Wild plants used by the Lhoba people in Douyu Village, characterized by high mountains and valleys, in southeastern Tibet, China

Background Douyu Village, inhabited by the Lhoba people, is situated within the Eastern Himalayas, in southeastern Tibet, China. The village is located among high mountains and valleys, which feature complex terrain with cold and dry climates and distinctive vegetation types and species. The Lhoba people in this village are isolated from other groups in China. The Lhoba people have lived in this village since the 15th century and mainly depended on gathering, hunting, and swidden agriculture before the 1960s. Because they have a long history and live under extreme climatic, geographical, and ecological conditions, the Lhoba people in Douyu Village may have unique traditional knowledge about wild plants. Thus, this research aims to record the traditional botanical knowledge of the Lhoba people in Douyu. Methods An ethnobotanical study was conducted on the Lhoba people in Douyu Village in Longzi County, Tibet, China. Semi-structured interviews and group discussions with informed consent were used in the study. We interviewed 41 informants (14 key informants) between 18 and 75 years of age. All information was collected, organized, and compiled into “use reports” for quantitative analysis. The informant consensus factor (ICF) was used to determine the homogeneity of the informants’ knowledge of medicinal plants, while the cultural importance index (CI) was used to estimate the cultural importance of shared species. Results A total of 91 wild species (90 vascular plants and 1 fungus) belonging to 71 genera and 39 families utilized by the Lhoba people in Douyu were documented. Of these species, Pimpinella xizangense and Wikstroemia lungtzeensis are endemic to Longzi County, while Sinopodophyllum hexandrum and Paeonia ludlowii are endangered species in China. All habitats, from the field vegetation at the valley bottoms to the alpine shrubland and meadows, were used for plant collection, and the numbers of species of plants collected from the various vegetation types (except for fields) decreased with increasing altitude. Our study found that 55 species are edible plants and fungi, 29 species are medicinal plants, and 38 species are used for other purposes. Medicinal plants are used for 11 categories of diseases, among which diseases of blood-forming organs (ICF = 0.96) and gastrointestinal diseases (ICF = 0.95) exhibited the highest ICF values. Based on the CI values, the most important plants in this study area are Berberis xanthophloea, B. kongboensis, Sinopodophyllum hexandrum, Vicatia thibetica, and Hippophae rhamnoides subsp. gyantsensis. Moreover, a comparison of the wild plants used by Lhoba ethnic groups in three counties in China showed significant differences among these regions. Conclusions Our study demonstrates that the wild plants utilized by the Lhoba people in Douyu Village are highly diverse, at 90 plant and one fungal species, which reflects not only the number of species but also their diversified functions. The extreme climatic, geographical, and ecological conditions of Douyu within the high mountains and valleys of the Eastern Himalayas potentially affect the Lhoba people’s culture, including plant utilization practices, and contribute to the rich diversity of the wild plants used by the local people.


