Introduction Of Exotic Plants Research Articles

Genetic mapping reveals the complex genetic architecture controlling slow canopy wilting in soybean

In soybean [Glycine max (L.) Merr.], drought stress is the leading cause of yield loss from abiotic stress in rain-fed US growing areas. Only 10% of the US soybean production is irrigated; therefore, plants must possess physiological mechanisms to tolerate drought stress. Slow canopy wilting is a physiological trait that is observed in a few exotic plant introductions (PIs) and may lead to yield improvement under drought stress. Canopy wilting of 130 recombinant inbred lines (RILs) derived from Hutcheson × PI 471938 grown under drought stress was visually evaluated and genotyped with the SoySNP6K BeadChip. Over four years, field evaluations of canopy wilting were conducted under rainfed conditions at three locations across the US (Georgia, Kansas, and North Carolina). Due to the variation in weather among locations and years, the phenotypic data were collected from seven environments. Substantial variation in canopy wilting was observed among the genotypes in the RIL population across environments. Three QTLs were identified for canopy wilting from the RIL population using composite interval mapping on chromosomes (Chrs) 2, 8, and 9 based on combined environmental analyses. These QTLs inherited the favorable alleles from PI 471938 and accounted for 11, 10, and 14% of phenotypic variation, respectively. A list of 106 candidate genes were narrowed down for these three QTLs based on the published information. The QTLs identified through this research can be used as targets for further investigation to understand the mechanisms of slow canopy wilting. These QTLs could be deployed to improve drought tolerance through a targeted selection of the genomic regions from PI 471938.

Larval performance and adult phenotypic variation of Acraea terpsicore (Lepidoptera: Nymphalidae) on congeneric Passiflora host plants.

The introduction of exotic plants into different habitats can have varied consequences for local herbivorous insects, such as altered the nutrient profiles that induce the host plant shifting or reduced food availability by competition with native plants. Acraea terpsicore (Linnaeus, 1758), a common butterfly in Southeast Asia that uses Passiflora as a host plant, has been studied to compare larval performance and adult phenotypes on one local wild Passiflora plant, P. foetida and 3 exotic congeneric plants, P. edulis, a fruit crop plant, and P. x alata-caerulea and P. x coccinea-caerulea, both hybrid ornamental plants. Laboratory caterpillars that fed on P. edulis and P. x alata-caerulea died within 1-10 days, while caterpillars fed on P. foetida and P. x coccinea-caerulea completed their life cycle in 30.42 ± 0.25 days. Although the caterpillars differed in several food utilization indices, the relative growth rate and consumption index were not affected. Adult butterflies that hatched from caterpillars fed on these experimental plants had different phenotypes, especially wing colors. Therefore, although some congeneric exotic plants may have a negative impact on the butterfly population, some exotic plants can serve as alternative larval host plants and expand the ecological niche of butterflies. Difference in the composition and concentration of nutrients and defensive chemicals in each host plant may exert an impact on the phenotypic traits of butterflies, such as their body size, coloration, and wing shape. Whether butterflies may separate into different subpopulations in the future due to phenotypic variation should be further examined.

Infiltration holes enhance the deep soil water replenishment from a level ditch on the Loess Plateau of China

AbstractThe introduction of exotic plants with high‐water consumption and high‐density planting have greatly changed the deep soil water environment on the Loess Plateau of China. Slope measures can intercept runoff to change slope soil water redistribution, however, the existing measures are not enough to improve deep soil water replenishment. Infiltration holes were used as a supplement of the existing slope measures. In this study, the effects of three different measures (the control without any measures, the level ditch, and the combination of level ditch and infiltration hole) on slope runoff and deep soil water redistribution were evaluated under field conditions. The results showed that the combined measure reduced the runoff by 44.1% and the sediments by 78.6% under an intense rainfall event compared with the control. After two rainy seasons, compared with the control and the level ditch, the combined measures significantly increased the soil water storage below 50 cm in the soil layer. Combining infiltration hole with level ditch improved the deep soil water replenishment within 30 cm from infiltration hole in a horizontal plane. Overall, the single‐level ditch was insufficient to improve deep soil water replenishment, and the combined measure can more effectively intercept runoff to increase the water replenishment of deep soils. Our findings provide a new thinking in regulating and utilizing slope runoff to effectively improve deep soil water replenishment in arid and semiarid areas.

