Background

A homegarden is a small land use system that is dominated by humans and includes residences, diverse flora and fauna, and certain structures and landscape features. It provides various services such as food, decoration, medicine, building materials, religion, and ceremonies [1, 2]. Typically, it consists of cottages, trees, and land of varying sizes used for growing flowers, fruits, and vegetables [3]. Known for its rich species diversity [4], its high level of inter and intra species plant genetic diversity makes it a repository of biodiversity [5], which can protect local biodiversity and maintain sustainability [6].

The diverse uses of homegarden plants provide various opportunities for the livelihoods and well-being of local communities. These include self-sustaining food production, commercial cultivation, medicinal plants, fodder, and ornamental purposes. The diversity of homegarden plants is closely related to local livelihoods [7], with most edible plants grown for self-sufficiency [8]. For example, in West Africa, leafy amaranth varieties are harvested and used as seasonal vegetables [9]. Furthermore, many homegardens in different regions also cultivate commercial plants [10]. For instance, coffee is a major commercial plant grown in the homegardens of every household in southwestern Ethiopia, with income from it accounting for 52.43% of the average annual income of wealthy families, 68.27% of middle-income families, and 65.01% of poor families [11]. Moreover, these gardens serve as important repositories of medicinal plants and traditional knowledge [12,13,14], particularly in remote areas where medicinal plants and traditional knowledge are well-preserved through human management. In Campo Hermoso and Zetaquira, Colombia, bitter plants are referred to as "hot plants," while plants with a sweet flavor are termed "cold plants." The terms "cold" and "hot" express the degree of caution that should be exercised when using these medicinal plants [15]. Homegarden also comprise an essential part of feed and ornamental plants [16, 17]. On the Indonesian island of Sumatra, residents grow large amounts of Paspalum conjugatum P.J.Bergius, Panicum maximum (Jacq.) B.K.Simon & S.W.L.Jacobs, and Pennisetum purpureum (Schumach.) Morrone in their homegardens for their own cattle and sheep feed [18]. Meanwhile, the Salar people in southern China plant various ornamental plants such as Bougainvillea spectabilis Willd., Pelargonium hortorum L.H.Bailey, Fuchsia hybrida Voss, and Hydrangea macrophylla (Thunb.) Ser. in their homegardens for decoration and to admire while relaxing [19]. Based on the above reports and for ease of classification, homegarden plants are divided into five types in this study: edible plants, trade plants, medicine plants, forage plants, and ornamental plants.

Homegarden surveys are an effective way to understand indigenous people's traditional knowledge related to biodiversity, as plant diversity and functional diversity are closely related to local people's plant knowledge, which encompasses their understanding of the surrounding environment's plant world [20]. Learning and protecting traditional knowledge related to gardens can promote biodiversity conservation and maintain local livelihoods [19, 21]. Additionally, the reasons for potential differences in homegarden plants and traditional knowledge between different communities need to be further elucidated [22].

The versatile nature of the mentioned homegardens has had a positive impact on the societal economy, ecological environment, and cultural heritage. Evidence indicates that the characteristics and functions of homegarden plants may vary under the influence of different homegarden operators and natural environmental conditions. The diversity in types and structures of homegarden plants is often associated with household traits like land ownership, income level, residential land area, and gardening time, especially notable in tropical and subtropical regions [23]. For example, in certain indigenous communities in Costa Rica, the diversity of edible plants in homegardens is exceptionally rich, encompassing nearly all edible plant resources in the surrounding ecosystem, including rare species [24]. To explore issues concerning the preservation of homegarden plant diversity and associated mechanisms in regions with well-maintained homegardens facing significant environmental changes, it is essential to determine an appropriate landscape scale for investigation. The research focuses on the Laershan region in western Hunan, a typical karst rocky area in southern China heavily influenced by policy-driven land use changes [25]. This area, a traditional settlement of the Miao ethnic group, boasts well-preserved homegardens. Consequently, an extensive field survey of homegarden plants in the Laershan region is conducted to address the following inquiries: What is the current status of traditional ecological knowledge pertaining to homegarden plants that support livelihoods and sustainable development in the Laershan region? What factors influence the distribution of homegarden plants across different townships in the Laershan region?