Introduction
The Eastern Himalayas are characterized by complex topographic terrain with different altitudinal ecological zones [1] and feature a diverse array of vegetation types and rich plant diversity [2][3][4][5]. This region is also extremely culturally diverse [2,[6][7][8]. Wild plants not only contribute to the sustenance of the Eastern Himalayan tribal communities but also form an integral part of the culture and traditions of these communities, where a large number of wild plants are used for various purposes, such as for food, medicine, fodder, fuel, dyes, essences, rituals, and other multifarious purposes by local people [9][10][11][12]. In particular, in comparison to other indigenous populations, those in high-altitude regions may be more closely dependent on locally available wild plant resources due to uncertainty related to agricultural practices and low agricultural yields at high altitudes [13,14], and ethnobotanical investigations of these communities could contribute to specialized knowledge about the culture of wild plant utilization by local people in high-altitude areas [11,13,15].
Douyu Village, a Lhoba-inhabited area, is located in Longzi County in the Eastern Himalayas, southeastern Tibet, China [16,17]. The Lhoba people have lived in Douyu since the 15th century AD. They show substantial cultural diversity based on their long-term existence and cultural integration [17]. Since the 8th century AD, Lhoba ethnic groups have been concentrated in the Lhoyü area in the Eastern Himalayas [18]. In China, the Lhoba people are distributed in Milin County, Medog County, Zayü County, and Longzi County in Tibet [19]. The Lhoba ethnic groups include many different tribes, such as the Bo'gaer, Bengni, Miguba, and Mixingba [16,17,19]. The Lhoba nationality is one of the smallest populations in China. Its population was 3682 according to the 2010 Census. The Lhoba people in Douyu Village belong to the Bengni tribe. Before the 1960s, they mainly depended on gathering, hunting activities, and swidden agriculture to maintain their livelihoods. For a long time, they made full use of the wild plant resources in the surrounding mountains to meet their daily needs and formed a rich diversity of traditional knowledge about wild plants [17]. However, to date, there have been no studies on the local utilization of wild plants by the Douyu Lhoba people.
The number of useful species appears to vary with altitude in mountainous regions [20][21][22][23][24][25]. It seems that around villages and fields, the diversity of useful plant species is higher than levels in other areas [8,20,25]. Convenience and cultural value contribute to the presence of settlements in the vicinity of areas favorable for plant collection [8,20,25]. Moreover, extreme geographical and ecological conditions not only isolate plant populations [26] and result in culturally unique biodiversity [6,7,14] but also shape traditional uses of wild plants [9,27]. Wild plants play an important role in daily life in these regions because they contribute to the sustenance of local people and form the diversity of knowledge and culture of plants utilized by local people in exceptional environments [9][10][11][12].
In recent years, research on the traditional utilization of wild plants by Lhoba ethnic groups in the Eastern Himalayas of China has been conducted. Previous studies on the Lhoba in Milin County and Medog County have shown that the local people have rich traditional knowledge about the uses of wild plants [9,11,12]. There are significant differences in the wild plants used by the Lhoba people in Milin and Medog, partly due to the different climatic environments and vegetation types in the two regions [9]. In contrast to the abovementioned studied areas, Douyu Village in Longzi County features a typical landform of high mountains and valleys with complex terrain and great altitude variation. This area experiences temperate and semiarid montane climates and includes various vegetation types and specific subalpine broadleaf deciduous shrubs [28]. In addition, Douyu is isolated from other regions in China due to its unique geographic environment and rough road conditions. Therefore, it is necessary to study whether the Lhoba people of Douyu, with a long history interacting with their living environment under extreme climatic, geographical, and ecological conditions in an isolated high altitude village, may have developed specialized lifestyles, cultures, and traditional knowledge of wild plants.
In the present study, our primary aim is to record the traditional botanical knowledge of the Lhoba people in Douyu Village of Longzi County characterized by high mountains and valleys in the Eastern Himalayas, southwestern China. Utilizing these recorded data, we investigate the distribution of useful plants along the altitude gradient, assess the most important plants used by the local people, and analyze the differences in plants utilized among the different Lhoba tribes in China. Finally, we also discuss the relationships of the wild plants used by the Lhoba people to their particular living environment.

Study site
Douyu Village (28°24′ 40″ N 92°88′ 11″ E, Fig. 1) is located in south-central Longzi County, Shannan Prefecture, southeastern Tibet. This village is in the Eastern Himalayas among high mountains and valleys. This area features complex terrain with extreme altitude variations from 5500 to 2800 m. Douyu experiences temperate and semiarid montane climates, the annual temperature is 4.2°C, the average temperature of the coldest month is -4.6°C, the average temperature of the hottest month is 13.1°C, the annual average precipitation is 279.4 mm, and the average humidity is 54.0%. Mountain brown soil and dark brown soil are the major types of soil. The vegetation of the area ranges from subalpine broadleaf The Lhoba ethnic group in Douyu is one of the main groups inhabiting Lhoba. This village is located at the western end of the entire area of distribution of the Lhoba in China. Geographically, the Douyu Village group is isolated from other groups in China, and the Lhoba population in this area only numbers 204. The Lhoba people began to thrive in Douyu in the 15th century [17]. The traditional house is built with timber, and staple foods are highland barley, buckwheat, corn, and potatoes. Barbecuing is the most common food preparation method, and all food can be grilled [17]. Before the 1960s, the Lhoba people mainly depended on gathering, hunting activities, and swidden agriculture to maintain their livelihoods. They have a clear division of labor: men are mainly engaged in hunting and reclaiming farmland, while women are responsible for gathering activities and agricultural production [17]. Their farmland per capita is quite limited, and agricultural yield is low because of extreme living conditions. They have learned to make full use of the wild plant resources in the surrounding mountains to support their daily needs [17]. Moreover, they have traded with Tibetans in San'an Qulin to support this subsistence production system [17,19]. The Lhoba express faith in the original religion of "all things and spirits". They worship nature, pray for blessings to it, and believe that the Shaman has the power to control spirits of nature [17,19,29]. The Lhoba in Douyu belong to the Bengni tribe and use the Bengni dialect, which belongs to the Tani language branch of the Sino-Tibetan language family of Tibeto-Burman languages. However, the Lhoba people do not have their own written characters [17].

