Study on medicinal food plants in the Gaoligongshan Biosphere Reserve, the richest biocultural diversity center in China

Abstract

Background

Traditional knowledge associated with medicinal food plants (MFPs) plays a vital role in fighting hidden hunger and safeguarding the health of local people. MFPs resources are abundant in the Gaoligongshan area, a biosphere reserve with the richest biocultural diversity in China. Local people of different linguistic groups also have rich traditional botanical knowledge. However, there are still few comprehensive and systematic studies on MFPs there.

Methods

Ethnobotanical investigation including market survey, semi-structured interviews, free listing and key informant interviews was conducted in the Gaoligongshan area, Western Yunnan, Southwest China. A total of 13 local farmers’ markets were selected and information about medicinal food plants, including food categories, medicinal and edible parts, modes of consumption, medicinal effects, and distribution were collected. The relative occurrence frequency (RFO) and cultural food significance index (CFSI) were calculated to identify the culturally significant MFPs.

Results

A total of 184 species of MFPs, belonging to 83 families, were collected in the Gaoligongshan area, including vegetables (77), medicinal diets (26), fruits (25), spices (18), herbal tea (13), tea substitutes (11), substitutes for staple food (8), nuts (5), oils and fats (4), and dye material (1). The most frequently used families were Fabaceae, Asteraceae and Apiaceae, with 11, 10, and 9 species, respectively. The most frequently used plant parts were the stems, followed by fruits and leaves. Based on the evaluation results of the CFSI and RFO indices, 18 species of MFPs with magnificent local cultural importance have been screened out, such as Houttuynia cordata, Eryngium foetidum, Sechium edule, Centella asiatica and Pseudocydonia sinensis.

Conclusion

These findings have guiding significance for conservation of traditional knowledge associated with MFPs and facilitation of scientific utilization of MFPs to meet local people’s needs for a healthy life.

Background

The greatest global challenge is to ensure that all people have access to nutritious food and healthy medicine. Medicinal food plants, or medicinal dietary plants, refer to plants that can be eaten and also be used as medicine to prevent and cure diseases [1,2,3,4]. For remote areas in developing countries, traditional knowledge of medicinal food plants plays a vital role in fighting hidden hunger and safeguarding the health of local people [5, 6].

At present, conducting ethnobotanical surveys of MFPs resources has attracted the interest of many ethnic botanists and has become the focus of research [7,8,9]. Especially in edible plants, international ethnobotanical research on edible plants is mainly concentrated in Europe, Africa and Asia, such as Italy, Poland, East Africa, the southern Sahara and the southern foothills of the Himalayas, while relatively little research in North America, South America and Oceania [10]. There are many domestic studies on MFPs, mainly concentrated on the utilization of plants by ethnic minorities in minority areas, such as Naxi, Hani, Mongolian, Tibetan and Yi. [11,12,13,14,15,16]. These studies document the traditional knowledge of edible plants and use different quantitative methods to assess the local importance of wild food plants, which play an essential role in protecting traditional knowledge and the sustainable use of WEPs and finding the most widely consumed varieties and analyzing their nutritional value [17, 18]. The nutritional analysis results will provide clues for finding excellent germplasm resources, help ensure the diversity of diet and achieve food security [19, 20].

Market research is a commonly used method in ethnobotanical research associated with MFPs [21]. Open-air markets are great places to gain a deep understanding of MFPs: A great variety of MFPs are traded in local markets. Besides, the demand of local people and their unique traditional culture can be easily reflected by the number of available MFPs [22, 23]. Even though there are tons of advanced grocery and supermarkets in modernized societies, open-air markets still remain important place of trading plant for both urban and rural dwellers. In recent years, some ethnobotanists have conducted a deep study on the Dragon Boat Festival in southwest China. These studies have used market survey methods to investigate the Dragon Boat Festival in Jianghua County of Hunan, Gongcheng County, Guangxi, and Qianxinan County of Guizhou and found that the local Yao and Zhuang ethnic groups sell hundreds of herbs in the medicine market during the Dragon Boat Festival [24,25,26,27]. Apart from domestic research, there is also an abundance of research using market survey abroad. Taking South America as an example, various market surveys have been done on Bolivia, Peru and Brazil markets [28,29,30,31]. Since the healers as well as the laypeople purchase their medicinal plants in local markets, researchers found local markets valuable places for having a deep insight into their specific medicinal plants which contain rich medical knowledge passed down from their ancestors in each different ethnic group. Market research is also a significant approach in Europe and Asian. Researchers adopted this method to figure out association between market trend and data results in Greece, and other researchers took this measure to fill vacancies in products sold in the markets in Poland [32, 33]. Additionally, some researchers used market research to access the diverse wild vegetable resources sold at the local markets of Manipur throughout different seasons in India [34], researchers used this method to draw a conclusion about medicinal plants on the markets composition which mainly was imported from outside in Iraq [35]. Researchers in Pakistan observed local medicine plants status quo and came up with some causing reasons like increased marketing pressure on medicinal plants, lack of job opportunities in the area, non-sustainable harvesting methods like digging of whole plant and increased population of the area in this way as well [36]. Besides, an ethnobotanical survey on the medicinal plant species marketed in Iran was conducted in order to document traditional medicinal knowledge and application of medicinal plants [37].

