Roads serve multiple functions that enhance exotic species invasion. In this paper, we examined the roles of disturbance, light availability, slope aspect, and climate in explaining density and frequency of exotic invasive plants. We analyzed the effect of main environmental factors along 13 roads with different levels of anthropological disturbances (heavy, moderate, and light) in the north tropical and south subtropical mountainous zones in Yunnan Province. The results demonstrated that density of four species, Eupatorium adenophorum, E. odoratum, Ageratum conyzoides and Tithonia diversifoli, and frequency of E. adenophorum were significantly associated with distance from roads. The curves of these four alien plants all presented a single-peak pattern, and their maximum abundance occurred within 4 m of roads. These four alien plants invaded native plant communities from primary colonization points along road margins. Density of E. adenophorum, E. odoratum, A. conyzoides, T. diversifoli and Synedrella nodiflora and frequency of E. adenophorum, E. odoratum, A. conyzoides and T. diversifoli tended to be significantly higher along highly disturbed roads than moderately and lightly disturbed roads, indicating that plant communities adjacent to highly disturbed roads might be more prone to invasion. Density of E. adenophorum, E. odoratum and A. conyzoides and frequency of E. adenophorum, A. conyzoidesand S. nodiflora were significantly higher in areas with high light level than those that had medium or low light levels. E. adenophorum, E. odoratum and A. conyzoides might obviously invade farther in habitats along roads that had high light level. Density of E. adenophorum, A. conyzoides and S. nodiflora were significantly higher on warm aspects than on cool aspects. E. adenophorum and T. diversifoli were mainly distributed in the south subtropical mountainous zones, while E. odoratum and S. nodiflora were mainly in the north tropical mountainous zones. A. conyzoides and Malvastrum coromandelianum were distributed in both zones. Tridax procumbens were very few along roadsides, which had no statistical significance. Management of roadside habitats should be considered a key to preventing and controlling alien plant invasion, and the maintenance of a dense canopy of native vegetation would benefit control of alien invasive plants.
In the context of increasing anthropogenic activities, nutrient enrichment and physical disturbances are among the most important environmental factors influencing biological invasions. On the other hand, clonal growth and vegetative propagation are considered important life history traits promoting the invasiveness of plants in high-resource and disturbed habitats. Alternanthera philoxeroides, endemic to South America, is an amphibious clonal weed invading areas worldwide. It is widely distributed in warm-temperate and subtropical regions, and tends to invade nutrient-rich and disturbed habitats such as riparian zones, wetlands, and arable areas. Throughout its introduced range, A. philoxeroides rarely produces viable seeds and reproduces mainly by vegetative propagation via storage roots and stems. Therefore, formation of storage roots, sprouting of root buds, and growth of new ramets are crucial characteristics in the life history of A. philoxeroides. We conducted three container experiments to examine the responses of vegetative propagation characteristics of A. philoxeroides to two factors—nutrient addition and physical disturbance (two types of physical disturbance: fragmentation and burial of storage roots). Nutrient addition increased total biomass and mean length of storage roots 1.5-fold, and biomass allocation to storage roots by 15% (i.e., vegetative reproductive allocation). Number of root buds increased by approximately 15 sprouts per g (dry mass) of storage root. Burial depth had no effect on number of sprouts per root fragment. Neither storage root size nor burial depth affected main stem length or mean relative growth rate of ramets. Our results suggest that adaptation of vegetative propagation characteristics to nutrient enrichment and physical disturbances may enable localA. philoxeroides populations to grow rapidly, and contribute greatly to the persistence of metapopulations at the watershed scale.