To address these questions, we conducted field research on homegarden plants and related traditional knowledge in three Miao communities in the Laershan Plateau of western Hunan province, China. The main work of this study included: (1) collecting, recording, and organizing homegarden plants and related traditional knowledge in the local communities; (2) analyzing the species and functional diversity of homegarden plants in this region, and to demonstrate the heterogeneous distribution characteristics in different communities by integrating GIS (Geographic information system) and remote sensing data; and (3) preliminarily elucidating how forest resource distribution and land use changes may affect homegarden plant management and traditional knowledge. This study helps policymakers scientifically understand the dynamics of homegarden plants and related traditional knowledge, allowing them to take appropriate measures tailored to local conditions to promote traditional knowledge protection and homegarden development. This study fills a research gap by investigating homegarden plants in the Miao ethnic region of ** conservation and sustainable utilization strategies.

Methods

Study area

The study area is located in the Laershan Plateau in the western part of Hunan Province, China, within the geographical coordinates of 109°18′00″ to 109°33′59″ east longitude and 28°02′00″ to 28°11′31″ north latitude (Fig. 1). The elevation ranges from 700 to 1000 m, with an average annual temperature of 14 °C. The area has a resident population of approximately 53,000 people. The study area is known for its scarcity and infertility of land, complex climate, and diverse small-scale farming practices [26]. Figure 1 illustrates that the scattered red patches labeled as "Building" on the plateau indicate the main settlement areas of the local Miao ethnic group, concentrated in three townships: Laershan, Lianglin, and Heku. These settlements are primarily situated in a handful of villages at elevations ranging from 750 to 860 m, representing some of the lower-altitude zones on the Laershan plateau with advantageous conditions for agriculture and livelihoods.

Fig. 1
figure 1

Geographical location of the study area: Laershan Plateau, **angxi Tujia and Miao Autonomous Prefecture, Hunan Province, China

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We chose these study villages because they have a long history of traditional mountain agriculture, and homegarden plants play a vital role in sustaining the daily livelihoods of families. For our field investigation, we selected three Miao ethnic townships in this region, namely Laershan Township, Lianglin Township, and Heku Township. Within these townships, three villages were selected for Heku and Laershan, while Liangliu selected two villages (Table 1).

Table 1 Study villages, locations, elevation, and number of households interviewed
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The vegetation of the Laershan Plateau is primarily composed of tree cover (81.35%), followed by cropland (13.79%). Barren and sparse vegetation accounts for 3.22%, while grassland (1.03%) and water resources (0.32%) are relatively scarce (see Fig. 1) [27]. The main crops in this region include corn, rice, sweet potatoes, and soybeans, which are well-suited to the subtropical monsoon humid climate with hot summers and mild winters. The population is mainly concentrated in township government headquarters and lower-altitude areas, where the local Miao people have long engaged in homegarden farming, resulting in a contiguous homegarden landscape. Knowledge about homegarden plants is still well-preserved to this day.

From a historical perspective, the Laershan region holds a significant position in the continuation of the Miao ethnic group. This area has been the birthplace of almost every Miao rebellion in Chinese history. Since the Ming and Qing dynasties, the central government built the Miao Frontier Wall in this region to isolate the Miao people, especially the term "Sheng Miao" (a term denoting Miao residents in secluded areas like the La'er Mountain plateau, who then faced restricted access to modern resources for production and daily life). This has allowed the Miao people in the Laershan region to maintain their traditional lifestyle.

Up to 2013, the Chinese government implemented a targeted poverty alleviation strategy to lift 70 million Chinese citizens out of poverty [28]. This endeavor entailed investments in sectors like transportation, healthcare, and education across extensive rural areas, including the Laershan region. Consequently, formerly underdeveloped areas started to witness enhanced access to transportation and improved educational prospects. Due to the lack of resources and insufficient food production in historical times, the local small-scale household economy prevailed. In this unique environment, the Miao people developed an adaptable and autonomous homegarden economic system, ensuring their stable livelihood.

Figure 2 displays a painting depicting the Miao homegarden landscape in the Laershan region in 1794. This artwork (Courtesy: The Palace Museum of China) showcases the living conditions of the Miao people during a politically turbulent period, providing valuable empirical data for studying the homegarden plants in this region.

