morphological characteristics of the insect pests and diseases are described.

Keywords: Aeolesthes sp., Anthracnose, Choerospondias axillaris, damping off, Hyposidra talaca

Từ khóa:: Hình thái, Sâu tre, Omphisa fuscidentalis

Some morphological, biological characteristics of bamboo caterpillar (Omphisa fuscidentalis Hampson)

Bamboo caterpillar (Omphisia fuscidentalis Hampson) is in Lepidoptera order, Crambidae family. Bamboo caterpillar is a favourite food of mountain people. Bamboo caterpillar is a pantamorphia insect. The larvae of Bamboo caterpillar has 13 segments, 3 pairs of thorax legs, 5 pairs of abdominal legs, a mandibulatory mouth part, non – complex eyes, 5 occelli near by antenna. The antenna is very short with 2 segments. The pupa is not contained in a cuccoon, and the adult moth has a sucking mouth part. Bamboo caterpillar life cycle lasts around 12 months. The larva phase has five instars and lasts from 9 to 10 months. The larvae bore a hole in the bamboo shoot, destroying the inner pulp, and then bore through the internodes moving upwards through the stem. The active larval phase lasts between 40 to 60 days. Then the larvae hang upside down inside the stem at an internode. The color of pupa changes over time as it matures. Several hours after emergence, the adult finds a mate to copulate, and this process takes place at night. The female lays a cluster of about 80 – 130 eggs in a newly developed bamboo shoot. The ova development takes place around 12 days, and adults live about 8 days. The bamboo caterpillar has only one lifecycle per year. Additionally, adults often appear in early July through to the middle of August. They lay eggs from the middle of July to the end of August. The larval period lasts from September to May. A larva metamorphoses into a chrysalis at the end of May to early July. The larvae then undergo a period of diapause, which lasts from the end of October to May. Bamboo caterpillar are confronted with many natural enemies such as woodpecker, house gecko and ant species.

Keywords: Biological characteristics, bamboo caterpillar, morphological characteristics, Omphisia fuscidentalis

Từ khóa: Động thái tái sinh, rừng lá rộng thường xanh, Vườn Quốc gia Xuân Sơn

Regeneration dynamics of broadleaf evergreen forests in Xuan Son National Park, Phu Tho provice

The observation of dynamics of broadleaf evergreen forests in the three permenant plots (each 1ha) suggested that there existed a species accumulation in time; the number new regenerated species in a certain period was lower than that of species accumulated in the older tree layers, specifically, there was an increasing in the number of species from tree regeneration layer (CTS:D_1.3<1.0cm) < low tree layer (TCN: 1.0cm<D_1.3<10.0cm) < high tree layer (TCC: D_1.3≥10.0cm). The tree regeneration density considerably fluctuated from 24,444 to 31,076 trees/ha. The number of regenerating trees was 13,418 trees/ha/year supplemented and 15,977 trees/ha/year died on average. The dead rate of regenerating trees was 73.30% for trees below 0.5m and 38.3% for trees above 1.5m in high. In a 5 – year observation period (2007 – 2012), from 64,000 to 69,000 regenerating trees/ha was supplemented and from 73,000 to 85,000 trees/ha died. The number of regenerating trees reached to the low tree layer ranged from 116 to 382 trees/ha. The tree number of the low tree layer was from 3 to 43 trees/ha for trees reached to the high tree layer, and from 99 to 184 trees/ha for trees died. The dead tree number of the high tree layer changed from 6 to 90 trees/ha.

Keywords: Regeneration dynamics, broadleaf evergreen forests, Xuan Son National Park

Từ khóa: Bắc Trung Bộ, đất cát, keo lá liềm, kỹ thuật chăm sóc, thời vụ trồng, tiêu chuẩn cây con.

