Faculty Profiles - YOKOYAMA Satoshi

Papers - YOKOYAMA Satoshi

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Tracing of fire-induced soil phosphorus transformations using phosphate oxygen isotope ratio Reviewed International journal Open Access

Takuya ISHIDA, Isao HIROTA, Satoshi YOKOYAMA

European Journal of Soil Science Vol. 75 ( 5 ) page： e13591 2024.10

Language：English Publishing type：Research paper (scientific journal) Publisher：The British Society of Soil Science

This study demonstrates that phosphate oxygen isotope (δ18OPO4) analysis effectively detects and monitors fire-induced transformation in soil phosphorus (P). Fires increase bioavailable P, potentially limiting primary production in terrestrial ecosystems. However, understanding the effects of fire on soil P dynamics in the field remains challenging due to the interaction between fire spread and soil properties with high spatial heterogeneity. Soil burning experiments were conducted using a surface soil sample collected in central Japan. The soil was burned in an electric furnace from 50 to 550°C for 3 h, and P concentrations and δ18OPO4 values were determined. The results revealed that high temperatures (>350°C) depleted the soil of organic P (Po) and increased labile and stable inorganic P (Pi) concentrations while significantly decreasing δ18OPO4 values. By contrast, low temperatures (150°C) increased labile Pi and Po concentrations without isotopic shift, indicating that low-intensity fires could increase bioavailable P while conserving soil organic matter. These findings indicate that δ18OPO4 analysis can provide insight into the relationship between P transformations and fire intensity and track subsequent changes in P dynamics over time. Our research highlights the potential of δ18OPO4 in predicting and managing postfire ecological and agricultural impacts.

DOI： 10.1111/ejss.13591

Open Access

Web of Science

Scopus

Other Link： https://bsssjournals.onlinelibrary.wiley.com/doi/10.1111/ejss.13591

Package tour distribution channels of major Japanese, Chinese, and South Korean travel agents Reviewed International journal

Zhina NANGONG, Satoshi YOKOYAMA

Journal of Quality Assurance in Hospitality & Tourism 2023.12

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Routledge

This study examines how overseas package tours are designed in China, South Korea, and Japan. It also examines how these tours are arranged between the three countries. The results of in-depth interviews and participant observation showed that the method of creating tours was almost the same across those three countries. However, there were differences in the method of operating tours. In terms of tours from China, Chinese wholesalers prefer other travel agencies as land operators instead of their own foreign subsidiaries; for Japan, they prefer to utilize their foreign subsidiaries; and for South Korea, the wholesaler considers both their subsidiaries and land operators for operating package tours. The concept of “operating power” explains the unique operation of these travel companies. The study concludes that the distribution channels of various package tours are strategically created by wholesalers according to the combination of markets and destinations. It contributes theoretical implications to the study of tourism distribution channels by focusing on regions that have not been included in previous studies. Additionally, it proposes a framework for the process of creating package tours and constructs a concept to explain the diverse ways in which package tours are operated. In terms of practical implications for travel agents, the study provides insights into various tourism distribution channels across different situations.

DOI： 10.1080/1528008X.2023.2294922

Web of Science

Scopus

Temporal-spatial distribution of swidden agriculturists’ daily activities in central Laos Reviewed

Hongwei JIANG, Ren'ya SATO, Satoshi YOKOYAMA, Futoshi NISHIMOTO

E-journal GEO Vol. 18 ( 2 ) page： 324 - 338 2023.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

The authors conducted three time-allocation surveys in a Mangkhong ethnic minority village in Central Laos, where swidden cultivation, fishing, hunting, and gathering are the main subsistence of the residents. In the surveys, three types of data were collected using the recall method to collect information on daily activities, a GPS logger and accelerometer to collect the spatial information, and energy consumption of daily activities. The results of the data analysis clarified the temporal-spatial pattern of daily activities, such as labor division between male and female adults in working-time allocation and activity space and it’s gender difference. Furthermore, from the balance of time allocation between various subsistence of swidden agriculturalists in Central Laos, where development is progressing at a rapid pace, the authors tried to provide important clues for understanding the changes in land use and subsistence in the target area.