Procambarus clarkiihas invaded many provinces in China, such as Jiangsu, Hubei, and Anhui. In order to evaluate its effect onRana limnocharis, we investigated the population density of P. clarkii and R.limnocharis in their natural habitat in Guilin between May and June in 2006. As a comparison, we also carried out indoor experiments to study P. clarkii predation on the tadpole of R. limnocharis and Microhyla ornata. The field investigation showed that there was a significantly negative correlation between the density of P. clarkii and that of R. limnocharis tadpoles, while indoor experiments showed that the number of R. limnocharis tadpoles preyed by Procambarus clarkii was positively correlated with P. clarkii’s body length, and moreR. limnocharis tadpoles were preyed than M. ornata tadpoles. Our results suggest that P. clarkii is likely to endanger amphibian larva, therefore, it should be monitored and controlled.
Soil seed banks are potential plant populations; therefore, their temporal and spatial patterns affect future plant community dynamics and stability. In the regions invaded by Eupatorium adenophorum, soil seed bank traits can play a key role in construction and function of future ecosystems. We studied the vegetation and soil seed banks in an area invaded by E. adenophorum in Panzhihua, Sichuan Province using a combination of field work and germination trails. We explored seed density and species composition in soil seed banks before and after a seed rain of E. adenophorum. The results showed that: (1) The experimental sites were so heavily damaged byE. adenophorum that the vegetation was simple; in shrub layers, mean coverage and frequency of Coriaria nepalensis, Ficus tikoua, Desmodiunm elegans, Abelia parvifolia and Pistacia weinmannifolia were higher than other shrubs. In herb layer, E. adenophorum, ranging in age between 0 and 4 years, was the most abundant as its Drude abundance was Soc and the frequency was 100%. (2) Seeds of 13 species were found in soil seed banks. The similarity index for species in the vegetation and in the soil seed bank was 0.31. The density ofE. adenophorum seeds was 1,950/m2, accounting for 61.3% of total storage in the soil seed bank (3,180/m2), and there were not significantly (P>0.05) fewer seeds in upper layer than other layers. (3) Total seed storage before the seed rain ofE. adenophorum (1,950 seeds/m2) accounted for 41.2% of the storage after the seed rain (4,733 seeds/m2). After the seed rain, germination of E. adenophorum seeds from the soil showed two peaks at the 9th and 17th day, implying that seeds could periodically break dormancy. Our results indicated that E. adenophorum played a priority role in the soil seeds. The scarcity of other species in the seed banks was the main reason that E. adenophorum population regenerated and flourished continuously, and the invasion of E. adenophorum was hard to control.
Invasive species pose risks to regional economies and public health as well as imposing serious damage to natural ecosystems. Urban ecosystems are more susceptible to biological invasions than other ecosystems because they are subjected to more frequent human disturbances. Green space acts as important channels for the spread of alien species into urban ecosystems. Risk analysis can be an effective tool used for preventing invasion of alien species. Although various risk analysis systems have been developed for agricultural and forest ecosystems or nature reserves, the domestic effort to manage risks associated with invasive species in urban green spaces has been limited in China. Therefore, there is a pressing need for formulating scientifically sound methods and approaches for risk analysis in this emerging field. Here, we presented a risk analysis system including risk identification, assessment and management for biological invasions in urban green spaces. Based on risk identification for alien species, we established a risk assessment index that consisted of 4 different layers, i.e. object, item, factor, index layers. A total of 26 index parameters were proposed to assess the risk level, which originated from the risks involved in introduction, colonization, spread and damage of alien species in urban green spaces. In addition, methods for index quantification, weight setting, modeling and risk grading were presented. Applying this system, we analyzed the risks of alien pest species potentially attached to trees brought from Japan to China to green landscapes for the 2010 Expo in Shanghai. Our results showed that 7 species posed a high risk (4 insects, 2 plant pathogens, and 1 plant nematode), 10 species a moderate risk (3 insects, 4 plant pathogens and 3 plant nematodes), and other 2 species (1 insect and 1 nematode) a low or extremely low risk. Based on this analysis, risk management measures were suggested to help local policy-makers set priorities for the management of these alien pests. Monitoring did not reveal the presence of any invasive pests during or after the Expo, suggesting that the risk analysis system may have provided an effective tool for preventing the introduction of invasive alien species and effectively ensuring the ecological security of the 2010 Expo, Shanghai, China.
