Hoa Binh Province Research Articles

First record of the genus Dolichomitus Smith (Hymenoptera: Ichneumonidae: Pimplinae) from Vietnam, with description of one new species

The genus Dolichomitus Smith, 1877 is recorded from Vietnam for the first time with description of a new species, D. lami sp. nov., from Hoang Lien National Park, Lao Cai Province. Besides, D. melanomerus (Vollenhoven) is recorded as new for the country from specimens collected in Tam Dao National Park, Vinh Phuc Province and Hang Kia-Pa Co Nature Reserve, Hoa Binh Province.

A new fish species of the walking snakehead group, the genus Channa (Channidae, Perciformes) in Vietnam

Channa longistomata sp. n. (Figs. 1, 2) Samples: 12 fish samples, L = 92-156 mm, Lo = 82-132 mm. Holotype: Sample code H.Na 011.04.001. L = 153 mm; Lo = 124 mm, collected at Tam Chuc lake, Ba Sao town, Kim Bang district, Ha Nam province, dated 21/04/2011. Paratypes: 5 samples, sample code H. Na.011.04.002. L = 132 mm. Lo = 106 mm, collected at Tam Chuc lake, Ba Sao town, Kim Bang district, Ha Nam province, dated 21/042011. Sample code H.B.65.11.011 L = 152 mm, Lo = 125 mm; H.B.65.11.012, L = 156 mm, Lo = 132 mm; H.B.65.11.013, L = 144 mm, Lo = 123 mm và H.B.65.11.014, L = 130 mm, Lo = 110 mm collected at Thac Bo, Da Bac district, Hoa Binh province, dated 20/11/1965. Samples preseved at Fish Museum of Research Institute for Aquaculture No.I, Bac Ninh. Diagnosis: Mouth arched, depth and narrow, mouth length wider than mouth width. Incision of lip along and little over the margin of eye equal eyes diameters origin. The dorsal fin origin in front of pelvic fin origin. The distant from pelvic fin origin to annal fin equal to meeting point of 2 gill arches. Especially toungue flat, thin and it has waist of middle toungue and small round proglossis. Description: Body length, the cylinder from the back side up gradually of high body close to the body thickness. The depth of caudal peduncle is short and height. The head is relative flat. Short snout. Round eyes located on the half first part of the head. Distances between 2 eyes were wide and relative flat. Mouth arched depth and narrow, mouth length wider than mouth width. Tougue flat thin and it has waist of middle toungue and small round of proglossis. (figs. 2a, b, c, d). Fins: D = 33 – 35; A = 22 -23; P = 14 – 15; V = 1,4 -5; C = 12; Scales: 42[...]46, scales around caudal peduncle =18, Lo = 5,48H = 3,8T T = 4,63Ot = 7,18O = 3,07 OO. OO = 2,33 O. H = 1,58 h. Fins of dorsal and anal are long. Dorsal fin origin in front of pelvic fin origin. The distant from pelvic fin origin to anal fin origin equal its to the start meeing point of 2 gill archs. Caudal fin shaped round of ending. All fins are soft. Head and body covered by scale. Lateral line discontinues which interrupted at the middle. Coloration: Color of body gray, no bar. Dorsal fin, annal fin and caudal fin have its outer of red-pink or spark yellow (white when preserved). Pectoral fins have from 3 to 5 black bars. Remarks: C. longistomata sp. n. distinguished from other species of C. gachua (Hamilton) and C.orientalis Bloch & Schneider by the combination of the following characters: mouth arched depth and narrow. The mouth length is bigger than the mouth width. The incision lip along reaching after the margin of eye which equals the eye diameter. Dorsal fin origin in front of pelvic fin origin. Toungue flat and its middle waist narrow, small round of proglossis. Two species C. gachua (Hamilton) and C. orientalis Bloch & Schneider have mouth arched shallow and wide, mouth length smaller than mouth width. The incision lip along reaching middle of eye or a little over margin of eye. Dorsal fin origin after or opposite of pelvic fin origin. Toungue flat and no waist, triangle long, small pointed of proglossis (C. gachua) or flat round of proglossis (C. orientalis). Distribution: Provinces of Da river basin (Dien Bien, Lai Chau, Son La and Hoa Binh) and distribution in lakes near regions of lime mountains of Ha Nam and Ninh Binh. Etymology: Channa longistomata was named according to specific characteristics with a long mouth which is different with the other similar species.

