Bang Nguyen Tran | University of Melbourne (original) (raw)

Papers by Bang Nguyen Tran

Ecology and Society, 2013

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2020 IEEE International Geoscience and Remote Sensing Symposium September 26 - October 2, 2020, Session: WE2.R10: Remote Sensing for Forest and Vegetation Structure, Health and Growth II, 2020

Wildfires worldwide are becoming more frequent but are they also becoming more severe? Here we us... more Wildfires worldwide are becoming more frequent but are they also becoming more severe? Here we used remotely sensed burn-severity data from wildfires in Victoria, southeastern Australia to address that question. We selected 162 wildfires of more than 1000 ha that occurred over the past 30 years across a wide range of forest types. Spectral indices derived from Landsat pre-and post-fire imagery were used to map fire severity. Our results show a significant increase in the absolute and proportional area burnt by high-severity fire over the last three decades. This study demonstrates that wildfires in the temperate forests of southern Australia are becoming more severe. Such change in fire regimes may have critical consequences for the sustainability and resilience of the studied forests.

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PLoS ONE 15(11), 2020

Wildfires have increased in size and frequency in recent decades in many biomes, but have they al... more Wildfires have increased in size and frequency in recent decades in many biomes, but have they also become more severe? This question remains under-examined despite fire severity being a critical aspect of fire regimes that indicates fire impacts on ecosystem attributes and associated post-fire recovery. We conducted a retrospective analysis of wildfires larger than 1000 ha in southeastern Australia to examine the extent and spatial pattern of high-severity burned areas between 1987 and 2017. High-severity maps were generated from Landsat remote sensing imagery. Total and proportional high-severity burned area increased through time. The number of high-severity patches per year remained unchanged but variability in patch size increased, and patches became more aggregated and more irregular in shape. Our results confirm that wildfires in southern Australia have become more severe. This shift in fire regime may have critical consequences for ecosystem dynamics, as fire-adapted temperate forests are more likely to be burned at high severities relative to historical ranges, a trend that seems set to continue under projections of a hotter, drier climate in southeastern Australia.

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SPIE Remote Sensing, 2019, Strasbourg, France, 2019

Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severi... more Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severity mapping from local to regional scales in a range of forest types worldwide. While index thresholding can be easily implemented, its operational utility over large areas is limited as the optimum index may vary with forest type and fire regimes. In contrast, machine learning algorithms allow for multivariate fire classifications. This study compared the accuracy of fire-severity classifications from SI thresholding with those from Random Forests (RF). Reference data were from 3730 plots within the boundaries of eight major wildfires across the six temperate forest 'functional' groups of Victoria, southeastern Australia. The reference plots were randomly divided into training and validation datasets (60/40) for each fire-severity class (unburnt, low, moderate, high) and forest functional group. SI fire-severity classifications were conducted using thresholds derived in a previous study based on the same datasets. A RF classification algorithm was trained to derive fire-severity levels based on appropriate spectral indices and their temporal difference. The RF classification outperformed the SI thresholding approach in most cases, increasing overall accuracy by 11% on a forest-group basis, and 16% on an individual wildfire basis. Adding more predictor variables into the RF algorithm did not improve classification accuracy. Greater overall accuracies (by 12% on average) were achieved when in situ data (rather than data from other fires) were used to train the RF algorithm. Our study shows the utility of Random Forest algorithms for streamlining fire-severity mapping across heterogeneous forested landscapes.

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J. Sci. & Devel. 2015, Vol. 13, No. 4: 586-597, 2015