Floristic homogenization as a result of the introduction of exotic species in China

AbstractAimThe introduction of exotic plants can both increase (homogenize) and decrease (differentiate) floristic similarity between areas. We have a poor understanding of the degree to which plant species introductions tend to homogenize or differentiate floras, and relevant studies covering large spatial extent are scarce. China has been heavily invaded by exotic plants. Here, we analyse a comprehensive dataset of vascular plants to determine whether the introduction of exotic plant species has homogenized or differentiated species composition in regions across China.LocationChina.MethodsWe calculated the Jaccard index and Simpson index of similarity for each pair of province‐level regions for native and exotic species separately and jointly, and calculated a homogenization index for each pair of regional floras. We correlated species richness of native and exotic plants to climatic factors, and correlated the Jaccard index and Simpson index to geographic and climatic distances. We used variation partitioning analysis to determine the relative importance of geographic and climatic distances on species turnover. We also examined the effect of human population density on florisitic similarity of exotic species.ResultsWe found that the geographic range of each species was, on average, larger for exotics than for natives; floristic similarity between regions was greater for exotics than for natives; the vast majority of pairwise regional floras have been homogenized; the introduction of exotic species has caused stronger biotic homogenization for pairwise floras with greater dissimilarity in their species composition; geographic distributions of exotic and native species were determined by different sets of climatic factors; and distributions of exotic species were determined by climatic factors more strongly, compared to those of native species. Human population density had a moderate effect on florisitic similarity of exotic species.Main conclusionsThe introduction of exotic plant species has homogenized regional floras across China. Because strong international trades between China and other countries and dramatic development of transportation systems are continuing in China, which help spread of exotic species, we predict that exotic species will continue to spread and will strengthen biotic homogenization in China.

Long evolutionary history of an emerging fungal pathogen of diverse tree species in eastern Asia, Australia and the Pacific Islands.

Emerging plant pathogens have been increasing exponentially over the last century. To address this issue, it is critical to determine whether these pathogens are native to ecosystems or have been recently introduced. Understanding the ecological and evolutionary processes fostering emergence can help to manage their spread and predict epidemics/epiphytotics. Using restriction site-associated DNA sequencing data, we studied genetic relationships, pathways of spread and the evolutionary history of Phellinus noxius, an emerging root-rotting fungus of unknown origin, in eastern Asia, Australia and the Pacific Islands. We analysed patterns of genetic variation using Bayesian inference, maximum-likelihood phylogeny, population splits and mixtures measuring correlations in allele frequencies and genetic drift, and finally applied coalescent-based theory using Approximate Bayesian computation (ABC) with supervised machine learning. Population structure analyses revealed five genetic groups with signatures of complex recent and ancient migration histories. The most probable scenario of ancient pathogen spread is movement from an unsampled population to Malaysia and the Pacific Islands, with subsequent spread to Taiwan and Australia. Furthermore, ABC analyses indicate P. noxius spread occurred thousands of generations ago, contradicting previous assumptions that this pathogen was recently introduced to multiple geographical regions. Our results suggest that recent emergence of P. noxius in eastern Asia, Australia and the Pacific Islands has probably been driven by anthropogenic and natural disturbances, such as deforestation, land-use change, severe weather events and/or introduction of exotic plants. This study provides a novel example of applying genome-wide allele frequency data to unravel the dynamics of pathogen emergence under changing ecosystem conditions.

Fire, herbivores and the management of temperate Eucalyptus savanna in Tasmania: Introducing the Beaufront fire – mammalian herbivore field experiment