DOI： 10.4157/ejgeo.18.324

Special issue on population dynamics and livelihood changes of small-scale society in Laos

Satoshi YOKOYAMA

E-journal GEO Vol. 18 ( 2 ) page： 258 - 263 2023.8

Population Growth and Generational Response to Livelihood Choices in a Rain-Fed Farming Village in Central Laos Reviewed

Shinichi TAKAHASHI, Satoshi YOKOYAMA, Futoshi NISHIMOTO, Takahito NIWA

E-journal GEO Vol. 18 ( 2 ) page： 264 - 278 2023.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

In a rain-fed rice farming village located in central Laos, we clarified the relationship between long-term population growth exceeding 2% per year and changes in livelihoods and various activities of villagers by generation. From the first to the fourth generation in the village that was established in the late 1920s, the acquisition of rice paddies, which was the key to livelihoods, changed from opening paddies to inheritance and then to purchase along with the population growth. Migration to other rural villages increased from the third generation who did not acquire sufficient paddy fields due to population growth. In the fourth generation who experienced continued population growth, the shortage of paddy fields was alleviated by the emergence of circular migrant workers to Thailand. The responses to population growth in this village did not improve agricultural productivity or migration to urban areas instead of the acceleration of rural-to-rural migration against the background of the expansion of paddy fields in central Laos and the increase in number of migrant workers to Thailand. In recent years, the spread of family planning has contributed to the end of population growth, which will likely change the direction of rural livelihood transition in this region.

DOI： 10.4157/ejgeo.18.264

Rural-rural migration in a rural village, Luang Prabang province, northern Laos: Focusing both on immigration and emigration in the village of HB Reviewed

Takahito NIWA, Futoshi NISHIMOTO, Shinichi TAKAHASHI, Satoshi YOKOYAMA

E-journal GEO Vol. 18 ( 2 ) page： 279 - 290 2023.8

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

This study investigated changes in population dynamics and paddy holdings over three generations in two villages established by the Lao people in a basin in northern Laos. In the study area, government policy has promoted migration from highlands since the 1970s. However, there was limited land for new paddy reclamation in the basin, and therefore many residents who migrated from highlands, mainly Khmu people, had limited opportunities to engage in wet-rice cultivation in the basin villages where they resided and ultimately continued the subsistence swidden agriculture they had practiced in the highlands. The common method of acquiring new paddies in basin villages, where it is difficult to develop new paddies, is to purchase paddies from residents who have moved away from the villages. Many residents waited for such opportunities and worked in urban areas to make money to purchase paddies. Migrants from highlands in these basin villages are faced with the choice of staying in the basin, where paddy fields are scarce, or migrating to urban areas. We found that the basin villages functioned as intermediate points for migration between highlands and urban areas.

DOI： 10.4157/ejgeo.18.279

Population dynamics and paddy holdings in remote rural villages of northern Laos Reviewed

Satoshi YOKOYAMA, Shinichi TAKAHASHI, Takahito NIWA, Futoshi NISHIMOTO

E-journal GEO Vol. 18 ( 2 ) page： 291 - 308 2023.8

Authorship：Lead author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

DOI： 10.4157/ejgeo.18.291

Food procurement strategies of swidden agriculturalists in central Laos: Analysis of side dish ingredient records in food diaries Reviewed

Ren'ya SATO, Hongwei JIANG, Futoshi NISHIMOTO, Satoshi YOKOYAMA

E-journal GEO Vol. 18 ( 2 ) page： 309 - 323 2023.8

Authorship：Last author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

We conducted research on the seasonal diet and food-acquisition strategies of households in a village inhabited by an ethnic minority group (Mankon) in Xepon district, central Laos, who maintain a subsistence economy by engaging in swidden agriculture, fishery, animal feeding, hunting, and gathering. We adopted the food diary method in which we collected data on everyday side dish menus as well as data concerning who acquired the main ingredients of those menus. The results suggested that the production–expenditure balance in household food acquisition changed from minus to plus during the period when children were in their teens, and the contribution of children to household food acquisition was important.