In order to discover their potential for development, this study aims to characterize the agro-fo... more In order to discover their potential for development, this study aims to characterize the agro-forestry systems (AFS) in Diem-a remote village of Chau Khe commune located within the buffer zone of Viet Nam's Pu Mat National Park. Secondary data collected from available district and provincial sources were combined with primary data obtained by seven different methods. In order to evaluate the potential of the current AFS models, the study focused on analyzing three aspects: social, economic and environmental benefits. Results of the study showed two types of AFS which were currently adopted in Diem village: traditional and innovative. The analytical results also showed that all land use types in current AFS in Diem were profitable with positive Net Present Values (NPV). The livelihoods of local people depended much on on-farm and off-farm activities. Of these, cassava planting, acacia plantation, and animal husbandry were considered the main productions contributing to household income. A cost benefit analysis of potential alternative livelihood options in Diem indicated that gross revenues for bamboo and acacia plantations were 6 million and 18 million VND/ha respectively while cassava growing generated only 2.5 million VND/ha. With regard to the environmental aspect of the AFS model, the study indicated that the average above-ground forest carbon stock in designed strata in Diem is 40.15 tons/ha, however there was more than 70 tons/ha in variance between the maximum and the minimum values. Interestingly, the plots that have few trees and where bamboo is the dominant tree, carbon stock is often low. Enhancing benefits from shifting cultivation planning area, conducting forest land allocation or contracts for forest protection, and developing home gardens and forest gardens are three proposed recommendations for sustainable development of AFS in Diem. Phân tích hệ thống nông lâm kết hợp tại Bản Diềm, xã Châu Khê, huyện Con Cuông, tỉnh Nghệ An TÓM TẮT Nghiên cứu này tập trung phân tích hệ thống nông lâm kết hợp tại bản Diềm, thuộc vùng đệm của Vườn quốc gia Pù Mát theo ba nhóm tiêu chí là trữ lượng carbon, hiệu quả kinh tế và đặc điểm sinh kế của người dân. Nghiên cứu sử dụng số liệu thống kê tại địa phương kết hợp với điều tra thực tế, bao gồm phỏng vấn hộ gia đình, thảo luận nhóm người dân và đo sinh khối rừng. Kết quả phân tích cho thấy tại địa bàn nghiên cứu có hai loại hệ thống nông lâm kết hợp chính là mô hình truyền thống và mô hình cải tiến; Hiệu quả kinh tế của những loại hình sử dụng đất thuộc các hệ thống nông lâm kết hợp đều có giá trị lợi nhuận ròng NPV dương. Sinh kế của người dân địa phương phụ thuộc chủ yếu vào trồng sắn, trồng keo, và chăn nuôi; Thu nhập ròng trong trồng Mét và Keo dao động từ 6-18 triệu đồng/ha trong khi đó thu nhập ròng từ trồng sắn chỉ đạt 2,5 triệu đồng/ha. Hiệu quả môi trường của các mô hình nông lâm kết hợp được thể hiện quả trữ lượng carbon bề mặt với mức dao động từ 12,17-84,58 tấn/ha. Những ô tiêu chuẩn có giá trị carbon bề mặt thấp thường có tre nứa chiếm ưu thế và rất ít cây thân gỗ. Đề xuất cho giải pháp phát triển các mô hình nông lâm kết hợp cho bản Diềm bao gồm (i) nâng cao lợi ích từ các khu vực quy hoạch canh tác nương rẫy; (ii) thực hiện giao đất lâm nghiệp hoặc thực hiện hợp đồng bảo vệ rừng và phát triển vườn nhà và vườn rừng. Từ khóa: Nông lâm kết hợp, trữ lượng carbon.

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World Agroforestry Centre (ICRAF) - Vietnam, 2015

Local knowledge and active participation in research is increasingly encouraged, not the least fo... more Local knowledge and active participation in research is increasingly encouraged, not the least for identifying sustainable adaptation options. However, despite that participatory mapping has advanced from sketches to informing digitalised maps since the 1990s this type of local knowledge is rarely included in agroecological zones (AEZ) mapping. For a new project on climate-smart agriculture and forestry local knowledge was incorporated to characterise agroecological zones in Huong Lien commune, Ha Tinh province, northcentral Viet Nam. The purpose was to determine adaptation options associated with particular agroecological zones. A GIS spatial database with land use, topography, NDVI was generated to derive an agroecological zones map and ground-truthed with the participation of local villagers through transect walks and SWOT analyses by land use type.
The study shows that local participation is vital for ground-truthing maps, to fill in gaps when time series data is available and for marking out natural hazard areas. In this particular case, local perceptions of strengths and potential adaptation options associated with particular agroecozones was useful for revealing adaptation gaps. The classification rules for the AEZ need careful consideration, especially when the mapped areas are small, to make the maps useful beyond the study area. This may require more careful transect walks to identify nuances in forest quality for determining forest management. Methodology for inclusive local knowledge needs to be further developed.

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Remote Sensing, 2018

Spectral indices derived from optical remote sensing data have been widely used for fire-severity... more Spectral indices derived from optical remote sensing data have been widely used for fire-severity classification in forests from local to global scales. However, comparative analyses of multiple indices across diverse forest types are few. This represents an information gap for fire management agencies in areas like temperate southeastern Australia, which is characterised by a diversity of natural forests that vary in structure, and in the fire-regeneration strategies of the dominant trees. We evaluate 10 spectral indices across eight areas burnt by wildfires in 1998, 2006, 2007, and 2009 in southeastern Australia. These wildfire areas encompass 13 forest types, which represent 86% of the 7.9M ha region's forest area. Forest types were aggregated into six forest groups based on their fire-regeneration strategies (seeders, resprouters) and structure (tree height and canopy cover). Index performance was evaluated for each forest type and forest group by examining its sensitivity to four fire-severity classes (unburnt, low, moderate, high) using three independent methods (anova, separability, and optimality). For the best-performing indices, we calculated index-specific thresholds (by forest types and groups) to separate between the four severity classes, and evaluated the accuracy of fire-severity classification on independent samples. Our results indicated that the best-performing indices of fire severity varied with forest type and group. Overall accuracy for the best-performing indices ranged from 0.50 to 0.78, and kappa values ranged from 0.33 (fair agreement) to 0.77 (substantial agreement), depending on the forest group and index. Fire severity in resprouter open forests and woodlands was most accurately mapped using the delta Normalised Burnt ratio (dNBR). In contrast, dNDVI (delta Normalised difference vegetation index) performed best for open forests with mixed fire responses (resprouters and seeders), and dNDWI (delta Normalised difference water index) was the most accurate for obligate seeder closed forests. Our analysis highlighted the low sensitivity of all indices to fire impacts in Rainforest. We conclude that the optimal spectral index for quantifying fire severity varies with forest type, but that there is scope to group forests by structure and fire-regeneration strategy to simplify fire-severity classification in heterogeneous forest landscapes.

