Changes in homegardens in relocation villages, a case study in the Baiku Yao area in Southern China

Abstract

Background

Baiku Yao is an ancient branch of the Yao people in China who have the custom of maintaining homegardens. The local government has relocated some villagers to improve their livelihood. To study the characteristics of Baiku Yao homegardens and the impact of relocation, we conducted an ethnobotanical study on homegardens in the relocated villages of Huaili and Yaozhai and in the ancient villages of Yaoshan and Duonu from January 2019 to May 2022.

Method

Data on homegarden plants were collected through semi-structured interviews with homegarden households. A total of 4 villages (i.e., two relocated and two ancient villages) were selected for detailed investigation. In each village, 60 homegardens were chosen randomly. In addition, the RFC index and Jaccard value were used to analyze and evaluate the homegarden plants we recorded.

Result

The study recorded a total of 213 species of homegarden plants with approximately 11 functions. Baiku Yao homegardens are small in size but rich in species and functions, and their utilization efficiency is extremely high. The Jaccard value shows that the homegarden plants in Huaili and Yaozhai have the highest similarity. Neighborhood sharing and market purchasing are the two most important sources of local homegarden plants. Additionally, medicine and food are the two most important uses of homegarden plants. Ornamental plants also play a significant part, especially in relocated villages. The comparisons indicate that the diversity of homegarden plants in the investigated ancient villages is better preserved than in relocated villages. Due to frequent exchanges between the villages and the outside world, Yaoshan Village, as an older relocated village, maintains a good traditional culture in its homegardens. As a newly relocated village, Duonu Community has developed a complicated homegarden system with only much less plant diversity. The development of local tourism has also impacted the composition of homegarden plants. The study found that plants such as Zea mays, Morus alba, and Capsicum annuum are closely related to local life and livelihood.

Conclusion

The traditional knowledge of homegarden plants in investigated ancient villiages maintained good diversity and has been affected much less by the modernization and tourism industry development compared to the relocated villages. The composition of homegarden plants is closely connected to the local livelihood. In the future development of Baiku Yao communities, protecting homegarden plant diversity and functional diversity is crucial.

Introduction

Baiku Yao is a branch of the Yao ethnic group mainly living in Nandan County in Guangxi Province and Libo County in Guizhou Province in China [1]. “Baiku Yao” means “Yao people wearing white pants”; they received this name because the grown men of Baiku Yao wear white pants daily. Many of the Baiku Yao people lived in a mountainous area inaccessible to the modernized world. However, the government recently constructed roads to easily access these isolated mountain villages. This infrastructure construction ultimately opened a corridor for Baiku Yao to exchange goods and information with the outside world. The traffic improvements eventually made considerable changes in Baiku Yao culture, from a completely traditional culture to a direct shift in modern life. We were interested in examining how this transformation from traditional to modern culture changed their lifestyle over time. Our past research on Baiku Yao focused on plants used for various purposes, such as herbal medicine, foraging, dyeing, and veterinary medicine [1,2,3], and showed that Baiku Yao holds wealthy traditional knowledge about plants and their applications.

The Baiku Yao community lived in mountainous areas for a long time and maintained the traditional livelihood. According to interviews with the local government, with support from the Chinese government's poverty alleviation policy, some Baiku Yao villages in Yaoshan Township in Libo County of Guizhou Province in China were relocated between the 1950s and 2000. In 2009, the local government began to develop tourism on a large scale to create employment and economic development. With the government's support, another Baiku Yao area, Nandan County in Guangxi Province, China, started construction of the “thousand households Yao village” project in 2017, completed it in 2020, and formed a new village dominated by Baiku Yao (accounting for more than 90% of the population), called the Duonu Community. Yaoshan village and Duonu Community, as relocated villages, their residents were moved from different villages. (According to local poverty alleviation policies, low-income families from different villages were encouraged to move out from their original village to reform a new village, Yaoshan village and Duonu Community, and those families were provided new houses and other infrastructure.) The relocation process of Baiku Yao village may have affected their traditional knowledge base. Therefore, comparing relocated and ancient villages could provide a good case for studying the dynamic changes in traditional knowledge during migration.