Result of studying tending technique, planting season and seedling age of Acacia crassicarpa in the Central Coastal Area

The result shows that with tending techniques: root cover + 50g NPK is the most suitable, bringing highest living ratio and biomass compare to other methods: uncover + 50g NPK, Root cover + no fertilizer, Uncover + no fertilizer. Result of planting season show that it is best to plant in November bringing highest living ratio. However, there was no difference in the tree biomass between the panting seasons. The result of seedling age show that there was no difference between the 4 month and 6 month old seedlings. Thus, we should choose the 4 month old to reduce the cost. From this, the study chose the tending technique: root cover + 50g NPK, planting seaon in November and seedling age of 4 month old.

Keywords: Northern Central, sandy soil, Acacia crassicarpa, stending techniques, planting season, seedling age

– Về năng suất theo trữ lượng gỗ không có mô hình nào đạt mức lớn hơn 20m³/ha/năm, phân cấp năng suất theo loài có 7 mô hình có triển vọng gồm 4 mô hình keo lai (A. mangium ´ A. auriculiformis) + 2 mô hình Keo tai tượng (Acacia mangium) cho năng suất mức trung bình (15 ≤ M < 20m³/ha/năm) + 1 mô hình Keo lá tràm (Acacia auriculiformis) cho năng suất trung bình đạt (10 ≤ M < 15m³/ha/năm).

– Về các dạng lập địa của các mô hình triển vọng có năng suất từ mức trung bình trở lên đều nằm ở vành đai độ cao tuyệt đối từ 30 – 371m, dốc ≤15°; đất vàng hay đỏ phát triển trên đá phún xuất chua hay mác ma kiềm, tầng đất từ trung bình đến dày, thực bì trước khi trồng rừng thuộc loại khá.

– Về tính chất vật lý – hóa học của đất tầng mặt có dung trọng dưới 1,50g/cm³; hàm lượng sét vật lý từ 50 – 70%; pH_KCl từ 3,7 – 4,2, tỷ lệ mùn đạt từ 1,14 – 4,20%; khả năng hấp phụ trao đổi (CEC) từ 5,63 – 42,78 me/100gam đất

Từ khóa: Gỗ lớn, năng suất, lập địa, đất, các loài keo, vùng Nam Trung Bộ

Growth and productivity of timber plantations of some main species in Binh Dinh and Phu Yen, South Central region

Combining assessment of forest status of productive plantations and protective plantations of Acacia species being age of 6-21 with the site conditions and characteristics of the soils where planting in Binh Dinh and Phu Yen provinces with specific methods and special techniques identify potential models for providing large timber to apply and develop. The results including:

– Timber volume: There is no models achieved average timber volume above of 20m³/ha/year. It is classified by species, there are 7 potential models including: 4 models of A. mangium ´ A. auriculiformis species, 2 models of A. mangium with average timber volume of 15 ≤ M < 20m³/ha/year, and 1 model of Acacia auriculiformis species with average timber volume of 10 ≤ M < 15 m³/ha/year.

– Site condition of potential models located in the belt absolute height of 30 – 371m, slope ≤ 15°; yellow or red soils developed on sour rock or alkaline magma, soil layer is from medium to thick, vegetation before planting is medium.

– Physical – chemical properties of topsoil: Bulk density below 1.50g/cm³, physical clay content of 50-70%, pH_KCl of 3.7 – 4.2, humus proportion of 1.14 – 4.20%, CEC from 5.63 to 42.78 me/100 grams of dry soil.

Keywords: Timber – productivity, site condition, soil, acacia species, the South Central

Từ khóa: Cộng đồng bản địa, nhận thức cộng đồng, tác động, Voọc Chà vá chân xám, VQG Kon Ka Kinh

Study on the indigenous community awareness and impact on grey-shanked douc langur (Pygathrix cinerea) in Kon Ka Kinh National Park, Gia Lai province