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Remote sensing MDPI, 2016

In recent years, the concepts of teleconnections and telecoupling have been introduced into land-... more In recent years, the concepts of teleconnections and telecoupling have been introduced into land-use and land-cover change literature as frameworks that seek to explain connections between areas that are not in close physical proximity to each other. The conceptual frameworks of teleconnections and telecoupling seek to explicitly link land changes in one place, or in a number of places, to distant, usually non-physically connected locations. These conceptual frameworks are offered as new ways of understanding land changes; rather than viewing land-use and land-cover change through discrete land classifications that have been based on the idea of land-use as seen through rural-urban dichotomies, path dependencies and sequential land transitions, and place-based relationships. Focusing on the land-use and land-cover changes taking place along the East-West Economic Corridor that runs from Dong Ha City in Quang Tri, Vietnam, through Sepon District, Savannakhet, Lao PDR, into Thailand this paper makes use of data gathered from fieldwork and remote sensing analysis to examine telecouplings between sending, receiving and spill-over systems on both sides of the Vietnam-Lao PDR border. Findings are that the telecouplings are driving changes in rural village and urban systems on both sides of the border, and are enabled by a policy environment that has sought to facilitate the cross-border transportation of goods within the region.

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Forests, 2014

Reducing emissions from deforestation and forest degradation in developing countries, and the rol... more Reducing emissions from deforestation and forest degradation in developing countries, and the role of conservation, sustainable management of forests, and enhancement of forest carbon stocks in developing countries (REDD+) is a potentially powerful international policy mechanism that many tropical countries are working towards implementing. Thus far, limited practical consideration has been paid to local rights to forests and forest resources in REDD+ readiness programs, beyond noting the importance of these issues. Previous studies have shown that community members can reliably and cost-effectively monitor forest biomass. At the same time, this can improve local ownership and forge important links between monitoring activities and local decision-making. Existing studies have, however, been static assessments of biomass at one point in time. REDD+ programs will require repeated surveys of biomass over extended time frames. Here, we examine trends in accuracy and costs of local forest monitoring over time. We analyse repeated measurements by community members and professional foresters of 289 plots over two years in four countries in Southeast Asia. This shows, for the first time, that with repeated measurements community members' biomass measurements become increasingly accurate and costs decline. These findings provide additional support to available evidence that community members can play a strong role in monitoring forest biomass in the local implementation of REDD+.

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Tropicultura, 2016

The melon hybrid variety, Kim Hoang Hau (KHH), was tested in a package of cultural practices to a... more The melon hybrid variety, Kim Hoang Hau (KHH), was tested in a package of cultural practices to adapt to climate change and avoid damages caused by diseases during spring-summer season (March to June 2015) in Giao Thuy district, Nam Dinh province. The results were analyzed and subsequently discussed with local farmers in focused groups. Analysis showed that the KHH was suitable to land conditions in the study area. Yields and pest diseases resistance of KHH were higher than those of the controls. The farmers preferred this new variety over the local melon because KHH is less vulnerable to the climatic stressors. The decision to grow the new variety is due also to the good market price. However, farmers only shifted away from the old melon when they could anticipate the possibility of selling the new product. Those who did not continue with the KHH had difficulty in actively accessing the market for this new product. This study suggests that the market information does not drive the process of the adaptation itself, but rather provides relevant stimuli to farmers enabling them to shift to new crop varieties successfully. This study also implies that such process-based understanding is crucial in formulating strategies to increase farmer’s capacity to adapt to climate change.

