Introduction
A garden is a space created by humans, not wild nature, and it continues to change its appearance yearly and seasonally. Gardens consist of plants that change over time as main materials, thus requiring continuous management. When gardens are filled more with immigration plants than planted plants, their original forms and the intention of creation can be reduced. Some species of immigration plants, however, play a positive role in being a source of feed for wild birds and fish, and habitats, and resources for medicine, food or fertilizer, and preventing soil loss, and they also act as an important element for biodiversity. Therefore, it is necessary to manage immigration plants individually based on the accurate information on their species.
Studies on immigration plants can be divided into three groups. The first one is about immigration plants in natural spaces, including those on the distribution of naturalized plants and immigration plants in natural ecosystems, and those on monitoring resources in national parks. The second one is about immigration plants in planned spaces, and studies in the second group were conducted mainly in large-scale parks, such as Gildong Ecological Park (Kim et al., 2000), Yeouido Saetgang Ecological Park (Choi and Lee, 2001), and World Cup Park (Son, 2004). The third group is on the management of plants in gardens, including a study on the management methods of planted plants and invasive plants through monitoring a rooftop garden in Seoul City Hall (Choi et al., 2003), and a study on the characteristics of immigration plants (Jang et al., 2010).
Since the ‘Act on the Creation and Furtherance of Arboretums and Gardens’ was enacted in July, 2015, a series of garden expos were held in `Korea, gaining attention from the public. At this point of time, it is necessary to conduct studies on methods of continuously maintaining gardens at a low cost with little management efforts in order to establish a gardening culture in daily life. It is necessary to remove immigration plants, viewing them as weeds, but it is also important to understand the characteristics of such plants and use them wisely, which changes gardens gradually into spaces harmonized with surrounding environments.
Against this backdrop, this study aims to monitor a wildflower garden in an elementary school in Seoul; analyze whether wild plants planted in the garden can grow well for a long time; examine immigration plants; and observe the relationship between planted plants and immigration plants. Based on the results, methods of managing plants in wildflower gardens created in urban areas are suggested in this study.
Research Methods
1 Subjects
This study was conducted at a wildflower garden (name as ‘Wildflower Garden Feeling the Wind’) created at Seoul Samgaksan Elementary School (141, Samyang-ro 19-gil, Gangbukgu, Seoul). The garden was constructed by the Korea National Arboretum within a large-scale apartment complex redeveloped in Samgaksan-dong (Mia 6 and 7 dongs), Gangbuk-gu in July, 2014. A fragmented green space at the foot of Bukhan Mountain is situated in the southern side of the elementary school, and the eastern, western and northern sides of the elementary school are surrounded by the apartment complex (Fig. 1). The playground of the school is located on the third floor of the building, and the floor is mostly made of concrete only with a very small green space. The elementary school shares its main gate with a middle school. The wildflower garden is created on the concrete floor (10.3×5.3×0.45 m) in an inner court surrounded by buildings, and the walls of the planting space were built with volcanic stone bricks. In the garden, 32 taxa1) of native plants (20 families, 28 genera) were planted (Table 1).
Table 1
Seoul Samgaksan Elementary School wildflower garden planting plants statue.
2 Methods
The wildflower garden was monitored in June and September, 2016, two years after the creation of the garden, when the growth and development of plants are most noticeable and all the weeds that grow in spring, summer and autumn can be observed. All the species of plants that were planted in the garden and other plants that were observed were surveyed, and their height and population, the coverage of planted plants and immigration plants, and their growth and development status (emergence, blooming, fruiting, seed disseminule form and withering) were recorded and photographed. In addition, to identify the route of introduction of immigration plants, plants that were observed within 500m from the garden (flower beds within the school, residential areas, streets, surrounding mountain areas) were also surveyed (Fig. 1). The life forms and disseminule forms of immigration plants were also analyzed to collect their information. The surveyed plants were identified and classified based on Coloured Flora of Korea (Lee, 2003) and New Illustrations and Photographs of Naturalized Plants of Korea (Park, 2009), and listed according to the Korean Plant Names Index (Nature, 2017). The life forms and disseminule forms of the observed plants were rearranged based on Lineamenta Florae Koreae (Lee, 1996).
Results and Discussion
1 Monitoring planted plants
The 32 taxa of plants planted by the Korea National Arboretum in July, 2014 were all native plants that can grow in temperate regions in the middle part of Korea. In particular, considering the windy environment in the location, 6 grass taxa with high environmental adaptability (5 Cyperaceae species, 1 Gramineae species) were planted to ensure people feel the directions of wind like the main concept of the garden (Fig. 2).