Several case studies have been conducted among migrants of ethnic groups to understand how relocation and migration affect traditional knowledge and ethnic cultures. Some studies have reported that many migrant groups have started to practice new plant application knowledge to adapt to environmental changes and the availability of the same plant resources at the relocation site [4]. Ecological migration is a phenomenon of population migration due to the interaction of the ecological environment and other factors [5]. Ma et al. (2019) explored changes in the knowledge of traditional forage plants in ecological migrant groups and found considerable differences in the diversity of related knowledge retained by ecological migrants in different regions [5]. The people who migrated to nearby areas from their original settlement retained more knowledge than those who moved far from their native place because of significant differences in natural resources [5]. Moreover,  in the same case, the younger generation mostly forgot about the traditional knowledge of forage grass [5]. Studying the dynamic change in traditional knowledge among migrant groups might help protect their biocultural diversity [6].

Homegarden is usually described as a small agroforestry system in or near local houses that can provide entertainment, food, medicine, income, and other essential functions [7]. Many studies on traditional homegardens are often related to agriculture, ecology, nutrition, botany, and many other fields [8]. Plant diversity, an important core component of homegarden ecology and function, is also the focus of many researchers [9]. Homegarden plants are plants with certain functions purposely preserved or cultivated in homegardens [10]. Usually, homegarden plants have multiple functions, are closely connected to the local livelihood, and can reflect the local culture [11]. Maintaining a homegarden is common practice in many rural communities, including Baiku Yao.

In the case of Baiku Yao, a pilot investigation showed that their homegardens are rich in plant resources and are important carriers of traditional genetic resources and knowledge, guaranteeing the community's livelihood. Thus, we also assumed that homegarden plants could indicate the difference between homegardens in ancient villages and relocated villages in the Baiku Yao area. This might also help explain the dynamic change in related culture and knowledge during the relocation.

In this study, we aimed to (1) determine the plant compositions and special characteristics of Baiku Yao homegarden plants and (2) explore the changes in Baiku Yao's traditional knowledge by comparing the plant compositions in homegardens in relocated and ancient villages. This ethnobotanical study not only helps to document and protect the traditional knowledge of homegarden plant but also provides a reference for protecting the biocultural diversity in other cases of community migration and community relocation in the future.

Method

Study area

The Baiku Yao residential area is located on the slope of the transition from the Yunnan-Guizhou Plateau to the Nanling Hills [12]. Its geographical environment features characteristics of both the Yunnan–Guizhou Plateau and the Nanling Mountains [12]. The area has a humid subtropical climate and rich surrounding vegetation species [12]. To explore the impact of relocation on traditional knowledge, we selected two Baiku Yao relocated villages (Yaoshan Village in Libo County and Duonu Community in Nandan County) and two Baiku Yao traditional ancient villages (Huaili Village and Yaozhai Village in Nandan County) for detailed investigation (Fig. 1). Huaili Village and Yaozhai Village are the two most traditional and ancient Baiku Yao villages. Both of them have thousands of years of history. The data sources mentioned in the following village introductions are from the local government.

Fig. 1

The study area

Yaoshan village is located in Yaoshan Township, Libo County (107.766609 N; 25.234635E; 514 m asl). This village was formed to relocate the Baiku Yao residents in 1953 to relieve poverty under the national plan. Currently, there are 738 households and 3177 people living in this village. However, due to the higher number of migrants and lower availability of land, most people engage in tourism activities (e.g., performances and exhibitions) to sustain their livelihood. Some migrants have returned to their native places to cultivate food crops and maintain their homegardens.

Duonu Community (village) is located in Lihu Township, Nandan County, Guangxi Province (107.653244° N; 25.094444° E; 575 m asl). The relocation of Baiku Yao people to this village started in 2017 and was completed in 2020. A total of 1123 households comprising 5903 people were reallocated to the Duonu Community, most of which were from the poor villages of Baiku Yao, such as Huaili, Dongjia, Yaoli, Badi, and Renguang in Lihu Township. The Duonu Community is located on the slopes of the Masson pine forest. Most houses are constructed close to each other due to limited land availability and high population density, and most villagers depend on the local market to fulfill their daily requirements. However, some old inhabitants return to their native areas to grow food and vegetables to sustain their livelihood.