SummaryThe temperate Eucalyptus savannas in the Midlands of Tasmania are ancient ecosystems where fire and grazing are intrinsic ecological disturbances. The arrival of Aboriginal people into Tasmania some 40,000 years ago altered natural fire regimes, and since the end of the last ice age, their skilful patch burning increased the grass cover and the abundance of large grazers in the Midlands savannas. This ancient socio‐ecological tradition abruptly ended following European invasion in the early 19th century, which resulted in the rapid establishment of pastoralism, causing profound adverse changes to the ecological integrity of the temperate savannas. These changes include widespread tree clearing, extinction of native biota, establishment of domestic and feral mammalian herbivores, the introduction of exotic plants, broadscale application of chemical fertilisers and more recently irrigation. The Midlands retains a small fraction of the original vegetation, which typically occurs in small fragments on private land. These have been colonised by non‐native plants and animals, and experience altered fire regimes. There is a growing awareness that to effectively manage temperate savanna fragments may require the intentional coupling of fire and herbivory. We describe the establishment of a field experiment designed to test four broad hypotheses: a) herbivore off‐take increases after fire; b) smaller burned areas experience more intense herbivory than larger ones; c) non‐native herbaceous plants are more tolerant of herbivory, whereas native herbaceous species are more tolerant of fire; and d) Eucalyptus seedlings are most likely to reach maturity in areas which are both burned and protected from herbivores. A novel aspect of the fire‐herbivore experiment was that the Tasmanian Aboriginal community were engaged with and were contracted to conduct the burning. The findings of this landscape ecology experiment will inform the management of remnant temperate Eucalyptus savannas.

From specimens to commodities: the London nursery trade and the introduction of exotic plants in the early nineteenth century*

Abstract Nursery owners played a critical role in transforming imported plants and trees from scientific specimens into commodities that became widespread in British gardens in the first half of the nineteenth century. This article uses rare surviving business records of London nurserymen to investigate the scale and structure of the nursery trade and its business practices between 1800 and 1850 and how nursery businesses innovated to meet the needs of an emerging middle class.

Controlling gully- and revegetation-induced dried soil layers across a slope–gully system

The introduction of exotic plants and improper management strategies with regard to plant species can change the soil-water balance of deep soils, which in turn results in the formation of a dried soil layer (DSL) within the soil profile. The Loess Plateau (LP) of China has a complex terrain; however, only a few studies have evaluated the effects of the gully-induced DSL patterns, especially in hilly and gully regions of the northern LP. In this study, we collected soil-water content data to a depth of 5 m at 40 sampling sites in a slope–gully system to investigate and characterize DSLs and their spatial patterns. Results show that the DSL indices vary greatly in different slope positions. The thickness of DSLs (DSLT) and quantitative index (QI) in the gully were significantly (p < 0.05) higher than those in the non-gully areas. The relative contribution of soil properties was higher than those of terrain factors in the gully, whereas the contribution of terrain factors was higher than those of soil properties under shrubland. Gullies contributed to the complex spatial DSL patterns in the slope–gully system. Partial least squares regression (PLSR) was used to detect the relative significance of 10 selected environmental factors that affect spatial DSL patterns. Variable importance in projection (VIP) demonstrated that soil properties, especially Clay and Silt content, significantly influenced the DSL formation depth (DSLFD), DSLT, and QI. Land-use and slope position were the most important factors that influenced the mean soil-water content (SWC) within DSLs (DSL-SWC), which exhibited the highest VIP values. PLSR models simulated DSL indices accurately in DSL-SWC; the values for variation in response (R2) and goodness of prediction (Q2) were 0.94 and 0.92, respectively. Therefore, our findings provide a helpful base reference for DSL management and reclamation of hill and gully regions of the LP.

Genome-Wide Association Analyses Reveal Genomic Regions Controlling Canopy Wilting in Soybean.

Drought stress causes the greatest soybean [Glycine max (L.) Merr.] yield losses among the abiotic stresses in rain-fed U.S. growing areas. Because less than 10% of U.S. soybean hectares are irrigated, combating this stress requires soybean plants which possess physiological mechanisms to tolerate drought for a period of time. Phenotyping for these mechanisms is challenging, and the genetic architecture for these traits is poorly understood. A morphological trait, slow or delayed canopy wilting, has been observed in a few exotic plant introductions (PIs), and may lead to yield improvement in drought stressed fields. In this study, we visually scored wilting during stress for a panel of 162 genetically diverse maturity group VI-VIII soybean lines genotyped with the SoySNP50K iSelect BeadChip. Field evaluation of canopy wilting was conducted under rain-fed conditions at two locations (Athens, GA and Salina, KS) in 2015 and 2016. Substantial variation in canopy wilting was observed among the genotypes. Using a genome-wide association mapping approach, 45 unique SNPs that tagged 44 loci were associated with canopy wilting in at least one environment with one region identified in a single environment and data from across all environments. Several new soybean accessions were identified with canopy wilting superior to those of check genotypes. The germplasm and genomic regions identified can be used to better understand the slow canopy wilting trait and be incorporated into elite germplasm to improve drought tolerance in soybean.

