The study areas of this research were located in Selajambe—Ciomas Rahayu Village, West Java, Indonesia; and in Tegal Yoso—Tanjung Kesuma Village, the transmigration area of East Lampung (Figure 1; Table 1). Research in Selajambe—Ciomas Rahayu was conducted in October–December 2019, and research in Tegal Yoso—Tanjung Kesuma was conducted in June–July 2021. Selajambe—Ciomas Rahayu village was chosen to be the representative of the Sundanese living on the island of Java, while Tegal Yoso—Tanjung Kesuma Village was chosen due to majority of the population being Sundanese who transmigrated to the East Lampung area. Selajambe—Ciomas Rahayu village was chosen due to being a rural area, and also, the average proximity of these villages to the city center (economic activities) ranges from 9 to 14 km. There were 40 pekarangans taken from each study area, so the total number of samples was 80 pekarangans. The samples were determined by the purposive sampling technique (Sundanese). The number of samples was determined according to the sample determination by Arifin et al. (1998) and Ali et al. (2021). In total, 10 samples in Ciomas Rahayu Village and 30 samples in Selajambe Village were based on the representation of the number of pekarangan in the research location, respectively. Therefore, the villages of Tegal Yoso and Tanjung Kesuma followed these provisions to make comparisons easier. By collecting the data during the COVID-19 pandemic, we conducted research by implementing strict health protocols. We also collected some respondent data by an online survey.

To analyze the biophysical conditions of a pekarangan, there were four minimal variables of a pekarangan, that is, measuring the area and size, pekarangan zoning, number of species and individual plants per pekarangan, and the vertical diversity and horizontal diversity of plants. In this article, some of the pekarangan conditions of the pekarangan are measured such as the pekarangan area (m²), size of the pekarangan (small to extra larges), the zone of the pekarangan, the number of species and individual plants per pekarangan, and the vertical and horizontal diversity of plants. In addition, this study also calculated the effect of the pekarangan area on the number of individual plants per pekarangan. These measurements were carried out to show the differences of biophysical conditions of the pekarangan between Sundanese migrants and non-migrants.

The area of the pekarangan (m²) and the size of pekarangan are the important things in ecological value because the owner can use it to plant various plants, especially tree species. This can provide natural shade, provide fresh air, and also benefit from the fruit. In addition, the area of the pekarangan can also be a water catchment area when it rains, so that it becomes a source of water reserves that can be used for plants. Loss of yard area due to conversion to other uses will cause impacts such as the increase in temperature around the house because of the unavailability of land to plant trees, making the air feel hotter, causing large run-off when it rains, and causing puddles. Although currently small pekarangans are widely used with vertical garden patterns and potted plants, shade functions, fresh air, and water absorption cannot be provided well by a small pekarangan.

The pekarangan sizes (Arifin et al., 1998) were determined by data-centered descriptive statistics (Kaur et al., 2018), such as the mean, median, minimum value, maximum value, and standard deviation. u   =   Land   Area   ( m 2 )   -   Building   Area   ( m 2 ) , (1) u ⌢ = 1 n ∑ i = 1 n u i . (2) u = pekarangan area. ȗ = average pekarangan area. ui = area of the i-th pekarangan. n = number of sample pekarangans

The pekarangan sizes were then grouped into Small ≤ 120 m², 120 m² < Medium ≤ 400 m², 400 m² < Large ≤ 1,000 m², and Extra Large > 1,000 m² (Arifin et al., 2012). The zoning of the pekarangan divided the pekarangan into four zones, that is, the front yard, left yard, right yard, and backyard (Arifin et al., 1998; Arifin et al., 2010). The number of species and individual plants per pekarangan was determined per 100 m². The same unit area was needed to compare (Peng et al., 2018) the number of plant species and individuals in migrants’ and non-migrants’ pekarangans. Vertical diversity was the grouping of plants based on the plant height, and horizontal diversity was the grouping of plants based on the plant function (Table 2) (Arifin et al., 1998; Arifin et al., 2010; Arifin et al., 2012).