Grey – shanked Douc Langur (Pygathrix cinerea) was recognized distribution in Kon Ka Kinh National Park. This species is classified as Critically Endangered (CR) on the IUCN Red List. In this study, we investigated the Ba Na ethnic community knowledge, their attitude toward the Grey -shanked Douc Langur and the awareness about the law to protect this species. The results showed that 63% responders know about the existence of Grey – shanked douc in Kon Ka Kinh National Park, however 59% responders don’t know about the conservation laws as well as the necessary to protect this species. The main directly impacts to species was hunting by homemade guns. Other impact was losing habitat by logging, burning forests for cultivation of local communities. The exploitation of NTFPs also indirectly affect habitat and behavior of this species. It is necessary to raise awareness of forest resources conservation (in general) and grey shanked douc langur conservation of local communities; strengthening management capacity and encouraging community participation in the forest resources management; improving livelihoods of community living in Kon Ka Kinh National Park buffer zone.

Keywords: Awareness, Grey – shanked Douc Langur, impact, Kon Ka Kinh National Park, local community

Từ khóa: Thú, thành phần loài, mối đe dọa, Ngọc Sơn – Ngổ Luông, Hòa Bình

Diversity of mammals In Ngoc Son – Ngo Luong Nature Reserve, Hoa Binh province

Ngoc Son – Ngo Luong nature reserve (NR) characterized by forest ecosystems on limestone are considered with high biological diversity. However, research on diversity of mammal composition, especially the updated information on the presence of the animals as well as the threats to the species and habitats are limited. This research will focus on revealing the above information and recommended conservation measures for fauna reserve. Data collection was conducted in 2 times: 2014 and 2015. Interview, line transects, and point methods were used to collect data. The results show that a total of 94 species of mammals belonging to 28 families, 9 sets were recorded in the reserve. Of these, 46 (50%) animals are identified important priorities for conservation. The two main threats to the mammal species are hunting and habitat destruction (illegal logging, encroachment of forest land for cultivation strategy, grazing…). Three solutions to improve the efficiency of managing conservation mammal species were recommended including: Protection of species and habitats, developing monitoring programs, improved livelihoods for local people.

Keywords: Mammals, composition, threats, Ngoc Son – Ngo Luong, Nature Reserve

Từ khóa: Đa dạng sinh học, cảnh quan, du lịch sinh thái, Kim Hỷ, Bắc Cạn

Assessment of biodiversity, landscapes and potential ecotourism development in Kim Hy Nature Reserve, Bac Kan province

Kim Hy nature reserve located in Na Ri District, Bac Kan Province, typical of forest ecosystems on limestone in Northern Vietnam, is considered to have a high diversity of plant and animal species composition, and beautiful landscapes. These are favorable conditions for the development of ecotourism. Research has combined several methods such as interviewing, line transects to collect data. The results show that several potential group of plants and animals, and 10 landscapes for ecotourism were identified in the reserve.

The study has analyzed the strengths, weaknesses, opportunities, challenges and development orientations for protected area ecotourism. Four (4) main tourist routes and 2 connective tourist routes were developed for nature tourist excursions, nature-explorer tour combined with local cultural understanding. Five key solutions are recommended for developing ecotourism combined with conservation of biodiversity in order to create conditions for livelihood improvement for reserve and local communities living in and outside the reserve incluidng management, solutions for policy mechanisms and training, marketing, investment.

Keywords: Biodiversity, landscapes, ecotourism, Kim Hy Nature Reserve, Bac Kan

Từ khóa: Hiệu quả môi trường, hiệu quả kinh tế – xã hội, mô hình rừng trồng sản xuất, huyện Thạch Hà, Hà Tĩnh

Socio-economic and environmental assessments of forest plantation models in Thach Ha district, Ha Tinh province

This paper presents the initial analysis of the effectiveness of the 3 models, namely a model of monoculture forest plantations at a 7- year Acacia forests (2007 to 2014), Acacia mangium and Eucalyptus Uro in Thach Ha district, Ha Tinh province. Based on the Net Prevent Value (NPV), Benefit Cost Ratio (BCR), the Internal Rate of Return (IRR), labor, erosion index (Ki), soil erosion intensity (d) and only efficient synthesis of (ECT), the study has identified patterns with monoculture Acacia plantations are the most effective in terms of economic, social and environment effectiveness compared to other models and plantation worth Ect = 0.97, followed by Acacia mangium with Ect = 0.94 and the Eucalyptus Uro is the least effective with Ect = 0.8. These findings will contribute to the scientific basis for further studies on solution development, enhancement of economic efficiency, social and environmental consequences of the typical plantation model in the study area to improve incomes and living conditions for local people.