The number of alien invasive plant species in Heilongjiang Province has increased in recent years due to frequent economic and cultural exchanges with the outside world. To understand the current status of invasive plants, we carried out field surveys for invasive plant species between June 2008 and October 2010. Integrating field and literature data, we compiled a checklist of 41 species of alien invasive plants from 35 genera and 17 families found in this region. Of them, 39 species (95.1%) are herbs. Compositae contains the largest number of species, i.e.12 species (29.3%). Further analysis showed that 22 species (53.7%) have a geographical origin in the Americas, and 14 species (34.2%) in Europe. In relation to introduction pathways, 40 species (97.6%) were intentionally or unintentionally introduced. Floristic analysis of the genera showed that the temperate element, containing 17 genera (68.0%), dominated among nine areal-types. Finally, we discuss the management, monitoring and control of these invasive species and suggest that a specific risk assessment system should be used in Heilongjiang Province.
Biotic homogenization is the process whereby the genetic, taxonomic and functional similarity of two or more biotas increases over time. As a new research agenda for conservation biogeography, biotic homogenization has become a rapidly emerging topic of interest in ecology and evolution over the past decade. However, research on this topic is rare in China. Herein, we introduce the development of the concept of biotic homogenization, and then discuss methods to quantify its three components (genetic, taxonomic, and functional homogenization), and their driving mechanisms. Species invasions and extinctions are the root cause of biotic homogenization, whilst other habitat alterations that facilitate these two processes, such as environment degradation and disturbance, urbanization, and habitat homogenization, also influence biotic homogenization. Biotic homogenization was tempo-spatial-scale dependant. The homogenization degree differed between various ecosystems and taxa, as well as in different regions. We also reviewed ecological and evolutionary consequences and effects on human dimension (economics and biodiversity conservation) due to biotic homogenization. Considering the distinctness of China’s biodiversity, we suggest that it is time to strengthen research on biotic homogenization in China. In our view, the most fundamental need is to establish open, reliable databases to foster biotic homogenization research. We hope this review will stimulate biotic homogenization research in China.
Wedelia trilobata, a creeping herb native to Central and South America, is one of the world’s 100 worst invasive alien species. It was introduced into South China and has become a noxious invasive weed in agricultural fields, plantations and natural forests. In natural communities, it is observed that the leaves of W. trilobata turn from green to red under high irradiance in summer. The aims of this study were to explore what causes the leaf color change in W. trilobata and what the physiological consequences are. Anthocyanin content was significantly higher in red than in green leaves of W. trilobata, suggesting that the accumulation of anthocyanin at high irradiance was related to the leaf color change. The increased content of anthocyanin contributed to a higher total antioxidant capability in red W. trilobata leaves . Consistent with the higher antioxidant capability, decreases in maximum quantum efficiency of photosystem II photochemistry and the effective PSII quantum yield caused by artificial photo-oxidative stress were respectively smaller in red (28.2% and 79.1%) than in green leaves of W. trilobata (70.9% and 93.8%). Leaf color change was not observed in native W. chinensis. Our results suggest that the color change may be a physiological mechanism employed by the invasive W. trilobata to acclimate to high irradiance in summer.
Interactions between vector insects, plant viruses and host plants are complex and diverse. Although much work has been done to study the tripartite relationships, their roles in biological invasions have been rarely explored. The limited case studies available indicate that the interactions may be mediated by the host plant susceptibility to viruses, the suitability of host plants to vector insects, and the insects’ capacity to utilize host plants. When a host plant is highly susceptible to the virus but shows a low level of suitability to the insect, and the insect has a strong capacity to use different host plants, an indirect mutualistic relationship is likely to occur between vector insect and plant virus via their shared host plants. This kind of mutualism can contribute to the widespread invasion of vector insects as well as the epidemics of plant viruses. In view of the significance of the tripartite interactions in biological invasions, future effort should be made to investigate comparatively many more combinations of different species, and various technologies can be used to reveal the physiological and molecular mechanisms of the interactions.
