Introduction

According to the World Health Organization (WHO), approximately 65–80% of the world’s population in developing countries essentially depends on plants for their primary health care [1]. China has kept the tradition of using herbs to treat diseases since ancient times, and this was the principal method for the treatment of disease before the popularization of modern medicine. For the remote minority, in particular, traditional medicinal plants hold a significant position in their daily livelihood. The value hidden behind them deserves to be explored. However, the sustainable utilization of traditional medicinal plants is threatened by the rapid development of the social economy in China. Although knowledge regarding traditional medicinal plants has been documented in some regions [2,3,4], more research is needed to document the knowledge about traditional medicinal plant usages, and urgent conservation measures should be implemented as well [5].

The Yi community is one of the oldest communities in China and lives in the Hengduan region, which has been rich in medicinal plants for a long time. This community created a unique traditional system of medicine with its own theory as it struggled with diseases. Because of the blockage of the traditional knowledge inheritance within the Yi community, such knowledge has only spread within the same clade, family or region, resulting in unbalanced development in different areas [6]. Compared with the adjacent Chuxiong and Shuangbai districts, which have both been systematically studied [7], however, the traditional medicinal plants of the Yi community in Jingdong are still under-researched.

In contrast to other clades, the Yi community in the Wuliang Mountains have no particular wordage. For this reason, the study of the traditional medicinal plants in this region is necessary and urgent [8]. In this survey, the ethnomedicine approach of the key informant interview is used to assess the utilization of traditional medicinal plants by local people.

Study area and data collection

Study area

The Wuliang Mountains are situated in the southwest of Yunnan Province and are located at 23°57′–24°44′ N latitude and 100°22′–101°04′ E longitude (Fig. 1). As an extension of the Hengduan mountain range, the Wuliang Mountains stretch for 89 km from north to south, with an average altitude above 2000 m. The northwestern side of Wuliang Mountains lies in the alternating transition zone between the eastern Asiatic and Paleotropical flora regions, and the southeastern part lies in the alternating transition zone between the China-Japan plant subregion and the China-Himalayan plant subregion. The Wuliang Mountains belong to the western monsoon climate zone, which is characterized by a distinctive south Asian monsoon with obvious wet and dry seasons, harbour plants that exhibit continuous blooming and have the climatic characteristics of plateaus at low latitudes [9]. These unique geographical and climatic conditions result in rich plant diversity in this area. As mentioned by Peng [10], there are more than 300 types of medicinal plants with significant research value.

Fig. 1
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Map of the study area showing the location of villages

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The Yi autonomous county of Jingdong has a total population of 35.55 million. The Han ethnic group comprises 18.35 million (50.21%), while the Yi comprises 15.46 million (42.36%) of the total population [11]. The Yi community in Jingdong is distributed on both sides of the Wuliang Mountains. As a clade of the Yi ethnic group, the Yi autonomous county of Jingdong is one of the settlements and birthplaces of Yi community medicine [10], with a lifestyle of mixed habitation for a long time. The mutual effects of the two ethnicities have resulted in the fusion of culture and utilization of medicinal plants.

Data collection

Ethnobotanical data were collected from September 2016 to August 2017 in the Yi autonomous county of Jingdong, southwest Yunnan. Seven townships and 16 villages distributed on the two sides of the Wuliang Mountains were selected for the field investigations (Additional file 1). Information was collected via key informant interviews. A total of 44 informants were interviewed in the study area, with all the informants being local inhabitants with a profession of herbalist or seller of herbs and who embrace lots of medicinal knowledge. Their gender, age, nationality, education level and occupation were recorded. Ethnobotanical investigations were carried out to collect data on the medicinal plants used to treat human ailments, including their Latin name, Chinese name, local name, family name, life form, plant parts used, preparation method and medicinal effect. All plants were identified according to the Flora Reipublicae Popularis Sinicae [12]. Voucher specimens of the plants cited by informants were collected and deposited at the Herbarium of Xishuangbanna Tropical Botanical Garden (HITBC).