Fig. 2
figure 2

In 1794, the Qing dynasty government dispatched troops to suppress a peasant uprising in the Laer shan region, led by Bayue Wu, also known as Tianban Wu. The accompanying image showcases the homegarden landscape of the Miao people in this area during that period (Courtesy: the Palace Museum of China), depicted through realistic painting techniques by Feng Ning, a court painter of the Qing dynasty

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Overall, due to the influence of factors such as natural geography, vegetation, climate, and historical background, the Laer Mountain region possesses a resilient homegarden plant system with a long history. This system has played a crucial role in sustaining the livelihood and well-being of the local people.

Data collection

Ethnobotanical data analysis

The investigation was conducted in the Laershan region from September 2021 to August 2023. A total of eight traditional Miao ethnic villages were randomly selected in the study area, and 102 well-preserved homegardens with traditional management were surveyed on-site (Table 1). The inclusion criteria for selecting gardens in our sample were as follows: (1) proximity to the house; (2) defined boundaries of the land (enclosed by bamboo, bricks, etc.); and (3) exclusion of abandoned land (homegarden of household engaged in continual migrant work without proper maintenance). To ensure sample representativeness and reduce bias, each village included a varying number of homegardens, ranging from 10 to 20.

To optimize the comprehensive documentation of homegarden flora and associated traditional knowledge, this investigation initially employed a semi-structured interview approach to engage with adults overseeing homegarden management on a household level. Given the prevalent limited proficiency in Mandarin among the local Miao population, community administrators and local plant experts, including herbalists and elders knowledgeable in plant utilization, were enlisted to facilitate the translation of Miao language used in daily communication to Mandarin. The participants were then presented with a set of five principal inquiries:

  1. (1)

    Introduction of homegarden plants: Can you provide an overview of the plants cultivated in your homegarden? How many distinct plant species are present?

  2. (2)

    Purpose of cultivation: What is the intended purpose behind cultivating these plants? Specifically, are they cultivated for self-sufficiency (including cooking methods such as steaming, stir-frying, and boiling), trade (mentioned by interviewees as plants intended for sale at markets), medicinal use, ornamental purposes, or as forage for poultry and livestock?

  3. (3)

    Utilization methods: How are these plants utilized, including the processing methods involved?

  4. (4)

    Plant part utilization: Which specific part of the plant is utilized?

  5. (5)

    Origin of plants/seeds: Where were these plants or seeds originally sourced from?

Utilizing semi-structured interviews, we implemented an inventory interview to validate on-site gathered information, encompassing details on plant species, life forms, sizes, uses, and frequency of use. To enhance the precision of the survey data, we eliminated ambiguous species names and rectified inaccuracies. Furthermore, in order to enhance the plant list and associated traditional knowledge, two focus group discussions were organized. These sessions involved botanical experts, local experts in traditional plant usage, and selected information providers. The primary objective was to validate the alignment between local and scientific plant names, establish standardized utilization descriptions, and enhance the compilation of the plant inventory and associated traditional knowledge.

Ethical considerations

Prior to commencing field surveys and data collection, consent agreements were secured from regional officials and traditional community leaders. Participants provided verbal consent after being briefed on the research objectives. Data collection took place following the receipt of verbal consent. The survey procedures adhered to the ethical guidelines of the International Society of Human Ethology [29].

Plant identification

During the field investigation, this study captured images of both ubiquitous and locally distinctive plants within the gardens. Additionally, plant specimens that posed identification challenges on-site were collected as voucher specimens. The acquisition of photographic materials and voucher specimens involved securing informed consent and authorization from both the local administrative authorities and garden owners. The identification of plant species primarily relied on the authoritative reference "Flora of China" [30] and relevant botanical websites such as http://www.iplant.cn/. Species name verification was conducted using the database available at https://wfoplantlist.org/plant-list.

Data analysis

To ascertain the comparative efficacy of plant species in homegardens and the extent of disparities in their utilization across townships, a quantitative assessment was undertaken. This involved the computation of various indicators, namely the Relative Importance Index (RI), Use Value Index (UV), Shannon–Wiener diversity indices, Jaccard Index (JI), and the Comprehensive Index of Land Use Degree. These metrics are detailed below.