Huaili Village is located on a rocky mountain near Lihu Township (107.693099 N; 25.119346E; 753 m asl), Nandan County, away from the township government. Baiku Yao people dominate the population of this village. A total of 609 households with 3169 people reside in this village. Huaili is one of the ancient villages of Baiku Yao, where these people have lived for more than a thousand years and still maintain their traditional culture. The villagers have sufficient land and produce corn as their primary food.

Like Huaili Village, Yaozhai is also a traditional Baiku Yao village (107.658019 N; 24.978054E; 741 m asl) located in Baxu Township, Nandan County. There are 321 households with 1492 residents residing in this village, and the Baiku Yao people dominate 90% of the population of this village. Most of the residents produce rice and corn to sustain their livelihood. However, some residents work as migrant workers.

Data collection

We conducted a preliminary investigation on the homegarden plants and their role in fulfilling the daily needs of the Baiku Yao communities. A total of 4 villages (i.e., two relocated and two ancient villages) were selected for detailed investigation from January 2019 to May 2022. Given the distribution characteristics of Baiku Yao families in four villages and the validity of data comparison, we numbered the homegardens of each village so that different homegardens corresponded to different numbers. Sixty households (homegardens) were randomly selected in each village by lottery, and appropriate fine-tuning was conducted with the help of local guides. We collected the data using semi-structured face-to-face interviews with homegarden households [13]. Since some Baiku Yao in the study area could not speak fluent Mandarin, assistance was obtained from local guides during the fieldwork. All interviews were conducted in the Baiku Yao language and translated into Mandarin with the help of a local guide. We asked five main questions: (i) what are the main plants in your garden, (ii) what are the functions of these plants, (iii) how do you use this plant (processing methods), (iv) which part is used and (v) where this plant/seed was collected [14, 15]?

We also collected herbarium voucher specimens or took photos during the survey to confirm species identification using Flora of China [16], Flora of Guangxi [17], and botanical Web sites (e.g., http://www.iplant.cn/, http://www.cvh.ac.cn/search, http://ppbc.iplant.cn/). Finally, the identified specimens were reaffirmed by taxonomic experts from the Guangxi Academy of Traditional Chinese Medicine and the inventory of homegarden plants. All specimens were preserved in the Herbarium of the Guangxi Zhuang Autonomous Region, Institute of Traditional Chinese Medicine (GXMI).

Quantitative analysis

We used the Jaccard index and the RFC index to evaluate the data. The Jaccard index was used to detect the similarity of homegarden plants among the different villages, whereas the RFC index was used to evaluate the importance of homegarden plants in the daily livelihood of Baiku Yao. The Jaccard index is calculated according to the following formula [5, 18]:

$${\mathrm{JI}} = \frac{{\mathrm{C}}}{{{\mathrm{A}} + {\mathrm{B}} - {\mathrm{C}}}} \times 100$$

where A and B represent the number of homegarden plants owned by each of the two villages. C represents the number of homegarden plants in both villages, and the JI value ranges between 0 and 100 [5, 18]. A higher JI value indicates a higher homegarden plant similarity between the two villages [5, 18].

The RFC values were calculated according to the following formula [19]:

$${\mathrm{RFC}} = \frac{{{\mathrm{FCs}}}}{N},$$

where FCs represent the frequency of citation (total number of frequencies mentioned by all respondents to a specific plant), and N represents the number of all respondents [19]. In this study, we made some changes. FCs represent the total frequency of a specific plant appearing in the homegardens of the investigated villages, while N represents the total number of homegardens (households) interviewed. The RFC value is between 0 and 1; the higher the RFC, the closer the connection between the homegarden plants and the daily life of Baiku Yao [19].

