Yasuyuki Kosaka

Plant–pollinator interactions in tropical monsoon forests in Southeast Asia

Forests with different flora and vegetation types harbor different assemblages of flower visitors, and plant-pollinator interactions vary among forests. In monsoon-dominated East and Southeast Asia, there is a characteristic gradient in climate along latitude, creating a broad spectrum of forest types with potentially diverse pollinator communities. To detect a geographical pattern of plant-pollinator interactions, we investigated flowering phenology and pollinator assemblages in the least-studied forest type, i.e., tropical monsoon forest, in the Vientiane plain in Laos. Throughout the 5-year study, we observed 171 plant species blooming and detected flower visitors on 145 species. Flowering occurred throughout the year, although the number of flowering plant species peaked at the end of dry season. The dominant canopy trees, including Dipterocarpaceae, bloomed annually, in contrast to the supra-annual general flowering that occurs in Southeast Asian tropical rain forests. Among the 134 native plant species, 68 were pollinated by hymenopterans and others by lepidopterans, beetles, flies, or diverse insects. Among the observed bees, Xylocopa, megachilids, and honeybees mainly contributed to the pollination of canopy trees, whereas long-tongued Amegilla bees pollinated diverse perennials with long corolla tubes. This is the first community-level study of plant-pollinator interactions in an Asian tropical monsoon forest ecosystem.

Comprehensive geriatric assessment of elderly highlanders in Qinghai, China IV: Comparison of food diversity and its relation to health of Han and Tibetan elderly

Aim:  To examine the association between food diversity and health status of Han and Tibetan elderly highlanders in Qinghai Plateau, China.

Roadside Distribution Patterns of Invasive Alien Plants Along an Altitudinal Gradient in Arunachal Himalaya, India

Abstract Invasive plants have spread all over the world, including the Himalayan region. In 2009, the distribution pattern of invasive alien plants was studied on 38 plots, from 100 to 4200 m, in Arunachal Pradesh and Assam, India. Eighteen invasive alien plants (frequency >5%) from 7 families were recorded, of which 15 species (83.3%) were from North and South America. The most common plants by both frequency and coverage (>50%) were Ageratum conyzoides, Chromolaena odorata, and Mikania micrantha. Species composition changed with altitude. Thirteen species grew in the tropical zone, 10 in the subtropical, 6 in the temperate. and 1, Taraxacum officinale, in the subalpine zone. We suggest that low temperature and snowfall in the highlands may filter nonadapted species from tropical regions and that recent construction and use of roads facilitate the establishment of invasive alien plants. Although several invasive alien plants were regarded as noxious weeds, local residents in the study area mentioned their beneficial uses: A. conyzoides and Solanum carolinense are used as medicine, Galinsoga quadriradiata is used as a vegetable, and Eichhornia crassipes is used to improve fish growth in aquaculture. Information from scientific assessment and local perception of invasive alien plants will assist in the development of appropriate plant resource management plans in Arunachal Himalaya.

Comprehensive geriatric assessment of elderly highlanders in Qinghai, China I: Activities of daily living, quality of life and metabolic syndrome

Aim:  To reveal the comparison of comprehensive geriatric functions of elderly highlanders in Qinghai Plateau in China among three different ethnic groups.

Plant Diversity in Paddy Fields in Relation to Agricultural Practices in Savannakhet Province, Laos

This paper reports a study of paddy vegetation in central Laos. Plants were inventoried and vegetation types classified. Relationships between vegetation and agricultural practices were identified. A total of 184 wild herbaceous species and 17 cultivated species were recorded in two villages. Of the wild species, 19 were used by local people, four were rare species, and three were major weeds. Paddy vegetation was arranged in order of water regime from shorter to longer hydroperiod by DCA. The factors contributing to high species diversity were: (1) the presence of species unique to different paddy types; (2) the presence of remnant species from original vegetation; and (3) the impact of agricultural practices. Thus, at this study site, multiple plant species coexisted in paddy fields under various agricultural practices, and some species were essential sources of food or were used in other ways to support the subsistence livelihoods of local residents.

Species composition, distribution and management of trees in rice paddy fields in central Lao, PDR

Presence of different types of trees dispersed singly or in small groups throughout the fields is a very common feature in the extensive rice paddies of Laos and Thailand. Factors such as land-settlement history, proximity to forest, and role of species in the local culture are known to influence the nature and distribution of tree species so retained. The extent of influence of these factors on tree-species composition and distribution in rice paddies was investigated in three villages in Central Laos: Dongmakngeo, a newly established village with an abundance of adjacent forest; Bak, an old village with adjacent forest; and Nakhou, an old village without any adjacent forest. At Dongmakngeo village, 23 species, mostly remnants from the original forest, were observed in paddy fields. At Bak village, few trees were found in the paddy fields because villagers had ample access to resources in the surrounding large forest. On the other hand, 119 species, 27 of which were planted, were recorded at the forest-deprived Nakhou village; the scarcity of forest resources at Nakhou was compensated for by the utilization and management of trees located among the fields, resulting in tree species changing from remnant to ruderal over time. Thus, our results demonstrate that the pattern of tree distribution and species composition in paddy landscapes is not uniform, but varies in relation to settlement history, topography, and human management. This has important implications for setting both landscape-level land-use management plans and local tree management policies for achieving sustainable tropical paddy-dominated agro-silvicultural systems.

