Agricultural practices and household organization in a Japanese pioneer community of lowland Bolivia

This article describes the colonization process of the Japanese pioneer farmers in the Bolivian subtropical lowlands. Quantitative data for each of the farm households that can be matched for comparison between the initial phase of colonization and a later phase provide the basis for an examination of a reciprocal relationship between household organization and successively introduced agricultural practices. Two hypotheses are tested: (a) pioneer agriculture stimulates the formation of large family households to cope with an assumed labor shortage; and (b) existing variation in household organization produces variation in agricultural practices. The analysis reveals that the size of swidden farming in the initial phase and the size of permanent field cultivation in the latter phase both relate positively to the size of the male labor force. Despite the significant advantage of a large family household for providing free labor during rapid agricultural growth, a diachronic analysis does not support the hypothesis that the pioneer condition stimulates adaptive social change toward the formation of large families. Rather, the data indicate that changes in household composition have major effects on the size of cropland and the transformation from swidden farming to mechanized cultivation. Underlying mechanisms of agricultural change are further explored, and the implications for a colonization project are discussed.     

The Last Swiddens of Sarawak, Malaysia

Swidden cultivation was observed to be under pressure but still persisting in many areas in Sarawak, Malaysia around 2000–2003. Since then rapid development of smallholder oil palm and rubber, continuing urbanization and rural to urban migration appear to have considerably reduced the area under swidden cultivation. With the aim of understanding the extent and impacts of this development, 55 households in three communities that were interviewed in 2002–2003 were re-interviewed in 2011. In an area with rapid oil palm development, the households engaged in smallholder oil palm production have experienced considerable improvements in income and wealth whereas the other households have experienced more limited wealth increases or even a decline in income. Many households have decreased or abandoned cultivation of upland rice, which used to be the core of the swidden cultivation system, and the upland soils in the area are now dominated by oil palm. In another area, where no oil palm development has taken place because of a hydroelectric dam, upland rice fields under swidden cultivation have also decreased and new high yielding rubber is now being planted because of the favorable rubber prices. Moreover, tourism has in this area gained further economic importance and overtaken agriculture as the main economic activity of households. The demise of swidden has not yet occurred in Sarawak, but a continued decline has been observed. However, there is a possibility that the new smallholder oil palm and rubber may provide an opportunity for a new type of ‘productive fallow’ that will allow continued cultivation of upland rice on a small scale.     

Comparing and Combining Landsat Satellite Imagery and Participatory Data to Assess Land-Use and Land-Cover Changes in a Coastal Village in Papua New Guinea

In regions lacking socio-economic data, pairing satellite imagery with participatory information is essential for accurate land-use/cover (LULC) change assessments. At the village scale in Papua New Guinea we compare swidden LULC classifications using remote sensing analyses alone and analyses that combine participatory information and remotely sensed data. These participatory remote sensing (PRS) methods include participatory land-use mapping, household surveys, and validation of image analysis in combination with remotely sensed data. The classifications of the swidden area made using only remote sensing analysis show swidden areas are, on average, two and a half times larger than land managers reported for 1999 and 2011. Classifications made using only remote sensing analysis are homogeneous and lack discrimination among swidden plots, fallow land, and non-swidden vegetation. The information derived from PRS methods allows us to amend the remote sensing analysis and as a result swidden areas are more similar to actual swidden area found when ground-truthing. We conclude that PRS methods are needed to understand swidden system LULC complexities.     

Archaeobotanical analysis of radiocarbon-dated plant remains with special attention to <Emphasis Type="Italic">Secale cereale</Emphasis> (rye) cultivation at the medieval village of Mankby in Espoo (Finland)

Several urban medieval sites in Finland (ad 1000–1500) have been archaeobotanically investigated, but until now only a few rural medieval settlements have been studied. Therefore, many aspects of the crops and agricultural methods of medieval villages in Finland still remain unknown. At the 12th to mid-16th century medieval village of Mankby, Espoo, a systematic sampling for archaeobotanical material was carried out. The analysed samples derived from hearths, building contexts and medieval field layers etc. The archaeobotanical material was carbonised, and it consisted mostly of conifer needles, cereal grains and weed seeds. Secale cereale (rye) and Hordeum vulgare (barley) were the only crop species found, Secale being the most frequent. Seeds of Bromus secalinus (rye brome) and achenes of Centaurea cyanus (cornflower), which are associated with autumn sown winter cereal crops, were also present. The archaeobotanical material shows areas of activity linked to storing crops, as well as cultivation within the village boundaries. Based on radiocarbon dated grains, cultivation of the fields started in the 12th century and continued until the abandonment of the village in 1556. Archaeobotanical material from Mankby has been compared to other contemporary sites in Finland, and differences between the sites can be seen. Results from Mankby have added to our knowledge of medieval agriculture, past areas of activity and economic conditions within the village.     