Dapingzi, la première chrétienté au coeur du Yunnan (1835-1925)

Catholicism was introduced from southern Sichuan to the northeastern reaches of Yunnan in the late 18th century. Following the settlement of a few rare Christian communities in the regions close to Sichuan, Dapingzi was the first “Christianity”, according to the term used by the missionaries, to be established in interior Yunnan in a more central position, north of Dali. It was also here that the first large western-style church in the province was built. The article focuses on the ninety years of this Christianity under the administration of the Fathers of the Missions étrangères de Paris (MEP), from its foundation in 1835 until its transfer in 1925 to the Betharramites or “Priests of the Sacred Heart of Betharram”. This period is characterised by the development of the missions in a multi-ethnic land on the margins of the Chinese empire and by the expansionist policy of the MEP, which went hand in hand with French colonisation. After locating the exact position of Dapingzi and other toponyms used for this same Christianity, this research highlights two phases in the evolution of Dapingzi, the clandestine (1835-1873) and then the expansion (1873-1925), as well as its strategic and multifunctional position in the foundation of the missions in Western Yunnan and Tibet. In addition, the collective contribution of the missionaries to the introduction of exotic plants is presented, especially the vine and coffee tree. Finally, the article presents the particular character of the evangelisation of the native populations, the establishment of the educational system and the fabrication of “miracles” around the water from Lourdes during the plague epidemic in Dapingzi, which lasted several decades during the time of the MEP missionaries.

Soils and Hydrologic Processes Drive Wet Meadow Formation and Approaches to Restoration, Western USA

In 1805, the Lewis and Clark Expedition encountered Nez Perce people at a wet meadow that now holds historical significance to both cultures. Over the past two centuries this northern Idaho site, known as Weippe Prairie, was modified by digging of drainage ditches and introduction of exotic plants for livestock forage. From 2013 to 2017 a restoration was implemented that included filling a drainage ditch and planting five native wetland species. Between 2008 and 2018 we analyzed monitoring well data to quantify water levels through time, soil oxidation/reduction stations to measure redox potential, vegetation plots to track community changes, and pits for soil characterization. Seasonal saturation occurred top-down from direct precipitation and sheet flow over fine-grained soil and a low permeability hardpan approximately 60 cm below ground. Resulting hydrologic effects included a mean water level rise of 23 cm and prolonged growing season saturation. Although the restoration appears to be on a desirable trajectory, two years were insufficient for the wet meadow to transition from dominance by exotic pasture grasses to native wetland species. A combination of recurring monitoring, adaptive management, time, and reevaluation of the physical and ecological processes driving wetland function is required to achieve longterm restoration success.

Los frutales del Nordeste Argentino en la “Materia Médica Misionera” del Jesuita Pedro Montenegro

Los misioneros jesuitas (siglos XVII-XVIII) no sólo cumplieron un rol importantísimo en la introducción de plantas exóticas de diversos enclaves del mundo, sino también en la circulación de saberes, medicamentos y prácticas curativas entre las misiones del Paraguay con las del resto del Nuevo y Viejo Mundo. Sin embargo, los trabajos científicos que abordan la identificación de estas plantas, tanto nativas como introducidas, son escasos y dispersos. El objetivo de la presente contribución fue identificar los frutales locales citados en la publicación “Materia Médica Misionera” de 2009 por el jesuita Pedro de Montenegro, como también discutir algunos aspectos relacionados a las dificultades de esta tarea de identificación. La metodología empleada fue la perteneciente a la etnobotánica histórica. A partir de la obra del jesuita Pedro Montenegro, se identificaron los frutales locales empleando las descripciones y láminas acompañantes del autor, y comparándolas con bibliografía científica. Se identificaron 12 etnogéneros y 31 etnoespecies pertenecientes a las familias botánicas Arecaceae, Bromeliaceae, Caricaceae, Fabaceae, Myrtaceae, Musaceae y Passifloraceae

Along urbanization sprawl, exotic plants distort native bee (Hymenoptera: Apoidea) assemblages in high elevation Andes ecosystem.