Keywords: Environmental effectiveness, socio-economic effectivenesses, forest plantation model, Thach Ha district, Ha Tinh province

Từ khóa: Ổn định kích thước, sơn PU nano,
sơn gỗ

Dimensional stability of wood through nanomaterials dispered polyurethane coating

Polyurethane coating containing nanomaterials of TiO₂ size 21nm and under 100nm evaluated the improvement of dimensional stability of Acacia hybrid and Styrax tonkinensis wood. With coatings for Aacacia hybrid wood, coatings dispered nanomaterials reduce 50% dimensional stability of wood less than that without nanomaterials. In contrast, addition of TiO₂ into polyurethane increase dimensional stability of Styrax tonkinensis wood. But maximum value of ASE is approximately 16% happening when TiO₂ with size less than 100nm added. The combination of TiO₂ and nanoclay in coating only improve dimenional stability in case nanoclay modified. With hydrophilic clay, the combination reduce this property. Almost result of this study indicate that, polyurethane coating improve dimensional stability limited.

Keywords: Dimensional stability, nanocoating, wood coating

Từ khóa: Cóc hành, tính chất vật lý, tính chất cơ học, sử dụng gỗ

Assessment of the possibility in wood utilization of Azadirachta excelsa (Jack) Jacobs

Azadirachta excelsa (Jack) Jacobs is an indigenous and multi-purpose tree species. It is one of the major timber for plantation in dry regions of South Central Coast of Vietnam. Study on wood properties of Azadirachta excelsa with the purpose of clarifying scientific base for utilization was carried out. Wood of Azadirachta excelsa collected from natural forests has higher density and strength capability than those of wood collected from plantations. Shrinkage and swelling in both radial and tangential direction and volume of wood collected from plantations or natural forests are similar. Wood properties were at medium to high grade, shrinkage and and swelling in both radial and tangential direction and volume are good characteristics for drying utilization. Wood properties of Azadirachta excelsa are similar to wood of some species in group I (for timber from natural forests) and group II (for timber from plantations) as classified according to physical and machenical properties applied to wood used in construction and transportation. However, when classified according to the characteristic for use of timber in some other purposes, the wood from natural forests and plantations are in the same group. Wood of Azadirachta excelsa is not suitable for veneer production but fairly good for the structure and inner door or furniture due to quyte hard and heavy with durability, wood surface is not very smooth, but brown – pink wood relatively nice to do furniture. Wood should be dried well because of hight shrinkage coefficient in volume and avoided exposure to water or in places with high humidity

Keywords: Azadirachta excelsa, wood physical properties, wood machenical properties, wood utilization

Từ khóa: Bạch đàn lai, sinh trưởng, tính chất gỗ, tỷ trọng gỗ, biến động

Study on fundamental properties of wood of 5 eucalyptus hybrid clones by artificial hybridization planted in Bau Bang, Binh Duong