Ethnobotanical surveys and data collection
Ethnobotanical field surveys were conducted in August 2019 and August 2020. This research was conducted after obtaining permission from the local government and community committee. During the survey, we explained our purpose to the community leaders and requested their assistance, which included providing local guides, translators, and other necessary aid. A total of 41 informants (18 male and 23 female) between 18 and 75 years of age were interviewed. Among them, 14 key informants were selected purposefully and systematically based on the recommendation of the local government, village head, forest rangers, and other personnel, while the other 27 informants were selected from Douyu Village by the snowball method (Table 1). Before each interview, prior informed consent was required, and international ethical standards were observed throughout the research process. After obtaining permission, a key informant interview involving semi-structured interviews and group discussions was conducted to collect information about the usage of wild plants and associated traditional knowledge of the local Lhoba people. The major questions were as follows: (1) What plant can be used in your daily life for nutrition, medicine, weaving, or other purposes; (2) what part do you use; (3) why do you use this species; (4) how do you process it; and (5) where and when do you collect it?
All plant specimens were identified by referencing the Flora of China. All specimens were collected and deposited at the herbarium of the Kunming Institute of Botany.

Data analysis
Two ethnobotanical quantitative indices, the informant consensus factor (ICF) and cultural importance index (CI), were adopted in this study. The ICF evaluates the distribution of medicinal plant information among information providers and determines the homogeneity of the information providers' knowledge of medicinal plants [30]. The CI is used to indicate the scope of use of each species and determine the diversity of use [31]. The ICF was calculated as follows: where N ur is the number of user reports of plants used for a certain type of disease. N t is the number of species reported being used for the specific disease category by informants who mention all the species. The ICF values range between 0 and 1, and a higher ICF value (close to 1) indicates greater consensus that a species can be used to treat a disease; in contrast, an ICF close to 0 indicates disagreement among the informants [30]. The CI was calculated as follows: where N is the total number of reports, NC is the total number of plant categories used, and i and u represent the interviewee and the categories of plants used, respectively. CIs is the sum of the proportions of the total numbers of reports for each use category of a given species (s). A higher CI value shows that there are a greater number of different uses of a species [31].
To investigate the number of useful plants within the vegetation zones and habitats across the study area, the collection sites of the species were classified as fields (2800-3100 m), subalpine broadleaf deciduous shrubland (3000-3350 m), mixed coniferous and broadleaf forests (3350-3800 m), and alpine shrubland and meadows (3800-4700 m) (Fig. 2).

Diversity of wild plants and their habitats
This study documented 91 wild species (90 vascular plants and 1 fungus) belonging to 71 genera and 39 families based on the ethnobotanical information on use by the Lhoba people in Douyu Village ( Table 2). The majority of plants belonged to Rosaceae (8 species), Compositae (6 species), Fabaceae (5 species), Labiatae (5 species), Liliaceae (5 species), Polygonaceae (5 species), and Ranunculaceae (4 species), and 17 families included only one species. At the genus level, the highest number of species were in the genus Allium (4 species), followed by Cynanchum (3 species) and Polygonum (3 species). Of these plant species, Pimpinella xizangense Shan & Pu and Wikstroemia lungtzeensis S. C. Huang are endemic to Longzi County [32]. Of the species with restricted ranges, Berberis kongboensis Ahrendt, B. xanthophloea Ahrendt, Berchemia longipedicellata Y. L. Chen & P. K. Chou, Hedysarum longigynophorum Ni, and Rosa sericea Lindl. f. glandulosa Yu & Ku are endemic to Tibet and are only distributed in the southeastern Himalayas [32]. In addition, Sinopodophyllum hexandrum (Royle) Ying was classified as an endangered species (grade 3) in the      [34]. Herbaceous species were the plants most used by the Lhoba people (54 species, 60.0%), while 22 shrub (24.4%), 9 tree (10.0%), and 5 liana (5.6%) species were used. In our survey, the most commonly used parts of these plants were fruits (31 species), followed by whole plants (23 species), stems (17 species), leaves (15 species), roots (14 species), flowers (9 species), a combination of stems and leaves (5 species), and bark (3 species). Figure 3 shows that all habitats, from the field vegetation at the valley bottoms to the alpine shrublands and meadows, are used for plant collection. Of the habitats, the number of species collected was highest in the

Diversity of wild plant uses
Our study showed that there are 55 species of edible plants and fungi, 29 species of medicinal plants, and 38 species used in the daily life of the Lhoba people for activities such as hunting (7 species) and for specific uses such as fodder (6 species), rituals (5 species), dyes (4 species), agricultural tools (3 species), detergent substitutes (clothes and hand) (3 species), papermaking (2 species), tobacco substitutes (2 species), processing technology (2 species), fuel (2 species), timber (1 species), and other uses (1 species) (Fig. 4).