Results

The characteristics of traditional Baiku Yao homegardens

Baiku Yao depends on natural resources for food and other domestic products for their daily needs. Therefore, they greatly respect nature and offer prayers for nature in their daily routine. They frequently use plants like Caesalpinia decapetala, Pterolobium punctatum, and Maclura cochinchinensis to make living fences (Fig. 2) for the homegardens, which they believe the living shrubs are robust. Also, they greatly respect the prominent and old trees growing near the houses (sometimes near or in the homegardens as part of the homegarden systems). Thus, they keep and protect most of the large and old trees at the village entrance or near houses to maintain shade, cool, and landscaping. According to all of our participants, every Baiku Yao believes that big trees next to homes are sacred, and they protect the village and its prosperity. They also think that destroying a sacred tree will destroy the village's Feng shui and negatively affect future generations' well-being. For example, Keteleeria davidiana var. calcarea tree, usually found near the homegardens or houses, is believed to be inhabited by gods (because its branches are relatively flat and suitable for gods to live). As a national second-class protected plant in China, Keteleeria davidiana var. calcarea has been particularly well protected in the Baiku Yao area.

Fig. 2

Baiku Yao homegardens

Baiku Yao mostly lives in mountainous areas and usually has few land holdings. Thus, their traditional homegardens are also very small (less than 10 square meters on average, Fig. 2). Locally, however, the homegarden space utilization efficiency is extremely high, and the space is clearly structured and hierarchical according to our observations. On the periphery, the fences of homegardens are mainly wild or cultivated plants with certain functions. Local people believe that a living fence is more stable and can increase the space use efficiency of homegardens. For example, planting Morus alba, Broussonetia papyrifera, and some fruit trees as fences is very common in the Baiku Yao area. In addition, the lower-layer space is often planted with shade-tolerant spices or medicinal herbs. Seasonal vegetables are usually cultivated in the middle area of homegardens. For example, during the winter and the spring, they usually grow Brassica rapa subsp. Campestris, Brassica juncea, and Spinacia oleracea, while during the summer, they usually grow Cucurbita moschata, Vigna unguiculata, Glycine max, and Phaseolus vulgaris.

The Baiku Yao people are well aware of the importance of maintaining high species diversity in their homegardens to fulfill their daily requirements. According to their living strategy, due to the poor soil and a changeable climate, the benefits of planting a single species may be low or risky, so planting a variety of plants can reduce the risk as much as possible and obtain better returns. The locals also believe that high plant diversity can effectively reduce the harm from pests or plant diseases. The traditional local philosophy of maintaining the homegarden system reflects the wisdom of the Baiku Yao people.

Plant diversity in Baiku Yao homegardens

As shown in Table 1, 213 species were identified in the homegardens of Baiku Yao, belonging to 172 genera and 80 families. The commonly represented families were Poaceae (15 species), Fabaceae (12 species), Asteraceae (9 species), Rosaceae (8 species), Rutaceae (8 species), and Solanaceae (8 species), most of which are edible and ornamental plants.

Table 1 Inventory of homegarden plants in Baiku Yao area

Herbaceous plants (101 species; 47.42%) are the dominant components of Baiku Yao homegardens, followed by trees (61 species; 28.64%), shrubs (31 species; 14.55%), and lianas (20 species; 9.39%). The rich species diversity and multiple layers of planting are the characteristic features of Baiku Yao homegardens.

Among the four investigated villages, Yaoshan Village had the highest diversity of homegarden plants (137 species; 64.32%), followed by Yaozhai Village (124 species; 58.22%), Huaili Village (119 species; 53.99%) and Duonu Community (47 species; 22.07%). The statistics in Fig. 3 show that Baiku Yao residing in Yaoshan Village have well-developed diversity of homegarden plants during relocation. Unlike the traditional homegardens in ancient Baiku Yao villages, ornamental plants are the key components of homegardens in Yaoshan. With increasing local tourism, the demand for ornamental species has increased. The traditional ancient villages (Yaozhai and Huaili Village) of Baiku Yao mainly cultivate food plants and medicinal plants in their homegardens to sustain their daily livelihood. Moreover, these two ancient villages have not been exposed to tourism; therefore, they maintain only those species they require for their own consumption, leading to similar species numbers in their homegardens. In contrast, Duonu Community is one of the newly built relocated villages for Baiku Yao. Therefore, their homegardens are still in the initial development and have less species diversity. According to observations, in Duonu Community, local people mainly grow ornamental species such as Podocarpus macrophyllus, Zoysia japonica, Bambusa ventricosa, and Bambusa vulgaris 'Vittata'.