Native bees contribute a considerable portion of pollination services for endemic as well as introduced plant species. Their decline has been attributed to several human-derived influences including global warming as well as the reduction, alteration, and loss of bees’ habitat. With human expansion comes along the introduction of exotic plant species with negative impacts over native ecosystems. Anthropic effects may even have a deeper impact on communities adapted to extreme environments, such as high elevation habitats, where abiotic stressors alone are a natural limitation to biodiversity. Among these effects, the introduction of exotic plants and urbanization may have a greater influence on native communities. In this work, we explored such problems, studying the relationship between the landscape and its effect over richness and abundance of native bees from the subandean belt in the Andes mountain chain. Furthermore, we investigated the effects of exotic plant abundance on this high-altitude bee assemblage. Despite the landscape not showing an effect over bee richness and abundance, exotic plants did have a significant influence over the native bee assemblage. The abundance of exotic plants was associated with a relative increase in the proportion of small and medium bee species. Moreover, Halictidae was the only family that appeared to be favored by an increase in the abundance of exotic plant species. We discuss these results and the urgent need for further research of high-altitude environments due to their vulnerability and high endemicity.

Exotic Spartina alterniflora Enhances the Soil Functions of a Coastal Ecosystem

Core Ideas Exotic species do not always have negative impacts on soils. Changes in soil functions were identified after the introduction of Spartina alterniflora. The basic functionality of soils could be enhanced by new species in areas that do not have native plants. The study highlights the potential benefits of non‐native plants for coastal soils. Coastal soils are recognized as a valuable global resource because of their important roles in maintaining ecosystem services, especially C storage. Exotic species often have negative impacts on biodiversity but less is known about their potential benefits for soil function. We investigated impacts of Spartina alterniflora Loisel. on soil functions (based on basic chemical and physical properties) related to soil depth on a coastline of the East China Sea. Subsequently, we assessed the trend of soil functions by integrating multiple soil functions into a single index. The results showed that significant relationships were observed between the age of S. alterniflora and the factors soil organic C (SOC) storage soil pH in the topsoil (30 cm), and soil salinity within the upper 1 m depth. These results implied that some soil functions were enhanced over time following the introduction of the species (i.e., C sequestration and desalinization). Spartina alterniflora had a positive effect on the basic functionality of soils in areas that do not have native salt marsh species. Over the course of exotic plant introduction, soil pH made the highest contribution at the beginning, whereas salinity gradually became the most important factor controlling the physicochemical functionality of soils. We suggest that it is essential to explicitly test the impacts of species introduction on soil functions to address key issues of the sustainable management of coastal soils.

Dynamics of host plant selection and host-switching by silver-spotted skipper caterpillars

Investigations of host plant selection in herbivorous arthropods have emphasized the importance of oviposition site selection by adults; however, a more complete picture of this process requires additional consideration of the factors influencing host plant choice during the immature feeding stages. We conducted a series of larval choice experiments to examine both the innate and induced preferences of larvae of the Silver-spotted skipper (Epargyreus clarus L.) on three commonly used hosts (Wisteria, Robinia, and Pueraria). Late instar E. clarus larvae reared on each of the three host plants displayed an overall pattern of innate preferences that correlated well with larval performance measures and reflected differences in foliar nutrient concentrations. Larval preferences were also influenced by rearing host species, indicating a role for feeding-induced preferences. When larvae reared on low-quality Wisteria for the first four instars were switched to higher quality Pueraria for the final instar, they developed more quickly and attained significantly higher pupal mass than larvae maintained on Wisteria throughout development. Similarly, larvae switched from Pueraria to Wisteria for the final instar suffered increased development time and produced significantly smaller pupae than those maintained on Pueraria throughout. Thus host-switching, particularly during the more mobile final instars, appears to offer larvae an opportunity to recoup fitness losses associated with early development on a low-quality host. For an equal amount of consumption, larvae feeding on Pueraria gained 50% more mass than those feeding on Wisteria, reflecting measured differences in foliar nitrogen concentration; despite these overall differences in quality, larval growth efficiency was similar among hosts. Especially in the age of common exotic plant introductions, a full understanding of the behavioral component of host selection by herbivorous insects requires appreciation of the dynamic role that immatures can play in host selection and use.

Resistance to Melanaphis sacchari (Hemiptera: Aphididae) in Forage and Grain Sorghums.