Simple linear regression analysis was largely used to analyze between two biophysical conditions (Nelson, 2009) and also was conducted to see the effect of the pekarangan area on the number of individual plants in each location. Calculations and data processing were carried out in Microsoft Excel 2016. Shorting data was carried out to discard data with a high error value.

Knowing the biophysical condition of the pekarangan based on the type of migrants and non-migrants from the same ethnicity (Sundanese) provides evidence that whether different pekarangan areas and sizes of the pekarangan will have an impact on different plant diversities, both in species and number of individuals.

As a comparison area for the native Sundanese ethnic, Selajambe and Ciomas Rahayu villages were chosen. They are located in the West Java Province. The population of two villages consisted of 80% of the original residents (Sundanese Bogor and Cianjur), and 20% were immigrants (Sundanese from another area). These two villages were characterized by rural areas that have been heavily affected by urbanization. There were fewer people working as farmers. Many residents switched to work as entrepreneurs or Indonesian migrant workers (TKI) in foreign countries (Kertawibawa and Harun, 2012). The average income of the population was 1.5–2.7 million rupiahs/person/month. The increasingly expensive prices of basic necessities have forced residents to switch jobs to more promising sectors. In the Selajambe Village, there were still irrigated rice fields, but their existence continued to be eroded by the construction of garment factories. This development occurred because this village was traversed by the highway that connected Cianjur and Bandung. This definitely affected the biophysical conditions of the area including the pekarangan.

Lampung province has been known as a transmigration area since the Dutch colonial era. The transmigration program in Lampung province, specifically in East Lampung Regency, occurred in the period 1952–1953. Most of the people who transmigrated came from the island of Java (Sundanese and Javanese ethnics). Purbolinggo, as one of the sub-districts in the East Lampung Regency, consisted of Sundanese transmigrants. Tegal Yoso and Tanjung Kesuma villages were villages where the majority of them were Sundanese ethnic. The population of the two villages was 45% from Bandung, 40% from Sumedang, 13% from Tasikmalaya, and 3% from Majalengka, West Java Province. The annual rainfall and temperature in the Purbolinggo sub-district were suitable for people to carry out agricultural activities. Both villages were characterized by rural areas with the main commodities, such as rice and corn. The agricultural land system was based on the irrigation system. In December, usually farmers planted rice, and in June, farmers planted corn. The distance between two villages and Sukadana (the capital city of East Lampung Regency) was about 14 km. The two villages were also close to the Sumatran East Coast National Road. The average monthly income of residents who work as farmers was 1–1.5 million rupiahs/person/month. This number was higher than the Lampung poverty line, which was IDR 457,495/person/month.

The dynamics of changes that occurred especially in non-migrant pekarangans were strongly influenced by urbanization factors. In Arifin et al. (1998), when the first research of a pekarangan had been conducted in those locations, the average area of the pekarangan in Selajambe—Ciomas Rahayu was 364.7 m². In 2019, the average area of the pekarangan was 150.7 m² (Ali et al., 2021), it was from the medium size in 1998 to be the small size in 2019. The reason of decrease was due to urbanization during 2 decades (1998–2019). The four urbanization factors that mostly influenced changes in the pekarangan were the increasing level of education, the use of technology, the increase in the average income of the community, and the increase in the built-up area (Ali et al., 2021). It happened because the economic development of the island of Java was much higher than the island of Sumatra. The level of education and ease of access to technology made the development of rural areas into suburban and even urban areas faster. The need for a place to live or a place to sell was also an important reason so that the pekarangan land became the first land to be converted into the new building. For the Sundanese themselves, the pekarangan became one of the inheritances that were divided among the children, thus making the pekarangan land fragmented and its size from medium to small. It was also happening in the migrant pekarangan. The pekarangan land that used to be large was handed down to children as a land to build a place to live (house). Although the decrease in the pekarangan area was still small, it was proven that the current pekarangan size was 80% large and extra-large. Does the difference in the size of the pekarangan between a migrant and non-migrant one affect the diversity of species and individual plants? This will be explained in the species and individual plants of pekarangan sections.