DOI： 10.4157/ejgeo.18.309

Commodification of food culture and the authenticity: The case of "Bouchon" in Lyon, France Reviewed

Mayuko MURAKAMI, Satoshi YOKOYAMA

Geographical Space Vol. 14 ( 1 ) page： 1 - 17 2021.6

Transition of farmland use in a Japanese mountainside settlement: An analysis of the residents' career histories Reviewed International coauthorship

Gen SHOJI, Kunimitsu YOSHIDA, Satoshi YOKOYAMA, Eric C. THOMPSON

Geographical Review of Japan Series B Vol. 93 ( 1 ) page： 15 - 26 2020.11

Language：English Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

A key problem faced by Japanese agriculture is the decline in the number of fulltime farmers due to the aging population, which combined with the absence of farm successors is leading to abandoned and under-used farmland. Under these conditions, we analyze the shifts in labor force allocation within households, between households, and between different communities, in order to secure the continuity of farming activities. Recent agricultural policies aim to increase the active participation in farming of women and of returning farmers, people who left their hometown to engage in non-agricultural work but return to or take up farming after retirement. The study examines strategies to maintain the continuous use of farmland despite the declining numbers of farmers by analyzing the Tachi settlement, whose residents commute for work to the nearby urban areas of Kanazawa and Komatsu cities in Ishikawa prefecture. The study analyzed the occupations of household members in this settlement and evaluated how the residents’ employment choices have influenced the continuous use of farmland in the area. Many studies in agricultural geography in Japan on systems of farmland use and community farming have focused on households centered on a male head-of-household. Our study is original in its focus on the occupations of all individuals in each household to assess the allocation of farming labor in rural households and other mechanisms to maintain their farmland, such as consigning work to other farmers, or renting out their farmland. Over the past decades, with the decline in the number of successors willing to inherit the farms, the number of farms taken over by the next generation has decreased in Tachi, and those responsible for the farmland have had to request help from outside their settlement. However, the study reports some recent positive trends (a family moving back to the settlement and taking up farming, including leasing previously abandoned land). Consequently, farmland use is being localized again within the settlement. Our case study, Tachi, can be considered a representative case study, as it encapsulates many of the recent trends in development of marginal rural communities Japan (rapid socio-demographic decline and its impact on the continuity of farmland use and management practices, especially in terms of labor allocation, but also regarding the mechanisms of renting out/lending farmland). The limited local scale allows for the detailed survey of the entire community as well as an in-depth analysis of data. Findings of this study might prove useful in the elaboration of rural/farming policies with the potential of wider implementation in similar areas in Japan but also (at the broader scale) in Asia.

DOI： 10.4157/geogrevjapanb.93.15

Smallholder's labor allocation for livelihood diversification: A case study in an upland village in northern Laos Reviewed International coauthorship