Relative important value (RI)

The Relative Importance Value (RI) is used to evaluate the degree of utilization of homegarden plants in daily life in the Laershan region. This evaluation employs a calculation formula outlined as follows [31]:

$${\text{RI}}={\text{NUC}}+{\text{NT}}$$

where NUC (Number of Use Categories) represents the ratio of a specific plant's use categories to those of the plant with the highest use categories; NT (Number of Types) denotes the ratio of a plant's use categories to the highest recorded in the region. The larger the RI value, the more types of uses and the larger the number of use categories for a certain plant.

Use value index (UV)

The Use Value Index (UV) [32] assesses the utilitarian value of plants within the local context. The calculation formula for the UV value is expressed as follows:

$${\text{UV}}=\sum \frac{{U}_{{\text{i}}}}{n}$$

In this formula, (Ui) denotes the frequency with which an individual plant is cited in the utilization information provided by an informant, and (n) represents the total number of informants. The UV value spans from zero to infinity, with a higher UV value signifying greater utilitarian value attributed to the plant.

Jaccard index (JI)

The Jaccard Index (JI) was utilized to assess the similarity of homegarden plants among three townships. By comparing the JI values of homegarden plants in different townships, the extent of similarity in traditional knowledge related to homegarden plant utilization can be evaluated. The formula used to calculate the JI is as follows [33]:

$${\text{JI}}=\frac{c}{\left(a+b-c\right)}*100$$

where "a" represents the number of species used by residents in Town A, "b" represents the number of species used by residents in Town B, and "c" is the number of species used commonly by residents in both Town A and Town B. A higher Jaccard Index (JI) value indicates greater similarity in homegarden plants between Town A and Town B.

Comprehensive index of land use degree

The Comprehensive Index of Land Use Degree [34] employed to assess the impact of land use changes on traditional knowledge related to homegarden plants in different townships. The formula used to calculate the Comprehensive Index of Land Use Degree is as follows:

$${\text{La}}=100\times \sum_{i=1}^{n}{A}_{i}\times {C}_{i}$$
$${\text{La}}\in \mathrm{100,400}$$

where La represents the Comprehensive Index of Land Use Degree, Ai represents the land use degree classification index of the i level, and Ci represents the percentage of land use degree classification area of the i level. The land use degree was classified based on the impact of land use types on homegarden plants, following the method described in literature [34]. The value of La ranges from 100 to 400, reflecting the degree of land use as a continuous indicator. A higher La value indicates a higher local land use degree.

Additionally, the cataloging of homegarden plants and associated traditional knowledge was conducted using Microsoft Office software for statistical analysis. Spatial map visualization and data processing were performed using ArcGIS 10.8 [35]. The geographic data utilized in this study were obtained from various sources including National Geomatics Center of China (https://www.ngcc.cn/ngcc/), Geospatial Data Cloud (https://www.gscloud.cn/), Standard Map Service (http://bzdt.ch.mnr.gov.cn/), and the research conducted by Li et al. [27].

Results and discussion

Demography of informants

Informants selected for this study were primarily household heads and the main managers of the homegardens. A total of 112 informants were interviewed, with 84 (75.0%) being male and 25 (25.0%) female. These informants were classified into three age groups, as shown in Table 2. We found that the local residents managing the homegardens tended to be older, with half of the informants being over 50 years old, and farmers accounting for 91.1% of the sample.

Table 2 Demographic information about the informants in the study area
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Species diversity of homegarden plants