The classification of snails belonging to the subfamily Triculinae (Hydrobiidae-Prosobranchia) in Vietnam

The classification of snails belonging to the subfamily Triculinae (Hydrobiidae-Prosobranchia) in Vietnam

Vegestation and flora diversities in Thung Rech, Kim Boi district, Hoa Binh province

Thung Rech vegetation covers on limestone and caster valley in high area at commune Tu Son, Kim Boi district, Hoa Binh province. To apply research traditional methods, such as principle structured forms - Ecology of UNESCO - 1973, Wittaker’s principle of component structure of the plant species (in 1962) and review ecosystems (Tansley, 1935) have been rated the resource of rich flora with 656 species belonging to 406 genus and 138 families of 5 phylum vascular of plant are Psilotophyta, Lycopodiophyta, Polypodiophyta, Pinophyta and Magnoliophyta. Although there is a variety of species, the density of individuals is so poor because its geological features are mainly limestone. Successions of vegetable plant including the recovery and the degradation are mainly secondary and complicated out of the impact of human being. Also, the ecosystem of the plant contains the vegetation communities’ specific to limestone northern Vietnam, it plays an important role in environmental protection, disaster reduction, balance, regulation of the flow and climate as well as the biodiversity conservation of the area. To need to build up the legal system and scientific measures to conserve the plant resources of this kind.

Choosing optimal medium for cultivation of rich - Astaxanthin green microalga Haematococcus pluvialis

Microalgae have a large biotechnology potential for production of a variety of compounds such as polysaccharides, lipids, proteins, carotenoids, pigments, vitamins, steroids. Recently, Haematococcus pluvialis has been widely studies as one of the best sources of ketocarotenoid pigment - astxanthin (3,3’-dihydroxy-b,b’-carotene-4,4’-dione), which holds high antioxidant activity approximately 10 times greater than other carotenoids, such as zeaxanthin, lutein, canthaxanthin and b-carotene, and over 500 times greater than a-tocopherol. For this reason, this alga is used for the pigmentation of cultured fish and shellfish, a food additive in the food industry, a superior antioxidant in the cosmetic industry, and an antiaging reagent as precusor of vitamin A, an anticancer agent through singlet oxygen quenching, and an immunomodulator in the pharmaceutical industry. Haematococcus pluvialis is unicellular fresh water microalga, green-colored, biflagellate, and motile in its vegetative stage. It belongs to Chlorophyta phylum, Chlorophyceae class, Volvocales order, Haematococcaceae family and Haematococcus genus. During the H. pluvialis life cycles, green vegetative cells mobile with two flagella grow both in the light and heterotrophically in the dark. Environmental stress induces encystment and morphological changes from motile vegetative cells to resting immotile aplanospores. When exposed to prolonged stress, H. pluvialis cell undergo enhanced carotenogenesis during the maturation of cyst cells. Astaxanthin could be accumulated up to 4-6% of dry cell weight. The massive accumulation of astaxanthin in cyst cell under light in extreme environmental condition (nutrient limitation, high light intensity, hight temperature, oxidative stress and salt stress) has been investigated by several authors. The techniques on H. pluvialis cultures for astxanthin production have been dramatically advanced in some countries. Currently, the use of two-stage processes for astaxanthin production has been fully reported. In this report, we have presented the effect of different culture media including C, modified BG-11, OHM and RM on the growth rate of H. pluvialis which was isolated from Hoa Binh province, Vietnam in different scales. Among four media, RM medium is the best for H. pluvialis cultivation expressed by maximal cell density (cells/ml): 50.74 ´ 104, 39 ´ 104, 144.90 ´ 104 and 38.3 ´ 104; chlorophyll a content (mg/l): 617.63, 743.82, 2010 and 689.06 and astaxanthin content (mg/l): 246.21, 399.15, 630 and 212.10; specific growth rate (m/day): 0.062, 0.192, 0.234 and 0.321, in 250 ml, 500 ml Erlenmeyer flask, 1.5 liter and 10 liter bottles, respectively after 30 days of cultivation. In cases of 1.5 and 10 liter bottles, dried weight was reached 4.92 and 1.86 g/l, respectively. In addition, the obtained results have indicated that cultivative process from test - tubes to 250 ml Erlenmeyer flasks with frequently in 2-4 days per time by supplementing 50% of refresh medium is necessary to maintain vegetative stage of cell for long time. In Vietnam, it is the first report on successful cultivation of green microalgae H. pluavialis - a potential source for astaxanthin which is a natural pigment used for food and pharmaceutical industries in the world in general and for salmon farming in particularly.