Khamphou PHOUYYAVONG, Shinsuke TOMITA, Satoshi YOKOYAMA

Tropics Vol. 29 ( 1 ) page： 9 - 24 2020.6

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Tropical Ecology

Livelihood diversification involves the well-characterized strategies of smallholder farmers to combine risk aversion under a market economy. Since livelihood diversification studies have focused on diversifying income sources to include non-farm and off-farm income, the benefit of adding subsistence-oriented farming to the livelihood portfolio has been underestimated. This form of livelihood diversification is broadly observable in Southeast Asia, and could be another risk aversion strategy to cope with unpredictable market conditions. This study examined the role of swidden farming in livelihood diversification through the analysis of individuals’ labor allocation in livelihood portfolio, annual working hours, and seasonal changes in working hours in a village in northern Laos. Information was obtained through direct interviews with 133 individuals. Interviews were conducted in 2017 and gathered information on demographic features, economic activities, and monthly working hours for individual in 2016. The results indicated: 1) Individual’s livelihood portfolio was determined by the assets that the ethnic group and each household held to a large extent; 2) Livelihood diversification took place at the individual level rather than at household level, through an increase in annual working hours, as well as monthly working hours during the peak period of labor demand; and 3) Labor demand for swidden farming was moderate, so villagers can incorporate it into their livelihood portfolio. The study highlighted that flexibility would be another facet of livelihood diversification. Swidden farming was likely to play a pivotal role in its flexibility, but it was not important as an income source.

DOI： 10.3759/tropics.MS19-08

CiNii Research

Impact of forage introduction on cattle grazing practices and crop-livestock systems: A case study in an upland village in northern Laos Reviewed International coauthorship International journal

Khamphou PHOUYYAVONG, Shinsuke TOMITA, Satoshi YOKOYAMA

Rangeland Journal Vol. 41 ( 4 ) page： 323 - 334 2019.8

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Australian Rangeland Society

Lao smallholders are experiencing livestock grazing land constraints due to resettlement, increasing cattle numbers and commercial cash crop plantations. In this paper we describe changes in cattle grazing systems in an upland village in northern Laos, including the role of forage crops and their effects on cattle productivity. We interviewed 92 Hmong and Khmu households about their migration history, cattle grazing practices, cattle productivity and other livelihood activities. In addition, we measured the heart girths of 231 cattle. We found that the traditional free-range cattle grazing has diverged into three distinct systems incorporating fields fenced to different degrees. Although none of the three systems increased cattle body size, the forage pasture and swidden-farming system successfully increased the grazing capacity compared with other systems. Thus, this method appeared to be the most suitable for Hmong smallholders to manage crop and cattle production in the context of land constraints. Efforts should be made to examine how the newly implemented systems could attenuate villager livelihood and pre-emptively address the problems associated with degrading fallow land.

DOI： 10.1071/RJ18102

Scopus

Trends in the application of <i>bacillus</i> in fermented foods Reviewed International journal

Keitarou KIMURA, Satoshi YOKOYAMA

Current opinion in biotechnology Vol. 56 page： 36 - 42 2019.4

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier

Bacillus species such as Bacillus subtilis and Bacillus amyloliquefaciens are widely used to produce fermented foods from soybeans and locust beans in Asian and West African countries, respectively. Genomic information for B. subtilis strains isolated from Asian Bacillus-fermented foods (BFFs) has been gathered, and the chemical components of fermented products were defined with metabolomic approaches, facilitating the development of new starter strains and the evaluation of health claims. On the other hand, although advanced studies have been performed for some commercially produced BFFs, home-manufactured products still remain to be characterized in rural areas. In West Africa, the microbial flora of BFFs was examined in detail, leading to the isolation of candidates of the starter that produced bacteriocin against Bacillus cereus contaminating the products. These studies may provide a choice of Bacillus strains in food application and increase opportunities for further usage of Bacillus in foods.

DOI： 10.1016/j.copbio.2018.09.001

Scopus

PubMed

Driving forces for livelihood structure changes in Vietnam's northwestern mountainous region: A case study on Yen Chau district, Son La province Reviewed International coauthorship