The survey recorded a total of 152 plant species, encompassing 62 families and 124 genera. Table 3 provides a summary of the homegarden plant species managed by the respondents, including information on their local common names, scientific names, life forms, uses, and plant parts utilized, use method, UV values, RI values, and cultivation status. The enduring management by local residents has fostered a sustainable and resilient traditional homegarden plant system. This traditional practice has been supported by research on homegarden plant diversity in areas like southwestern China, India, and Thailand [3, 36, 37]. This suggests that the long-term management by local inhabitants has fostered a sustainable and resilient traditional homegarden plant system. Several prevalent plant families discovered in these homegardens include Asteraceae (12 species), Cucurbitaceae (9 species), Fabaceae (9 species), Rosaceae (8 species), and Apiaceae (7 species). For example, plants from the Asteraceae and Cucurbitaceae families exhibit high ornamental value while providing additional advantages such as wind resistance, soil conservation, and climate regulation. Fabaceae plants fulfill the dietary requirements of the local population, and notably, they possess robust nitrogen fixation abilities that enhance soil fertility in the karst region of the Laershan Mountains. Our research aligns with a homegarden plant survey carried out in the Sebeta-Awas District of the Oromia Region in Ethiopia. The prevalent plants in local homegardens belong to the Fabaceae and Asteraceae families. These species play a vital role in providing food to assist local communities in addressing food insecurity. [38]. Despite the locals' potential lack of awareness regarding these beneficial functions during field surveys, their significance should not be overlooked.

Table 3 List of homegarden plants in the study area (in alphabetical order)
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Based on our survey results, herbaceous plants constituted 56.6% of the total, followed by trees (23.7%), shrubs (12.5%), and vines (7.2%). Herbaceous plants display greater diversity within homegarden ecosystems, potentially attributed to their rapid growth rates, adaptability, and diverse functional attributes that cater to various daily requirements, including medicinal, culinary, and commercial uses. The choice of trees and shrubs may be influenced by economically significant tree species as well as the provision of shade and shelter for housing purposes. Additionally, this composition of life forms among homegarden plants exemplifies the traditional local wisdom pertaining to the sustainable utilization and conservation of plant resources.

Multifunctionality of homegarden plants

The homegarden plants in the Laershan Plateau exhibit rich diversity while also serving various functions and utilitarian values. This study categorizes the homegarden plants into five primary functional types: edible plants, trade plants, ornamental plants, medicinal plants, and forage plants. The data indicate that there are 106 species of both edible and trade plants, signifying that local homegardens in the area mainly serve the needs of food consumption and livelihood maintenance. By classifying various plant types, we can enhance our comprehension of the importance of local homegardens in fulfilling food needs and supporting livelihoods.

These homegardens also play a significant role in planting ornamental plants for aesthetic enhancement and medicinal plants for health purposes. Certain residents plant various ornamental plants in their homegardens to enhance their happiness. Ornamental plants are easily exchanged between gardens. In the survey, a homeowner in "Dehe Village" discovered beautiful Yucca gloriosa in a neighbor's homegarden and transplanted it to their own garden after communication with the neighbor. Medicinal plants play an important role in the Laershan Plateau. For example, Diospyros cathayensis is used to treat sudden heart pain, and many indigenous medicinal plants for injuries, snake bites, and other ailments are distributed in homegardens. Homegarden owners who plant these plants usually have traditional knowledge of treating common local diseases. Homegardens have garnered considerable scholarly interest due to their social and cultural significance. Recently, several studies have offered detailed insights into the cultural roles of homegardens, specifically focusing on the traditional practices of local inhabitants in utilizing and preserving natural resources. These studies highlight the transmission and utilization of indigenous traditional knowledge within homegardens [20, 23, 24, 31].

Additionally, we found 30 species of forage plants for animal consumption that locals can collect for home breeding. Through the investigation, we learned that locals have traditionally used plants grown in gardens as animal feed rather than market feed. They have accumulated abundant plant knowledge, such as the fact that long-term feeding of Galium spurium to pigs can cause toxicity or even death, but short-term feeding is harmless. Therefore, they alternate feeding Brassica rapa and Galium spurium to pigs. Accurate identification and effective use of forage plants demonstrate the wisdom and practical knowledge of local inhabitants in harnessing natural resources and managing animal husbandry. Conducting additional research on the attributes and appropriateness of these forage plants is advantageous in mitigating feed shortages and fostering the sustainable advancement of animal husbandry.