Evidence suggests that increased nitrogen levels heighten exotic species’ invasiveness and reduce the competitive potential of native species. To reveal the impact of nitrogen deposition on competition between invasive and native species, we compared the growth ofAmbrosia artemisiifolia, an invasive species, and two native species, Artemisia annua and Artemisia mongolica under three nitrogen regimes through replacement series experiments in a greenhouse at the Chinese Academy of Science’s Beijing Forest Station. Our results showed that heights of the three species significantly increased, but total biomass did not respond to the enhancement of nitrogen levels in monoculture plantings. When planted in mixtures, however, the heights and total biomass of some species responded to increasing nitrogen levels;Ambrosia artemisiifolia significantly increased, Artemisia annua exhibited no difference, and Artemisia mongolica first increased and then decreased with the increase of nitrogen levels. The growth response of Ambrosia artemisiifolia led to a competitive advantage over two native species. The dynamics of this competition differed at different nitrogen levels: Ambrosia artemisiifolia was a weaker competitor than native species at low level of nitrogen availability, but was a stronger competitor under high nitrogen level. Moreover, the competitive effects of Ambrosia artemisiifolia on Artemisia annua were stronger than on Artemisia mongolica. Nitrogen addition significantly enhanced the competitive ability of Ambrosia artemisiifolia and altered the competition relationship between these species, tipping the scales in favor of the Ambrosia artemisiifolia. Our study indicated that nitrogen deposition associated with global change may facilitate the invasion of Ambrosia artemisiifolia, and may enhance the vulnerability of native communities to invasion.
Based on the environmental variables that associated with species’ occurrence records, ecological niche modeling (ENM) seeks to characterize environmental conditions suitable for a particular species and then identify where suitable environmental habitats are distributed in the space. Recently, ENM has been used increasingly in biological invasion, conservation biology, biological responses to climate change, disease spatial transmission, and variety aspects of ecology and evolutionary biology research. However, the theoretical background of these applications is generally poorly understood, leading to artifactual conclusions in some studies (e.g. niche differentiation during species’ invasion). In this paper we discuss the relationship between niche and geographic distribution and introduce the theoretical basis of ENM, along with relationships between the niche and ENM. Abiotic/biotic, historical and dispersal factors are three key elements that determine species’ geographic distributions at different scales. By using environmental variables derived from distributional records, ENM is based on observations that already include effects of biotic interactions, therefore ENM is used to characterize somewhere between the realized niche and potential niche, not the fundamental niche. Grinnellian and Eltonian niches are both manifested in ENM calibration, depending on the types of variables used to fit model, the natural spatial scale at which they can be measured, and the dispersal of individuals throughout the environment. Applications of ENM in understanding ecological requirements of species, discovery of new species or populations, nature reserve design, predicting potential invasion, modeling biological responses to climate change, niche conservatism, and species delimitation are discussed in this paper.
Although China has a very rich biodiversity, it is also part of a region where biodiversity resources have declined rapidly. Threats to biodiversity in China include a large human population, economic and industrial development, climate change, and exotic invasive species. In situ conservation of biodiversity is needed for sustainable development and natural resource management in China. We provide a summary of results of in situ conservation research and use these data to develop future research directions. The focal areas of in situ conservation research over the last 6 decades focused on biodiversity resource investigation, endangered species management, and the construction of nature reserves. Large efforts including a series of protection action plans were implemented by the Chinese government to improve biodiversity conservation. Future research on in situ biodiversity conservation in China should focus on: (1) the mechanisms of the formation and maintenance of biodiversity; (2) identify the major threats to the conservation of biodiversity; (3) be coupled with long-term monitoring for the effective management and (4) legislation of natural resources.