Results and discussion

Profile of informants

The constituent information regarding age, gender, nationality, education and occupation of informants is shown in Table 1. Most of the informants were males, and they played a significant role in the activities of collecting and using traditional medicinal plants. Females only had some knowledge about postpartum diseases.

Table 1 The background information of informants in this study
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All of the informants were split into six age groups, with an average of 49.64 years old. The 40–49-year-old group comprised 43.18%. The Yi population accounted for 70.45%. The educational level of the informants centred on primary and middle school. In our study, 5 out of 12 herbalists who participated in the interview changed their profession, and the 7 herbalists left were still engaged in this profession. In addition, only 2 herbalists had successors, since no young people were willing to engage in this hard and difficult work. According to our investigation, the main reason for this observation is the fact that the low income as an herbalist makes it difficult to make a living. The trend of this phenomenon poses a significant threat to the inheritance of this traditional culture.

Traditional medicinal plant diversity in the study

This study recorded 302 medicinal plant species belonging to 252 genera and 117 families that were used to treat more than 93 ailments (Table 2). The traditional medicinal plants showed high diversity in terms of the composition of species at the family and genus level, with the single-species family and the single-species genus having an absolute advantage in number. Among these medicinal plants, the most species-rich family was Asteraceae, represented by 27 species, followed by family Fabaceae, with 14 species, which is similar to Li [3]. The main reason for this result is likely the abundance of species in these two families. Furthermore, the richest plant genera were Cinnamomum, Aconitum, Artemisia and Polygonum, each represented by 4 species. The most commonly utilized species is Dactylicapnos scandens (D. Don) Hutch., which belongs to Papaveraceae and is used as an antipyretic drug.

Table 2 The inventory of medicinal plants traditionally used by local people
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The traditional medicinal plants used in the study area possess a high ratio of being documented in the literature. Of all 302 species, 76 were recorded in the Chinese Pharmacopoeia, which is an authoritative masterwork in China, and 233 species were recorded in Traditional Chinese Medicine Resources. The local medicine journal Plant Medicine of Yi and Simao Herbal Medicine recorded 34 and 99 species, respectively (Fig. 2).

Fig. 2
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Document evidence of traditional medicinal plants in the study area

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According to the analysis of the constitution of medicinal plants, the single-species family and the single-species genus had an absolute advantage in number (Tables 3 and 4), indicating that the medicinal plants in this region have high diversity in the composition of species at the family and genus level, which is similar to the survey of Shen [13].

Table 3 The statistics of traditional medicinal plants at the family level
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Table 4 The statistics of traditional medicinal plants at the genus level
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In Fig. 3, the life form analysis of traditional medicinal plants showed that herbaceous plants constituted the highest proportion, represented by 151 (50%) species, while there were 53 (17.55%) shrub species, 25 (8.28%) herbaceous lianas, 29 (9.60%) woody climbers and 44 (14.57%) tree species. This result is similar to the study of Lisu community in Nujiang, which is a minority community of China and lives in the Hengduan Mountains area as well [14, 15]. The main reason why herbs are the main medicinal plants is likely due to their diversity and convenience.

Fig. 3
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Life forms of medicinal plants in the study area

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Informants in the study area used different plant parts for the preparation of traditional drugs. Based on the data from informants, the majority of the traditional medicinal plant species were harvested as a whole plant (130), followed by the roots (127), leaves (37), stems (33), bark (24), fruits (22), flowers (10) and other parts (4) (Fig. 4). However, some studies suggest that this mode of utilization may lead to the depletion of traditional medicinal resources [16, 17].