The performance of the migrant pekarangan is not much different from the non-migrant one. They still brought Sundanese habits and culture to the transmigration area. The difference was showed by the different sizes of the pekarangan. Migrant pekarangans were wider because the transmigration program provided land to build houses and pekarangans on average of 0.25 ha. Currently, the average land area has been only 1,200 m². Since 1952 until now, the average pekarangan area of his/her house is 733.1 m² (large size), and 80% of the migrant pekarangan size is still in large and extra-large sizes (Table 3; Figure 2). The median value indicated that the size of the migrant pekarangan was ecologically well. Its size was above the minimum size of 100 m², while the non-migrant pekarangan was already below 100 m² (Arifin et al., 1998).

The front yard zone was almost found in migrant and nonmigrant pekarangans (Figure 3). The existence of a right and left yard in migrant pekarangans was higher than that of the non-migrant one and also the existence of a backyard. The front yard is still predominant because it is an important part of the house and can be used as a welcoming area. By that reason, the front yard was planted with many ornamental plants and other decoration stuff. Furthermore, the front yard was a characteristic sign of a house. It was shown by the Sundanese pekarangans. The other three zones began to decline due to the widening of houses or the construction of new buildings, for example, store, garage, etc. (Azra et al., 2014; Ali et al., 2020). Another reason for their decline in existence was due to being sold (Ali et al., 2021). The front yard zone was expected to be the most durable zone in a pekarangan because it had an important role and function for householders, especially the small pekarangan in urban areas. Nowadays, the front yard is not only being planted with the ornamental plants but also planted with vegetables, fruits, medicine, and spice plants. In particular, during this COVID 19 pandemic, many householders used their pekarangan while at home (work from home) for gardening, exercising, and other activities (Arifin et al., 2021; Montefrio, 2020; Sofo and Sofo 2020). However, in Arifin et al. (1998), the potential zone to be the most durable zone was the backyard. It was considered to be a potential space for biodiversity conservation such as food and medicinal plants, livestock, and fish ponds. The front yard was prone to change because it had a huge potential of being used for the construction of new buildings such as stall, workshop, and garage. (Arifin et al., 1998). Those activities were believed to have a positive influence in maintaining and increasing the immunity of the human body both physically and psychologically (Clatworthy et al., 2013; Buck, 2016; Soga et al., 2017; Corley et al., 2021). Because of that, the pekarangan, as the closest landscape unit in the house, was considered to be the best choice for doing those activities. This phenomenon was occurring in urban, suburban, and rural areas (Sofo and Sofo, 2020).

Sundanese migrants and non-migrants lived close to their families. It has been proven by the position of their house. There was a place to dry agricultural products (rice or corn) in the front yard of Sundanese migrants’ pekarangan (Figure 4A). The front yard, called buruan in Sundanese, was not only planted with ornamental plants such as in non-migrant pekarangans but also planted with food crops, for example, fruits, vegetables, spices, medicine, etc. (Figure 4A). The characteristics of the front yard of the Sundanese non-migrants were dominated by ornamental plants (Figure 4B). The majority of the front yards of non-migrants have been paved with concrete, asphalt, or cone blocks, while for non-migrants, the front yard was still left with soil. In migrant pekarangans, almost all the vegetations were directly planted on the ground, without the use of pots or planter boxes, while in non-migrant pekarangans, they planted them in pots or planter boxes.