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Hanoi Agricultural University - Regional Conference on Environmental Planning and Management in Southeast Asian Countries, 2007

Historically, large amounts of opium were planted in the remote areas of the Northern... more Historically, large amounts of opium were planted in the remote areas of the Northern Mountain Region (NMR) of Vietnam, where the crop was closely connected with ethnic cultivation practices and livelihoods. In 1993, the Government of Vietnam set up Program 6 in order to encourage farmers to stop planting opium and promote other agricultural activities. This paper aims to show land use changes over time in Bao Thang, a commune in the Ca River Basin that traditionally engaged in opium production and implemented Program 6 in 1995. This research uses methodology that includes a field survey based on group interviews, field transects, and spatial analyses and interpretation of Landsat images . The results show that after stopping opium cultivation, farmer livelihoods in the commune depended mainly on swidden cultivation. The swidden area sharply increased to 474 ha in 1998 (a 72 % increase from 1993). It is notable that not only did farmers cultivate more swidden area but they also planted many different types of crops, such as maize, cassava and vegetables. In addition, the number of fields and the average field size also increased following the increase in cultivated swidden area. Moreover, many people had to travel further from residential areas and streams to find agricultural land for cultivation.
Keywords: land use, GIS, remote sensing, swidden agriculture, opium reduction, slope, aspect

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Nhà xuất bản Nông nghiệp, 2008

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Kyoto University Press and Trans Pacific Press, 2009

Volume 18 of Kyoto area studies on Asia, ISSN 1445-9663 ISBN 1920901299, 9781920901295

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Hanoi University of Agriculture, 2012

The project of "Impacts of Reducing Emiss ions from Deforestation and Forest Degradation... more The project of "Impacts of Reducing Emiss ions from Deforestation and Forest Degradation and Enhancing Carbon Stocks" (I-REDD+) is funded by the 7th Frnmework Programme of the European Commission for four years (201 1 to 2014). The objectives of l-REDD+ is to enhance the understanding of the implementation of a REDD+ mechanisms. The issues related to increase in posit ive impacts and mitigat ion of poten tially negative impacts of REDD+ are addressed at national to local level in four countries, inc luding Laos, Vietnam, China, and Indonesia. TI1e seven work packages (WPs) of the project work closely together to reach the objectives of the project. Up to now, the first results from the six thematic work packages (WP) are emerging. WP2 focuses on GHG emissions and has completed the first rounds of biomass and soil sampling in the Lao and Indonesian sites and reviewed allometric models. WP3 works on developing improved remote sensing based methods for monitoring land use change and C-stocks to specifically address the monitoring problems related to forest degradation. The results of WP3 include I ) development of a land cover classification system based land cover legend to compare the I-REDD+ field sites 2) and a landscape mosaic approach to detect the spatially and temporally dynamic swidden cultivation. In WP4, community based monitoring is compared to scientist executed monitorin g in order to assess the feasibility of local monitoring. The preliminary results show that local communit ies can effectively estimate carbon stocks. In WPS, the loca l costs and benefits of R EDD+ are
assessed through opportunity costs analysis and participatory simulation of land use planning with hypothetical REDD+ schemes. Results are still preliminary as field work was only completed in June 2012, but a high variability in villagers' interest in REDD+ between study sites was observed. WP6 works at several levels and analyzes how REDD+ payments may work under different payment scenarios and under different governance and institutional structures in the four case countries. Twelve benefit distribution mechanisms were identified in the four countries and these are current ly being analyzed in terms of the disttibution of use rights, control rights, and authoritative rights among involved actors as well as social outcomes. WP7 works towards guiding the improvement of measurement, reporting and verification (MRV) system by integrating the results of other work packages and establishing drivers of land use change and reference emission levels in the four field sites. The work completed so far is on drivers and this shows that increases in commodity price caused a significant share of the large-scale land use changes. Other underlying drivers such as population growth and improvement in transportation networks played the crucial role for forest degradation (mainly in Laos and Vietnam). The expected final results of I-REDD+ are closely linked to the objectives men tioned above and should provide a better basis for implementing - or, perhaps, for not implementing - REDD+, especia lly with regard to avoided forest degradation. · The results will be disseminated accord ing to a detailed dissemination plan that besides scientific publications, envisage reaching policy-makers at local, nat ional and global levels.
KEYWORDS : Carbon stock, Deforestation, Forest degradation, R EDD+

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Ecology and Society 18(3): 41, 2013

ABSTRACT. Will community monitoring assist in delivering just and equitable REDD+? We assessed w... more ABSTRACT.
Will community monitoring assist in delivering just and equitable REDD+? We assessed whether local communities can effectively estimate carbon stocks in some of the world’s most carbon rich forests, using simple field protocols, and we reviewed whether community monitoring exists in current REDD+ pilots. We obtained similar results for forest carbon when measured by communities and professional foresters in 289 vegetation plots in Southeast Asia. Most REDD+ monitoring schemes, however, contain no community involvement. To close the gulf between United Nations Framework Convention on Climate Change texts on involving communities and field implementation realities, we propose greater embedding of community monitoring within national REDD+ pilot schemes, which we argue will lead to a more just REDD+.
Key Words: biodiversity; Climate, Community and Biodiversity Alliance standard; forest carbon; governance; livelihood; monitoring; Payment for Ecosystem Service programs; REDD+; Southeast Asia