Fig. 4
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Parts of the plants used for medicinal purposes in the study area

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Efficacy analysis of traditional medicinal plants was carried out based on Chinese Medicinal Materials [18]. The results showed that the medicinal plants were used for treating 93 human ailments in the study area. Antipyretics drugs occupy the highest proportion, followed by activating blood and eliminating stasis, diaphoretics and antirheumatics (Fig. 5). This result differed from the study of medicinal plants used by the Yi ethnic group in Chuxiong of Yunnan, showed that trauma was the most common disease. The particular geology and climate are ideal for unique Yi medicine effective in treating pyretic toxicity, rheumatism and other ailments [14].

Fig. 5
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Statistic of therapeutic effects from the study area

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Endangered category assessment

According to the Red List of Chinese Biodiversity (Higher Plant Volume) [19], the level of endangerment of the traditional medicinal plants in the study area was assessed. The ratio of endangered species of traditional medicinal plants in the Jingdong Yi community area (Fig. 6) was higher than that in the Wuliang Mountains National Nature Reserve but lower than that observed nationwide [20], which does not suggest that the harvest of traditional medicinal plants by local people to treat disease is the main reason for their decrease.

Fig. 6
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Endangerment level of traditional medicinal plants in the study area

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Comparison differences of medicinal plants between Yi and Han communities

The Yi and Han communities in the study area have lived in the Yi autonomous county of Jingdong in a multi-ethnic association for many years. When comparing their traditional medicinal plants, an extremely dissimilar relationship was found. The Jaccard similarity index was 0.232, which indicated a low degree of medicinal species overlap between the two communities. This result could be explained by the viewpoint that different cultural backgrounds play an essential role in the utilization of traditional medicinal plants [21]. Comparisons of different communities within the same area proved that a massive discrepancy in terms of traditional medicinal plants still exists even after being fused for a long time. Therefore, the national specificity in the utilization of medicinal plants persists in the region and modern society as well [22]. However, more ethnobotanical documentation research from Yunan Province have shown that minority’s medicinal culture is facing the increasing danger of dying out, under the great impact from Han community’s culture and way of life [4, 5, 23].

Conclusion

This is the first ethnobotanical study conducted in the Wuliang Mountains of Jingdong, and a total of 302 species were recorded. The results show a high diversity of traditional medicinal plants, as we previously suspected. By assessment of endangered status, the traditional medicinal plants in the study area exhibit excellent conditions. This indicates that folk utilization is not the main reason for the degeneration of wild resources. The use of a large number of certain herbs as merchandize may contribute to the deteriorating situation of wild medicinal plants, such as the reduction of Panax notoginseng (Burkill) F.H. Chen ex C. Chow & W.G. Huang and Paris polyphylla var. yunnanensis (Franchet) Handel-Mazzetti. In contrast, some minority communities have traditional methods to protect their precious wild resources. For example, the Red-Headed Yao People in China select different parts of medicinal plants to treat diseases and selectively harvest old roots, leaving the new roots, according to different seasons and climatic conditions [24]. The Yi community in Jingdong Autonomous County also has a belief in nature, which plays a vital role in the sustainable utilization of wild resources. They have a belief of animism and believe that every tree is divine and thus deserves to be protected and respected. The people who engage in the destruction of the sacred trees have a fear of future retaliation and punishment [25].

Despite the abundance of medicinal plants in the study area, the inheritance of this valuable culture is facing a serious threat, mainly due to the rapid development of modern medicine. The ageing of herbalists without inheritors results in the rapid loss of valuable knowledge. In addition, the knowledge of traditional medicinal plants in Jingdong inherited via the oral mode and the accuracy of inheritance are difficult to determine. The most critical challenge is the lack of wild resources. According to statistics, approximately 96% of traditional medicinal plants come from the wild [26]. Especially in China, with the increasing demand for resources, tremendous pressure from overexploitation is faced by many regions. Hence, these regions should take some effective measures to protect these valuable resources and maintain their sustainable utilization in the future.

As one of the birthplaces of Yi medicine, knowledge about traditional medicinal plants is infinite, and it is a precious wealth left behind by ancestors. With regard to the application of these species, there are still many limitations that should be addressed and improved by modern science and techniques.