Figure 3 shows the multifunctionality of some plants among the five categories, and we found that Artemisia argyi, Mentha canadensis, and Taraxacum mongolicum are homegarden plants that exhibit all five functions. Most plants have more than two basic functions. The existence of multifunctional plants reflects the unique traditional knowledge of plant utilization held by local residents. The potential for maintaining resilient homegarden ecosystems, cultural heritage, and high-quality homegarden economic development is evident. Hence, there is a critical need to prioritize the optimization of homegarden planning and management to improve their overall efficiency and sustainability. This is particularly important considering the pivotal role of multifunctional plants in supporting homegarden ecosystems, conserving cultural heritage, and fostering economic development [16, 17, 19].

Fig. 3
figure 3

Wayne diagram of plant functional diversity in Miao homegarden on the Laershan Plateau

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RI value

In addition to descriptive statistics on the multifunctionality of homegarden plants, we evaluate the local utilization of each plant based on its RI value. A higher RI value reflects a greater traditional knowledge of the local community regarding a specific plant. Among the surveyed plants, eight species, namely Mentha canadensis, A. argyi, Elaeagnus pungens, Taraxacum mongolicum, Lindera reflexa, Mirabilis jalapa, Nelumbo nucifera, and Raphanus raphanistrum subsp. Sativus, have an RI value exceeding 1.5. These three plants, M. canadensis, A. argyi, and T. mongolicum, possess all five basic functions (Fig. 4).

Fig. 4
figure 4

JI value of homegarden plants among three townships

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The findings highlight the significant traditional knowledge value of these plants in the Laershan region of western Hunan. Our research indicates that these species primarily serve functions related to food provision and sustaining livelihoods. For instance, M. canadensis is predominantly employed for consumption and trade, while A. argyi is also principally utilized for commercial transactions and monetary exchange. This implies that the prioritization of these plant resources by local residents aligns with the region's production methods and living circumstances.

M. canadensis stands out with the highest RI value of 2.00, indicating its wide range of uses and popularity within the local communities. Our investigation uncovered the utilization of its tender shoots and leaves as vegetables or seasonings in a variety of dishes. It is also available for sale in numerous market stalls. Additionally, its beautiful flowers and distinctive aroma are greatly valued. Some residents even brew it as herbal tea to alleviate headaches and cold symptoms. Moreover, it serves as fodder for poultry and livestock. These diverse uses illustrate the deep understanding and extensive knowledge that local residents possess regarding this plant.

A. argyi, with an RI value of 1.75, is also widely employed in various domains, potentially attributed to its traditional medicinal applications and the customs of the Miao ethnic group. Our findings indicate extensive trading of this plant in local markets to meet the distinctive cultural needs of the region. The attentive care given to plants with higher RI values in the homegardens indicates a longstanding tradition of utilizing plant resources, fostering the preservation and advancement of traditional knowledge. It also signifies the local residents' reverence and safeguarding of native plant resources.

UV value

The study aims to analyze the practical value of plants in the local area by ranking them according to their UV value. Table 3 shows that Zea mays has the highest UV value (1.43), followed by Ziziphus jujube (1.39). Additionally, Morus alba, Zanthoxylum bungeanum, Brassica rapa, Ipomoea batatas, and Eriobotrya japonica all have a UV value of 1.35, thus ranking them third. Plants with high UV values play a crucial role in the daily life of the local communities. Besides being adaptable and yielding high crops, Z. mays also serves as a staple food source for the locals and a primary feed for livestock. Z. jujube and M. alba fruits are popular and essential components of homegarden planting. Furthermore, Z. bungeanum seeds are utilized as a seasoning in local cuisine, and B. rapa is a crucial ingredient in pickling. The traditional knowledge of plant utilization by local residents helps recognize their practical value better and provides a foundation for the sustainable use of homegarden plants.

The UV value reflects the practical value of plants and their importance within the local communities. Contrasting plants with higher and lower UV values enables us to identify the preferences and demands of the local communities, obtain insights into the current utilization status of local plant resources, and provide references for the selection and promotion of these plants. For instance, although B. vulgaris and A. hookeri are non-essential in the local area, they may be more valuable in other regions. In conclusion, these homegarden plants hold substantial ecological, economic, social, and cultural importance. Similar research work, through ranking plants based on their UV values, allows us to observe the geographical specificity of plant resources in different regions, hel** us understand the preferences and needs of local communities [13,14,15, 18]. This approach enables a better comprehension of the role and significance of homegarden plants in local livelihoods.