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Ecology and Society, 2013

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2020 IEEE International Geoscience and Remote Sensing Symposium September 26 - October 2, 2020, Session: WE2.R10: Remote Sensing for Forest and Vegetation Structure, Health and Growth II, 2020

Wildfires worldwide are becoming more frequent but are they also becoming more severe? Here we us... more Wildfires worldwide are becoming more frequent but are they also becoming more severe? Here we used remotely sensed burn-severity data from wildfires in Victoria, southeastern Australia to address that question. We selected 162 wildfires of more than 1000 ha that occurred over the past 30 years across a wide range of forest types. Spectral indices derived from Landsat pre-and post-fire imagery were used to map fire severity. Our results show a significant increase in the absolute and proportional area burnt by high-severity fire over the last three decades. This study demonstrates that wildfires in the temperate forests of southern Australia are becoming more severe. Such change in fire regimes may have critical consequences for the sustainability and resilience of the studied forests.

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PLoS ONE 15(11), 2020

Wildfires have increased in size and frequency in recent decades in many biomes, but have they al... more Wildfires have increased in size and frequency in recent decades in many biomes, but have they also become more severe? This question remains under-examined despite fire severity being a critical aspect of fire regimes that indicates fire impacts on ecosystem attributes and associated post-fire recovery. We conducted a retrospective analysis of wildfires larger than 1000 ha in southeastern Australia to examine the extent and spatial pattern of high-severity burned areas between 1987 and 2017. High-severity maps were generated from Landsat remote sensing imagery. Total and proportional high-severity burned area increased through time. The number of high-severity patches per year remained unchanged but variability in patch size increased, and patches became more aggregated and more irregular in shape. Our results confirm that wildfires in southern Australia have become more severe. This shift in fire regime may have critical consequences for ecosystem dynamics, as fire-adapted temperate forests are more likely to be burned at high severities relative to historical ranges, a trend that seems set to continue under projections of a hotter, drier climate in southeastern Australia.

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SPIE Remote Sensing, 2019, Strasbourg, France, 2019

Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severi... more Machine learning and spectral index (SI) thresholding approaches have been tested for fire-severity mapping from local to regional scales in a range of forest types worldwide. While index thresholding can be easily implemented, its operational utility over large areas is limited as the optimum index may vary with forest type and fire regimes. In contrast, machine learning algorithms allow for multivariate fire classifications. This study compared the accuracy of fire-severity classifications from SI thresholding with those from Random Forests (RF). Reference data were from 3730 plots within the boundaries of eight major wildfires across the six temperate forest 'functional' groups of Victoria, southeastern Australia. The reference plots were randomly divided into training and validation datasets (60/40) for each fire-severity class (unburnt, low, moderate, high) and forest functional group. SI fire-severity classifications were conducted using thresholds derived in a previous study based on the same datasets. A RF classification algorithm was trained to derive fire-severity levels based on appropriate spectral indices and their temporal difference. The RF classification outperformed the SI thresholding approach in most cases, increasing overall accuracy by 11% on a forest-group basis, and 16% on an individual wildfire basis. Adding more predictor variables into the RF algorithm did not improve classification accuracy. Greater overall accuracies (by 12% on average) were achieved when in situ data (rather than data from other fires) were used to train the RF algorithm. Our study shows the utility of Random Forest algorithms for streamlining fire-severity mapping across heterogeneous forested landscapes.

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J. Sci. & Devel. 2015, Vol. 13, No. 4: 586-597, 2015