The difference in the average number of species planted in pekarangan migrants and non-migrants was different, but the number of individual plants was almost the same. This indicated that per 100 m² of the pekarangan area had almost the same number of individual plants, although the number of species was different (Table 4). The difference in the number of species occurs because the average area of the pekarangan was different. The average area of 150 m² in non-migrant pekarangan was used to plant various types of plant species as much as possible, both for ornamental and food functions. This also indicated that both migrant and non-migrant pekarangans were being used well by their owners. This can be seen in the number of individual plants which are almost the same in every 100 m² of the pekarangan area. The differences in the number of species depend on the type of plant (ground cover plants to high trees). In the migrant pekarangan, it was proven by three plant species with a large number of individuals, such as kale, leek (vegetable), and cassava (starch). In non-migrant pekarangans, it was also proven by 19 plant species with 53 individual plants. The plant species consisted of Pleomele, wild tea, euphorbia, Sansevieria, aloe vera, cordyline, asplenium (ornamental), banana, rambutan, mango, papaya, jackfruit (fruit), tree spinach, Polyscias (vegetable), turmeric, cayenne pepper, galangal (spice), sweet potato, and cassava (starch).

The vertical diversity of plants in the pekarangan showed plant strata ranging from ground cover to high trees because the pekarangan looked like a forest which had layers of plants. In addition, there was also horizontal diversity which groups plants according to the functions mentioned by the owner of the pekarangan. Therefore, the use of plants in each ethnic was different. It was influenced by culture, mainly culinary and belief systems. The differences in the vertical diversity and horizontal diversity of plants between migrant and non-migrant pekarangans were not much different.

The total species of plants in migrant and non-migrant pekarangans were 189 and 167 species, respectively. From that number, it was clearly divided into the vertical diversity and horizontal diversity. In vertical diversity of plants in the pekarangan, there were 14 species in stratum V in both migrant and non-migrant pekarangans. There were 19 and 12 species of stratum IV in migrant and non-migrant pekarangans. There were 26 and 34 species of stratum III in migrant and non-migrant pekarangans. There were 61 and 42 species of stratum II in migrant and non-migrant pekarangans. Therefore, there were 69 and 65 species of stratum I in migrant and non-migrant pekarangans. The total ornamental (Or) and fruit (Fr) plants in migrant and non-migrant pekarangans were 80 and 28 species, respectively. The total vegetable (Ve), spice (Sp), medicine (Me), and starch (St) plants in migrant and non-migrant pekarangans were 24 and 16, 15 and 16, 15 and 11, and 9 and 5 species, respectively. The total industrial (In) plants in both migrant and non-migrant pekarangan were 9 species, respectively, and the last one, other (Ot) uses of plants were 9 and 2 species, respectively.

In Figure 5A, it can be seen that the condition of the vertical diversity of pekarangans in migrants showed the presence of stratum I (height of plant under 1 m), which was higher than the other four strata. The interesting one was that the percentage of strata IV (height of trees 5–10 m) and V (height of tree > 10 m) was almost the same between the two research sites. It indicated that plants with a height of more than 5 m were still present in non-migrant pekarangans, even though the size of the pekarangans has declined. The tree plants that were maintained a lot must have had more functions for the owner. These trees usually had ecological functions such as climate amelioration (shelters) and food functions (fruit trees). The existence of shady trees, especially in sub-urban pekarangan areas such as Ciomas Rahayu Village, was still widely maintained.