The sugarcane aphid, Melanaphis sacchari (Zehntner), has established itself as a perennial pest of grain and forage sorghums in the United States since the summer of 2013. We conducted traditional plant resistance studies that determine tolerance, antibiosis, and antixenosis in 32 sorghum genotypes when challenged with sugarcane aphids. The genotypes included one exotic plant introduction and 31 seed and pollinator parental lines that are used to produce grain, sudangrass, and forage sorghum hybrids. One seed parent (B11055) and one grain pollinator parent (R13219) expressed significant degrees of tolerance, antibiosis, and antixenosis and were top performers in all three resistance type experiments. An additional group of seed parents (B13045 and B1057) and grain pollinator parents (R11159, R13422, and RTx2908) and the plant introduction (PI 550610) resulted in an intermediate range of phenotypic resistance (i.e., 4.0 < 6.0) indicative of antibiosis from reduced fecundity, increased intrinsic rate of increase, and increased generation times. The forms of resistance expressed in these lines, especially B11055 and R13219, have great potential in breeding programs that can be integrated into useable forms of resistant sorghums.

Contemporary accounts of the Killarney Woods 1580–1870

Numerous references to the history of woodland at Killarney can be found in accessible literature. The present woodlands represent survival from charcoal burning for iron-works, from estate management practices during the eighteenth century and from clear-felling and replanting during the period of the Napoleonic Wars. With the possible exception of woods on the Muckross Peninsula, all woodland stands in the Killarney Valley have been disturbed by various forms of human use in recent centuries. In the nineteenth century prior to modern afforestation with non-native trees, the introduction of exotic plants and animals has had a major impact on the landscape. The present protection of much of the Valley's woods in the National Park provides hope that natural woodland conditions will be re-established extensively with time. The existence of records of woodland in the literature is of great value in understanding the present condition of the Valley and in resolving the management problems it poses for conservation.

영국 정원문화의 대중화 전개 양상에 대한 연구 - 19세기 왕립원예협회(RHS)의 활동을 중심으로 -

영국은 정원의 역사와 문화가 대표되는 국가로서, 크고 작은 비영리 단체 및 자선단체들이 활동을 하고 있다. 이 중 RHS는 영국의 정원문화 및 산업의 저변확대에 큰 영향을 준 핵심단체이다. 본 연구에서는 RHS의 등장 배경과 전개 과정을 통해 전문 자선단체로서의 정원문화 대중화에 기여한 전개 양상과 그 가치를 살펴보고자 하였다. 19세기 빅토리안 시대의 식물 수집에 대한 열정은 협회 창립의 배경이 되었으며, 영국의 시민정원문화와 관련이 깊다. 19세기 RHS의 전개양상과 정원문화 대중화에 대한 연구는 다음과 같이 요약될 수 있다. 첫째, 19세기 식물사냥꾼들의 해외 파견을 통한 이국적 식물의 전문적인 도입은 수집과 표본작업, 기록 등을 통해 전문적인 식물연구를 지원하는 단체로 발전되었으며, 이는 영국 내 원예기술의 발달, 묘목업의 성장 등의 결과로서 정원문화가 대중화되기 위한 기반 틀을 마련하였다. 둘째, 원예 및 가드닝의 전문서적의 출간은 로우든의 협회 가입 시점으로부터 실천적인 정보와 내용들이 편집됨으로써 대중적(특히, 여성과 중산계층) 독자 폭을 넓힐 수 있었다. 그리하여 생산 활동에 소외되어 있던 여성들의 가정적 원예활동은 새로운 정원 양식을 만들어 내기 시작했다. 셋째, 식물수집 전시를 통해 회원들과 소통하고자 했던 협회의 활동이 여러 형태의 축제로 변형되어 이어져 오다 지금의 첼시플라워쇼를 탄생시켰다. 첼시플라워쇼는 현재까지 세계 정원문화의 중추적인 역할을 하고 있으며, 대표적인 영국 정원문화의 아이콘이다. 넷째, 이러한 RHS의 활동의 과정과 19세기 영국의 근대성은 독특한 영국만의 대중적 정원양식을 이끌어 냈으며, 이는 매우 실천적인 정원술을 요하는 영국 중산층 가정 정원의 형태로서 대중적이면서도 영국적인 성격을 갖는다. 이러한 RHS의 역사와 활동들은 결국 정원의 나라로서의 국가적 위상과도 연결되며, 우리에게 시민 중심의 정원문화 정착을 위해 지향해야할 가치 및 실천방안의 단서를 제시해 준다. RHS is a core organization with huge influences on the expansion of the base for the garden culture and industry. This study aimed to examine the meaning and value of the professional charity's role through the appearance background and developmental process of RHS. The passion for plant collection in the Victorian Age of the <TEX>$19^{th}$</TEX> century became the background of establishing the society. Such background of the times and the root of the society are deeply related to the British civil garden culture. The consideration of the forming process of RHS and the study can be summarized as below. First, the professional introduction of exotic plants by plant hunters was developed into an organization supporting professional plant research through collection, sampling, and records, which led to the development of horticulture techniques, growth of plant nursery businesses and established the foundation of the civil garden culture in the UK. Second, after John Loudon was involved in RHS, inspired by the press editing more practical information contents, middle-class and women became new patrons to gardening. Therefore, the care of gardens became a source of agreeable domestic recreation, especially to the female sex. Third, <TEX>$19^{th}$</TEX> century plant collection and exhibition was seen in the Chelsea Flower Show which a key role beyond the UK garden culture. Fourth, those acts of RHS and modernity in <TEX>$19^{th}$</TEX> developed British middle-class domestic gardens which have the character of the ordinary and national garden style in the UK. Such history and activities of RHS are connected to the national status as a country of gardens, which suggests clues to practical measures and values we should aim for in order to settle citizen-centered garden culture.