Coppice swidden fallows in tropical deciduous forest: Biological,technological, and sociocultural determinants of secondary forest successions

Secondary succession in tropical deciduous forest is often characterized by vegetative reproduction, or coppicing. Coppicing is also observed in forest sites that are disturbed by farming activity. This observation raises questions about the role of established management practices in determining the succession of vegetation on farmsites once they are abandoned to fallow. To what extent is the coppicing succession the result of specific aspects of swidden farming technology and management? And what variations in coppice successions occur in swidden sites following deviations from the standard farming practice? In research on swidden farming among the Susu of Sierra Leone, I examined the successional pathway in an age series of forest fallow sites. I show that the standard pattern of minimal cultivation favors the coppicing of felled trees in the subsequent fallow periods. By contrast, deviation from this pattern results in stump deaths and favors the invasion of fallow sites by grasses and vegetatively reproducing pioneer trees from the savanna. Variations in the environmental outcome of disturbance to plant communities, then, are the result of interactions between processes of tropical tree reproduction and the agricultural practices of local farmers.     

农业结构转型对生态系统服务与人类福祉的影响——以西安都市圈两种农业类型为例

研究城市化地区农业类型转变对农业生态系统服务与人类福祉的影响,对调控都市农业发展、维持农业生态系统服务以及提升农户福祉等具有重要意义。以西安都市圈两个农业类型转变的村庄为案例,通过入户调查对村域的生态系统服务价值及人类福祉进行测算,分析农业转型下生态系统服务与人类福祉的相互影响。结果表明:(1)农业结构转型过程中,以粮食耕种为主的马家村的生态系统服务价值由2000年141.88×10~4元减少至2017年117.58×10~4元(降幅为17.13%);而以蔬菜种植为主的火箭村生态系统服务价值由727.23×10~4元增长至1753.23×10~4元(增幅达141.08%),其变化主要源于农业劳动力、农户行为及农业类型的影响。(2)不同农业类型下人类福祉差异明显,以蔬菜种植为主的火箭村人类福祉比以粮食种植为主的马家村高出89%;表明由传统粮食种植转向现代都市农业可以提高人类福祉,在各福祉指标中农业纯收入对农户福祉影响最为显著。(3)不同农业类型下生态系统服务与人类福祉的相关程度不同,但都与农产品供给呈正相关,与农业纯收入呈负相关。以传统粮食种植为主的马家村村民对生态环境的关注度较低,而转向蔬菜种植的火箭村对水质等生态环境的关注度开始提高。生态系统服务价值和农户福祉的提升与农业类型显著相关,因此,可通过政府引导农户规划农业用地类型以优化景观格局,从而维持农业生态系统服务的可持续发展。     

Potential Management of <Emphasis Type="Italic">Chamaedorea seifrizii</Emphasis> (Palmae), a Non-timber Forest Product from the Tropical Forest of Calakmul,Southeast Mexico<Superscript>1</Superscript>