China is a country with a long history, rich biodiversity and diverse ethnic cultures [38]. Over the long history and development of different linguistic groups, they have accumulated traditional knowledge of using MFPs to treat diseases and to resist the harsh natural environment [39].

The Gaoligong Mountains or the Gaoligongshan area (24°34’-28°22’N, 97°30’-99°30’E) refers to the diverging mountains between the Nujiang River (upstream of Salween River) and Dulong River (a branch of Irrawaddy River) and the areas on both sides of the mountains. The Gaoligong Mountains have been designated as a biosphere reserve by United Nations Educational, Scientific and Cultural Organization since 2010. It is also the core area of the Three Rivers Parallel World Natural Heritage site and has been listed as one of the world’s 25 new biodiversity hotspots [40, 41]. The Gaoligongshan area not only boasts the highest number of species per unit area in China, but also is one of the areas with the richest cultural diversity in China. More than ten ethnic groups live in and enjoy a rich culture of medicinal food plants [42].

Previous ethnobotanical studies in the Gaoligong Mountains have proven that local people have rich traditional knowledge about medicinal food plants [40, 43,44,45,46,47]. In addition, some studies on Maianthemum atropurpurea, an important medicinal food plant in the Gaoligong Mountains, show that it is a functional wild vegetable that can meet the requirements of modern healthy diet [48]. Another study on lacquer oil from the drupes of Toxicodendron vernicifluum preliminarily verified the rationality and scientificity of lacquer oil in treating gynaecopathia ailment [49]. However, systematical and comprehensive studies on medicinal food plants of the Gaoligong Mountains are very limited.

With the acceleration of population aging and the increase of people with sub-health and chronic diseases, the codified knowledge from traditional Chinese medicine therapy has been received considerable attention [50]. However, with the infiltration of mainstream cultures, the destruction of the natural environment and the expansion of urbanization, the traditional knowledge associated with MFPs is facing the danger of assimilation and loss [51,52,53,54]. Many studies from various regions have found that sociocultural factors are the main drivers of reduced consumption of medicinal and edible plants [55, 56]. Other studies pointed out that the main drivers of decreased abundance are perceived to be land-use change and direct exploitation of medicinal and edible plants. These changes have potential negative implications on food systems from local to global scales [57]. The resources of MFPs are constantly threatened by various natural factors and human activities. Furthermore, global climate change leads to various extreme weather events, for example thunderstorms, mudslides and flash floods, which significantly contribute to largescale plant deaths. In addition, various human activities (single-crop cultivation, habitat destruction, excessive harvesting, overgrazing, etc.) also pose a considerable threat to wild plant resources.

A comprehensive study should be carried out to document the traditional knowledge of MFPs. Besides, the endangered traditional knowledge should be identified and evaluated, which will help promote regional economic development and ensure the conservation and sustainable use of MFPs. The objectives of this study were to: (1) conduct a comprehensive study on MFPs used by local people living in the Gaoligongshan area, (2) record the traditional knowledge associated with MFPs, (3) identify species of important cultural significance to local people, and (4) analyze the opportunities and challenges for the protection of MFPs.