Fig. 2.
Planting plan of wildflower garden.
1.구상나무 Abies koreana Wilson 2. 흰말채나무 Cornus alba L. 3. 인동덩굴 Lonicera japonica Thunb. 4. 큰꽃으아리 Clematis patens C.Morren & Decne. 5. 수크령 Pennisetum alopecuroides (L.)Spreng. 6. 밀사초 Carex boottiana Hook. & Arn. 7. 밀사초(무늬종) Carex boottiana Hook. & Arn. 8. 개찌버리사초 Carex japonica Thunb. 9. 골풀 Juncus effusus var. decipiens Buchenau 10. 그늘사초 Carex lanceolata Boott 11. 골사초 Carex aphanolepis Franch. & Sav. 12. 포천구절초 Dendranthema zawadskii var. tenuisectum Kitag. 13. 미나리아재비 Ranunculus japonicus Thunb. 14. 큰까치수염 Lysimachia clethroides Duby 15. 꼬리풀 Veronica linariifolia Pall. ex Link 16. 원추리 Hemerocallis fulva (L.) L. 17. 부채붓꽃 Iris setosa Pall. ex Link 18. 돌단풍 Mukdenia rossii (Oliv.) Koidz. 19. 좀개미취 Aster maackii Regel 20. 백리향 Thymus quinquecostatus Celak. 21. 가지복수초 Adonis amurensis var. ramosa Makino 22. 뱀딸기 Duchesnea indica (Andr.) Focke 23. 노루오줌 Astilbe rubra Hook.f. & Thomas ex Hook.f. 24. 털부처꽃 Lythrum salicaria L. 25. 꿩의비름 Hylotelephium erythrostictum (Miq.) H.Ohba 26. 도라지 Platycodon grandiflorum (Jacq.) A.DC. 27. 금낭화 Dicentra spectabilis (L.) Lem. 28. 한라개승마 Aruncus aethusifolius (H.Lév.) Nakai 29. 벼룩이울타리 Arenaria juncea M.Bieb. 30. 매발톱 Aquilegia buergeriana var. oxysepala (Trautv. & Meyer) Kitam. 31. 할미꽃 Pulsatilla koreana (Yabe ex Nakai) Nakai ex Mori 32. 앵초 Primula sieboldii E.Morren
The results of monitoring showed that most of the planted plants grew well, but Clematis patens C.Morren & Decne. was weakened, indicating that the species failed to survive in the competition with Lonicera japonica Thunb., planted along the species. In addition, one of the five Abies koreana Wilson trees withered one year after planting, but the rest 4 trees grew well, which indicates that the tree withered due to other reasons than environmental conditions.
Most species maintained or increased their population, and those that maintained their populations but showed no growth in thickness were 6 taxa including Abies koreana Wilson, Hylotelephium erythrostictum (Miq.) H.Ohba, Iris setosa Pall. ex Link, Adonis amurensis var. ramosa Makino, Primula sieboldii E.Morren, and Dicentra spectabilis (L.) Lem. Those that maintained their population, and showed a growth in thickness were 5 taxa (Mukdenia rossii (Oliv.) Koidz, Duchesnea indica (Andr.) Focke, Carex lanceolata Boott, Carex boottiana Hook. & Arn., and Carex boottiana Hook. & Arn.), and among them, Mukdenia rossii (Oliv.) Koidz. and Cyperaceae species planted along the sides of native rocks grew in thickness only without increase in population. Those that showed increase in population were divided into two groups based on their dispersion patterns as follows: first, those that spread out near the area where they were originally planted, and second, those that were sporadically dispersed beyond the area. The first group included 15 taxa (Cornus alba L.; Lonicera japonica Thunb; Aquilegia buergeriana var. oxysepala (Trautv. & Meyer) Kitam.; Ranunculus japonicus Thunb; Pulsatilla koreana (Yabe ex Nakai) Nakai ex Mori; Juncus effusus var. decipiens Buchenau; Thymus quinquecostatus Celak; Hemerocallis fulva (L.) L.; Pennisetum alopecuroides (L.) Spreng; Lythrum salicaria L.; Carex japonica Thunb.; Carex aphanolepis Franch. & Sav.; Arenaria juncea M.Bieb.; Aruncus aethusifolius (H.Lév.) Nakai; Platycodon grandiflorum (Jacq.) A.DC.), and Lonicera japonica Thunb. covered almost all the wood fences, showing a noticeable growth and development. Cornus alba L., an arbor plant, extended their brachyblast. The second group included 5 taxa (Aster maackii Regel; Dendranthema zawadskii var. tenuisectum Kitag.; Astilbe rubra Hook.f. & Thomas ex Hook.f.; Lysimachia clethroides Duby; Veronica linariifolia Pall. ex Link) (Table 2).