Potential Management of Chamaedorea seifrizii (Palmae), a Non-timber Forest Product from the Tropical Forest of Calakmul, Southeast Mexico. Leaves and seeds of Chamaedorea (xate) palms are important non-timber forest products (NTFPs). In the Calakmul region (Yucatan Peninsula) of Mexico, several communities have sporadically collected and sold seeds of C. seifrizii since 1980. However, harvesting has intensified recently, raising concerns about overexploitation. To evaluate the economic potential of leaf and seed exploitation in the area, we collected information on abundance, population patterns, and leaf and seed stocks in Ejido Conhuas, a community within the Calakmul Biosphere Reserve (CBR). Then we combined these data with current market values and hypothetical management regimes obtained from the literature for leaves and seeds. Conducting a quantitative analysis of 43 0.1^ha plots with differences in forest and soil type, we assessed the abundance of C. seifrizzi in the area. We also conducted interviews to estimate the importance of xate in the local economy. We found C. seifrizii density to be highly variable, with a mean (±SE) of 295 (±35), with forest type being the most influential factor. Population structures differ between forest types, with healthy populations in medium and lower forest. We found a mean density of leaves of harvestable size of 3,750 (±380) leaves ha^-1, while seed production was 1.5 (±0.3) kg/ha^-1 of fresh seeds. Assuming sustainable harvest rates of 30–50% for leaves and 80% for seeds, one hectare of forest could generate USD 7.0–15.9/ha^-1. Considering the number of households (102) and 10% of the total area managed each year (5,700 ha), this harvest could generate a household income of USD 391–838 annually. At the moment, xate trade represents a minor component in the economy of the community, but given the area’s extensive forest (>57,000 ha), the resource abundance, and the low human population, we believe the NTFPs derived from C. seifrizii have a potentially great economic impact in the area.     

Swidden cultivation in forest and savanna in lowland southwest Papua New Guinea

Ecological aspects of traditional swidden cultivation by Bine- speaking groups in wetland areas of lowland southwest Papua New Guinea are examined. A notable feature of the area is the coexistence of extensive, polycultural forest cultivation and more intensive, specialized savanna cultivation. Both agrosystems occur on soils of inherently similar properties. The savanna vegetation is secondary in character and, once established, is better suited to more intensive swidden cultivation based on taro (Colocasia esculenta). The agrosystems in question represent stages in the local development of agriculture, and, although multiple causes of intensification may be involved, the study confirms that lowland, as well as highland, areas of New Guinea have provided development opportunities for traditional cultivators.     

Agricultural intensification in a Philippine frontier community: Impact on labor efficiency and farm diversity

There continues to be much debate in anthropology concerning the mechanism by which agricultural intensification takes place and its impact on labor efficiency, farm diversity, and quality of diet. A major reason for this lack of consensus is the paucity of data from case studies that focus on specific agricultural systems at the point of transition from extensive to intensive methods of cultivation. Research in a frontier community in the Philippines, where farmers are making the shift from swidden cultivation to small-scale irrigated rice production, indicates that intensification does not necessarily result in lower efficiency or a decline in dietary standards. Rather, farmers faced with growing population pressure and an unproductive short fallow swidden system have been motivated to adopt irrigation because it increases the efficiency of their labor while maintaining a reliable and diverse farming system.     

Swidden Transformations and Rural Livelihoods in Southeast Asia

This paper explores the major interactions between the transformation of swidden farming and the pursuit of rural livelihoods in the uplands of Southeast Asia. The paper draws on selected literature, workshop reflections, and six case studies to describe the causal processes and livelihood consequences of swidden change. Household-level livelihood responses have included both the intensification and ‘dis-intensification’ of swidden land-use, the insertion of cash crops, the redeployment of household labour, and the taking on of broader (often non-rural) livelihood aspirations and strategies. At the community level there have been emerging institutional arrangements for management of land and forests, and varying degrees of participation in or resistance to government schemes and programs. Swidden change has led to the loss and also the reassertion, realignment, and redefinition of cultures and identities, with important implications for access to resources. The impacts of these changes have been varied. Cash crops have often improved livelihoods but complete specialisation for the market increases vulnerability. Thus swidden can still provide an important safety net in the face of market fluctuations. Improved access to markets and social provision of education and health care have mostly improved the welfare of previously isolated groups. However, growing differences within and between communities in the course of swidden transformations can leave some groups marginalized and worse off. These processes of differentiation can be accentuated by heavy-handed state interventions based on swidden stereotypes. Nevertheless, communities have not passively accepted these pressures and have mobilized to protect their livelihood assets and strategies. Thus swidden farmers are not resisting appropriate and supportive forms of development. They are adopting new practices and engaging with markets, but in many situations swidden is still important to their livelihood strategies, providing resilience in the face of turbulent change. Active involvement of local people is essential in planning, implementing, monitoring and evaluating development and conservation programs in swidden lands. Positive market incentives and supportive government policies are better than standardised, top-down directives.