Wild edible plants
In this study, fifty-four wild plant species were identified as being used as food. This result is consistent with the results of several previous studies in the Himalayas in which fruits and vegetables were found to play an important role in the diets of those living in these regions [9-11, 35, 36]. Edible plants are also commonly used for staple foods in Douyu. A total of 14 species were found to be consumed, and these plants are usually eaten during times of food shortage and famine. Traditionally, the rhizomes of Polygonatum verticillatum (L.) All. and the roots of Codonopsis convolvulacea Kurz. var. vinciflora (Kom.) L. T. Shen are used as starchy foods. Currently, seed powders of Paeonia ludlowii, Polygonum macrophyllum D. Don, and Incarvillea beresowskii Batalin are used as tsampa. In particular, P. ludlowii is an endangered species [34] that is restricted to Longzi County and Linzhi County of southeastern Tibet [37]. Recently, this plant has been cultivated by local people in their courtyards for food as well as for ornamental purposes due to its beautiful flowers. P. ludlowii seeds can be ground into powder to make tsampa. In Douyu, P. ludlowii seed powder combined with the powder of locally grown black highland barley was used to develop a product, "hei-qing-ke mu-dan fen" (黑青稞牡丹粉) (Fig. 5). Moreover, the Lhoba people in Douyu consume a variety of wild oils and seasoning plants, which are commonly used in daily cuisine to improve a dish's taste. Among these seasoning plants, four species belong to the genus Allium, including A. chrysanthum Regel, A. fasciculatum Rendle (Fig. 6), A. hookeri Thwaites, and A. sikkimense Baker. These wild plants are popular condiments of the local people and serve as seasoning for improving flavor when they are cooked, usually by boiling or frying, with other vegetables or meat. In addition, the Lhoba used nine species for beverages. These plants are used to make tea substitutes or yellow wine or are boiled in hot water and served as traditional beverages.

Wild medicinal plants
During the investigation, we recorded information on 29 medicinal plants used by the Lhoba people in Douyu Village. The greatest proportion of medicinal plants consisted of herbs (69.0%), followed by shrubs (21.0%), trees (7.0%), and one liana (3.0%). These results are similar to those of several previous studies in the Himalayas [10,11,38]. Parts of these medicinal plants used include whole plants (37.9%), followed by fruits (24.1%), roots (24.1%), leaves (1.0%), flowers (1.0%), bark (1.0%), and stems (1.0%). There are four main types of prepared traditional medicines: decoctions, medicinal foods, poultices, and medical liquors. Decoctions are the most commonly used type of prepared traditional medicine, with a total of 16 species used in decoctions, and medicinal foods are the second most often consumed type of prepared traditional medicine (11 species), consumed directly or after cooking. Four species are used in poultices, either mashed into a paste or made into a solid extract. Only one species is used for the preparation of medical liquor. A decoction being the most commonly used type of prepared traditional medicine is consistent with the results of other studies [39][40][41]. According to the information provided by the informants, all illnesses reported to be treated by the wild medicinal plants are classified into 11 categories in Table 3. The ICF results ranged from 0 to 0.96 for the 11 illness categories, with the highest ICF values for diseases of blood forming organs (ICF = 0.96) and gastrointestinal diseases (ICF = 0.95), followed by the ICF values for diseases in animals (0.94) and urology (0.94)-related diseases. Living in remote regions and eating too varied of a diet or excessively, especially in high-altitude areas, may lead to gastrointestinal diseases [42,43]. Similarly, our study shows that many medicinal plants are commonly used to treat gastrointestinal disease. For example, Berberis kongboensis and B. xanthophloea are used to treat diarrhea, while Rumex nepalensis is used for indigestion by the Lhoba people. Treating diseases of blood-forming organs is also one of the most common uses of medicinal plants, such as Sinopodophyllum hexandrum, Rosa sericea f. glandulosa, and Sambucus adnata Wall.