NGUYEN Thi Hong Ngoc, Satoshi YOKOYAMA

Tropics Vol. 27 ( 4 ) page： 81 - 97 2019.3

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Tropical Ecology

Twenty years of long-term maize monoculture that began in the 1990s have resulted in the heavily maize-dependent economy of the northwestern mountainous region of Vietnam, especially in Yen Chau, the core production area. Before 2014, maize accounted for over 70% of the agricultural area. The continuous decrease in maize production value has strongly affected the Tai Dam community in Yen Chau and led to the replacement of various livelihood activities. This contributed to a major shrinkage of the maize area by 28.2% by the end of 2017. This study aims to investigate the determinants of the rapid development of different livelihood trends in Lac Ken, Suoi Bun, and Luong Me villages. A detailed social and statistical investigation was conducted of 198 households in 2016 and 220 households in 2017. The findings of this study indicate that small differences in cultivated land areas and infrastructure facilities have fostered the formation of and changes in livelihood structures. The areal withdrawal of maize occurred concurrently with the increasing trend of fruit tree and sugarcane cultivation. Never-before-seen migrant work unexpectedly became a promising livelihood activity for local farmers. Differences in internal and external forces are believed to be the driving factors behind the new forms of livelihood activities.

DOI： 10.3759/tropics.MS18-09

Web of Science

CiNii Research

Influence of trading structure on maize seed selection by farmers in Vietnam: Case study on Yen Chau district, Son La province Reviewed

NGUYEN Thi Hong Ngoc, Satoshi YOKOYAMA

Geographical review of Japan series B Vol. 91 ( 2 ) page： 40 - 53 2018.12

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

Maize is the most important cash crop in Vietnam’s northern mountainous region. It is credited with eradicating hunger and alleviating poverty. However, the continuous decreasing trend in the global maize price since 2013 has resulted in various socioeconomic problems. Yen Chau district follows a cultivation regime of annually changing maize varieties. This goes against the objectives of national test procedures for new seed. This study aimed to establish whether the annually changing seed cultivation regime is the consequence of the fierce competition between seed enterprises. We found that the maize trading structure is centered on a three-level trader network that plays a crucial role in connecting stakeholders. Strong social relationships along with weak credit/production commitments between farmers and traders have facilitated maize production throughout the region. Seed and supply enterprises target traders to promote their products and are the most important information channel for farmers. This study’s findings suggest that seed selection in Yen Chau has no scientific basis but is the result of market factors.

DOI： 10.4157/geogrevjapanb.91.40

日本納豆とアジア納豆—おかずか調味料か？ Invited

横山　智

科学 Vol. 88 ( 12 ) page： 1228 - 1234 2018.12

The origin of natto (Fermented Soybean) in Southeast Asia and the Himalayas Reviewed

Satoshi YOKOYAMA

Clinical & Functional Nutriology Vol. 8 ( 1 ) page： 19 - 23 2016.2

Authorship：Lead author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Humanus Societatem Natura

Many Japanese think Natto (fermented soybeans) is a traditional Japanese food. Natto is undeniably the traditional Japanese food, but it is not a unique Japanese food. In "The Lucidophyllous Forest Culture (Syoyo-jyurin Bunka)" proposed in the end the 1960s, it was shown that fermented soybean foods such as Miso and Natto are produced inlucidophyllous forest zone extending into Southeast Asia and the Himalayas. Moreover, in the hypothesis of "Natto Triangle (Natto no Dai-sankakukei)" presented by Sasuke NAKAO in the 1970s, Natto was thought to have originated in Yunnan Province, China. Academic research to explore the origin of Natto, however, has not been completely implemented since then. In this paper, we would like to introduce an Natto culture in Southeast Asia and the Himalayas which is little known to Japanese, and approach the origin of Natto from a new perspective.

Access to livelihood assets under the influence of a climate event in upland northern Laos Reviewed International coauthorship

Phanxay INXAY, Isao HIROTA, Satoshi YOKOYAMA

Geographical Review of Japan Series B Vol. 87 ( 2 ) page： 131 - 145 2015.7

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Association of Japanese Geographers