Table 2
Wildflower garden planting plants monitoring results.
2 Monitoring immigration plants
The results of monitoring immigration plants are as follows. In June, 51 taxa, and in September, 67 taxa of immigration plants were observed, and among them, 35 taxa overlapped. The number of immigration plants 2 years after the creation of the garden was 83 taxa in total, 2.6 times the number of planted plants (32 taxa).
The life forms of immigration plants observed in this study include annual plants (37 taxa, including winter annual plants), biennial plants (7 taxa), and perennial plants (33 taxa). Most of them were herbaceous plants, but 6 taxa of arbor plants were also observed (Fraxinus rhynchophylla Hance; Acer tataricum subsp. ginnala (Maxim.) Wesm.; Nandina domestica Thunb.; Zanthoxylum schinifolium Siebold & Zucc.; Spiraea prunifolia f. simpliciflora Nakai; Celastrus orbiculatus Thunb.). Among the immigration plants observed in this study, Compositae species were observed most (20 taxa, 24%), followed by Gramineae species (11 taxa, 13%), and Cyperaceae (5 taxa, 6%) and Polygonaceae species (5 taxa, 6%).
In terms of population, immigration plants were reclassified into 4 types based on the disseminule forms as follows: anemochory & hydrochory, zoochory, autochory, and barochory (Lee, 1996). Those that showed two disseminule forms were recorded twice. Those of the barochory type accounted for 52%, followed by the anemochory & hydrochory type (27%), the autochory type (16%), and the zoochory type (5%) (Table 3). Weedy immigration plants can survive for a long time under the ground (Rural Development Administration National Institute of Agricultural Sciences, 2008), and most of the immigration plants observed in an artificially created area in early years are grown from buried seeds. Although many species of the barochory type were observed in this study, the share of those of the anemochory & hydrochory type is expected to gradually increase over time as more species immigrated from surrounding areas (Jang et al., 2010).
Table 3
Wildflower garden immigration plants statue and analysis.
To trace their route of introduction, plants that were observed within 500m from the wildflower garden in the elementary school were surveyed, and the results show that out of 83 taxa of immigration plants, 49 taxa were observed near the garden as follows: 25 taxa in flower beds within the school; 28 taxa in residential areas and on streets; 22 taxa in surrounding mountain areas (including overlapping species). The rest 34 taxa were not observed near the garden. Out of the species of which immigration routes were not identified, 2 taxa seemed to be introduced from surrounding mountain areas, 4 taxa from residential areas and streets, and 28 taxa from buried seeds that were brought with planted plants considering the disseminule forms of seeds and the ecology of plants. Among the immigration plants observed in this study, 8 taxa that showed the barochory and hydrochory types were observed in surrounding mountain areas, but it is difficult to assume that they were introduced from there within a short period of time, like 2 years. Thus, they are expected to grow from buried seeds.
Immigration plants are largely grouped into native plants and naturalized plants, and in this study 65 taxa of native plants, 1 taxon of cultivated plant, and 17 taxa of naturalized plants (22%) were observed, more indicating native plants immigrated than naturalized plants. Out of the 17 taxa of naturalized plants, the disseminule form of 11 taxa is the anemochory & hydrochory type, and they, except Veronica arvensis L., were all distributed in surrounding areas, indicating a high possibility of immigration from surrounding areas. Aster subulatus var. sandwicensis A.G.Jones, Ambrosia trifida L., Aster pilosus Willd., and Eupatorium rugosum Houtt. showed naturalized degree 4 (distributed in a limited area, but with large population) or 5 (cosmopolitan species with large population). They are categorized into the 3 rd stage of immigration (from 1964 to present), and thus they need to be monitored continuously (Park, 2009).