Wild plants used for other purposes
In addition to edible and medicinal plants, we also recorded 38 plant species used in the daily life of the Lhoba, including those for hunting, fodder, and ritual uses (Fig. 4). After edible plants and medicinal plants, use for hunting (7 species) was the third most important   [11] and Medog County [12] in China, and this custom is derived from the religious rituals of Tibetan Buddhism. The fresh or dry branches of these species are burned in a censer, which is placed on the flat roof of a house or at the entrance to the village. The first two plants are collected on high-elevation mountains while herding yaks and are occasionally used as incense. The latter species, however, is collected in the subalpine broadleaf deciduous shrub vegetation surrounding the village and is usually burned as incense during the daily morning ritual. Quercus aquifolioides Rehd. & Wils. is another type of ritual plant and is used for decoration in sacrificial ceremonies. The use of this species is related to a Lhoba festival traditionally held in Douyu in autumn to celebrate harvest [19]. At present, the festival is called the Yu Luo Cultural Festival, is the most important religious festival of the Lhoba people in Douyu, and is usually held at the end of July every year. Before the festival, local people go to the mountains and collect ge rui xi (Q. aquifolioides). A sacred yak is made from this plant (apart from the head, for which a real yak head is used), which is placed in the middle of a square during the sacrificial ceremony. On that day, Lhoba people dress in traditional costumes, surround the sacred yak and dance and sing songs. Under the guidance of the wizard, local people celebrated harvest this year and prayed for a good harvest and greater wellbeing during the coming year. Certainly, the occasion provided a feast with abundant food after the sacrificial ceremony. When local people were asked why the sacred yak was made from Quercus aquifolioides, they said that this plant was one of a few broadleaf evergreen species surrounding Douyu Village. They also use Polypodiodes subamoena (C. B. Clarke) Ching for simple divination activities to determine the appropriateness of an action. When local people go out hunting or collecting, they use the leaves of this plant to predict probable outcomes. In this activity, a leaflet of the lamina of the plant is selected to denote good luck, and then leaflets are alternately designated good or bad; favorable outcomes for the day's work are expected if the terminal leaflet is good.

Mushrooms
Our study only recorded one fungal species used by the Lhoba people in Douyu Village. It is worth noting that the mushroom Leucoagaricus leucothites (Vittad.) Wasser was encountered during transect walks for supplementary field surveys in August 2020. Although our objectives were to focus on vascular plants, we also added this species to our dataset because the local leader and translator mentioned that a variety of mushrooms were distributed in Douyu Village and were commonly eaten by local people. In our survey, the entire fruiting body of L. leucothites was usually eaten boiled, barbecued, in a fried dish, or raw ( Table 2).
These species are used for more than one purpose. For instance, the fresh fruits of Berberis kongboensis and B. xanthophloea are edible without any particular preparation, their flowers can be used to make a salad, and the bark, phloem, fruits, and flowers can be used to treat diarrhea. In the same way, the ripe fruits of Sinopodophyllum hexandrum are edible, and its fruits can be used as a treatment for human anemia, a cosmetic to maintain beauty and youth, and an oxytocic for yaks. Roots of Vicatia thibetica are used to treat high blood pressure and relieve altitude sickness, its roots are also used as vegetables to stew with meat or to cook in soup, and its leaves can be mixed with flour and baked into cakes. Fruits of Hippophae rhamnoides subsp. gyantsensis are used to relieve altitude sickness, its fresh fruits are edible, and its fresh or dried fruits can be soaked in wine or water to be used as a beverage.

Comparison of utilized plant species among Lhoba ethnic groups in different areas
To investigate how environmental factors may have affected plant use by the Lhoba people, the recorded data were subjected to regional comparisons among the Lhoba ethnic groups in three counties (Longzi County, Medog County, and Milin County) in China. There is only one plant, namely, Pteridium aquilinum var. latiusculum (Desv.) Underw. ex Heller (Fig. 7), used by the Lhoba people in all three areas. There are eight plant species, Aconitum kongboense, Berberis kongboensis, Berchemia yunnanensis, Polygonum tortuosum D. Don, Pteridium aquilinum var. latiusculum, Quercus aquifolioides, Rubus biflorus Buch.-Ham. ex Smith, and Sinopodophyllum hexandrum, used by Lhoba ethnic groups in both Longzi County and Milin County. Pteridium aquilinum var. latiusculum and Solanum nigrum L. are used in both Longzi County and Medog County (Fig. 7). Similarly, there were only two species, Pteridium aquilinum var. latiusculum and Senecio scandens Buch.-Ham. ex D. Don, used in both Milin County and Medog County [9].