Landslide susceptibility assessment in the Hoa Binh province of Vietnam: A comparison of the Levenberg–Marquardt and Bayesian regularized neural networks

This study investigates the potential application of artificial neural networks in landslide susceptibility mapping in the Hoa Binh province of Vietnam. A landslide inventory map of the study area was prepared by combining landslide locations investigated through three projects during the last 10years. Some recent landslide locations were identified based on SPOT satellite images, field surveys, and existing literature. The images have a spatial resolution of 2.5m. Ten landslide conditioning factors were utilized in the multilayer feed-forward neural network analysis: slope, aspect, relief amplitude, lithology, land use, soil type, rainfall, distance to roads, distance to rivers and distance to faults. Two back-propagation training algorithms, Levenberg–Marquardt and Bayesian regularization, were utilized to determine synoptic weights using a training dataset. Relative importance of each landslide conditioning factor was assessed using the above mentioned synoptic weights. The final connection weights obtained in the training phase were applied to the entire study area to produce landslide susceptibility indexes. The results were then imported to a GIS and landslide susceptibility maps were constructed. Landslide locations not used in the training phase were used to verify and compare the results of the landslide susceptibility maps. Finally, the two landslide susceptibility maps were validated using the prediction-rate method. Subsequently, areas under the prediction curves were assessed. The prediction accuracy of landslide susceptibility maps produced by the Bayesian regularization neural network and the Levenberg–Marquardt neural network were 90.3% and 86.1% respectively. These results indicate that the two models seem to have good predictive capability. The Bayesian regularization network model appears more robust and efficient than the Levenberg–Marquardt network model for landslide susceptibility mapping.

Spatial prediction of landslide hazards in Hoa Binh province (Vietnam): A comparative assessment of the efficacy of evidential belief functions and fuzzy logic models

The main objective of this study is to evaluate and compare the results of evidential belief functions and fuzzy logic models for spatial prediction of landslide hazards in the Hoa Binh province of Vietnam, using geographic information systems. First, a landslide inventory map showing the locations of 118 landslides that have occurred during the last ten years was constructed using data from various sources. Then, the landslide inventory was randomly partitioned into training and validation datasets (70% of the known landslide locations were used for training and building the landslide models and the remaining 30% for the model validation). Secondly, nine landslide conditioning factors were selected (i.e., slope, aspect, relief amplitude, lithology, landuse, soil type, distance to roads, distance to rivers and distance to faults). Using these factors, landslide susceptibility index values were calculated using evidential belief functions and fuzzy logic models. Finally, landslide susceptibility maps were validated and compared using the validation dataset that was not used in the model building. The prediction-rate curves and area under the curves were calculated to assess prediction capability. The results show that all the models have good prediction capabilities. The model derived using evidential belief functions has the highest prediction capability. The model derived using fuzzy SUM has the lowest prediction capability. The fuzzy PRODUCT and fuzzy GAMMA models have almost the same prediction capabilities. In general, all the models yield reasonable results that may be used for preliminary landuse planning purposes.