Spartina alterniflora,originating in North America, has been introduced to China and has now invaded many inter-tidal zones of gulfs and estuaries in China. With its spread, Scirpus mariqueter,a native grass species, has experienced a concurrent decrease in area. Based on field investigation at Chongming Dongtan Wetland and potted plant competition experiments at Fudan University, we compared growth characteristics and relative competitive ability between the two species. The results indicated that in terms of height, coverage, above-ground biomass, below-ground biomass, and mean seed number per spike, values for Spartina alterniflora were all significantly higher than those of Scirpus mariqueter.However, the density and number of flowering tillers per square meter for Spartina alterniflora were significantly lower than those of Scirpus mariqueter.In terms of seed output per square meter and seed germination rate, there were no significant differences between the mature populations of the two species. Both interspecific and intraspecific competition between Spartina alterniflora and Scirpus mariqueter remarkably reduced the number of ramets, the proportion of fruiting ramets, the above-ground biomass and the number of corms (only Scirpus mariqueter has corms). The interspecific relative competitive ability (measured as relative neighbour effect index, RNE) of Spartina alterniflora was significantly greater than that of Scirpus mariqueter. The obvious growing advantage of Spartina alterniflora compared with Scirpus mariqueter might explain its greater interspecific competitive ability, which might explain its successful invasiveness into the native Scirpus mariqueter community in the Yangtze River estuary.
Phenacoccus solenopsis, an exotic invasive species, was firstly reported in 2008 in Guangdong, China. Since it’s discovery, P. solenopsis has been observed in Zhejiang, Guangxi and Yunnan provinces. To discuss whether two cryptic evolutionary lineages or the P. solenopsis complex species existed, we surveyed and sequenced P. solenopsis in Zhejiang Province. During surveys for P. solenopsis in Zhejiang Province, we found P. solenopsis individuals with yellowish color on the body and three pairs of yellow spots on the back. To evaluate potential genetic divergence among these phenotypes, we sequenced mtDNA COI gene sequences (694 bp) of 25 individuals from seven host plants in six locations. We analyzed these sequences and the known sequences of P. solenopsis from GenBank and discovered three haplotypes. Additionally, we calculated intra-species genetic distance of P. solenopsis and inter-species genetic distance of the genus Phenacoccus and constructed phylogenetic trees of P. solenopsis. We found that genetic divergence of P. solenopsis was 0-1.0% compared to samples from Chinese provinces (i.e., Zhejiang, Hainan, Guangdong), the United States (i.e., California), and Pakistan, and varied from 3-3.6% to samples collected from other areas of the United States (i.e., Florida). Further, intra-species genetic distance was obviously smaller than inter-species genetic distance in Phenacoccus(13.0-17.2%). Based on the morphological characters and mt COI gene sequence analysis, these individuals with phenotypic differences are likely true P. solenopsis. However, two distinct evolutionary lineages appear to exist in P. solenopsis, and further evidence is necessary to draw reliable conclusions on the existence of a P. solenopsis complex species.
As the main components of marine biota, zooplankton play vital roles in the marine biodiversity, trophic relationships and ecosystem dynamics. However, morphological identification of zooplankton is time-consuming and even impossible for some taxa, especially for pelagic larvae. Diversity of marine zooplankton is believed to be underestimated. DNA Barcodes (short DNA sequences for species recognition and discrimination) provide powerful tools for rapid species identification and are quickly applied in marine zooplankton ecological researches. Here we give a general introduction on the concept, advantages, and limitations of DNA barcoding. We review the multiple applications of DNA barcodes (mainly focused on the mitochondrial cytochrome c oxidase subunit I (mtCOI) gene) in the marine zooplankton ecological researches, which include rapid species identification, cryptic species reveal, trophic relationship analysis, invasive species monitoring, historical range expansion, population genetic and biogeographic analysis. We anticipate that DNA barcoding techniques will be increasingly used by marine ecologists. With the DNA barcode reference libraries completing and new high-throughput tools such as next generation sequencing developing, DNA barcoding will provides more information that, not only for species identification and discovery, but also help to improve our understanding of zooplankton biodiversity and their functions in marine ecosystems.