Useful wild plants along an altitudinal gradient
Our study showed that all habitats, from the field vegetation at the valley bottoms to the alpine shrublands and meadows, are used for plant collection. The species richness of all used plants, edible plants, and medicinal plants collected in each vegetation type (apart from field vegetation) decreased with increasing altitude (Fig. 3).
These results are consistent with those from previous studies [20,25]. For example, according to Salick et al., the number of species used by the Dusun people of Mt. Kinablu is significantly and negatively correlated with altitude [20]. Similarly, Weckerle et al. observed that collection sites for useful plants in the Hengduan Mountains substantially increase in number with decreasing altitude [25]. In addition, a similar pattern occurs in different places in the Qinling Mountains between Shaanxi and Gansu provinces, where the number of wild edible plants used has been found to be highest near Xi'an [44], and then west from there on the edges of the Tibetan Plateau, studies have found fewer edible species at intermediate elevations [45], with the lowest number at higher elevations [46].
Previous studies have shown that convenience or accessibility for collecting a plant contributes to the tendency for local people to collect that plant in the vicinity of settlements [20,25,[47][48][49]. Our study area, Douyu Village, contains complex terrain in a small geographical area with an extreme variety in altitude. Thus, which wild plants are used by the Lhoba people in Douyu is strongly influenced by the accessibility of plant collection sites. Our study shows that 58.2% of the total plant species used are collected in the vicinity of the village, where the habitats are field vegetation and subalpine broadleaf deciduous shrubland (Fig. 3).
On the other hand, cultural value is another factor influencing local people to collect plants, such as ritual plants, medicinal plants, and plants with special uses, at remote locations and in high-altitude places. The Lhoba people's faith in the original religion of "all things and spirits" involves praying to the gods and seeking blessings [17,19,29]. Our results showed that ritual plants play an important role in daily life in Douyu, with a total of five species used in ritual activities. The habitats where ritual plants are collected are not near the village but at relatively remote distances. For instance, local people climb high-elevation mountains to collect Rhododendron anthopogon and R. lepidotum in alpine shrublands and meadows. These two plants are burned as incense to please the deities. They also travel a certain geographical distance to collect Quercus aquifolioides in mixed coniferous and broadleaf forests. This plant is used for decoration at sacrificial ceremonies.
Similarly, the Lhoba people collect important or particular plants at remote and high altitudes. For example, Berberis kongboensis, Sinopodophyllum hexandrum, and Hippophae rhamnoides subsp. gyantsensis are collected in mixed coniferous and broadleaf forests. Swertia hookeri C. B. Clarke is collected in alpine shrub areas and meadows. Its roots are used to treat traumatic injury, wounds, and high blood pressure. The Lhoba people also collect Polygonum lapathifolium L. var. salicifolium Sibth. and P. tortuosum from alpine shrublands and meadow habitats to serve as tobacco substitutes.
Therefore, our study demonstrates that accessibility and cultural value affect where useful plants are collected.