Prevalence of hypertension at high altitude: cross-sectional survey in Ladakh, Northern India 2007–2011

Objective Prevalence of hypertension was examined in a widely dispersed (45 110 km2) representative group of Ladakhi in Northern India. The influence of hypoxic environment of wide-ranged altitude (2600–4900 m) and lifestyle change on hypertension was studied. Methods 2800 participants (age 20–94 years) were enrolled. Systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure of ≥90 mm Hg and/or taking current anti-hypertensive medicine was defined as hypertension. Height and weight for body mass index and SpO2 were examined. The rural population comprised six subdivisions with a distinct altitude, dietary and occupational pattern. Participants in the urban area of Leh consist of two groups, that is, migrants settled in Leh from the Changthang nomadic area, and dwellers born in Leh. The prevalence of hypertension in the two groups was compared with that in the farmers and nomads in rural areas. The effects of ageing, hypoxia, dwelling at high altitude, obesity, modernised occupation, dwelling in an urban area, and rural-to-urban migration to hypertension were analysed by multiple logistic regression. Results The prevalence of hypertension was 37.0% in all participants and highest in migrants settled in Leh (48.3%), followed by dwellers born in Leh town (41.1%) compared with those in rural areas (33.5). The prevalence of hypertension in nomads (all: 27.7%, Tibetan/Ladakhi: 19.7/31.9%)) living at higher altitude (4000–4900 m) was relatively low. The associated factors with hypertension were ageing, overweight, dwelling at higher altitude, engagement in modernised sedentary occupations, dwelling in urban areas, and rural-to-urban migration. The effects of lifestyle change and dwelling at high altitude were independently associated with hypertension by multivariate analysis adjusted with confounding factors. Conclusions Socioeconomic and cultural factors play a big role with the effect of high altitude itself on high prevalence of hypertension in highlanders in Ladakh.

Glucose intolerance associated with hypoxia in people living at high altitudes in the Tibetan highland

Objectives To clarify the association between glucose intolerance and high altitudes (2900–4800 m) in a hypoxic environment in Tibetan highlanders and to verify the hypothesis that high altitude dwelling increases vulnerability to diabetes mellitus (DM) accelerated by lifestyle change or ageing. Design Cross-sectional epidemiological study on Tibetan highlanders. Participants We enrolled 1258 participants aged 40–87 years. The rural population comprised farmers in Domkhar (altitude 2900–3800 m) and nomads in Haiyan (3000–3100 m), Ryuho (4400 m) and Changthang (4300–4800 m). Urban area participants were from Leh (3300 m) and Jiegu (3700 m). Main outcome measure Participants were classified into six glucose tolerance-based groups: DM, intermediate hyperglycaemia (IHG), normoglycaemia (NG), fasting DM, fasting IHG and fasting NG. Prevalence of glucose intolerance was compared in farmers, nomads and urban dwellers. Effects of dwelling at high altitude or hypoxia on glucose intolerance were analysed with the confounding factors of age, sex, obesity, lipids, haemoglobin, hypertension and lifestyle, using multiple logistic regression. Results The prevalence of DM (fasting DM)/IHG (fasting IHG) was 8.9% (6.5%)/25.1% (12.7%), respectively, in all participants. This prevalence was higher in urban dwellers (9.5% (7.1%)/28.5% (11.7%)) and in farmers (8.5% (6.1%)/28.5% (18.3%)) compared with nomads (8.2% (5.7%)/15.7% (9.7%)) (p=0.0140/0.0001). Dwelling at high altitude was significantly associated with fasting IHG+fasting DM/fasting DM (ORs for >4500 and 3500–4499 m were 3.59/4.36 and 2.07/1.76 vs <3500 m, respectively). After adjusting for lifestyle change, hypoxaemia and polycythaemia were closely associated with glucose intolerance. Conclusions Socioeconomic factors, hypoxaemia and the effects of altitudes >3500 m play a major role in the high prevalence of glucose intolerance in highlanders. Tibetan highlanders may be vulnerable to glucose intolerance, with polycythaemia as a sign of poor hypoxic adaptation, accelerated by lifestyle change and ageing.

Comprehensive geriatric assessment of elderly highlanders in Qinghai, China, III: Oxidative stress and aging in Tibetan and Han elderly highlanders

Background:  Although there are several factors which may contribute to oxidative stress at high altitude, little is known about the association between oxidative stress and aging in the community‐dwelling elderly in the Tibetan Plateau.

Comprehensive geriatric assessment of elderly highlanders in Qinghai, China II: The association of polycythemia with lifestyle‐related diseases among the three ethnicities

Aim:  The objective of this study is to disclose the association of polycythemia with lifestyle‐related diseases (hypertension, obesity and glucose intolerance) among the three ethnicities in Qinghai, China.