The Convention on Biological Diversity (CBD) was adopted by United Nations Conference of Environment and Development (UNCED) in June 1992 as a milestone event. During the past 20 years, China established the national coordination mechanisms for CBD implementation in 1993, conducted a country study for biodiversity conservation during 1995-1997, formulated China National Biodiversity Conservation Strategy and Action Plan during 2007-2010, founded the National Committee for Biodiversity Conservation in 2011, and, aiming to CBD’s objectives, implemented a lot of researches and actions for biodiversity conservation, including: protection of ecosystems such as forests, grasslands, deserts, wetlands and marine areas; investigations, inventory and databases for species; increased protection of rare and endangered species; control of alien invasive species; and risk assessment for genetically-modified organisms. Challenges to biodiversity conservation include, establishment of biodiversity monitoring system, in situ conservation, access and benefit sharing of genetic resources, and protection and application of traditional knowledge. Lastly, we report potential research topics for biodiversity conservation.
As one of the five major global environmental problems, invasive species have posed serious threats to native ecosystems, public health, and regional economies. Although much progress has been made in the field of biological invasions research in China over the last decade, there are still large knowledge gaps. This paper reviews progress in the field of biological invasions research since 2000 as it relates to China, covering the diversity, colonization and immigration patterns of invasive species, mechanisms and ecological effects of biological invasions, and management and control of invasive species. In China, 529 invasive alien species have been identified, which originated primarily from South and North America, and the major taxa included terrestrial plants, terrestrial invertebrates, and microorganisms. We found a higher prevalence of invasive species in the eastern and southern provinces, compared to the western and northern provinces in China. This pattern is likely due to the differences in the level of economic development and environmental suitability between the two regions. Moreover, with further economic development, China may face more serious biological invasions in the future. These invasions of alien species are largely the combined results of the interactions between the intrinsic traits of these species along with resource opportunities and disturbances by human beings. Many mechanisms are responsible for successful invasions of alien species, but phenotypic plasticity, adaptive evolution, enemy release, interspecific mutualism or commensalism, and new allelochemicals may be primary causative factors. Biological invasions in China have caused serious impacts on native ecosystems, including biodiversity and ecosystem services, alteration of biogeochemical cycles, threats to agricultural and forestry production, traffic and shipping, environmental safety, and public facilities. China has also made progress in the detection and monitoring of invasive species, risk analysis, biological control, radical elimination, and ecological restoration of degraded ecosystems. We suggest several issues that need to be addressed in invasive species research in the future, including territory-wide inventories, evolutionary ecology and genomics, direct and indirect ecosystem-level consequences, interactions between major components of global change and biological invasions, and management and control technologies.
Since Biodiversity Science (formerly Chinese Biodiversity) was founded in October 1993 by the Biodiversity Committee of Chinese Academy of Sciences, it has been well received by authors and readers in China. The scope and focus of the journal that put forward by the first Editor-in-chief, Prof. Yingqian Qian have been well carried out by his successors. As the only nationwide academic journal in China, the Journal specifically addresses the major issues of biodiversity, and comprehensively reports on achievements in the field of biodiversity research. To gain an overview of the Journal, we analyzed publication trends including study organisms and subject areas, authors and affiliation, funding agency, and citation frequency based on data from the database CNKI and the Journal’s website. Major research topics included biological invasion, biodiversity and global change, DNA barcoding, biodiversity monitoring, phylodiversity, biodiversity informatics, along with research regarding the implementation of the Convention on Biological Diversity. Overall, 13 special issues/special features were published since 2000. Among 1,189 papers (excluding four English supplements), 149 papers were on species diversity, 113 papers on genetic diversity, and 38 papers on ecosystem diversity. Studies on plant diversity and animal diversity represented a significant proportion of the publications, whereas few papers were published on microbial diversity. Among all the authors, Fang Jingyun ranked first with 41 papers, followed by Ma Keping (31 papers), and Chen Jiakuan (22 papers). The top 10 authors in terms of number of published papers came from the Chinese Academy of Sciences, Peking University, and Fudan University. The mean number of authors per paper was ~1.5 in 1993 and increased to ~4 in 2011, showing increased collaboration in the study work. Concordantly, the mean number of pages per paper increased from 5 pages of 1993 to ~10 pages of 2011. There were more than 200 papers that were cited >400 times, with the largest up to 970 (as of August 10, 2012). This resulted in two peaks of papers with high citation numbers in 1993-1994 (50 times per paper) and 1998-2004 (40 times per paper). Papers were mainly from projects financially supported by the National Natural Science Foundation of China, the Ministry of Science and Technology, and the Chinese Academy of Sciences. The Journal has been ranked one of the leading scientific journals in the field of biology in the country. However, the Journal faces strong competition from international journals. Based on our findings, we provide corresponding countermeasures and suggestions.