Important plant uses
Our study showed that some plants are important based on their CI values ( Table 2). These plants exhibit a wide range of uses and are highly recognized and accepted locally.
Berberis kongboensis (CI = 2.37) and B. xanthophloea (CI = 2.37) are the most important plants in Douyu Village. These two species, which are distributed in southeastern Tibet, are endemic to Tibet [32]. B. kongboensis and B. xanthophloea are used in almost the same manner by the Lhoba people. Their fresh fruits are eaten directly; their flowers are used to make salad; their bark, phloem, fruits, flowers are used to treat diarrhea; and their fruits are also used in dyes. The uses of fresh fruit are similar to those for other Berberis species in the Himalayas [11,15,50,51]. This genus is also rich in pharmacologically active compounds, such as berberine, berbamine, palmatine, oxyacanthine, and jatrorrhizine [52]. Berberine is widely used to treat diarrhea by inhibiting intestinal inflammation and regulating intestinal bacteria [53][54][55][56][57].
Sinopodophyllum hexandrum (CI = 2.24), the only species of this genus in China, is an endangered species native to the Himalayan region [32,33]. In our survey, its ripe fruits were eaten directly, and its fruits were also renowned for their medicinal value in Douyu Village. Local people use it as a treatment for anemia, a cosmetic to maintain beauty and youth, or as an oxytocic for yaks. A previous study observed that this plant is a popular fruit [11,15], and it is called Himalayan mayapple [58]. This species exhibits effective anticancer activity. Its secondary metabolite is effective against tumors, gynecological diseases, and rheumatism [59]. In Tibetan medicine, it is used to promote blood circulation and eliminate blood stasis and to treat gynecological diseases, bruises, dermatological diseases, and antenatal pain [60].
Vicatia thibetica (CI = 2.15) is a perennial herb distributed in the Himalayan and Hengduan Mountains [32]. In Douyu, its leaves are mixed with flour and baked into cakes, and the roots are used as a vegetable to stew with meat or cook in soup. Moreover, the roots can also be used to treat high blood pressure and relieve altitude sickness. Acute and subacute toxicity studies on root and leaf extracts of V. thibetica have shown that there is no toxic effect after long-term use, and it is quite safe as food [61,62].
Hippophae rhamnoides subsp. gyantsensis (CI = 2.02) is distributed in the southeastern Himalayas [32]. In our survey, it was locally used as a fruit, a beverage, and a treatment for altitude sickness. Fruits of this plant contain fat-soluble vitamins, fatty acids, carotenoids, and amino acids that are beneficial to health [63][64][65]. Its fresh fruits are also used in many areas, and berries can be made into jams, juices, and other products [15,58,65,66]. One new usage was recorded in this study: a medical liquor preparation of its fruits can be used to relieve altitude sickness.

Relationships between utilized wild plants and environment Relationships between utilized wild plants and geographic environments
In this study, the wild plants used by the Lhoba people in Douyu Village were richly diverse, reflecting the number of species and diversified functions. A total of 91 wild plant and fungal species are used in the daily lives of the Lhoba people for various purposes, serving as edible plants, medicinal plants, hunting aids, fodder, ritual plants, dyes, agricultural tools, detergent substitutes, papermaking materials, and tobacco substitutes (Fig. 4). This result is consistent with previous results from the Eastern Himalayas, which have shown that wild plants provide the sustenance for these communities and form an integral part of the culture and traditions of these communities [9][10][11][12].
In our study area, Douyu Village is situated among high mountains and valleys. This village is isolated from other regions in China due to its unique geographic environment and difficult road conditions. In these extreme areas, the Lhoba people have thus learned to make full use of the wild plant resources in the area surrounding their village to support their daily needs [17], and this scenario has contributed to the high diversity of traditional knowledge on wild plants. In addition, their cultivated land is quite limited, and agricultural yields are low because of the complex terrain and high altitude. The livelihood of the Lhoba people is dependent on forests and other natural resources apart from agricultural and animal production. It is noted that 14 wild plants are used as staple foods, which may help the local people address seasonal food shortages and withstand famine. For example, the seed powders of Paeonia ludlowii, Polygonum macrophyllum, and Incarvillea beresowskii are used to make tsampa, while rhizomes of Polygonatum verticillatum and the roots of Codonopsis convolvulacea var. vinciflora are used as starchy food.
Moreover, the Lhoba people have accumulated a wealth of knowledge about the traditional uses of wild plants because they have lived in the Eastern Himalayas for hundreds of years. They have developed many unique cultural traditions around useful wild plants. In addition to the edible and medicinal plants, there are diverse wild plant species used in the daily life of the Lhoba documented in this survey. For instance, they use Aconitum kongboense, a poisonous plant, for hunting and Polygonatum verticillatum, Medicago sativa, and Vicia cracca as fodder; Thalictrum finetii Boivin and Impatiens cristata Wall. are used to produce dyes; Cerasus rufa Wall. and Cotoneaster microphyllus Wall. ex Lindl. var. thymifolius (Baker) Koehne are used to make agricultural tools; Wikstroemia lungtzeensis and Stellera chamaejasme are used to make paper. Previous studies have noted that geographical isolation could contribute to the preservation of diverse cultural traditions of local people in Himalayan regions [14] and could help preserve diverse traditional botanical knowledge [9][10][11]67]. These findings have shown that useful wild plants are highly diverse in geographically isolated areas, and this diversity in Douyu Village is based not only on the number of species but also on their diversified functions.