Heterogeneous distribution of homegarden plants

The present study conducted a quantitative analysis of the variations in homegarden plant species across three different communities, utilizing the Jaccard Index (JI). A higher JI value signifies a stronger resemblance in homegarden plant species between two villages, whereas a lower JI value implies a greater disparity. The computed results demonstrated that Lianglin Township and Laershan Township achieved the highest JI value of 50.5, which considerably exceeded the values observed between Heku Township and the other two locations. More specifically, the JI value between Heku Township and Laershan Township stood at 40.7, whereas the JI value between Heku Township and Lianglin Township was recorded as 39.0. In summary, the homegarden plant species in Lianglin and Laershan Township exhibit a higher degree of similarity, potentially attributed to frequent exchanges of traditional knowledge between these regions.

The plants with limited utilization and known value, mainly concentrated in the homegarden of Heku Township, include Malva verticillata and Allium hookeri, which are used for stir-frying vegetables and are only planted by residents of Heku Township. Podocarpus macrophyllus, known for its high ornamental value in garden landscapes, is cultivated only by residents of Lianglin Township. Biancaea decapetala, adorned with thorns, is planted exclusively by residents of Laershan Township to embellish their homegardens.

All three townships in the study area are inhabited by the Miao ethnic group and situated on the Laershan Plateau. Despite their similar geographical locations and cultural-historical backgrounds, we have noted varying degrees of homegarden plant utilization across these townships. We hypothesize that this variance could be associated with shifts in vegetation types and land utilization practices.

Factors affecting the heterogeneous distribution of homegarden plants in communities

According to the forest resource distribution shown in Fig. 5, there are significant differences in the composition of forest resources among the three surveyed areas. In Heku Township, Chinese fir forest accounts for the highest proportion, reaching 35%, while broad leaved forest and pine forest make up 13.22% and 12.52%, respectively. In contrast, Lianglin Township has the highest proportion of pine forest at 32.84%, followed by broad leaved forest at 14.12%, and Chinese fir forest with the lowest coverage at 8.72%. In Laershan Township, pine forest covers nearly half of the community area at 48.11%, followed by Chinese fir forest at 7.78%, and broad leaved forest with the lowest coverage at 5.26%. These data indicate substantial differences in the forest resource composition of Heku Township compared to the other two townships. However, the spatial distribution of forest resources in Lianglin and Laershan Township is more similar. This observation aligns with the Jaccard Index, which reflects the diversity of homegarden plants among communities and indicates the significant influence of forest resource distribution on the selection of homegarden plants by local residents. Based on this, we speculate that communities with similar forest resource compositions are likely to have similar compositions of homegarden plants. This finding implies that the forest resource composition may influence the lifestyle and economic development of local residents, impacting the selection and cultivation practices of homegarden plants, along with potential variations in resource utilization patterns among communities. Comparable scenarios have also been identified in Martin's research [39].

Fig. 5
figure 5

Distribution map of woodland resources in the Laershan Plateau

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In the three surveyed townships, Heku Township has a significantly higher proportion of buildings (0.41%) compared to Lianglin Township (0.12%) and Laershan Township (0.21%), as observed in the survey data of the three townships. The results of the field surveys reveal that Heku Township has the highest number of homegardens, followed by Laershan Township, while Lianglin Township has the fewest. Due to the prevalence and good maintenance of buildings in the study area, they serve as an effective representation of homegarden spatial distribution, which is consistent with the findings of the field surveys (Fig. 5). Furthermore, the number of homegardens not only reflects the degree of focus on plant diversity and conservation awareness but also signifies the transmission of traditional knowledge [40]. Moreover, simulation results provide further evidence of the strong correlation between homegardens and traditional knowledge [41]. Consequently, it is hypothesized that the quantity and area of homegardens in an area are directly proportional to the extent of traditional knowledge it possesses (Fig. 6).