In Figure 5B, the horizontal diversity of pekarangans in the two research locations was also not too different. Ornamental plants still dominated among the eight functions of pekarangan plants. It was in accordance with the results of research Ortiz-Sanchez et al. (2015) and Irwan and Sarwadi, (2017) which stated that the home garden was dominated by ornamental plants. Ornamental plants in non-migrant pekarangans were higher than migrants due to urbanization. The urbanized pekarangans were dominated by ornamental plant species (Ali et al., 2021). Acalypha siamensis (wild tea) as an ornamental plant and Musa paradisiaca (banana) as a fruit plant were most commonly found in migrant and non-migrant pekarangans. This was in accordance with the conditions of rural pekarangans which were widely planted with ornamental and fruit plants (Mathewos et al., 2018; ElfridaMubarak and Suwardi, 2020) Curcuma longa Linn. (curcuma) as a spice plant was most commonly found in migrant and non-migrant pekarangans as well. In rural areas, there are still many people who grow plants for spices and seasoning in the pekarangan (Zuberi et al., 2014; Villa and García, 2017). Plants with other functions were more commonly found in migrant pekarangans. Plants with other functions are plants that function other than for food (Arifin et al., 1998), such as land boundary marker plants (Cordyline fruticose L. and Dracaena fragrans L.) (Werdiningsih, 2007) and fodder plants (Pennisetum purpureum), which were often found in rural pekarangans Schumach (Ivanova et al., 2021).

The effect of the pekarangan area was analyzed by simple linear regression and resulted in the effect of pekarangan area on the number of individual plants. In the migrant pekarangan (Figure 6), it can be seen that the regression graph showed a positive linear line, where upon the addition of 0.3905 m of the pekarangan area, the number of individual plants will be added. However, the concerned variable in this analysis is the x-value (increase in the area of the pekarangan). The r value (0.69) of the migrant pekarangan was in the category of strong correlation (Ridwan Aldila Melania Care et al., 2018), with a significant value = 0.000 < 0.05. The 48.02% of the number of plants can be explained by the influence of the pekarangan area and the other influences came from outside variables of the analysis.

In the non-migrant pekarangan (Figure 6), it can be seen that the regression graph also showed a positive linear line, where upon the addition of every 1 m² of the pekarangan area, the individual plants will increase by 0.4205. The r value (0.88) of non-migrant pekarangans was in the category of strong correlation (Ridwan Aldila Melania Care et al., 2018) with a significant value = 0.00 < 0.05. There are 77.77% of the number of plants that can be explained by the influence of the pekarangan area and the other influences also came from outside variables of the analysis. From the regression graph, it was found that the area of the non-migrant pekarangan was very strongly correlated with the number of plants in the pekarangan.

It can be seen that the area of the pekarangan had strong to very strong correlations (0.69–0.88) with the number of individual plants. Although migrant and non-migrant pekarangans have different areas, they have a strong relationship with plant diversity. The larger the pekarangan, the greater is the diversity of the plants. It was different from the findings of Antoh et al. (2019) on their pekarangan research in Arguni Bawah, West Papua Province, where they found a large pekarangan with low diversity of plants (the correlation was positive, but weak). It was proven by the comparison of plant diversity (number of individual plants) per 100 m² of the pekarangan area. Adjustments were made to the area of the pekarangan owned. The large pekarangan was planted with a large number of individuals, although the variety of species was little. The small pekarangan was being planted with a large variety of species but the number of individuals/species was the same as the large pekarangan as well per 100 m². Wherever the Sundanese lived, whether the size of pekarangan was large or small, the plant diversity of the pekarangan was high. It was due to their habit and culture. Mazumdar and Mazumdar (2012) stated that there was a functional value between the garden (plant diversity) and the family and culture.

Differences in conditions of migrant and Sundanese non-migrant pekarangans can be seen from the different types of plants planted. In migrants’ pekarangan, plants from food types dominated, while in non-migrants’ pekarangan, plants with ornamental functions dominated. This could be due to urbanization factors that are more influential on the Island of Java so that the dominant types of plants planted were also different. It must be improved so that the use of food plants also dominated in addition to the ornamental plants in small-medium sizes of the pekarangan.

All types of pekarangan sizes can display plant diversity. However, in non-migrants’ pekarangan, the use of plants for food was still less when compared to migrants’ pekarangan, so that the selection of multifunctional vegetation types can be suggested. In migrants’ pekarangan, the potential for the loss of pekarangan area in the future was quite high due to development and urbanizations. Therefore, steps are needed in the utilization pekarangan so that the area can be maintained. So we made some considerations that can be applied to improve the condition of the pekarangan, both for migrant and non-migrant and other types of pekarangans.