Relationships between utilized wild plants and special ecological environments
Douyu Village is located among high mountains and valleys in the Eastern Himalayas, with temperate and semiarid montane climates. The annual temperature is 4.2°C , and the annual average precipitation is 279.4 mm. This area features very typical vegetation types and species. Along the elevational gradient, vegetation from the low valleys to the high-altitude mountains consists mainly of subalpine broadleaf deciduous shrublands, mixed coniferous and broadleaf forests, and alpine shrublands and meadows.
In particular, the subalpine broadleaf deciduous shrubland is a special vegetation type that is found only in southeastern Tibet. This vegetation can withstand cold and dry climates and poor soils, forming forests on the upper slopes and valleys at altitudes ranging from 3000 to 4000 m in the Eastern Himalayas. In addition, the vegetation exhibits low coverage, ranging from 20 to 60%, and the dominant plant is Leptodermis pilosa Diels [28]. The Lhoba people make full use of the wild plants in this area. Our study showed that the numbers of all used plants, edible plants, and medicinal plants collected from the subalpine broadleaf deciduous shrub areas were 40 species, 29 species, and 14 species, respectively, and each use category exhibited a high number of species for all vegetation types (Fig. 3 (Fig. 7). For instance, there is only one plant, Pteridium aquilinum var. latiusculum, used by the Lhoba people in all three counties. Eight of the same species are present in both Longzi and Minlin Counties, two plants occur in both Longzi and Medog Counties, and two species occur in Minlin and Medog Counties (Fig. 7).
Longzi County (Douyu Village), Milin County (Nanyi Township), and Medog County (Damu Township) are all located in the eastern Himalayas, and these three counties are relatively isolated from other regions in China. However, the ecological environments differ significantly among these three areas in terms of climate and vegetation types. For example, Douyu experiences a semiarid climate, where the annual average precipitation is only 279.4 mm, and the vegetation is mainly alpinesubalpine broadleaf deciduous shrubland. In contrast, Nanyi Township features temperate to cool temperate climates, the annual average precipitation is 600 mm, and the main vegetation is coniferous broadleaf mixed forests [11]. Damu Township exhibits a subtropical climate, the average annual precipitation is 2400 mm, and the vegetation mainly consists of broadleaf evergreen forests [12]. Compared with that of Damu, the ecologic environments of both Douyu and Nanyi are similar to a certain extent. As a result, there were more plant species shared between Douyu and Nanyi than between Douyu and Damu: the former two shared eight of the same plant species, and the latter two had two of the same plant species. A similar result was also found for Nanyi and Damu. There were only two species shared by Nanyi and Damu due to their relatively different ecological environments (Fig. 7).
Therefore, the extreme environmental conditions of Douyu Village may have affected the lifestyles and cultures of the Lhoba people, leading to substantial plant utilization.
The relevance of this study for rural development, food sovereignty, and food security in the study area Local people not only use wild plants to meet their own needs but can also profit from using plant products. Paeonia ludlowii has been developed as a special food product in Douyu Village (Fig. 5). Other plants, such as Sinopodophyllum hexandrum and Hippophae rhamnoides subsp. gyantsensis with high CI values, as well as Pimpinella xizangense and Wikstroemia lungtzeensis that are endemic to Longzi County, also hold potential for rural economic development. To utilize these plants in sustainable ways, it is important to carry out intentional planting in the future.
The opinion of food sovereignty has been raised by the International Peasants' Movement (La Via Campesina, LVC) [70]. Some of the views expressed by LVC are helpful for rural sustainable development. For example, LVC has stated: "food is a key part of culture, and the neoliberal agenda is destroying the very basis of our lives and cultures. We do not accept the hunger and displacement. We demand food sovereignty, which means the right to produce our own food" [71]. The loss of traditional knowledge in rural communities is actually a key problem. This is the reason why we do ethnobotanical studies. We want to try to delay the process of loss.
Although these wild edible plants might be beneficial to the local people, we should also notice the possible hazards of these plants to the human body after consuming them. According to previous reports, humans and animals are affected by Pteridium aquilinum var. latiusculum, which contains ptaquiloside, a carcinogenic toxin [72]. The toxicity of Solanum nigrum is mainly due to the presence of solanine, with symptoms of poisoning in humans including nausea, vomiting, diarrhea, headache, dizziness, loss of speech, fever, sweating, tachycardia, pupil dilation, blindness, mental confusion, convulsions, coma, and death [73]. It is necessary to inform the local people and local government in Longzi County about the hazards of these plants. In two other studies, no acute or subacute toxicity was observed in mice administered Hippophae rhamnoides or Vicatia thibetica [61,74]. However, no toxicological information was found for other wild plants eaten by the Lhoba people in Douyu Village. Researchers should devote more attention to food security.