Methods

Study site

The Gaoligong Mountains (24°40′ to 28°30′ N, 97°30′ to 99°30′ E) is located at the junction of southwestern Yunnan and northern Myanmar. The administrative region covers Baoshan (Tengchong, Longyang and Longling), Nujiang (Lushui, Fugong and Gongshan) and Linzhi (Chayu) of China, and Kachin State of northern Myanmar [41, 45]. Due to the special geological history and unique ecological environment, there are diverse biological species in the Gaoligong Mountain. It has been recognized as the richest area in biodiversity of China and listed as one of the world’s 25 biodiversity hotspots [41]. Up to now, 5139 species of seed plants have been recorded in the Gaoligong Mountains. The richness of endemic species is higher than most areas in the country. The Gaoligongshan region is also very rich in medicinal plant resources, with as many as 1298 species, including about 300 species traditionally used by ethnic groups [58].

The Gaoligongshan area is also one of the richest centers of cultural diversity in China. Nearly 2/3 of the ethnic minorities in Yunnan Province are concentrated in this area. The Bai, Naxi, Lisu, Tibetan, Nu, Dulong, Pumi, Wa, Achang and other ethnic minorities together with Han Chinese have lived in the area and showed diverse traditional customs and cultures [40]. The economic and social status of the Gaoligong Mountains is in developing stage, with low productivity. Although it is one of the poorest areas in Yunnan, the local people of various linguistic groups have very rich traditional knowledge associated with biodiversity. Such a variety of life forms and national traditional cultures in the Gaoligong Mountains have created its world-renowned biocultural diversity.

The study area included five county-level administrative units, including three in Nujiang Lisu Autonomous Prefecture (Gongshan Dulong and Nu Autonomous County, Fugong County, and Lushui City), and two in Baoshan City (Longyang District, and Tengchong City) (Fig. 1). Based on the natural and cultural conditions of every conties in the Gaoligongshan area, 13 representative local farmers' markets belong to different ethnic groups were uniformly selected in the area, as shown in Table 1.

Fig. 1

Study site. a Location of study sites; b Jietou Famers’ market; c Semi-structured interviews

Table 1 The location and linguistic groups of markets investigated

Literature research

Through investigating local chronicles and flora, the general information was collected, including topography, climatic conditions, and vegetation of the Gaoligong Mountains, history, customs, religious beliefs, and social culture of the local people. Such information helped to choose suitable markets and seasons for field surveys before the ethnobotanical investigations were implemented.

Market survey

Market surveys included semi-structured interviews, key informant interviews and participatory observation. During the market investigation, some stallholder was invited to list all medicinal dietary plants that are still regularly used. The interviews consisted of two parts, the first part was about the basic situation of the informants (linguistic group, age, education, occupation), and the other part contained questions related to recording detailed information on MFPs, including their local names, availability, used part, processing methods, frequency of use, mouthfeel, whether they are used as a medical diet, application methods, medicinal effects, and other uses.

Voucher specimen collection and identification

The voucher specimen of each medicinal food plant was collected, and deposited in the herbarium at Minzu University of China. For the identification of plants, the voucher specimens were studied and compared with reference books (Flora Republicae Popularis Sinicae and Flora of China) and electronic online resources (http://www.iplant.cn/ and https://powo.science.kew.org).

Quantitative ethnobotanical research

An improvement is made on the basis of the relative frequency of citation (RFC), using relative occurrence frequency (RFO) index to quantify the frequency of certain MFPs in the market. N represents the number of all markets investigated. RFO ranges from 0 to 1.

$${\text{RFO}} = \frac{{{\text{FO}}}}{{\text{N}}}$$

It is calculated by dividing the number of markets in which the medicinal diet plant appears by the total number of markets. FO refers to the number of markets in which a particular herbal diet plant appears. N represents the number of all the markets investigated. RFO value ranges from 0 to 1. The higher the RFO value, the more widespread the use of the plant in the region. The prevalence of each medicinal diet plant is expressed by the value of the RFO, which allows all medicinal diet plants mentioned in the survey to be listed in the order of their prevalence sizes.

The cultural food significance index (CFSI) is calculated to evaluate the cultural significance of MFPs [59].

$${\text{CFSI}} = {\text{RFO}} \times {\text{AI}} \times {\text{FUI}} \times {\text{PUI}} \times {\text{MFFI}} \times {\text{TSAI}} \times {\text{FMRI}} \times {1}0^{{ - {2}}}$$

It is composed of seven factors including the relative occurrence frequency (RFO) index, availability index (AI), frequency of utilization index (FUI), parts used index (PUI), multifunctional food use index (MFFI), taste score evaluation index (TSAI) and food-medicinal role index (FMRI). The larger the CFSI is, the more important the role of this plant is in diet.