Golden apple snails seriously damage crops and aquatic ecosystem in China. Two invasive apple snail species, Pomacea canaliculata and P. maculata, have been reported in China since 2010. Only the distribution of P. canaliculata was reported in Zhejiang Province. It is difficult to distinguish the two species due to their close morphological characteristics and high diversity of shell morphology, which are influenced by both environmental factors and food types. We collected samples from seven localities from Zhejiang Province and sequenced 101 individuals of mitochondrial COI fragments of the DNA barcode region. We also downloaded 55 sequences of five species of the P. canaliculata group, which included all public sequences of P. lineata, P. dolioides, and P. paludosa, and South American sample sequences of P. canaliculata and P. maculata. Analyses including similarity alignments, DNA barcoding gaps, and phylogenetic relationships, revealed that COI sequences were effective to distinguish apple snail species. We detected P. canaliculata and P. maculata distributed in the Jianggan region of Hangzhou, while only P. canaliculata was distributed in the Putuo region of Zhoushan, the Shanyu and Xinchang regions of Shaoxing, the Ouhai region of Wenzhou and the Xihu regoin of Hangzhou. P. canaliculata revealed a much wider distribution range. P. canaliculata and P. maculata were collapsed into 4 haplotypes and 2 haplotypes, respectively. There were 1 to 3 haplotypes in each locality, which indicated a low genetic diversity. The phylogenetic analyses deduced that P. canaliculata and P. maculata were probably introduced from Argentina and Brazil, respectively.
Ex-situ conservation is an effective measure to prevent extinction of species. In order to learn the plant-pollinator relationship in ex situ habitat and shed insights into the ex situ conservation, we studied the pollination system and reproductive strategy of two orchids Ludisia discolor from Wutong Mountains, Shenzhen and Calanthe argenteo-striata from Malipo, Yunnan in the Botanical Garden of the National Orchid Conservation Center (NOCC), Shenzhen, southeastern China in 2007 and 2008. Both species have inflorescences with many white flowers which have spur with a narrow entrance. The butterfly, Pieris rapae, was their solely legitimate pollinators. The pollinaria of L. discolor were carried on the legs of butterflies, while that of C. argenteo-striata on the proboscis. The pollination efficiency in both orchids was high, and the ratio of pollinaria removal to massulae deposition was 1.14:1 and 0.74:1 in L. discolor and C. argenteo-striata, respectively. In 2007 and 2008, fruit set of open pollination in L. discolor was higher than that in C. argenteo-striata, which could be explained by that the former provides rewards to its pollinators while the latter is deceptive, as well as by that the flowering period of L. discolor was synchronized with the abundance of butterflies, which favored the orchid to exploit its pollinators, whereas the flowering period of C. argenteo-striata was lagged behind the outbreak period of butterflies, which made the flowers suffer insufficient pollinator visitation. Both species were self-compatible but there were no spontaneous autogamy or apomixes. The fruit sets of cross-pollination and self-pollination showed no significant difference. Ludisia discolor and C. argenteo-striata grow well after being transplanted to NOCC, and new seedlings were found near parent plants, indicating the population tended to expand, and the ex situ conservation was feasible. It could be predicted that these two orchids have the potential to establish stable populations in NOCC in the future.