Serologic Evidence of Nipah Virus Infection in Bats, Vietnam

To the Editor: Bats are potential reservoir for highly pathogenic viruses, such as Nipah virus (NiV) and Hendra virus, which can cross species barriers (1). However, only limited surveillance has been conducted to assess risk for infection by these deadly emerging viruses. We conducted a study in Vietnam from 2007 to 2008 to assess the prevalence of these pathogens in bats. Different species of live bats were obtained from hunters or were captured in caves, pepper fields, and residential areas by using mist nets or harp traps (Technical Appendix Figure 1). A total of 451 serum samples were collected and subjected to IgG ELISA by using an Escherichia coli–derived recombinant nucleocapsid (N) protein of NiV (NiV-N-ELISA) (2). Two Leschenault’s rousette bats (Rousettus leschenaulti) were vaccinated with the same recombinant N protein to obtain positive serum specimens that contained antibodies against NiV-N. An optical density of 492 nm for negative control serum (1,000× dilution) was designated as 1:1,000 ELISA units. ELISA titers of sample serum specimens were obtained at a single dilution (1,000×) by using a standard curve of positive serum with high titers. A sample titer >3,000 was considered positive for IgG against NiV. Positive results were detected from only 2 fruit bat species, R. leschenaulti (31 bats [49.1%]) and Cynopterus sphinx (3 bats [2.8%]) (Table). Of the 34 samples positive by ELISA, only 22 (20 from the former and 2 from the latter bat species), which had enough volume left, were further analyzed by Western blot (WB) with E. coli–expressed recombinant N protein of NiV (Table; Technical Appendix Figure 2). Twenty of the 22 specimens were confirmed as positive by WB. ELISA-positive samples with high titers were also positive by WB for both bat species. However, only 1 sample from an R. leschenaulti bat was positive by WB that used a baculovirus-expressed recombinant N protein. Because of the different protein expression systems, the reactivity of bat antibody against NiV protein in WBs showed different patterns (Technical Appendix Figure 2). Neutralization tests (NTs) in which live NiVs (strain Ma-JMR-01–98) were used were performed at the Institute of Tropical Medicine, Nagasaki University. No specimens of C. sphinx bats were positive by NT; however, 2 specimens from R. leschenaulti bats, both positive with low titers, were confirmed to be positive by NT (50% cytopathic effect after NT, titers of 33.6 and 14.1). However, the latter specimen was negative by WB analysis. Table Results of serologic tests for Nipah virus on bats captured in Vietnam, 2007–2008* Seroepidemiologic studies in other countries have indicated that Pteropus spp. bats (fruit-eating bats) are the main reservoirs for NiV (3–6). Pteropid bats are usually found only in southern Vietnam. We could not obtain these bats for our study. However, a relatively high prevalence (49.1%) of henipavirus antibody was found in R. leschenaulti specimens from Hoa Binh Province. Rousettus spp. bats are the only megabats that use echolocation. These bats hang together on cave ceilings in a tightly packed manner and in groups composed of bats of both sexes and of different ages. They roost in large colonies and fly vast distances to find fruit (7). This behavior might be related to their high rate of seropositivity for viral infections. In southern China, bats of the same species showed a high prevalence of henipavirus antibody (8). R. leschenaulti bats are distributed from central to northern Vietnam and southern China. C. sphinx bats are common all over Vietnam, and their habitat overlaps with that of pteropid bats in southern Vietnam. Previous studies showed that IgG ELISA results for NiV-positive flying foxes correlated well with NT results (3,4). However, in our study, discrepancies existed between NT results and NiV-N-ELISA and WB results. A reason for these differences could be that Nipah-like viruses are circulating among bats in Vietnam, producing antibodies that are cross-reactive by ELISA and WB, but poorly cross-reactive by NT. The cross-reactive antibodies were probably not directed against neutralizing epitopes. To date, no reports have been made of an increased number of febrile encephalitis cases among the residents in Hoa Binh and Dak Lak Provinces where seropositive bats were captured. The circulating viruses may lack the pathogenic potential of Hendra and Nipah viruses. A survey by questionnaire was conducted among residents of Dak Nong and Dak Lak Provinces, where NiV-N-ELISA–positive C. sphinx bats were captured, to determine the frequency of contact between humans and bats. Risk factors for infection were observed in this study, such as bat hunting and cooking and drinking bat blood. In such situations, persons have direct contact with bat body fluids and feces and might be bitten during bat hunting. Thus, long-term systematic surveillance of bats is needed to determine the ecologic relationship between bats, humans, other animals, and the environment.

Landslide Susceptibility Assessment in Vietnam Using Support Vector Machines, Decision Tree, and Naïve Bayes Models

The objective of this study is to investigate and compare the results of three data mining approaches, the support vector machines (SVM), decision tree (DT), and Naïve Bayes (NB) models for spatial prediction of landslide hazards in the Hoa Binh province (Vietnam). First, a landslide inventory map showing the locations of 118 landslides was constructed from various sources. The landslide inventory was then randomly partitioned into 70% for training the models and 30% for the model validation. Second, ten landslide conditioning factors were selected (i.e., slope angle, slope aspect, relief amplitude, lithology, soil type, land use, distance to roads, distance to rivers, distance to faults, and rainfall). Using these factors, landslide susceptibility indexes were calculated using SVM, DT, and NB models. Finally, landslide locations that were not used in the training phase were used to validate and compare the landslide susceptibility maps. The validation results show that the models derived using SVM have the highest prediction capability. The model derived using DT has the lowest prediction capability. Compared to the logistic regression model, the prediction capability of the SVM models is slightly better. The prediction capability of the DT and NB models is lower.