The results of monitoring the rooftop garden ‘Choroktteul’ in Seoul City Hall showed that there were more naturalized plants than native plants (Choi et al., 2003). The rooftop garden is located in downtown and surrounded by high-rise buildings, and it was created on a rooftop in an open environment with 10 cm deep soil. There is a stream (Cheonggyecheon (Stream) restoration) within 500 m from the garden, and green spaces at the foot of Inwang Mountain are 800 m away from the garden. For these reasons, unlike the wildflower garden, the target of this study, more naturalized plants seemed to be observed in the study. In the target of this study, unlike the Choroktteul rooftop garden, many native plants were introduced which is attributable to the fact that a fragmented green space at the foot of Bukhan Mountain is located in the southern side of the garden. The results of the monitoring the wildflower garden ‘Wild Flower Garden Starting from Landfill’ located within Pyeonghwa Park in World Cup Park in Sangam-dong, Seoul showed that 38% of immigration plants were naturalized plants and 62%, native plants. This indicates a possibility of using native plants that immigrated from other places as gardening materials in a garden created with native plants. In addition, in an study on the immigration plants in the Garden of the Korea National Arboretum (Nam et al., 2017), over 75% of immigration plants were found to be introduced from the Gwangneung forest located close to the garden, which shows that the number and population of immigration plants are greatly affected by the distance from and the quality of surrounding green spaces.
3 Methods of managing plants in gardens
1) Managing planted plants
As the results of monitoring planted plants show in Table 4, except Clematis patens C.Morren & Decne. of which population decreased, most of the planted plants grew well, and thus they did not require any special management. However, in the case of those that grew rapidly and are sporadically dispersed beyond the areas where they were originally planted, their population density needs to be managed to prevent the reduction of the intention of gardens. Population density can be relatively easily controlled by taking action at a seedling stage in early years.
Table 4
Management method of wildflower garden’s planting plants.
Clematis patens C.Morren & Decne. was the only species of which population decreased, and planted along with Lonicera japonica Thunb. Some leaves of Lonicera japonica Thunb. remained green even in winter, and it can grow well in any environment including shade, dry lands, rock fields, and coastal reclaimed lands. Lonicera japonica Thunb. is so prolific that just one tree can turn a whole village into a forest of Lonicera japonica Thunb. (Choi, 1997), and thus it seemed to suppress the growth and development of Clematis patens C.Morren & Decne. that was planted along with it. Runners of this excessively prolific plant grew on the ground and into the areas where Clematis patens C.Morren & Decne. was planted, and the runners have to be cut out in early spring to control its population density and to ensure visitors to see flowers of both plants.
There were 5 taxa that were sporadically dispersed beyond the planted areas into unpredictable areas (Aster maackii Regel; Dendranthema zawadskii var. tenuisectum Kitag.; Astilbe rubra Hook.f. & Thomas ex Hook.f.; Lysimachia clethroides Duby; Veronica linariifolia Pall. ex Link). It is important to pull such species up by the roots when their new leaves are out in spring. In the case of Compositae plants within the planted areas (Aster maackii Regel, Dendranthema zawadskii var. tenuisectum Kitag.), their stems or branch tips, that is, their growing points, should be cut out to let axillary buds and side shoots grow using a shoot-top-cutting technique. By doing so, planted spaces can be filled with luxuriant plants (Korea National Arboretum, 2015).
2) Managing immigration plants
Methods of managing immigration plants including nonnative plants can be divided, depending on management materials and means, into ecological, physical, biological and chemical management types (Rural Development Administration National Institute of Agricultural Sciences, 2008). In this study, physical management methods are suggested only.
In this study, three types of physical management methods for immigration plants are suggested as follows: elimination, transplanting and utilization. Those that did not meet the original plans and intention of the garden should be eliminated or transplanted into other places, and those that did not reduce the intention and threat the ecosystem of the garden can be utilized in the garden.