First: a large pekarangan can be planted with various types of plant species in various functions. These can fulfill the criteria for the existence of vertical and horizontal diversities of plants. The valuable and important plants can be planted in the pekarangan, such as commercial crops (Abdoellah et al., 2020). Based on experience, the area of the pekarangan can exist if there was something valuable in it.

Second: for non-migrant pekarangans, a small pekarangan area was not a problem to display a shady and green pekarangan. Currently, there are many farming systems that do not require a lot of land for gardening, such as vertical gardens (do Valle Santos et al., 2019), hydroponic systems (Lal et al., 2020; Solis-Topanta et al., 2020), fish farming in buckets, hanging gardens, rooftop gardens, and planter boxes (Lal et al., 2020). These systems can be applied in the pekarangan to grow mainly vegetables, medicine, herbs, fruits, starch-producing shrubs, or herbs (Azra et al., 2014; Jesica et al., 2019), and wherever possible annual plants are chosen to be more sustainable. Although the area of the pekarangan was small, the diversity of species and individual plants remains high. Sundanese, who were attached to the culture of eating lalap (raw or boiled vegetables) should maintain this habit (way) (Septiani et al., 2020). They can grow various types of vegetables, apart from shrubs or herbs, but also from tree species, for example, petai (Parkia speciosa Hassk.), jengkol (Pithecellobium jiringa (Jack) Prain), melinjo leaf (Gnetum gnemon L.), moringa leaf (Moringa oleifera lamk.), and cashew leaf (Anacardium occidental L.). Therefore, the vertical diversity function existed too. In addition, high trees can also be a shelter, climate amelioration, windbreak (Turner-Skoff and Cavender, 2019), carbon sequestration (Mattsson et al., 2015), and as a place to live for wild animals (Turner-Skoff and Cavender, 2019). This would very well be applied on a regional scale where the owners of the pekarangan can form a community. It was widely evident in urban and sub-urban areas where the pekarangan size was small, and it gave a positive perception for urban communities (Grebitus et al., 2020; Wood et al., 2020). There were many related government programs from the Ministry of Agriculture via National Food Agency (BPN) that could be a way out in funding for pekarangan revitalization.

Third: to achieve a good condition, sustainability of the pekarangan did not only depend on improving the biophysical condition (pekarangan area, plant diversity) but also the positive role of economic, social, and cultural aspects (Mazumdar and Mazumdar, 2012; Antoh et al., 2019). As long as the pekarangan had these roles for its owner, its existence and biophysical condition will be good and sustainable. Therefore, the owner’s preference in managing and utilizing pekarangan was an important factor to be considered because these three aspects were highly dependent on it. Therefore, campaigns on the need to maintain and improve biophysical conditions must continue to be carried out by the government and non-governmental organizations (NGOs) to create higher public awareness. Environmental awareness can be effectively carried out by social media, and it made a positive impact for the environment (Ragusa and Crampton, 2017; Kuppuswamy, 2018). Several activities and programs by both the government and NGOs continued to grow, especially those related to the use of pekarangans. The existing government programs are “Sustainable Food from Pekarangan” (P2L), Family Farming (PK), Creative Village Development, and Local Food Diversification (Asmoro et al., 2020; Food Security Agency, 2020). The examples from NGOs are Community of Indonesian Pekarangan and Productive Garden (KPKPID), Bogor Gardening, and other relevant communities. The main principle of these programs was how the pekarangan can be used as productively as possible. Group members can exchange ideas and experiences in utilizing the pekarangan. In addition, community members can also share their seeds, seedlings, and crops. In the future, the pekarangan can be one of the potential tourism destinations that will be diverse and interesting.