Landslide susceptibility mapping at Hoa Binh province (Vietnam) using an adaptive neuro-fuzzy inference system and GIS

The objective of this study is to investigate a potential application of the Adaptive Neuro-Fuzzy Inference System (ANFIS) and the Geographic Information System (GIS) as a relatively new approach for landslide susceptibility mapping in the Hoa Binh province of Vietnam. Firstly, a landslide inventory map with a total of 118 landslide locations was constructed from various sources. Then the landslide inventory was randomly split into a testing dataset 70% (82 landslide locations) for training the models and the remaining 30% (36 landslides locations) was used for validation purpose. Ten landslide conditioning factors such as slope, aspect, curvature, lithology, land use, soil type, rainfall, distance to roads, distance to rivers, and distance to faults were considered in the analysis. The hybrid learning algorithm and six different membership functions (Gaussmf, Gauss2mf, Gbellmf, Sigmf, Dsigmf, Psigmf) were applied to generate the landslide susceptibility maps. The validation dataset, which was not considered in the ANFIS modeling process, was used to validate the landslide susceptibility maps using the prediction rate method. The validation results showed that the area under the curve (AUC) for six ANFIS models vary from 0.739 to 0.848. It indicates that the prediction capability depends on the membership functions used in the ANFIS. The models with Sigmf (0.848) and Gaussmf (0.825) have shown the highest prediction capability. The results of this study show that landslide susceptibility mapping in the Hoa Binh province of Vietnam using the ANFIS approach is viable. As far as the performance of the ANFIS approach is concerned, the results appeared to be quite satisfactory, the zones determined on the map being zones of relative susceptibility.

Landslide susceptibility analysis in the Hoa Binh province of Vietnam using statistical index and logistic regression

The purpose of this study is to evaluate and compare the results of applying the statistical index and the logistic regression methods for estimating landslide susceptibility in the Hoa Binh province of Vietnam. In order to do this, first, a landslide inventory map was constructed mainly based on investigated landslide locations from three projects conducted over the last 10 years. In addition, some recent landslide locations were identified from SPOT satellite images, fieldwork, and literature. Secondly, ten influencing factors for landslide occurrence were utilized. The slope gradient map, the slope curvature map, and the slope aspect map were derived from a digital elevation model (DEM) with resolution 20 × 20 m. The DEM was generated from topographic maps at a scale of 1:25,000. The lithology map and the distance to faults map were extracted from Geological and Mineral Resources maps. The soil type and the land use maps were extracted from National Pedology maps and National Land Use Status maps, respectively. Distance to rivers and distance to roads were computed based on river and road networks from topographic maps. In addition, a rainfall map was included in the models. Actual landslide locations were used to verify and to compare the results of landslide susceptibility maps. The accuracy of the results was evaluated by ROC analysis. The area under the curve (AUC) for the statistical index model was 0.946 and for the logistic regression model, 0.950, indicating an almost equal predicting capacity.

An Empirical Study of Factors Impacting School Management Based on Schools in Hoa Binh Province of Vietnam

Today, the development of information technology (IT) and communication has helped to largely change the working mode and to improve the effectiveness of the work in all areas. The application of IT in the education and training so as to improve the effectiveness of the management is vital to meet the needs for the development of education in the current stage. Whether or not School Management Software (SMS) is a tool for management and provides data to the Education Management Information System (EMIS) should be assessed. In this study, to assess the impact of the SMS on the school management and the EMIS, questionnaires were sent and responses were obtained from 210 education managers, teachers and staff of 24 lower secondary schools, which are piloting SMS. Based on the data analysis of the survey data, it is reasonable to urge education managers to implement SMS in all schools so as to enhance the management capacity of schools in Hoa Binh province. During the implementation of SMS, information quality, system quality and service quality of the system should be increased because they positively impact the effectiveness of school management.