Analysis of Pig Consumption by Smallholders in a Hillside Swidden Agriculture Society of Northern Thailand

Previous studies on the hillside farmers of northern Thailand often focused on their swidden (slash-and-burn) agriculture of upland rice and cash crop cultivation and paid little attention to livestock production and consumption, including that of pigs. I describe the household-level pig production and consumption in terms of the number of pigs slaughtered and the number of pigs supplied to others, or acquired from others, in a Hmong village of smallholders in northern Thailand. Study results are based on pig consumption in 17 selected households over two years (January 2005 to December 2006). The number of pigs slaughtered in each household ranged from zero to ten, with an average of 2.4 pigs per household per year. Pigs were slaughtered mainly for ritual events, particularly for annual ancestor worship and New Year ceremonies. A total of 80 pigs were slaughtered, with 78% being killed during ritual events including Christmas and 22% for non-ritual events including children moving up a grade in school. Most Christian households stopped slaughtering of pigs in ancestor worship conducted by a shaman, but continued to do so in Christmas and New Year rituals. A total of 23 pigs were supplied to others, of which two were given to people outside the village, while of a total of 37 pigs acquired, 17 were obtained from outside the village. A total of 80 pigs were slaughtered, including one improved-breed pig that was killed during a marriage ceremony soon after it was acquired from the city. The following changes in pig consumption are inferred to have taken place due to recent socioeconomic changes: (1) diversification of the type of events in which pigs are slaughtered as a result of the introduction of Christianity and the national educational system; (2) active pig acquisition from outside the village as a result of the use of motor vehicles; and (3) the acquisition and slaughtering for events of improved-breeds of pigs which are not kept and used for breeding.     

Variation in Swidden practices in four central Brazilian Indian societies

It has been suggested that indigenous tropical forest agriculture, in contrast with other agricultural systems, is characterized by a high degree of polyculture, and, being similar in diversity to the forest itself, has little disturbing effect on the generalized ecosystem that surrounds native gardens. Our comparative study of four Central Brazilian Indian groups shows, however, that while each of these groups practices polyculture to some extent, the crop mix found in their swidden plots is highly patterned, and includes single crop stands at certain stages of garden life. Different crops are planted in the same swidden plot from year to year, in accordance with variation in soil fertility within the swidden cycle. None of the swiddens we observed compares in complexity to the surrounding forest. We suggest that polyculture, rather than being regarded as the distinguishing characteristic of swidden cultivation, should be considered as a varying dimension—along with other variables such as use of wild plants, soil fertility and exhaustion, tillage practices, the introduction of novel crops, and production for the market—within the overall subsistence strategy of a group.     

Before it disappeared: ethnobotanical study of fleagrass (<Emphasis Type="Italic">Adenosma buchneroides</Emphasis>), a traditional aromatic plant used by the Akha people

Background

Fleagrass, Adenosma buchneroides, is an aromatic perennial herb that occupies an important position in the life of the Akha people. They regard it as a tribal symbol and a gift of love. Fleagrass also has many medicinal uses, and there is considerable potential for its development as an insect repellent. Traditionally, Akha people plant it in swidden fields, but there are few swidden fields in China now. Therefore, the first question this study aims to answer is as follows: how is fleagrass planted and utilized now? At present, fleagrass is only reported to be used by Akha people in Mengla. We also try to understand the following questions: Is fleagrass used in nearby area? If so, how is fleagrass used in nearby area? Furthermore, why is fleagrass used in that way?

Methods

From August 2016 to July 2018, field surveys were conducted six times. The ethnobotanical and ethnopharmacological uses of A. buchneroides in 13 Akha villages were investigated by means of semi-structured interviews. We assessed the responses of a total of 64 interviewees (32 men and 32 women; mean age, 58.6) from the Xishuangbanna Dai Autonomous Prefecture, southwest China, and from Phongsaly Province, Laos. To explain the bases for the ethnobotanical uses of fleagrass, we used Google Scholar, Web of Science, and China National Knowledge Infrastructure to review the bioactivities of the chemical constituents of A. buchneroides.