Climate events pose major challenges to food production and the livelihoods of rural inhabitants in northern Laos, where upland rice using swidden production is an important crop. The onset of the rainy season in this area is one such climate event, and it has occurred earlier and with less regularity in recent years. Not all households are able to cope with these changes. This study examines the ability of local farmers to cope with rice insufficiency. This investigation also clarifies household strategies in dealing with the climate event. We randomly interviewed 63 of 95 household heads, and performed a paired sample t test to examine the significance of differences in three household groups between the 2010 normal climate and the 2011 climate event. The groups were categorized according to rice self-sufficiency in 2011: groups I are households with rice self-sufficiency, group II are those facing a rice shortage of up to 3 months, and group III are those with insufficient rice for over 3 months. We also conducted a one-way ANOVA to examine the significance of differences in livelihood strategies among the three groups. We found that the household labor force was the most important factor in enhancing the villagers’ ability to deal with the climate event and that the level of impact of that event shaped their coping strategies. Households with substantial labor force had more options for coping strategies than those with smaller ones. The villagers faced different levels of impact and adopted different coping strategies accordingly. Non-timber forest product collection was the principle livelihood strategy in response to non-climate factors such as education, access to health services, provision of equipment and clothing, and overcoming the impact of the climate event. Households heavily affected by the early rainy season onset tended to engage in intensive activities such as off-farm activity and outside work, rather than their major livelihood activities in the village (upland crop and livestock production).

DOI： 10.4157/geogrevjapanb.87.131

Livelihood factors and household strategies for an unexpected climate event in upland northern Laos Reviewed International coauthorship International journal

Phanxay INXAY, Satoshi YOKOYAMA, Isao HIROTA

Journal of Mountain Science Vol. 12 ( 2 ) page： 483 - 500 2015

Language：English Publishing type：Research paper (scientific journal) Publisher：The Chinese Academy of Sciences

This study examines the effects of a climate event on livelihood assets of households in upland northern Laos, when the early onset of the rainy season as a result of climate change led to a failure to burn swidden systems. A Sustainable Livelihoods Framework is applied to estimate rural livelihood assets associated with differences in climate conditions, such as the 2010 normal climate and the 2011 climate event, and to compare household strategies in each climate condition. The findings indicate that natural capital had the highest index value in the 2010 normal climate, whereas human capital had the highest value in the 2011 climate event. Financial capital had the lowest index in both climate conditions. Residents at the research site were better off in terms of natural capital but worse off in terms of financial capital. This indicates that the government and other rural development agencies should not only manage natural resources; income-generation activities are also needed. We conclude that natural resources, as well as non-timber forest product (NTFP) gathering and off-farm activity, were the most important strategies for the entire research site under the normal climate condition. NTFP gathering and outside work are important in meeting subsistence needs and augmenting income levels in households when the rainy season begins early as a result of climate change. Outside employment was an additional strategy in households to achieve their livelihood goals, including food security and household income generation, under conditions of economic change and climate events.

DOI： 10.1007/s11629-013-2879-y

A review of studies on swidden agriculture in Japan: cropping system and disappearing process Reviewed

Satoshi YOKOYAMA, Isao HIROTA, Sota TANAKA, Yukino OCHIAI, Eiji NAWATA, Yasuyuki KONO

Tropics Vol. 22 ( 4 ) page： 131 - 155 2014.3

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Tropical Ecology

This paper reviewed some of the major study results published mainly in Japanese on swidden agriculture which was once practiced in Japan. In this review, a focus was placed on the natural environment in which swidden agriculture was practiced, cropping systems, crop cultivation in swidden fields, the transition of swidden agriculture at the end of the disappearing stage, and the utilization of millet cultivated in swidden agriculture. Swidden agriculture of temperate Japan featured cultivation primarily of millet, and was characterized by highly sophisticated and complex cropping systems according to the natural environment, which varied from one region to another. In the 1970s, however, swidden agriculture which had been continuously practiced as a primary means of subsistence in mountainous areas of Japan ceased to exist. Accordingly, the review will primarily focus on studies from the 1950s to 1970s, the post-war period in which a large number of research findings were produced from the perspectives of the humanities and natural sciences. The methodologies and perspectives adopted in the studies on Japanese swidden agriculture are definitely applicable to currently conducted studies of swidden agriculture in tropical regions.

DOI： 10.3759/tropics.22.131

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Papers - YOKOYAMA Satoshi