Growth of several indigenous species in the degraded forest in the northern Vietnam

This study was conducted in the northern mountainous region of Vietnam. Research occurred at two main sites: the Hoa Binh province and the Phu Tho province. The objective of this study was to compare growth rate and the physiological characteristics of the indigenous tree species; with the ultimate goal of selecting a suitable species for the restoration of the degraded forest area. Except for an Acacia hybrid, this study indicated that Pelthophorum tonlinensis, Lithocarpus ducampii and Cinamomum obtusifolium, in the Hoa Binh Province, and Pygeum arboretum, Cinamomum parthenoxylon andEndospermum sinensis, in the Phu Tho Province, showed higher height growth. Quercus poilanei, E. sinensis, Lithocarpus ducampii, and P. tonlinensisi exhibited good physiological performances, and had potential for use in the restoration of degraded forest. The results of this study will improve the success of restoration programs, by selecting suitable species for planting on the degraded lands; according to their specific reforestation objectives. Key words: Vietnam, degraded forest, growth, indigenous species, photosynthesis, water use efficiency.

Stand structure and natural regeneration of degraded forestland in the northern mountainous region of Vietnam

Vietnam experienced significant alterations of forest environments during the last half of the twentieth century, and reforestation efforts have increased since the 1990s. This study developed comparisons of naturally regenerated and plantation forestlands in northern Vietnam in order to gain a better understanding of reforestation options for the dual objectives of biodiversity and commercial tree production. Stand structure of secondary natural forest after logging and shifting cultivation were investigated at two study sites (Hoa Binh Province and Phu Tho Province). Natural regeneration of seedlings between the secondary natural forests and nearby mixed species plantations were measured and compared. The dominant tree species consisted of Aporosa villosa, Ficus racemosa, Machilus bonii and Vernicia montan at the Hoa Binh site and Cinnamomum parthenoxylum, Ormosia balabsae and Lithocarpus gigantophyllus at the Phu Tho site, which are mostly pioneer species. The secondary natural forests had higher abundance and diversity indices of seedlings than the mixed species plantations. Soil fertility of the secondary natural forests was better than that of the mixed species plantations (P < 0.05). An important finding is that, for the study sites examined, secondary natural forest resulted in more diverse and better-stocked forests than plantation forestry, implying that in areas where reforestation is undertaken the silvicultural potential of natural regeneration should not be underestimated.

High latrine coverage is not reducing the prevalence of soil-transmitted helminthiasis in Hoa Binh province, Vietnam

A baseline epidemiological survey for parasite infections was conducted between December 2007 and January 2008 in 155 villagers in a rural commune in Hoa Binh province, Vietnam. The prevalence of Ascaris lumbricoides, Trichuris trichiura and hookworm infection was 13.5%, 45.2% and 58.1%, respectively. At least one of the parasites was detected in 72.3% of the samples. We found no association between infection with A. lumbricoides or T. trichiura and engagement in agriculture, while hookworm infection was more prevalent in populations having frequent contact with soil. Agricultural use of human faeces was not correlated with any of the infections. We suggest that the consumption of vegetables that are commonly fertilized with human faeces in the community has led to the high infection rates with A. lumbricoides and T. trichiura, rather than the manipulation of faeces in farming activity. This also explains the high infection prevalence, despite high latrine coverage (98.1%) in the study population. The presence of latrines alone is not sufficient to reduce the prevalence of helminthiasis in a rural agricultural community if fresh faeces are used as fertilizer.

Evaluating Ethnopedological Knowledge Systems for Classifying Soil Quality. A Case Study in Bo Hamlet with Muong People of Northern Vietnam

AbstractEthnopedological knowledge is incorporated in a case study for sustainable land management of mountain karst areas in Vietnam. The research is based on a multidisciplinary approach, including participation of local inhabitants for identifying and classifying local indicators of soil quality, next to scientifically sound approaches to soil quality assessment based on analytical soil data and a statistical treatment of the results. The case study focuses on Bo hamlet, located in the Ngo Luong commune of the Tan Lac district, Hoa Binh province. The participatory approach reveals that local people of the Muong ethnic group distinguish seven land use types and six soil types. They also identified nine local indicators of soil quality: presence of earthworms; crop productivity; topsoil colour; presence of a humus layer; soil surface compaction; erosion; slope gradient; surface water, and soil moisture status. Based on this indigenous knowledge, 19 soil samples from nine soil profiles in Bo hamlet were analysed for fertility indicators. Laboratory results confirmed the validity of indigenous knowledge for identifying and classifying local indicators of soil fertility, compared to scientific standards of soil quality.