Those that have to be eliminated include invasive alien plants among naturalized plants; fast spreading plants; plants that expand sideways with rhizomes; and plants taller than 1m and climbing plants that interfere with the growth of planted plants. Invasive alien plants among naturalized plants are species that cause serious risk to ecosystem, etc., and they need to be controlled under ‘the Act on the Conservation and Utilization of Biological Diversity’. In the wildflower garden in this study, 4 taxa were observed (Ambrosia trifida L.; Aster pilosus Willd.; Eupatorium rugosum Houtt.; Rumex acetosella L.) and they should be immediately removed as soon as they are found. Fast spreading plants include 19 taxa (Setaria viridis (L.) P.Beauv.; Panicum bisulcatum Thunb; Erigeron annuus (L.) Pers.; Acalypha australis L.; Microstegium vimineum (Trin.) A.Camus; Echinochloa crusgalli (L.) P.Beauv.; Conyza canadensis (L.) Cronquist; Digitaria violascens Link; Digitaria ciliaris (Retz.) Koel.; Erechtites hieracifolia Raf.; Veronica arvensis L.; Euphorbia supina Raf.; Aster subulatus var. sandwicensis A.G.Jones; Galinsoga ciliata (Raf.) S.F.Blake; Sonchus oleraceus L.; Setaria faberii Herrm.; Agropyron tsukushiense var. transiens (Hack.) Ohwi; Erigeron philadelphicus L.; Taraxacum officinale Weber). If they are not removed at a seedling stage, they spread exponentially, so that it becomes difficult to control their population. Therefore, they should be eliminated when they start to flower in spring. Plants that expand sideways with rhizomes include 5 taxa (Equisetum arvense L.; Artemisia princeps Pamp.; Rumex acetosella L.; Poa pratensis L.; Trifolium repens L.), and it is important to completely eliminate the plants including roots. In particular, Equisetum arvense L. spreads and puts down root deep into the ground so quickly that it becomes very difficult to remove it later unless controlling at an early stage. Therefore, it should be immediately removed as soon as they are found before their sporangium cones disperse spores in early spring. Trifolium repens L. is a familiar plant to people as it is introduced in elementary school textbooks. Some can be transplanted to use as a learning material for students, and the rest should be all removed. Since it expands sideways, it should be managed within a container to prevent its roots from going farther. Plants taller than 1m (5 taxa including Panicum bisulcatum Thunb.; Echinochloa crusgalli (L.) P.Beauv.; Aster subulatus var. sandwicensis A.G.Jones; Sonchus oleraceus L.; Setaria faberii Herrm.) are indistinguishable from planted plants, and thus they should be eliminated at an early stage to maintain the intention of planting. Climbing plants (6 taxa including Glycine soja Siebold & Zucc.; Amphicarpaea bracteata subsp. edgeworthii (Benth.) H.Ohashi; Vigna angularis var. nipponensis (Ohwi) Ohwi & H.Ohashi; Humulus japonicus Siebold & Zucc.; Metaplexis japonica (Thunb.) Makino; Dioscorea nipponica Makino) also interfere with the growth of planted plants, and should be removed. Dry, sunny and windy days, not rainy days are suitable for removing plants, because the wind can quickly evaporate moisture in weeds rooted out, and keep them from taking root in the ground again (Oh, 2009).
Transplanted plants are removed from the wildflower garden to maintain the original plan and intention of the garden, but they can be utilized elsewhere. They include tree plants, plants not suitable for the habitat, and plants introduced in elementary school textbooks. In the case of tree plants, they are likely to naturally die out from a long-term perspective, and also to grow taller than the capacity of the garden, and thus they need to be transplanted into other environments suitable for them at an early stage. Plants that are not suitable for the habitat of the garden were 2 taxa including Persicaria thunbergii (Siebold & Zucc.) H.Gross ex Nakai, and Pilea mongolica Wedd. Since they grow in wet areas, they seem to grow from buried seeds. They can be utilized as scenic materials, and thus need to be transplanted into other environments suitable for their growth and development. Meanwhile, as the target of monitoring in this study is a garden in an elementary school, plants that are introduced in elementary school textbooks (Reu, 2016) can be used for educational purposes to increase the effectiveness of learning. In the case of Setaria viridis (L.) P.Beauv., as it spreads very quickly, it is necessary to pull it up by the roots after transplanting some for educational purposes.
Among immigration plants, those that can be maintained and utilized in the garden can be divided into landscaping and ground-covering types. Plants for landscaping should have ornamental values in their flowers, leaf colors and textures, and autumn leaf colors, and do not reduce the intention of gardens. In the wildflower garden monitored in this study, 21 taxa can be utilized for landscaping. Plants for ground-covering are usually of short height (20 cm or shorter), spread quickly and have shallow roots. In the wildflower garden, 16 taxa can be maintained and utilized (Table 5).
Table 5
Management method of wildflower garden’s immigration plants.
Conclusions
As gardens use plants as main materials, they continue to change their appearance yearly and seasonally. To maintain the original forms and intention of gardens, continuous management is essential. This study aimed to monitor a wildflower garden created at Seoul Samgaksan Elementary School, to observe the relationship between planted plants and immigration plants, and thus to suggest methods of managing plants, and the results of monitoring and the suggested methods are as follows. The characteristics of planted plants and immigration plants should be fully understood in other wildflower gardens created in urban areas, and based on the understanding, they should be managed by plant types.