Fig. 3

Comparison of species numbers among different villages

In this study, the JI value is used to express the similarity of homegarden plants in four villages (Fig. 4); the higher the JI value is, the higher the similarity of homegarden plants between the two villages [5]. According to the calculation, Yaozhai Village and Huaili Village had the highest JI values (59.87%), reflecting the very high similarity of homegarden plants and indicating the frequent communication and exchange of traditional knowledge between these two ancient Baiku Yao villages. The similarity between Yaoshan and Yaozhai (41.85%) and Yaoshan and Huaili (32.64%) also seems relatively good. Compared to Duonu Community, Yaoshan villagers may communicate more with ancient villages and practice cultivating different homegarden plants even after relocation. However, the lower similarity of homegarden plants of Duonu Community with other villages, such as Yaozhai (25.74%), Huaili (24.81%), and Yaoshan (21.05%), could be linked to the limited period since their recent relocation. Most of the homegardens have not started cultivating crops or transplanted wild plants.

Fig. 4

JI value of homegarden plants among four villages

Sources of homegarden plants

Homegarden plants of Baiku Yao normally come from various sources, such as (i) primary species (originally found in the locality even before any human interventions, 27 species), (ii) the wild environment (transplanted from the wild, 35 species) and (iii) neighborhood exchanges (71 species). Propagules (i.e., seeds and seedlings) of some species are purchased from the market (78 species), and some species are self-preserved (27 species) by Baiku Yao to maintain their homegardens (Fig. 5). In relocated villages, the local government also encourages them to grow ornamental species (21 species) and provides them with planting material to enhance their livelihood and decorate the community. Many homegarden plant provenances come from multiple sources, such as Perilla frutescens, Agastache rugosa, and Zea mays, from both markets and self-preservation; Acorus tatarinowii comes not only from the wild but also from neighbor sharing. According to the investigation, among all villages we visited, market purchases contributed the most to maintaining Baiku Yao homegardens (36.62%), followed by neighborhood sharing (33.33%), wild (16.43%), primary species (12.68%), government issuance (9.86%) and self-preserved species (7.98%).

Fig. 5

Heatmap of plant sources of homegarden plants in Baiku Yao villages

According to Fig. 5, most of the homegarden plants in ancient villages were from neighbor sharing (61 species in Yaozhai and 51 species in Huaili), followed by purchasing from the market (40 species in Yaozhai, 31 species in Huaili) and self-preservation species (26 species in Yaozhai, 24 species in Huaili). However, in Yaoshan, an early relocated village, most homegarden plants were purchased from the market (55 species), followed by neighbor sharing (48 species). According to the interviews, Yaoshan villagers depend on exchange plants with other villages for complementary resources. However, in Duonu Community, which was recently relocated, homegarden plants mainly come from neighbor sharing (18 species) and market purchases (16 species).

The introduction of homegarden plants from neighbor-sharing accounts for a very high proportion in the four villages, indicating the presence of frequent internal communication in Baiku Yao village; they have a regular seed and seedling exchange network. Moreover, Baiku Yao has a high degree of recognition of food, culture, aesthetic appreciation, and consistent living habits. We also observed that a certain number of primary species are common in the homegardens of each study village, of which Huaili (21 species) is the highest, indicating worship and respect for nature among Baiku Yao, who make full use of the value of primary plants in homegarden design. As an ancient village, Huaili has well preserved and inherited the life concept of Baiku Yao.

Analysis of the functions of homegarden plants

The homegarden plants of Baiku Yao have a wide range of uses. We classified these plants into 11 types (Fig. 6) based on their use value, including medicine, timber, ornamental, food, foraging, veterinary medicine, religious rites, sacred trees, fences, dyes, and others (cigarettes, beauty, rope, and treat Gudu, a poison produced by venomous insects or evil curses). Edible plants accounted for the majority (90 species), followed by ornamentals (72 species), medicine (62 species), forage (28 species), veterinary medicine (11 species), religious rituals (11 species), timber (10 species), fences (10 species), dyes (8 species), and sacred trees (7 species).

Fig. 6

Heatmap of plant functions of homegarden plants in Baiku Yao villages

The number of edible plant species was high (above 50% of all plant species) in the homegarden of each village (Fig. 6), indicating that the homegardens of Baiku Yao are the primary source for providing food by cultivating crops, vegetables, and fruits.