Results

With the vanishing of swidden agriculture and the development of modern products, fleagrass cultivation is disappearing in China. However, most Akha people in Xishuangbanna still remember and yearn for its traditional uses, and Akha people in a nearby area (northern Laos) continue to plant and utilize it. We documented ten uses of A. buchneroides within five discrete categories. The whole plant of fleagrass has a distinct strong aroma, of which Akha villagers are particularly fond. Akha villagers mostly use this aromatic property as a decoration, perfume, and insect repellent. A. buchneroides is also used as a condiment and for medicinal and ritual purposes, including its use as a cure for insect bites, headaches, influenza, and diarrhoea, and as a part of pray ritual for a bumper harvest. From our literature review, we identified many major chemical compounds contained in the essential oil of A. buchneroides, including thymol, carvacrol, 3-carene, and p-cymene, which have insecticidal or insect-repellent, antimicrobial, and anti-inflammatory properties.

Conclusion

Fleagrass is an aromatic plant that is widely used by Aka people. Its chemical composition also has a variety of biological activities. With the vanishing of swidden agriculture and the development of modern products, fleagrass utilization in China is disappearing and its cultural importance is reduced. However, its economic and medicinal value is assignable.

     

Energy dissipation in photosystem 2 complexes of peanut leaves subjected to light pulses

To increase crop yields, intercropping agricultural cultivation approach (IACA) and relay cropping agricultural cultivation approach (RACA) were introduced into cultivation of peanut (Arachis hypogaca L.), one of the most important oil crops in the world. IACA/RACA improves the yield of the crop per unit area, but rather decreases the yield of a single crop compared with mono-cropping agricultural cultivation approach. In peanut IACA/RACA, peanut plants would grow under low light and high light pulses (HLP) before maize/wheat harvest. Energy dissipation in photosystem 2 (PS2) complexes was evaluated in peanut leaves after being induced by light pulses and continuous light with different light intensities. Actual photochemical efficiency of PS2 (ΦPS2) and non-photochemical quenching induced by light pulses in peanut leaves generally were significantly lower compared with those induced by continuous light. In addition, the degree of PS2 reaction center closure (1-qP) induced by light pulses in peanut leaves was significantly higher compared with those induced by continuous light. Different results were obtained only for ΦPS2 and 1-qP induced by 20 s HLP. In methyl viologen (MV) treated samples, ΦPS2 and the quantum yield of light induced thermal dissipation by non-functional PS2 (Φ_NF) were similar to those observed in non-MV treatments. These results implied that light pulses could induce photoinactivation of PS2 reaction centers but not the xanthophyll cycle to dissipate excess energy.     

汉、藏、回族地区农户的环境影响——以甘肃省张掖市、甘南藏族自治州、临夏回族自治州为例

农户作为我国最主要的经济活动主体与最基本的决策单位,已成为影响生态环境的最重要单元,当前急需理解农户的环境影响,并依此为依据找寻缓解环境压力的对策.以甘肃省张掖市、甘南藏族自治州、临夏回族自治州为研究区,以生态足迹作为测度环境影响的指标,利用入户调查资料,基于成分法核算了农户的生态足迹,对比分析了汉、藏、回族地区农户的环境影响,并利用STIRPAT模型分解了各因素对农户环境影响的作用.研究发现:(1)甘南州农户的人均生态足迹高于张掖市与临夏州,其中甘南州农户的人均草地足迹远高于张掖市与临夏州,而张掖市农户的人均化石能源地足迹远高于甘南州与临夏州;(2)3个地区农户对耕地影响的差距均较小,但对水域、林地、草地影响的差距都较悬殊;(3)农户的家庭规模、富裕水平、受教育程度、非农化水平是影响生态环境的主要驱动因子,扩大家庭规模、提高富裕水平将加剧对环境的影响,而提高农户的受教育程度及非农化水平将减缓对环境的影响,但它们引起的环境影响变化速度均低于其自身的变化速度;(4)民族属性对农户的环境影响具有显著作用,张掖市、甘南藏族自治州、临夏回族自治州的现有样本数据支持环境Kuznets曲线假说.     