In order to discover their potential for development, this study aims to characterize the agro-fo... more In order to discover their potential for development, this study aims to characterize the agro-forestry systems (AFS) in Diem-a remote village of Chau Khe commune located within the buffer zone of Viet Nam's Pu Mat National Park. Secondary data collected from available district and provincial sources were combined with primary data obtained by seven different methods. In order to evaluate the potential of the current AFS models, the study focused on analyzing three aspects: social, economic and environmental benefits. Results of the study showed two types of AFS which were currently adopted in Diem village: traditional and innovative. The analytical results also showed that all land use types in current AFS in Diem were profitable with positive Net Present Values (NPV). The livelihoods of local people depended much on on-farm and off-farm activities. Of these, cassava planting, acacia plantation, and animal husbandry were considered the main productions contributing to household income. A cost benefit analysis of potential alternative livelihood options in Diem indicated that gross revenues for bamboo and acacia plantations were 6 million and 18 million VND/ha respectively while cassava growing generated only 2.5 million VND/ha. With regard to the environmental aspect of the AFS model, the study indicated that the average above-ground forest carbon stock in designed strata in Diem is 40.15 tons/ha, however there was more than 70 tons/ha in variance between the maximum and the minimum values. Interestingly, the plots that have few trees and where bamboo is the dominant tree, carbon stock is often low. Enhancing benefits from shifting cultivation planning area, conducting forest land allocation or contracts for forest protection, and developing home gardens and forest gardens are three proposed recommendations for sustainable development of AFS in Diem. Phân tích hệ thống nông lâm kết hợp tại Bản Diềm, xã Châu Khê, huyện Con Cuông, tỉnh Nghệ An TÓM TẮT Nghiên cứu này tập trung phân tích hệ thống nông lâm kết hợp tại bản Diềm, thuộc vùng đệm của Vườn quốc gia Pù Mát theo ba nhóm tiêu chí là trữ lượng carbon, hiệu quả kinh tế và đặc điểm sinh kế của người dân. Nghiên cứu sử dụng số liệu thống kê tại địa phương kết hợp với điều tra thực tế, bao gồm phỏng vấn hộ gia đình, thảo luận nhóm người dân và đo sinh khối rừng. Kết quả phân tích cho thấy tại địa bàn nghiên cứu có hai loại hệ thống nông lâm kết hợp chính là mô hình truyền thống và mô hình cải tiến; Hiệu quả kinh tế của những loại hình sử dụng đất thuộc các hệ thống nông lâm kết hợp đều có giá trị lợi nhuận ròng NPV dương. Sinh kế của người dân địa phương phụ thuộc chủ yếu vào trồng sắn, trồng keo, và chăn nuôi; Thu nhập ròng trong trồng Mét và Keo dao động từ 6-18 triệu đồng/ha trong khi đó thu nhập ròng từ trồng sắn chỉ đạt 2,5 triệu đồng/ha. Hiệu quả môi trường của các mô hình nông lâm kết hợp được thể hiện quả trữ lượng carbon bề mặt với mức dao động từ 12,17-84,58 tấn/ha. Những ô tiêu chuẩn có giá trị carbon bề mặt thấp thường có tre nứa chiếm ưu thế và rất ít cây thân gỗ. Đề xuất cho giải pháp phát triển các mô hình nông lâm kết hợp cho bản Diềm bao gồm (i) nâng cao lợi ích từ các khu vực quy hoạch canh tác nương rẫy; (ii) thực hiện giao đất lâm nghiệp hoặc thực hiện hợp đồng bảo vệ rừng và phát triển vườn nhà và vườn rừng. Từ khóa: Nông lâm kết hợp, trữ lượng carbon.

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World Agroforestry Centre (ICRAF) - Vietnam, 2015

Local knowledge and active participation in research is increasingly encouraged, not the least fo... more Local knowledge and active participation in research is increasingly encouraged, not the least for identifying sustainable adaptation options. However, despite that participatory mapping has advanced from sketches to informing digitalised maps since the 1990s this type of local knowledge is rarely included in agroecological zones (AEZ) mapping. For a new project on climate-smart agriculture and forestry local knowledge was incorporated to characterise agroecological zones in Huong Lien commune, Ha Tinh province, northcentral Viet Nam. The purpose was to determine adaptation options associated with particular agroecological zones. A GIS spatial database with land use, topography, NDVI was generated to derive an agroecological zones map and ground-truthed with the participation of local villagers through transect walks and SWOT analyses by land use type.
The study shows that local participation is vital for ground-truthing maps, to fill in gaps when time series data is available and for marking out natural hazard areas. In this particular case, local perceptions of strengths and potential adaptation options associated with particular agroecozones was useful for revealing adaptation gaps. The classification rules for the AEZ need careful consideration, especially when the mapped areas are small, to make the maps useful beyond the study area. This may require more careful transect walks to identify nuances in forest quality for determining forest management. Methodology for inclusive local knowledge needs to be further developed.

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Remote Sensing, 2018

Spectral indices derived from optical remote sensing data have been widely used for fire-severity... more Spectral indices derived from optical remote sensing data have been widely used for fire-severity classification in forests from local to global scales. However, comparative analyses of multiple indices across diverse forest types are few. This represents an information gap for fire management agencies in areas like temperate southeastern Australia, which is characterised by a diversity of natural forests that vary in structure, and in the fire-regeneration strategies of the dominant trees. We evaluate 10 spectral indices across eight areas burnt by wildfires in 1998, 2006, 2007, and 2009 in southeastern Australia. These wildfire areas encompass 13 forest types, which represent 86% of the 7.9M ha region's forest area. Forest types were aggregated into six forest groups based on their fire-regeneration strategies (seeders, resprouters) and structure (tree height and canopy cover). Index performance was evaluated for each forest type and forest group by examining its sensitivity to four fire-severity classes (unburnt, low, moderate, high) using three independent methods (anova, separability, and optimality). For the best-performing indices, we calculated index-specific thresholds (by forest types and groups) to separate between the four severity classes, and evaluated the accuracy of fire-severity classification on independent samples. Our results indicated that the best-performing indices of fire severity varied with forest type and group. Overall accuracy for the best-performing indices ranged from 0.50 to 0.78, and kappa values ranged from 0.33 (fair agreement) to 0.77 (substantial agreement), depending on the forest group and index. Fire severity in resprouter open forests and woodlands was most accurately mapped using the delta Normalised Burnt ratio (dNBR). In contrast, dNDVI (delta Normalised difference vegetation index) performed best for open forests with mixed fire responses (resprouters and seeders), and dNDWI (delta Normalised difference water index) was the most accurate for obligate seeder closed forests. Our analysis highlighted the low sensitivity of all indices to fire impacts in Rainforest. We conclude that the optimal spectral index for quantifying fire severity varies with forest type, but that there is scope to group forests by structure and fire-regeneration strategy to simplify fire-severity classification in heterogeneous forest landscapes.