Fig. 6
figure 6

The change map of land use type in the Laershan Plateau

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During the interviews conducted in Laershan Township, it was found that limited transportation hindered interactions between communities in the past, resulting in a restricted dissemination of knowledge about homegardens and wild plants. Most residents focused on the economic benefits brought by farming and neglected the management of homegarden plants. However, improved roads have strengthened communication between communities, leading to the widespread dissemination of knowledge about homegardens and wild plants. This has promoted plant diversity and renewed recognition of the economic value of homegardens among residents. To analyze this change in depth, we collected land use data for Laershan Plateau in 2000, 2010, and 2020 and analyzed the changes in land types related to homegarden management. A comparison revealed no significant changes in land use types from 2000 to 2010. However, by 2020, there was an increase in artificial surfaces, a decrease in cultivated land, minimal changes in water bodies, and an increase in forest and grassland areas. These changes align with the "returning farmland to forest" policy implemented by the local government between 2010 and 2020 [28], as mentioned in the interviews. Therefore, we hypothesize that transportation accessibility and policy orientation are key factors influencing homegarden plant diversity.

According to our analysis of the comprehensive index of land utilization intensity (La) in Table 4, there was almost no change in the land utilization intensity of the entire survey area or the three individual communities between 2000 and 2010. However, compared to the past, there was an improvement in land utilization intensity in 2020, primarily reflected in a significant increase in forest and artificial surfaces. The expansion of forest areas provided more space for wild edible plants (WEPs), which are rich in nutritional and medicinal value and hold significant importance for the lives and health of residents [42, 43].During field investigations, residents expressed that the implementation of the rural revitalization strategy has provided them with more time and energy to learn about plant knowledge and take care of their own homegardens, as their material lives have been guaranteed. Therefore, plants with various uses and knowledge acquired through knowledge exchange were discovered in the wild and planted in their own homegardens. The increase in artificial surfaces means that more homegardens are being maintained, thereby enhancing the diversity of homegarden plants [44].

Table 4 Comprehensive index of land use degree (La) of Laershan
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Our analysis reveals a positive correlation between the richness of homegarden plants and related traditional knowledge with land utilization intensity. The highest level of land utilization intensity in 2020 was observed in Heku Township, which also had the highest homegarden plant diversity. Conversely, Lianglin Township, with the lowest land utilization intensity, had the lowest homegarden plant diversity. In other words, higher land utilization intensity is associated with greater richness of plants and related traditional knowledge, while lower land utilization intensity is linked to lower richness of plants and related traditional knowledge. This finding contributes to a better understanding of the ecological and cultural diversity in rural areas, as well as the impact of policy promotion and improved transportation conditions on homegarden plant diversity. This study revealed that shifts in land use have impacted the utilization of homegarden plants, affirming the substantial role of enhanced land policies and infrastructure in promoting local ecology and culture [45, 46]. Further attention and research on this phenomenon can provide strong support for the rural revitalization strategy and the construction of an ecological civilization, promoting sustainable development in rural areas.

Conclusion

This study recorded 152 plant species from 62 families and 124 genera, which play a crucial role in maintaining ecological balance and enhancing the resilience of homegarden ecosystems against disturbance in Miao ethnic communities in Laershan Region. Their multifunctionality, including use for food, trade, ornamentation, medicine, and fodder, highlights the significant impact of human activities on the diversity of homegarden plant species. The diversity of homegarden plant species varies among the three communities in the Laershan region, which may be influenced by the selection of plants from similar forest resource communities.

This reflects the different lifestyles and needs of residents as well as the correlation between cultural exchange among communities and distribution patterns of plant species. The residents of the Laershan Plateau use plants based on their lifestyles and needs, demonstrating the close connection between homegarden plant species and the local residents' way of life. Multiple factors influence the heterogeneous distribution of homegarden plants, including resource distribution, cultural exchange, natural conditions, and lifestyle. Future research should further investigate these factors to provide a theoretical basis for the conservation, utilization, and sustainable development of homegarden plant resources.

Although this study provides a systematic understanding of the diversity of homegarden plant species in the Laershan Plateau, the time span was relatively short, limited to the years 2000, 2010, and 2020, and may not fully demonstrate long-term trends in analyzing the relationship between changes in land use types and plant diversity. Future research should consider extending the time frame to obtain a more comprehensive understanding.

This paper offers a preliminary exploration of the connection between plant species diversity and traditional culture. Future research should further investigate this topic to reveal more culturally valuable plant species and the applications of these plants in traditional knowledge and practices.