Medicinal plants occupied the second position in the homegardens of different villages, i.e., Huaili (36 species, 30.25%), Yaozhai (40 species, 32.26%), Yaoshan (31 species, 22.63%), and Daonu (10 species, 21.3%). These findings indicate that Baiku Yao homegardens play an important role in community disease prevention and treatment, especially in Baiku Yao's ancient villages.

Approximately 15–20% of species represent forage plants in the homegardens of each village. The villagers have generally raised poultry and livestock since ancient times. Most Baiku Yao insists on using traditional wild vegetables or planting coarse grains in the feeding process instead of market feeds. The locals believe that the calories of commercial feed are too high, and the livestock is prone to internal fever and digestion problems [3]. Therefore, forage species are important components of homegardens in both traditional and relocated villages.

Ornamental plant diversity varies significantly among the studied villages. For example, Yaoshan Village has the highest number of ornamental plants (55 species; 40.15%), followed by Yaozhai (21 species, 16.94%), Duonu (15 species, 31.9%), and Huaili (14 species; 11.76%). The statistics of ornamental species indicate that Baiku Yao integrates various ornamental plants in constructing and designing homegardens; thus, they have a rich diversity of ornamental plants. Yaoshan Village has the most diverse ornamental plants because of local tourism development. In addition to the traditional ornamental plants the locals like, there are many landscape plants planned by the local government and tourism companies.

A comparison of homegarden plants among the four villages revealed that the distribution of plants utilized for veterinary medicine, religious rites, timber, fence, and dyes is much higher in the homegardens of ancient villages (Yaozhai and Huaili) compared to relocated villages (Yaoshan and Duonu). We found scarcely any sacred trees in Yaoshan Village, while Duonu Community homegardens had only one species of veterinary plant, one species of dye plant, and one species of the sacred tree. The comparison indicates that the traditional practice of homegarden plants in Baiku Yao ancient villages is higher and more comprehensive than in relocated villages. Because the relocated population may need to deal with a new natural resources composition or even face a different social environment, which leads to a changing livelihood or a different frequency of practice of traditional knowledge, relocation could be responsible for eroding some traditional knowledge. There are fewer types of homegarden plants in the Duonu Community than in other villages, meaning that establishing plant diversity in traditional homegardens requires a long-term process.

The impact of the tourism industry on studied villages

Our results show that ancient Baiku Yao villages (Huaili and Yaozhai) have more diversity of homegarden plants, which may suggest that compared to relocated villages, traditional culture related to homegarden plants in the ancient villages has been affected less by the modernization or the development of tourist industry. Duonu Community has much less diversity of homegarden plants. After relocation, these people moved to a different area with different environmental conditions and topography compared to their native location. They may not have been able to find and cultivate the same species as they used to grow in their native locations, and some of the traditional knowledge could be lost with time, which is somehow reflected by the low species richness in their homegardens. In contrast, homegardens in Yaoshan Village have a high diversity of species, similar to the two ancient villages. The field visit showed that Yaoshan villagers preserved not only relevant traditional knowledge but also incorporated new species into their homegardens even after relocation. A higher proportion of homegarden plants in Yaoshan Village comes from the market because, after relocation, they had more opportunities to travel to different places due to convenient transportation facilities. Therefore, they incorporated many new species into their homegardens. Due to local tourism development, they also incorporated many horticultural species in their homegardens compared to ancient villages.

Tourism activities were introduced in Yaoshan Village in 2009 to generate employment for local people under the national poverty reduction program and present the Baiku Yao ethnic culture to others. The tourism company improved road connectivity and developed infrastructure facilities to attract tourists, thus increasing local employment for the Baiku Yao people. During the investigation, we observed that although Yaoshan Village had become a tourist destination, it still maintained and preserved many traditional practices for homegarden plants. These practices might help maintain their traditional knowledge during tourism development. According to the introduction from the tourism company staff, the company believes that tourism should focus on the folk culture of Baiku Yao rather than paying attention to and interfering in the development of regional economy. This is reflected by the rich species diversity they plant in their homegardens to sustain their daily requirements. Tourism companies provide good infrastructure (such as roads, tap water, electricity, and house repair), but they keep their best not to interfere with the routine life of Baiku Yao, such as growing vegetables, sericulture, keeping chickens, and pigs. Therefore, the concept of traditional cultural protection preserves not only local traditional knowledge but also gives local tourism more cultural connotation and experience. Consequently, many people are attracted by the local tourism and ecotourism, which ultimately drives the development of the regional economy.