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Remote sensing MDPI, 2016

In recent years, the concepts of teleconnections and telecoupling have been introduced into land-... more In recent years, the concepts of teleconnections and telecoupling have been introduced into land-use and land-cover change literature as frameworks that seek to explain connections between areas that are not in close physical proximity to each other. The conceptual frameworks of teleconnections and telecoupling seek to explicitly link land changes in one place, or in a number of places, to distant, usually non-physically connected locations. These conceptual frameworks are offered as new ways of understanding land changes; rather than viewing land-use and land-cover change through discrete land classifications that have been based on the idea of land-use as seen through rural-urban dichotomies, path dependencies and sequential land transitions, and place-based relationships. Focusing on the land-use and land-cover changes taking place along the East-West Economic Corridor that runs from Dong Ha City in Quang Tri, Vietnam, through Sepon District, Savannakhet, Lao PDR, into Thailand this paper makes use of data gathered from fieldwork and remote sensing analysis to examine telecouplings between sending, receiving and spill-over systems on both sides of the Vietnam-Lao PDR border. Findings are that the telecouplings are driving changes in rural village and urban systems on both sides of the border, and are enabled by a policy environment that has sought to facilitate the cross-border transportation of goods within the region.

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Forests, 2014

Reducing emissions from deforestation and forest degradation in developing countries, and the rol... more Reducing emissions from deforestation and forest degradation in developing countries, and the role of conservation, sustainable management of forests, and enhancement of forest carbon stocks in developing countries (REDD+) is a potentially powerful international policy mechanism that many tropical countries are working towards implementing. Thus far, limited practical consideration has been paid to local rights to forests and forest resources in REDD+ readiness programs, beyond noting the importance of these issues. Previous studies have shown that community members can reliably and cost-effectively monitor forest biomass. At the same time, this can improve local ownership and forge important links between monitoring activities and local decision-making. Existing studies have, however, been static assessments of biomass at one point in time. REDD+ programs will require repeated surveys of biomass over extended time frames. Here, we examine trends in accuracy and costs of local forest monitoring over time. We analyse repeated measurements by community members and professional foresters of 289 plots over two years in four countries in Southeast Asia. This shows, for the first time, that with repeated measurements community members' biomass measurements become increasingly accurate and costs decline. These findings provide additional support to available evidence that community members can play a strong role in monitoring forest biomass in the local implementation of REDD+.

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Tropicultura, 2016

The melon hybrid variety, Kim Hoang Hau (KHH), was tested in a package of cultural practices to a... more The melon hybrid variety, Kim Hoang Hau (KHH), was tested in a package of cultural practices to adapt to climate change and avoid damages caused by diseases during spring-summer season (March to June 2015) in Giao Thuy district, Nam Dinh province. The results were analyzed and subsequently discussed with local farmers in focused groups. Analysis showed that the KHH was suitable to land conditions in the study area. Yields and pest diseases resistance of KHH were higher than those of the controls. The farmers preferred this new variety over the local melon because KHH is less vulnerable to the climatic stressors. The decision to grow the new variety is due also to the good market price. However, farmers only shifted away from the old melon when they could anticipate the possibility of selling the new product. Those who did not continue with the KHH had difficulty in actively accessing the market for this new product. This study suggests that the market information does not drive the process of the adaptation itself, but rather provides relevant stimuli to farmers enabling them to shift to new crop varieties successfully. This study also implies that such process-based understanding is crucial in formulating strategies to increase farmer’s capacity to adapt to climate change.

