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Nam S.,Tokyo University of Agriculture and Technology | Hiraoka M.,Tokyo University of Agriculture and Technology | Gomi T.,Tokyo University of Agriculture and Technology | Dung B.X.,Vietnam Forestry University | And 2 more authors.
Landscape and Ecological Engineering | Year: 2016

We examined changes in suspended-sediment yields (SSY) after a 50 % strip thinning in headwater streams draining a Japanese cedar (Cryptomeria japonica) and cypress (Chamaecyparis obtusa) plantation forest. We applied a paired-catchment analysis to treated (KT: 17.1 ha) and control (KC: 8.9 ha) catchments. Annual suspended-sediment yield (SSYan) in the prethinning period in the KT and KC catchments was 110.0 and 142.1 kg/ha per year. For the postthinning period, SSYan in the KT catchment became 5055.6 kg/ha per year, whereas that in the KC catchment increased 893.2 kg/ha per year. The paired-catchment analysis revealed that SSY in the KT catchment increased 17.0-fold compared with the prethinning period. However, the dominant hysteresis pattern remained clockwise in both pre- and postthinning periods. Sequences of large storm events in the postthinning period elevated SSY in both catchments. Increase in suspended sediment in the KT catchment was associated with the combined impacts of thinning and sequences of storm events during the period of thinning operation. © 2016 International Consortium of Landscape and Ecological Engineering and Springer Japan Source

Wang H.,Northeast Forestry University | Nguyen T.T.H.,Northeast Forestry University | Nguyen T.T.H.,Vietnam Forestry University | Li S.,Northeast Forestry University | And 3 more authors.
Bioorganic and Medicinal Chemistry Letters | Year: 2015

To develop new rosin-based wood preservatives with good antifungal activity, 24 rosin derivatives were synthesized, bioassay tested with Trametes versicolor and Gloeophyllum trabeum, and subjected to analysis of their quantitative structure-activity relationships (QSAR). A QSAR analysis using Ampac 9.2.1 and Codessa 2.7.16 software built two QSAR models of antifungal ratio for T. versicolor and G. trabeum with values of R2 = 0.9740 and 0.9692, respectively. Based on the models, tri-N-(3-hydroabietoxy-2-hydroxy) propyl-triethyl ammonium chloride was designed and the bioassay test result proved its better inhibitory effect against the two selected fungi as expected. © 2014 Elsevier Ltd. All rights reserved. Source

Bao T.Q.,Vietnam Forestry University
Oceanologia | Year: 2011

This paper analyses wave attenuation in coastal mangrove forests in Vietnam. Data from 32 mangrove plots of six species located in 2 coastal regions are used for this study. In each plot, mangrove forest structures and wave height at different cross-shore distances are measured. Wave height closely relates to cross- shore distances. 92 exponential regression equations are highly significant with R 2 >0.95 and P val. <0.001. Wave height reduction depends on initial wave height, cross-shore distances, and mangrove forest structures. This relationship is used to define minimum mangrove band width for coastal protection from waves in Vietnam. © by Polish Academy of Sciences, Institute of Oceanology, 2011. Source

Nguyen T.T.H.,Northeast Forestry University | Nguyen T.T.H.,Vietnam Forestry University | Li S.,Northeast Forestry University | Li J.,Northeast Forestry University | Liang T.,Northeast Forestry University
International Biodeterioration and Biodegradation | Year: 2013

A new rosin-based micronized-copper preservative containing rosin sizing agent and copper sulfate was investigated. The effect of rosin sizing agent on the distribution and fixation of copper in treated wood was determined. Poplar wood samples that had been treated with the rosin-based micronized-copper preservatives were analyzed by a scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDS). Copper was detected both in the lumens and the cell walls of the treated wood. The atomic absorption spectrophotometry (AAS) analysis showed that the leaching of copper from wood impregnated with rosin-based micronized-copper preservatives was significantly reduced. Moreover, SEM-EDS proved that most of the copper was still in the treated wood after leaching. The X-ray photoelectron spectrometer (XPS) analysis also indicated that copper in the treated wood was Cu(II). After leaching, treated wood blocks were exposed to the decay fungi Gloeophyllum trabeum and Trametes versicolor. Results showed that the use of rosin-based micronized copper to impregnate wood can protect wood against fungal attack as effectively as ammoniacal copper quaternary (ACQ). © 2013 Elsevier Ltd. Source

Ha T.T.T.,Wageningen University | Ha T.T.T.,Vietnam Forestry University | Bush S.R.,Wageningen University | Mol A.P.J.,Wageningen University | Van Dijk H.,Wageningen University
Journal of Rural Studies | Year: 2012

The Vietnamese government aims to expand the scale of Naturland certified organic production in integrated shrimp-mangrove farming systems across the coast of Ca Mau province by 2015. In doing so the division between public and private regulation has become blurred. We analyze the government's goal by examining the regulatory challenges of using organic certification as a means of linking farm-level management to the sustainability of coastal (mangrove) landscapes. The results show the importance of farmer perceptions of sustainable farm and landscape management, fair benefit sharing mechanisms in the certified value chain, and legitimate private sector-led auditing. We conclude that in order to overcome conflicts of interest and legitimate representation in organic certification, the social and economic conditions of production require regulatory intervention from provincial and local level government. To achieve benefits beyond the scale of the farm, the role of shrimp producers should be redefined as partners in rather than targets of regulation. © 2012 Elsevier Ltd. Source

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