With the goal to clarify the variation in wood fundamental properties of 5 eucalyptus artificial hybrid clones UE3, UC1, UE4, GU94, UE24 grown in silvicultural experiment station Bau Bang, Binh Duong province to find clones with fast-growing and good quality timber for expanding the planting area. The timber may serves well for the wood processing industry, especially for lumber purposes. Data collected on growing of 5 eucalyptus hybrid clones shows the ability of fast and stable growth in the range of 0.9 to 1.9cm/year in diameter and 0.35 to 1.8m/year in height, reaching from 89 to 543dm³/tree in volume. The wood specific gravity, wood fiber length increases from the pith to the bark with a small variation (specific grvity increased from (0.5 – 0.7) near the pith to (06 – 0,8) near the bark; fiber length increased from (1.4- 1.5) mm near the pith to (1.7- 1.8) near the bark). UE3 and UE24 was the out-standing clones with strong points in both growth and wood specific gravity. They should be expanded in to the other ecologycal region and assessed the quality of wood for the lumber purposes. However, due to great value of total shrinkage and swelling ratio, preservation in logging and processing to avoid cracking, warping should be marked.

Keywords: Hybrid eucalyptus, growth, wood properties, specific gravity, variation

Từ khóa: Keo lai nhân tạo, cơ lý gỗ, bạch đàn lai, giống lai

Growth and wood properties of new clones of acacia and eucalyptus hybrid

Artificial Acacia hybrids have been created, of which 3 hybrids of AM₂, AM₃, MAM₈ AM (approved as national varieties and advanced technological varieties in 2008) have high yield and higher than natural Acacia hybrids (BV10, BV33). Assessment of wood properties of these artificial acacia hybrids at age of 7 shows that wood properties of these artificial acacia hybrids (such as specific gravity, length compress resistance, bending strength) are better than that of A. auriculifomis, A. mangium and natural Acacia hybrid. As a result, two artificial acacia hybrids (AM₂, AM₃) have preponderance in both growth and wood quality. Apart from artificial acacia hybrids created, artificial Eucalyptus hybrids also have been successful created, of which 3 hybrids (UE24, UE27, UC80) were approved as national varieties, and 10 hybrids (UE3, UE23, UE33, UC1,UC2, CU91, UE73, UC75, CU90, UU8) were approved as advanced technological varieties. Among those approved varieties, the hybrid of UE24 has preponderance in both growth and wood quality.

Keywords: Artificial acacia hybrid, wood properties, Eucalyptus hybrid, hybrid

Từ khóa: Gỗ Xoan nhừ Choerospondias axillaris, độ bền tự nhiên, khả năng chịu lực

Properties of Choerospondias axillaris (roxb.) Burtt & Hill wood and timber

The native tree species Choerospondias axillaris is distributed widely in Northern and Central of Vietnam, and is known as a fast growing tree. The results of study shown that: Choerospondias axillaris could be graded in a big tree group, its round logs are met the saw log requyrements (the big diameter and the high quality of logs). The durability of Choerospondias axillaris wood to be good in the environment with Daedalea quercina fungi and Trametes corrugata fungi, but it is easy damaged by Coptotermes formosanus. Choerospondias axillaris wood is graded in the group of medium density, low rate of volume shrinkage and medium mechanical strength. This timber should be applied preservation solution before utilization and should be not used as a construction parts under strong forces.

Keywords: Choerospondias axillaris wood, durability, mechanical strength

Từ khóa: Mộc bản, hiện trạng ngoại quan mộc bản

Current situation of the buddhistical woodblocks in Bo Da pagoda and Vinh Nghiem pagoda in Bac Giang province

Buddhistical woodblocks are wooden boards encrypted with Chinese scripts or Vietnamese scripts modified from Chinese scripts (chữ Nôm) for printing in order to popularize buddhistical philosophy. Wooden blocks are invaluable treasures of Vietnam not only in terms of religious importance but also in the soul and culture reflected in the manuscripts and the artistic values of the encryption works. In Bac Giang, most important woodblocks have been preserved in Vinh Nghiem pagoda and Bo Da pagoda, although there have not been any scientific study on woodblock storages and preservation. Our study illustrated that most of the woodblocks in the two storages have been damaged to certain extent, mostly due to disfiguration, cracking, molding and attacks of insects. This comprehensive evaluation of the current situation of the two woodblock storages can be used in designing appropriate preservation method for the treasures in the future.

Keywords: Woodblock, current situation of woodblocks