Results

Diversity of medicinal food plants

The survey results showed that there were 184 species of medicinal food plants in Gaoligong Mountains area, including 173 angiosperm species, 1 gymnosperm species, 8 fern species, and 2 lichen species. Among the 13 markets surveyed, the Mangkuan Market in Longyang District, Baoshan City has the most medicinal food plants with 80 species, and the Luobenzhuo Market in Fugong County has the least, only 34 species (Table 2). Other information of all MFPs is provided in the supplementary materials (Additional file 1: Table S1).

Table 2 The inventory of medicinal food plants in Gaoligong Mountains area

A total of 184 medicinal food plant species belonging to different 83 families were recorded. The plant species recorded in the study area were presented in Table 2, arranged in alphabetical order for families and entities. The most frequently used families Fabaceae, Asteraceae and Apiaceae were the most genera, with 11, 10 and 9 species, respectively. Followed by Labiatae and Cucurbitaceae, both containing 8 species. There are seven species in the Amaryllidaceae family. The remaining families were represented by 6 or fewer entities (Fig. 2a). In previous studies, these families were also reported to be widely used by ethnic minorities in northwest Yunnan, China [60].

Fig. 2

Diversity of medicinal food plants. a Distribution of medicinal food plants’ family; b distribution of food types in market survey results; c the edible and medicinal parts of medicinal dietary plant; d the mode of consumption of medicinal food plants; e the CFSI of medicinal food plants; f the top 50 CFSI of medicinal food plants

Different medicinal and edible parts are used by the residents in Gaoligong Mountains area, such as the seeds, leaves, stems, flowers, seeds, and other eight parts. In terms of edible parts, the most commonly used parts are stems, leaves, fruits, and flowers. These parts of the plant are used more as edible parts than medicinal parts. In terms of medicinal parts, the most commonly used parts are whole plants, bark, roots, and seeds. Plants that utilize these parts for medicine more than for edible purposes (Fig. 2c).

This shows that people are more inclined to reuse for edible plants, and most of the used parts are sustainable. For medicinal plants, local people use more unsustainable parts. Some previous studies have also found a similar phenomenon, which may be related to the accumulation of active ingredients in roots, bark, and other parts [60].

Classification of medicinal food plants

According to the purpose of the medicinal food plants investigated and combined with the food-preparing methods of the local people, the edible types of all medicinal food plants can be divided into ten categories: vegetables, medicinal diet, fruits, spices, herbal tea, tea substitute, staple food substitute, nuts, oils and dyes.

Among the 184 species of MFPs in the Gaoligong Mountains area, the most used food categories by local people are vegetables, with 77 species, followed by medicinal diet and fruits, with 26 and 25 species respectively, followed by spices, herbal tea, tea substitute, substitute for staple food, nuts, and edible oils. Dye use is the least category, with only 1 species (Fig. 2b).

Vegetables

Vegetables are the largest type of medicinal food plants used by residents in the Galigong Mountains area, with a total of 77 kinds. The main edible parts of vegetables are stems and leaves, and the cooking methods mainly include stir-fried, boiled, cooked soup, fried with eggs and so on (Fig. 2d). Examples include Sechium edule, Centella asiatica, Taraxacum mongolicum, Oenanthe javanica, and Aralia chinensis (Fig. 3a–e). Vegetables can supplement dietary fiber, vitamins, amino acids and a variety of mineral elements for the human body, so they are an indispensable food every day [61]. The great market demand and high healthcare value make the Gaoligong Mountains area have unlimited development potential for the MFPs as vegetables, which can increase the income of local residents and improve their living conditions.