RFC value analysis of homegarden plants

The RFC values ranged from 0.01 to 0.93. The RFC value indicates the frequency of a specific species in the homegardens of Baiku Yao and reflects its importance in local daily life. Approximately 22 homegarden plants showed a high RFC value (> 0.5). Among them, Zea mays had the highest RFC value (0.93), followed by Morus alba (0.87), Capsicum annuum (0.87), Eriobotrya japonica (0.68), Ipomoea batatas (0.68), Solanum melongena (0.68), Glycine max (0.67), Phaseolus vulgaris (0.66), Agastache rugosa (0.65), Cannabis sativa (0.65), Brassica rapa var. oleifera (0.62), Cucurbita moschata (0.62), Zingiber officinale (0.6), Amaranthus tricolor (0.58), Allium sativum (0.58), Osmanthus fragrans (0.57), Fagopyrum dibotrys (0.57), Anredera cordifolia (0.56), Leucocasia gigantea (0.52), Broussonetia papyrifera (0.52) and Cinnamomum camphora (0.52).

Zea mays is planted by almost every household; therefore, this species has the highest RFC value. Baiku Yao lives in mountainous areas with minimum landholding, and they grow Zea mays as both a staple food and forage because of its high adaptability to such areas and high-yield production. As an important feed plant, Morus alba is mainly used to raise silkworms and can also be fed to pigs and cattle. Baiku Yao retains the traditional “farming and weaving culture” in the local area. Their traditional ethnic costumes are all woven from the silk. Therefore, as the only food source for sericulture, Morus alba also has a significant local position and value (Fig. 7). Eriobotrya japonica has the third-highest RFC value and is utilized for fruit and medicinal purposes (treating cough).

Fig. 7

Morus alba and the sericulture of Baiku Yao

Ipomoea batatas, Solanum melongena, Glycine max, Phaseolus vulgaris, Anredera cordifolia, Brassica rapa var. oleifera, Amaranthus tricolor, Cucurbita moschata, and Leucocasia gigantea also have relatively high RFC values. These species are the most common vegetables in the Baiku Yao area for daily needs.

During the interviews, local people said they liked to boil vegetables and meat instead of stir-frying; thus, they could avoid using cooking oil and preserve food nutrition as much as possible. In the past, because of transportation limitations and the economy, Baiku Yao seldom used seasonings such as soy sauce, monosodium glutamate, and salts. They still prefer cultivating various spice species such as Capsicum annuum, Agastache rugosa, Cannabis sativa, Zingiber officinale, and Allium sativum for more diverse flavors.

As a traditional farming ethnic group, Baiku Yao has a limited income source, and the meat supply mainly comes from self-raised poultry and livestock. Therefore, they grow various fodder species, such as Zea mays, Morus alba, Fagopyrum dibotrys, and Broussonetia papyrifera, in their homegardens.

Generally, the homegardens of different villages differ in species preference and utilization patterns. For example, the homegardens of Yaoshan Village and Duonu Community have a higher frequency of ornamental plants such as Ficus microcarpa, Bougainvillea glabra, and Zoysia japonica, but very few people grow these species in Huaili and Yao Villages. However, Huaili and Yaozhai villagers prefer to grow forage species in their homegardens, such as Broussonetia papyrifera and Fagopyrum dibotrys. These differences in species preferences among the studied villages indicate that they maintained some of the most commonly used species but also introduced various new species to their homegardens after relocation.

Ailanthus vilmoriniana, the totem tree of Baiku Yao, has an important cultural status in the local area. The resin of Ailanthus vilmoriniana is an anti-staining agent locally used in the dyeing and patterning of the traditional clothing of Baiku Yao (Fig. 8). Among the villages surveyed, Ailanthus vilmoriniana is only distributed in the homegardens of Huaili Village, so its RFC value is very low, yet all the local people of the surveyed villages are very familiar with relevant knowledge of Ailanthus vilmoriniana. In fact, market circulation and neighborhood exchanges make up for insufficient Ailanthus vilmoriniana resin resources in some villages. In addition, Baiku Yao has a very strong sense of ethnic and cultural identity and often wears traditional costumes, so to a certain extent, it also ensures the preservation of traditional knowledge related to Ailanthus vilmoriniana.