Soil translocation by weeding on steep-slope swidden fields in northern Vietnam

This study investigated soil translocation associated with weeding on steeply sloped swidden fields attended by ethnic Da Bac Tay farmers in Hoa Binh Province in northern Vietnam. Annual soil loss rates of 4–6 Mg ha −1 year −1 were found on 20 m plots located on two separate hillslopes. Median soil flux rates were equivalent to 2.6–3.9 kg m −1 pass −1 for experiments conducted on slopes ranging from 0.54 to 0.84 m m −1. The primary soil translocation process, the mechanical movement of soil via contact with a small hoe ( ngheo), contributed approximately 60% of the weeding-related soil flux. Ravel, which is the rolling, bouncing, and sliding of soil clods downslope, was a secondary translocation process that accounted for almost 40% of the soil flux. Soil flux was most appropriately described with an exponential function that could predict the occurrence of ravel on steeper slopes. The observed soil fluxes were much smaller than those determined during weeding and hoeing at other tropical and subtropical sites, primarily because the tillage depth was very shallow (<1 cm) and weed density was low at the time of experimentation. The erosion rates associated with weeding were an order of magnitude lower than reported water erosion rates; therefore, the contribution to landscape change was believed to be small. Combined water and tillage erosion estimates indicated a possible unsustainable increase in soil loss on some steep-slope fields within the last few decades that has resulted from shorter fallow periods, longer periods of cultivation before fallowing, and greater weed pressure. Additional work is needed to verify these latter interpretations.

Land-Use Sustainability of Composite Swiddening in the Uplands of Northern Vietnam: Nutrient Balances of Swidden Fields during the Cropping Period and Changes of Soil Nutrients over the Swidden Cycle

This study examined the sustainability of the swidden component of the composite swiddening system practiced by the Tay ethnic minority in Tat hamlet, Hoa Binh province in Northern Vietnam. This farming system is thought to be suitable for the uplands where land degradation is a serious problem. The common swidden rotation of two years of rice, two years of cassava and five years of bush-tall grass fallow was evaluated for the extent of land degradation during the cropping period by nutrient balance analysis, and for soil nutrient status throughout the swidden cycle through soil analysis. Four fields representing the individual years of cropping and three fields representing the first, the third and the fifth years of bush-tall grass fallow were selected for field measurements. Nutrient balance analysis indicated substantial losses of all major nutrients, particularly K, in all cropping years. Soil analysis also showed a decline in soil fertility during the cropping period and a partial restoration of soil fertility during the fallow period. However, only five years of bush-tall grass fallow was not sufficient to restore the original level of soil fertility. Thus, swidden fields in Tat hamlet are degrading, posing a serious threat to their land-use sustainability.

The first discovery of a complete skeleton of a fossil orang-utan in a cave of the Hoa Binh Province, Vietnam

Here we provide a description of the first complete adult fossil orang-utan skeleton from the Asian mainland. This specimen, and remains of a juvenile orang, were collected in a late Pleistocene cavern in the Hoa Binh Province of The Socialist Republic of Vietnam. The results confirm the suggestions by Hooijer (1948) Zool. Meded. Leiden29, 175–301 and later by Schwartz et al. (1995) Anthrop. Pap. Am. Mus. Nat. Hist.76, 1–24, that ancient orang-utans had bigger teeth than those of modern Pongo pygmaeus (P. p. pygmaeus and P. p. abelii), while the dental morphology is similar. Body proportions of the adult individual of Hoa Binh show a large skull with very large teeth but proportionally a small body. This individual is also singular in having high intermembral and brachial indices, in comparison with those of modern subspecies.

Cytotoxicity of Rhamnosylanthraquinones and Rhamnosylanthrones from Rhamnus nepalensis

An extract of the fruits of Rhamnus nepalensis collected in Hoa Binh Province, Vietnam, was cytotoxic to KB cells. A bioassay-guided fractionation led to the isolation of a series of known anthraquinones and anthrones, one new rhamnosylanthraquinone, 3'-O-acetylfrangulin A (8), several new rhamnosylanthrones, the prinoidin-emodin bianthrones (9A-D), the prinoidin bianthrones (10A,B), and the rhamnepalins (11A-C). A structure-cytotoxic activity relationship study was performed on these isolates and some semisynthetic derivatives.