Environmental Consequences of the Demise in Swidden Cultivation in Southeast Asia: Carbon Storage and Soil Quality

The effects of swidden cultivation on carbon storage and soil quality are outlined and compared to the effects of the intensified production systems that swidden systems of Southeast Asia transform into. Time-averaged aboveground carbon stocks decline by about 90% if the long fallow periods of traditional swidden cultivation are reduced to 4 years and by about 60% if swidden cultivation is converted to oil palm plantations. Stocks of soil organic carbon (SOC) in tree plantations are 0–40% lower than stocks in swidden cultivation, with the largest losses found in mechanically established oil palm plantations. Impacts of tree plantations on soil quality are to a large extent determined by management. Conversion of swiddening to continuous annual cropping systems brings about substantial losses of time-averaged aboveground carbon stocks, reductions of SOC stocks and generally leads to declining soil quality. Knowledge of carbon storage in belowground biomass of tree based systems of the tropics is sparse but failure to include this pool in carbon inventories may significantly underestimate the total biomass of the systems. Moreover, studies that consider the ecological reasons behind farmers’ land use decisions as well as spatial variability in biogeophysical and edaphological parameters are needed to evaluate the effects of the ongoing land use transitions in Southeast Asia.     

Ethnobotanical Knowledge and Crop Diversity in Swidden Fields: A Study in a Native Amazonian Society

Crop diversity protects food consumption in poor households within developing nations. Here we estimate the association between crop diversity on swidden fields and ethnobotanical knowledge. We conducted research among 215 male household heads from a native Amazonian society. Using multivariate regressions, we found higher crop diversity among households that depend on agricultural production for household consumption. We also found a statistically significant and positive, but low, association between the ethnobotanical knowledge of the male household head and crop diversity. Doubling the stock of ethnobotanical knowledge of the male household head is associated with a 9% increase in the number of crops sown by a household. The association remained after we controlled for the household level of market exposure, but vanished after we controlled for the social capital of the male household head. Future research should compare the association between ethnobotanical knowledge and crop diversity across different agricultural systems (i.e., home gardens, fallow fields).     

History of agriculture in Mikkeli Orijärvi,eastern Finland as reflected by palynological and archaeological data

The introduction and development of cultivation in eastern Finland was studied by pollen and charcoal analysis of a palaeomagnetically dated sediment profile from Lake Orijärvi, in the vicinity of permanent prehistoric fields. The earliest changes of possibly anthropogenic origin are visible in the pollen data from 1630 b.c. onwards and indications of human impact become more evident from 500 b.c. onwards. According to finds of cereal pollen and AMS-dating of charred cereal grains from the oldest field layer, the onset of cultivation can be dated to the Merovingian period around a.d. 600. To a significant extent the pollen data reflect only the cultivation of Secale during the first 600 years. The marked intensification of agricultural activities including cultivation in permanent fields only becomes evident in the pollen data from about a.d. 1050 to 1080 onwards and the most intensive land use phase dates to a.d. 1300–1965. Archaeological and palaeoecological material indicate that swidden cultivation and permanent field cultivation were in use simultaneously during the late Iron Age. The combination of these techniques together with animal husbandry and hunting formed a subsistence strategy in the climatic border-zone outside the centres of the agricultural core areas.     

Predictors of bovine Schistosoma japonicum infection in rural Sichuan,China

In China, bovines are believed to be the most common animal source of human schistosomiasis infections, though little is known about what factors promote bovine infections. The current body of literature features inconsistent, and sometimes contradictory results, and to date, few studies have looked beyond physical characteristics to identify the broader environmental conditions that predict bovine schistosomiasis. Because schistosomiasis is a sanitation-related, water-borne disease transmitted by many animals, we hypothesised that several environmental factors – such as the lack of improved sanitation systems, or participation in agricultural production that is water-intensive – could promote schistosomiasis infection in bovines. Using data collected as part of a repeat cross-sectional study conducted in rural villages in Sichuan, China from 2007 to 2016, we used a Random Forests, machine learning approach to identify the best physical and environmental predictors of bovine Schistosoma japonicum infection. Candidate predictors included: (i) physical/biological characteristics of bovines, (ii) human sources of environmental schistosomes, (iii) socio-economic indicators, (iv) animal reservoirs, and (v) agricultural practices. The density of bovines in a village and agricultural practices such as the area of rice and dry summer crops planted, and the use of night soil as an agricultural fertilizer, were among the top predictors of bovine S. japonicum infection in all collection years. Additionally, human infection prevalence, pig ownership and bovine age were found to be strong predictors of bovine infection in at least 1 year. Our findings highlight that presumptively treating bovines in villages with high bovine density or human infection prevalence may help to interrupt transmission. Furthermore, village-level predictors were stronger predictors of bovine infection than household-level predictors, suggesting future investigations may need to apply a broad ecological lens to identify potential underlying sources of persistent transmission.