First, among the 32 taxa of planted plants in the garden, most of them, except Clematis patens C.Morren & Decne. that was weakened, maintained or increased their populations. Those that maintained their populations but showed no growth in thickness were 6 taxa (Abies koreana Wilson, Hylotelephium erythrostictum (Miq.) H.Ohba, Iris setosa Pall. ex Link, Adonis amurensis var. ramosa Makino, Primula sieboldii E.Morren, and Dicentra spectabilis (L.) Lem). Those that maintained their population, and showed a growth in thickness were 5 taxa (Mukdenia rossii (Oliv.) Koidz, Duchesnea indica (Andr.) Focke, Carex lanceolata Boott, Carex boottiana Hook. & Arn., and Carex boottiana Hook. & Arn.). Plants that spread out near the area where they were originally planted included 15 taxa (Cornus alba L.; Lonicera japonica Thunb; Aquilegia buergeriana var. oxysepala (Trautv. & Meyer) Kitam.; Ranunculus japonicus Thunb; Pulsatilla koreana (Yabe ex Nakai) Nakai ex Mori; Juncus effusus var. decipiens Buchenau; Thymus quinquecostatus Celak; Hemerocallis fulva (L.) L.; Pennisetum alopecuroides (L.)Spreng; Lythrum salicaria L.; Carex japonica Thunb.; Carex aphanolepis Franch. & Sav.; Arenaria juncea M.Bieb.; Aruncus aethusifolius (H.Lév.) Nakai; Platycodon grandiflorum (Jacq.) A.DC.). Plants that were sporadically dispersed into unpredictable areas beyond the area included 5 taxa (Aster maackii Regel; Dendranthema zawadskii var. tenuisectum Kitag.; Astilbe rubra Hook.f. & Thomas ex Hook.f.; Lysimachia clethroides Duby; Veronica linariifolia Pall. ex Link). Most of the planted plants have grown well, and thus they do not require any special management. However, it is necessary to cut out runners of Lonicera japonica Thunb. in early spring for density management. As the 5 taxa that are sporadically dispersed beyond the planted areas can reduce the intention of the garden, it is necessary to pull them out by the roots and be transplanted when their new leaves are out in spring.
Second, the number of immigration plants 2 years after the creation of the garden was 83 taxa in total, 2.6 times the number of planted plants. In terms of disseminule forms, those of the barochory type accounted for 52%, followed by the anemochory & hydrochory type 27%, the autochory type 16%, and the zoochory type 5%. Approximately 43% of the immigration plants seemed to grow from buried seeds, and thus it is important to consider that other seeds in soil can be brought with planted plants when managing gardens.
Third, immigration plants are largely grouped into native plants and naturalized plants, and in this study 65 taxa of native plants, 1 taxon of cultivated plant, and 17 taxa of naturalized plants (22%) were observed, indicating native plants immigrated more than naturalized plants. The results are inconsistent with those of monitoring the rooftop garden ‘Choroktteul’ in Seoul City Hall where naturalized plants were observed more. This indicates that the number and population of immigration plants are affected by the distance from and the quality of surrounding green spaces.
Fourth, in this study, three types (elimination, transplanting and utilization) of management methods for immigration plants were suggested. Plants that should be eliminated were 39 taxa, including invasive alien plants among naturalized plants; fast spreading plants; plants that expand sideways with rhizomes; and plants taller than 1m and climbing plants that interfere with the growth of planted plants. It is important to pull them out by the roots on dry, sunny and windy days, not rainy days at a seedling stage. Plants that should be transplanted were 18 taxa including tree plants, plants not suitable for the habitat, and plants introduced in elementary school textbooks. Plants that can be maintained and utilized in the garden were 26 taxa, including those for landscaping that have ornamental values in their flowers, leaf colors and textures, and autumn leaf colors, and do not reduce the intention of gardens, and those for ground-covering that have short height, spread quickly and have shallow roots. When creating a garden, immigration plants can be also prevented by mulching plants with barks, wood chips, straw, and coarse decomposed granite or gravels, or covering the land densely with ground-covering plants without any vacant space. In this study, physical methods of management were suggested only. As species in the wildflower garden are diversified over time, it will be necessary to develop biological management methods that use interactions between living organisms such as microorganisms, insects and allelopathy.
As this study monitored planted plants and immigration plants 2 years after the creation of the wildflower garden and suggested methods of managing the garden at an early stage only, it will be necessary to continue to monitor plants and suggest measures to manage the wildflower garden by stages.
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