Fig. 3

Plants with high Cultural food significance index (CFSI) index in Gaoligong Mountains area. a Sechium edule, b Centella asiatica, c Taraxacum mongolicum, d Oenanthe javanica, e Aralia chinensis, f Ligusticum sinense ‘Chuanxiong’, g Cirsium spicatum, h Pimpinella candolleana, i Arctium lappa, j Panax japonicus, k Pseudocydonia sinensis, l Elaeocarpus braceanus, m Phyllanthus emblica, n Hovenia acerba, o Elaeagnus conferta, p Houttuynia cordata, q Persicaria viscosa, r Eryngium foetidum, s Amomum tsaoko, t Mentha canadensis, u Gynostemma pentaphyllum, v Curculigo orchioides, w Cymbopogon citratus, x Citrus medica, y Elsholtzia rugulosa, z Colocasia esculenta, A Toxicodendron vernicifluum, B Lindera communis, C Ginkgo biloba, D Pinus armandii

Medicinal diet

Medicinal diet is the second category of MFPs used by local people in Gaoligong Mountains area, with a total of 26 species. The main part of medicinal food used is stem, and the main cooking method is boiling with meat, such as Ligusticum sinense 'Chuanxiong', Cirsium spicatum, Pimpinella candolleana, Arctium lappa, and Panax japonicus (Fig. 3f–j). The social and economic level of Gaoligong Mountain area is not high, and fighting against the harsh natural environment is a compulsory course for local residents, which leads to their high demand for medicinal diet and accumulation of a large amount of traditional knowledge related to MFPs with national characteristics, which is of great promotion value in contemporary times [57].

Fruit

Fruits are the third category of MFPs used by Gaoligong Mountains residents, with a total of 25 species. Most of the plants used as fruits are not processed by local residents and are eaten freshly, such as Pseudocydonia sinensis, Elaeocarpus braceanus, Phyllanthus emblica, Hovenia acerba, and Elaeagnus conferta (Fig. 3k–o). The unique natural conditions and different climate types in Gaoligong Mountains region making it suitable for the growth of different fruits. Many fruits rich in nutrition and medicinal value are very popular in the local area.

Spices

Spices are the fourth category of MFPs used by Gaoligong Mountain residents, with a total of 18 species. Spices’ main used parts are stems, leaves and fruits, the processing methods are stir-fried and boiled. Such as Houttuynia cordata, Persicaria viscosa, Eryngium foetidum, Amomum tsaoko, and Mentha canadensis (Fig. 3p–t). Some spices, are popular in the kitchen of local residents, can not only add flavor to the dishes on the table, but also have an antiseptic and medicinal effect.

Herbal tea and tea substitute

Herbal tea and substitute tea are the fifth and sixth category of MFPs in Gaoligong Mountains area, with 13 kinds and 11 kinds respectively. Their main use parts are stems and leaves, the main processing method is soaking in water. Such as Gynostemma pentaphyllum, Curculigo orchioides, Cymbopogon citratus, Citrus medica, and Elsholtzia rugulosa (Fig. 3u–y). Many studies have proved that herbal tea and substitute tea is rich in abundance active substances, which are good for human body. These teas also have medicinal properties, which can help fight disease and condition the body [49].

Substitutes for staple food, nuts, oil and fats, and dyes

Substitutes for staple food, nuts, oils and fats, and dyes are the seventh, eighth, ninth, and tenth categories of MFPs, with 8, 5, 4, and 1 species, respectively. The main parts of staple food substitute are stems (including rhizomes or tubers) and roots, and the main processing way is boiling and processing into starch or gel food, such as Colocasia esculenta (Fig. 3z). Many species are substitutes for food in Gaoligong Mountains area, reflecting the diversity and demand of staple food of local residents, which can help local residents to survive the period of food shortage to a certain extent [44, 62]. Buddleja officinalis is the only plant used as dye, and its flowers (inflorescences) are consumed (Fig. 3A–D).

Quantitative evaluation of medicinal food plants

The CFSI were different among different MFPs. The minimum value was 0.15 while the maximum value was 1365. According to Pieroni’s analysis of the index value, wild edible plants can be divided into six categories according to the sizes of CFSI value, which are: very high (CFSI = 300 and above), high (CFSI = 100–299), medium (CFSI = 20–99), low (CFSI = 5–19), very low (CFSI = 1–4), negligible (CFSI < 1) [59]. The numbers of plants in these six groups were different. Most belonged to the following three groups of very low, low, negligible, and Medium, with 51 species, 44 species, 38 species, and 33 species respectively. This was followed by the very high and high groups, with 10 and 8 species, respectively (Fig. 2e).