Effects of Urochloa humidicola on Plant Diversity in Native Grasslands in a Neotropical Wetland

Studies on species invasion in wetlands are fundamental to understanding the consequences of the introduction of exotic plants, which are often utilized in grasslands. The loss of native plant diversity is of increasing concern. We evaluated the effect of Urochloa humidicola on floristic similarity between native and cultivated grasslands and the differences in spatial distributions between species. To analyze the effect of seasonality, we collected samples at the end of flood and dry periods. In native grasslands and another area cultivated with U. humidicola, samples were collected at three elevations (bottom; intermediate; and top). We identified 90 species and observed a high similarity between the cultivated and native grassland during the flood period; both grasslands exhibited significant differences during the drought period. This difference was due to an increased presence of grasses, mainly U. humidicola, in the cultivated grassland. Increased similarity between bottom and intermediate elevations was due to an increased proportion of aquatic macrophytes. In contrast, the top elevation differed due to the contribution of terrestrial species. We conclude that the native and cultivated grasslands exhibit differences in vegetation composition and are primarily structured by seasonal flooding, and small variations in elevation promote zonation within the plant community.

Bárcena Volcano, 1952: a 60-year report on the repopulation of San Benedicto Island, Mexico, with a review of the ecological impacts of disastrous events

Long-term ecological studies are desirable, but rare. I here present data from a 60-year study on the repopulation of San Benedicto Island following a volcano eruption in 1952. Bárcena Volcano appeared on 1 August 1952 on San Benedicto Island, Revillagigedo Islands, Mexico. Within 20 min, the entire island was engulfed in a cloud of ash and pumice, which covered all the plants, killed an estimated 20 000 sea birds within hours and caused the subsequent extinction of an endemic race of rock wren (Salpinctes obsoleta exsul). The results of studies on revegetation and repopulation of the island for the first 10 years after the volcanic eruption were summarised by Brattstrom in 1963. This report extends the studies to 2012. The distribution of the land crab (Aegecarcinus planatus) has increased on the island. By 1971 the crab occurred only over the northern one-eighth of the island, but by 1978 it could be found on one-third of the island. No studies on its distribution have been made since then. Total sea bird populations steadily increased up to 1971 and then rapidly declined, though these changes in numbers are largely due to a fluctuation in the populations of the masked booby (Sula dactylatra). The changes in the booby population may have been due to reproductive and feeding success or to immigration and emigration. The decline in the shearwater (Puffinus ssp.) populations are largely due to erosion and destruction of their burrows; their numbers did not increase until 2000. The formation of a large lava delta created a new habitat, which permitted the establishment of a species of sea bird new to the island, the red-footed booby (Sula sula). Numerous non-resident waifs or stray birds have been observed on the island but most have not become established. The exception is the Laysan albatross (Phoebastria immutabilis), breeding at present in low (3–712) numbers. The original flora consisted of 10 species. The volcano caused four species to become extinct, two re-established themselves, and two species new to the island arrived. There have been marked erosional changes, and the accidental introduction of exotic plants may dramatically alter the vegetation of the island.