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Hanoi Agricultural University - Regional Conference on Environmental Planning and Management in Southeast Asian Countries, 2007

Historically, large amounts of opium were planted in the remote areas of the Northern... more Historically, large amounts of opium were planted in the remote areas of the Northern Mountain Region (NMR) of Vietnam, where the crop was closely connected with ethnic cultivation practices and livelihoods. In 1993, the Government of Vietnam set up Program 6 in order to encourage farmers to stop planting opium and promote other agricultural activities. This paper aims to show land use changes over time in Bao Thang, a commune in the Ca River Basin that traditionally engaged in opium production and implemented Program 6 in 1995. This research uses methodology that includes a field survey based on group interviews, field transects, and spatial analyses and interpretation of Landsat images . The results show that after stopping opium cultivation, farmer livelihoods in the commune depended mainly on swidden cultivation. The swidden area sharply increased to 474 ha in 1998 (a 72 % increase from 1993). It is notable that not only did farmers cultivate more swidden area but they also planted many different types of crops, such as maize, cassava and vegetables. In addition, the number of fields and the average field size also increased following the increase in cultivated swidden area. Moreover, many people had to travel further from residential areas and streams to find agricultural land for cultivation.
Keywords: land use, GIS, remote sensing, swidden agriculture, opium reduction, slope, aspect

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Nhà xuất bản Nông nghiệp, 2008

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Kyoto University Press and Trans Pacific Press, 2009

Volume 18 of Kyoto area studies on Asia, ISSN 1445-9663 ISBN 1920901299, 9781920901295

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Hanoi University of Agriculture, 2012

The project of "Impacts of Reducing Emiss ions from Deforestation and Forest Degradation... more The project of "Impacts of Reducing Emiss ions from Deforestation and Forest Degradation and Enhancing Carbon Stocks" (I-REDD+) is funded by the 7th Frnmework Programme of the European Commission for four years (201 1 to 2014). The objectives of l-REDD+ is to enhance the understanding of the implementation of a REDD+ mechanisms. The issues related to increase in posit ive impacts and mitigat ion of poten tially negative impacts of REDD+ are addressed at national to local level in four countries, inc luding Laos, Vietnam, China, and Indonesia. TI1e seven work packages (WPs) of the project work closely together to reach the objectives of the project. Up to now, the first results from the six thematic work packages (WP) are emerging. WP2 focuses on GHG emissions and has completed the first rounds of biomass and soil sampling in the Lao and Indonesian sites and reviewed allometric models. WP3 works on developing improved remote sensing based methods for monitoring land use change and C-stocks to specifically address the monitoring problems related to forest degradation. The results of WP3 include I ) development of a land cover classification system based land cover legend to compare the I-REDD+ field sites 2) and a landscape mosaic approach to detect the spatially and temporally dynamic swidden cultivation. In WP4, community based monitoring is compared to scientist executed monitorin g in order to assess the feasibility of local monitoring. The preliminary results show that local communit ies can effectively estimate carbon stocks. In WPS, the loca l costs and benefits of R EDD+ are
assessed through opportunity costs analysis and participatory simulation of land use planning with hypothetical REDD+ schemes. Results are still preliminary as field work was only completed in June 2012, but a high variability in villagers' interest in REDD+ between study sites was observed. WP6 works at several levels and analyzes how REDD+ payments may work under different payment scenarios and under different governance and institutional structures in the four case countries. Twelve benefit distribution mechanisms were identified in the four countries and these are current ly being analyzed in terms of the disttibution of use rights, control rights, and authoritative rights among involved actors as well as social outcomes. WP7 works towards guiding the improvement of measurement, reporting and verification (MRV) system by integrating the results of other work packages and establishing drivers of land use change and reference emission levels in the four field sites. The work completed so far is on drivers and this shows that increases in commodity price caused a significant share of the large-scale land use changes. Other underlying drivers such as population growth and improvement in transportation networks played the crucial role for forest degradation (mainly in Laos and Vietnam). The expected final results of I-REDD+ are closely linked to the objectives men tioned above and should provide a better basis for implementing - or, perhaps, for not implementing - REDD+, especia lly with regard to avoided forest degradation. · The results will be disseminated accord ing to a detailed dissemination plan that besides scientific publications, envisage reaching policy-makers at local, nat ional and global levels.
KEYWORDS : Carbon stock, Deforestation, Forest degradation, R EDD+

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Ecology and Society 18(3): 41, 2013

ABSTRACT. Will community monitoring assist in delivering just and equitable REDD+? We assessed w... more ABSTRACT.
Will community monitoring assist in delivering just and equitable REDD+? We assessed whether local communities can effectively estimate carbon stocks in some of the world’s most carbon rich forests, using simple field protocols, and we reviewed whether community monitoring exists in current REDD+ pilots. We obtained similar results for forest carbon when measured by communities and professional foresters in 289 vegetation plots in Southeast Asia. Most REDD+ monitoring schemes, however, contain no community involvement. To close the gulf between United Nations Framework Convention on Climate Change texts on involving communities and field implementation realities, we propose greater embedding of community monitoring within national REDD+ pilot schemes, which we argue will lead to a more just REDD+.
Key Words: biodiversity; Climate, Community and Biodiversity Alliance standard; forest carbon; governance; livelihood; monitoring; Payment for Ecosystem Service programs; REDD+; Southeast Asia

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