The CFSI value was ranked, and the top 51 MFPs (with very high significance (10 species), high significance (8 species), and medium significance (33 species)) were evaluated of which heat maps were made (Fig. 2f). The comparison of CFSI and RFO showed that 38 out of 51 plants were the same, indicating that the plants evaluated and screened by these two indexes were very consistent and had relatively high reliability. The grades of some species were different according to different indexes, indicating that different indicators have different importance attribute to the evaluation. For example, CFSI also included the evaluation of taste and function.

Discussion

Due to the advantaged natural environment and rich plant resources, Gaoligong Mountains area is known as one of the world’s 25 biodiversity hotspots [41]. The altitude difference of the Gaoligong Mountains area is as high as 4038 m, forming significant climatic changes in the vertical direction [63, 64]. From the top of the mountain to the valley, there are four vertical climatic zones, such as cold zone, subcold zone, temperate zone, and subtropical zone, which have obvious vertical characteristics in terms of temperature, precipitation, soil nutrients and light intensity, thus creating a rich variety of medicinal food plants [65].

The Gaoligong Mountains area is also a multi-linguistic settlement area. There are 16 linguisitc groups in the region, including Han, Dai, Lisu, Pumi, Jingpo, Nu, Dulong, Achang, Naxi, Hui, Bai, Miao, Wa, Yi, Tibetan, and De’ang [66,67,68]. According to the records, all the linguistic groups living in the Gaoligong Mountains area have the tradition use of MFPs. Local people incorporate their customs, religious beliefs, and dietary ways into the plants for MFPs. Many MFPs used in Gaoligongshan areas have been reported to have high nutritional value. Previous studies have proved that the use of MFPs by ethnic minorities in the Nujiang area is scientific in terms of food nutrition, chemical composition, and pharmacological activity, such as Caryota obtusa, Maianthemum atropurpureum, Toxicodendron vernicifluum, and Angiopteris esculenta [13, 17, 18, 27]. Some MFPs are very important in the local area. For example, Houttuynia houttuynia is rich in protein, fat, polysaccharide, vitamin and other components, which has high development potential [69, 70]. The local people grow Sechium edule in their home gardens and eat their roots, tender stems, leaves, seeds, and fruits. This vegetable has a long consumption cycle and can be used not only as a vegetable, but also for medicinal purposes to clear heat and toxic materials away, and also has a good effect on anorexia. The different cultures and living environments of different linguistic groups lead to different demands for MFPs, which results in the differences of MFPs in different regions [71, 72].

The potential value of traditional knowledge associated with medicinal food plants

Limited transportation conditions and complex geographical environment in Gaoligong Mountains area make local residents more dependent on local natural resources, and these abundant MFPs resources play an indispensable role in their daily life (Fig. 4).

Fig. 4

The potential value, opportunities, and challenges for traditional knowledge associated with medicinal food plants

Firstly, traditional knowledge associated with MFPs can alleviate hidden hunger in remote areas. It can not only provide local residents with essential nutrients, but also ensures their food security [2, 53].

Secondly, traditional knowledge associated with MFPs plays an important role in safeguarding the health and disease resistance for residents in remote areas. In the process of getting along with the local natural environment for thousands of years, the local peoples have accumulated a large amount of traditional knowledge related to disease prevention and treatment and formed the methods of using MFPs with local cultural characteristics [73,74,75]. These methods can still reflect the survival wisdom of the working people and its unique and indispensable value in modern times. With the growing desire of modern people to pursue a healthy life, people's need for food is no longer just to satisfy their hunger. Local abundant MFPs resources have medicinal value and healthcare function, for example, taking Ligusticum sinense 'Chuanxiong' can promote blood circulation, and taking Pimpinella candolleana internally can treat jaundice hepatitis and acute cholecystitis [39, 76], which just meet people's needs in this respect [46, 67].

Thirdly, MFPs resources can provide local residents with a source of livelihood and solve their livelihood problems. And these economic sources can ensure their basic living needs, but also maintain the local national culture and traditional lifestyle of the important material basis. Therefore, MFPs have promoted the development of local economy and brought fruitful results for poverty alleviation and rural revitalization [77, 78].

Finally, These MFPs resources have unique and excellent characteristics in all aspects, such as drought tolerance, heat tolerance, and cold tolerance. If the use of its own genetic characteristics, as genetic material, to create a better variety, artificial cultivation, play its greater value. If the genetic characteristics of MFPs are more fully utilized as genetic material, better varieties can be created and artificially cultivated, which can exert greater value [79, 80].