Fig. 8

Ailanthus vilmoriniana Dode and its resin application

Discussion

Protection strategy of local homegarden culture

The case of Yaoshan Village can be used as a reference for rural revitalization or tourism development in other regions. While building and developing the local industry, Yaoshan Village pays attention to protecting the traditional livelihood and related culture of the local people, which not only helps the continuation of traditional knowledge but also indirectly protects some special local cultural species. Perhaps, the future development of the Duonu Community can take Yaoshan Village as a template. However, some previous studies have shown that the local industrial structure changed with the gradual development of the regional economy, and these changes altered residents' livelihood and deteriorated the local biodiversity and traditional culture [20,21,22]. Therefore, attention needs to be paid to maintaining the plant diversity of homegardens by maintaining their ecological and sociocultural functions. Identifying and protecting key species could be one of the most feasible options to protect the traditional knowledge related to homegardens [23]. For example, Ailanthus vilmoriniana and some plants with high RFC are likely to be key local cultural species, so their protection should be prioritized [23].

Maintaining the species diversity of homegarden plants can not only help to protect local traditional knowledge but also assist in maintaining the functional diversity of Baiku Yao homegardens to be fully self-sufficient. In the current era, disease epidemics, extreme disasters, and international disputes are more frequent. Responding to the food crisis and sub-disasters has become a prime research interest worldwide. Homegardens have long been reported to be an effective buffer zone for people to resist disasters, and plant diversity and functional diversity are the keys to ensuring social–ecological resilience [24, 25]. Therefore, protecting the plant diversity and functional diversity of Baiku Yao homegardens should be prioritized.

The traditional knowledge change when migrating

In this case, we can find the difference in the traditional knowledge practice in homegardens between the ancient villages and the relocated ones, brought mainly by the relocation. Traditional knowledge is not immutable but changes dynamically because of environmental change and social development [26]. Historically, there are often cases of population migration around the world, many of them for better living resources and climate or to avoid wars and natural disasters, and the relevant traditional knowledge changes dynamically [27]. For example, in the process of moving south from northern China, the culture of one of the largest migrant groups in history, the Hakka people, blended with the She, Yao, and other ethnic groups [28]. The separation of Hakkas from their original natural resources and cultural atmosphere in the process of migration brought new changes to the traditional experience handed down from generation to generation [28]. The change in traditional knowledge is not necessarily negative, and it may manifest in the local people's adaptation to the new environment and the growth rate of local development.

In many parts of the world, to improve the lives of local people or protect the ecology, local governments are currently building infrastructures and conducting ecological migrations or relocations to make local life more stable and safer [29,30,31]. However, interfering with the original local livelihood, like banning all wild collection or dramatic environmental changes caused by the long-distance migration, could threaten many traditional practices and lead to cultural damage [31]. However, biodiversity and cultural diversity are inextricably linked [32]. For example, when the species that are available and recognized by local people are significantly reduced in the new environment, the corresponding experience, language, and stories gradually disappear over time. Thus, changes in the original livelihood may also bring negative impact, which needs to be carefully considered by the local government in decision-making.

Conclusion

We selected two ancient (Huaili and Yaozhai) and two relocated villages (Yaoshan and Duonu) in the Baiku Yao area of China for ethnobotanical investigation. The results show that the traditional knowledge of homegarden plants in Huaili and Yaozhai villages is well preserved, showing good plant diversity and versatility. Due to frequent exchanges between the village and the outside world, Yaoshan Village preserves a good traditional culture and adds many new plants to its homegardens, especially ornamental plants. As a newly relocated village with a short history, Duonu Community has lost some traditional knowledge related to homegarden plants. In addition, the study found that plants such as Zea mays, Morus alba, and Capsicum annuum are the most important in the Baiku Yao homegardens and are closely related to local life and livelihood. In the future development of Baiku Yao communities, protecting homegarden plants and functional diversity is crucial.