Opportunities and challenges for the protection of medicinal food plants

MFPs face multiple threats and opportunities in the Gaoligong Mountains area. Nowadays, environmental pollution and changes in diet structure make cardiovascular, cerebrovascular, immune and other diseases frequent and younger, and people’s requirements for a healthy life are constantly increasing. Dietary therapy instead of drug therapy can not only avoid the harmful residue of drugs in the human body, but also reduce people's economic burden [81, 82]. As human beings pay more and more attention to health care, it will become a trend to use MFPs to protect their health, which is a good news for MFPs; another reason is the support by national policies, which have introduced a series of regulations to promote the development of the dual-use industry of MFPs [83] (Fig. 4).

The rapid development of e-commerce and the role of MFPs in promoting rural revitalization are also important factors. With the rise of short video platforms, live-streaming provides a new development opportunity, builds a platform for the sales of MFPs and their products, saves operating costs, and injects new vitality into the Gaoligong Mountains market [84, 85].

Although the widely use brings opportunities, at the same time, medicinal food plants are also facing challenges and threats. (1) Lacking of traditional knowledge database associated with MFPs. At present, there is insufficient ethnobotanical data on MFPs, and relevant traditional knowledge is rapidly disappearing. We should conduct a more comprehensive investigation, recording and cataloging of the endangered knowledge through ethnobotanical methods. (2) Lacking of in-depth research on traditional knowledge associated with MFPs. We should use modern ethnobotanical methods to explain the folk use of MFPs with scientific evidence revealing the scientific basis, which is conducive to traditional knowledge protection and sustainable development. (3) With the acceleration of urbanization, the inheritance of traditional knowledge is also seriously threatened. The traditional knowledge left by the older generation has no one to inherit it. Many studies in different places have emphasized this problem [65, 86, 87]. The foreign culture shock is also an important reason for the loss of traditional knowledge, which means that the cultural dissemination of Han and other ethnic groups has led to local people gradually ignoring and forgetting their own traditional knowledge, just like the loss situation of traditional knowledge related to medicinal plants in other regions [88].

Through the statistics of the endangered situation of MFPs in Gaoligongshan area, it was found that there were one endangered species, Coptis teeta, and two vulnerable species, Gastrodia elata and Fritillaria cirrhosa. These medicinal plants are in urgent need of protection. Some taboo cultures of the ethnic people in Gaoligongshan area are of great significance to the protection and sustainable utilization of both MFPs. On the one hand, it is reflected in the customary law or religious taboo derived from their historical and cultural situatedness, some ethnic people worship some plants as totems and prohibit cutting them down. For example, the Lisu, Nu and Dulong ethnic groups have provisions that prohibit cutting “sacred trees” [10]. On the other hand, due to the cultural taboos, people will restrict the use of MFPs to achieve sustainable utilization. Dulong people have a very strong cultivation and management culture of Caryota obtusa. During their farming activities, the Dulong people remove weeds from C. obtusa or transplant some seedlings from the mountains into their home gardens or next to the villages. Generally, for major events like building a house or getting married, C. obtusa is often planted in the home gardens in case of famine. It is not only related to the local environmental conditions but also to the traditional culture, which helps maintain the population of C. obtusa [43,44,45]. In addition, when collecting medicinal plants, the ethnic people will follow the principle of “gathering the large and leaving the small” [58].

Traditional knowledge associated with MFPs in the Gaoligong Mountains area are precious wealth passed down from generation to generation by local residents. This traditional knowledge is the guarantee of people's livelihood and health, and it is also the culture, customs, and even the blood of the nation. If it is not investigated, cataloged, organized and studied in time, this knowledge will disappear forever, and the consequences of losing it will be immeasurable.

Conclusion

This study is the first ethnobotanical survey of MFPs in Gaoligong Mountains areas. A total of 184 MFPs species belonging to 83 families used by local people were investigated and recorded, reflecting local people have rich traditional knowledge about MFPs, which plays an important role in their livelihoods. Some MFPs like Houttuynia cordata, Eryngium foetidum, Sechium edule, Centella asiatica, Pseudocydonia sinensis, and others had high CFSI. These findings have guiding significance for protection of traditional knowledge associate with MFPs, facilitation of scientific utilization of MFPs to meet local people's needs for a healthy life in the Gaoligong Mountains area.