To explore the traits related to the invasiveness of exotic Bidens species in China, we compared the morphology, growth, biomass allocation, photosynthesis, and phenotypic plasticity of two invasive Bidens species (B. pilosa and B. frondosa) with two native congeners (B. biternata and B. tripartita) under different light and water conditions in a common garden. The results showed that the invasive and native species displayed similar plant heights and total biomass under unfavorable conditions (i.e. low light and low water treatment). However, under favorable light and water conditions (i.e. high light and high water treatment), the invasive species showed significantly greater plant height and total biomass than the native congeners. Furthermore, in high light treatments, the relative growth rate of the invasive species was higher than that of the native species. The invasive species allocated more resources to root biomass at high light levels compared to low light levels, while they allocated more resources to leaf biomass at low light levels compared to high light levels. Specific leaf area of the invasive species was greater than that of the native congeners under low light conditions. These traits may enhance the abilities of invasive species to capture and utilize resources, enabling them to withstand adverse environmental conditions or to respond more positively to favorable conditions. The phenotypic plasticity indices of invasive and native species for morphology, growth, and photosynthetic parameters were low for water availability and high for light intensity. However, for most variables, invasive species showed a higher phenotypic plasticity index than native congeners, and this may contribute to their invasion success. In addition, there were no significant differences for photosynthetic parameters between invasive and native Bidens species under any treatment. In conclusion, this study shows that morphology, growth, biomass allocation, and phenotypic plasticity may play more important roles than photosynthetic parameters in the success of invasive Bidens species.

Mikania micrantha is the most dangerous invasive weed in South China, due to its harmful effects on natural secondary forest habitats and other habitats. In order to illustrate the possibility of using the native legume Pueraria lobata var. thomsonii to replace M. micrantha, three water gradients (soil water content < 10%, 60-70% and 120-130%) that simulate drought, normal soil water content (as control) and waterlogged conditions, respectively, were established to study the physiological response of these two plant species to drought and waterlogging. Results showed that under drought stress, the total biomass of M. micrantha decreased significantly by 72% as compared to controls. Under waterlogging stress, the total biomass of P. lobata var. thomsonii increased by 16% compared to the control treatment, while M. micrantha decreased by 15%. Under drought conditions, the root-shoot ratio and chlorophyll content of native species P. lobata var. thomsonii were significantly greater than those found in the control (P < 0.05); while there were no significant differences in the root-shoot ratio of M. micrantha compared to the control (P > 0.05), but the chlorophyll content was significantly higher than that found in the control but lower than the normal level after rewatering. This may be the result of a significant increase in the proline and soluble sugar in P. lobata var. thomsonii. Following waterlogging stress, the malondialdehyde content of P. lobata var. thomsonii was approximately 2.1 times higher than the control, while that of M. micrantha was 3 times the control. After soil water content returned to normal levels, the malondialdehyde content of M. micrantha and P. lobata var. thomsonii maintained high levels, which were 1.72 times and 1.45 times the control group, respectively, indicating that the membrane lipid peroxidation level of P. lobata var. thomsonii was lower than that of M. micrantha as affected by waterlogging. Thus, it was concluded that P. lobata var. thomsonii exhibited better drought and waterlogging tolerance than M. micrantha. The resistance index also confirmed this conclusion. The results provide theoretical support for the control of M. micrantha through replacement by applying the native legume P. lobata var. thomsonii to natural habitats like forest edges or windows in areas of South China.

Evolution of Increased Competitive Ability (EICA) has suggested that exotic plants may reduce resource allocation to anti-herbivore defenses and increase allocation to growth due to reduced specialist herbivores in introduced ranges. However, the major limitation for the hypothesis may be that, as important defensive strategies, induced resistance and tolerance were seldom tested and little information is known regarding the evolution of defensive strategies as influenced by resource availability. Nine introduced and nine native populations of Alternanthera philoxeroides were compared for fitness and two morphological traits that influence herbivory, specifically specific stem length (SSL, plants with low SSL have hollow stems favoured by a stem-boring specialist insect Agasicles hygrophila) and root/shoot ratio (RSR) under low and high nutrient availability and with or without A. hygrophila. Introduced populations showed greater total biomass (+14.7%) and lower SSL (-27.5%), demonstrating increased growth and decreased levels of constitutive defense. Tolerance to herbivory was similar between introduced and native populations. SSL plasticity to herbivory was greater in introduced populations under high nutrient levels, and was positively correlated with total biomass. These results suggest that although both functional trait values and plasticity contribute to the adaptation of alligator weeds to a wide range of nutrient availabilities and specialist insect herbivory, introduced populations have evolved higher production of biomass, lower levels of constitutive structural defense, and greater plasticity of structural defense in high nutrient conditions, indicating that the present control practice for A. philoxeroides where introducing A. hygrophila will face great challenges in the future.

The control of invasive alien plants (IAP) that jeopardize our ecosystems and economy constitutes a significant challenge for natural resource management. Classical biological control referring to the introduction of specialist antagonists from the native range has proven to be a highly cost-effective management tool against IAP. A critical issue in biological control research is to guide informed decision-making on the potential spread and distribution and thus impact of biological control candidates, especially under climate change. Here we propose a biogeographic modeling approach to predict the cover of the suitable area of a plant invader in East Asia (EA) by two biological control agents and their combinations. Our study system is Ambrosia artemisiifolia, native to North America and invasive worldwide, and two North American biological control agents, Ophraella communa and Epiblema strenuana that were accidentally and deliberately introduced into East Asia (EA) in the late 20th century, respectively. Specifically, we ask: (1) what percentage of the suitable A. artemisiifolia area is also suitable for the two agents in EA, and (2) which part of the suitable A. artemisiifolia area in EA is likely to remain uncovered by these two agents, both under current and future climatic scenarios; and (3) which particular biotypes would be needed to fill in the yet uncovered part of the suitable A. artemisiifolia range in East Asia? For this, we simultaneously modelled the species distributions based on worldwide occurrences and important bioclimatic variables for the target invasive plant and its two biological control agents. Ordination techniques were used to explore climatic constraints of each species and to perform niche overlap and similarity tests with A. artemisiifolia between its native North American and introduced EA range. Our results show that O. communa has a larger overlap with the geographic range of A. artemisiifolia than E. strenuana, both under current (40.3% vs. 21.6% for O. communa and E. strenuana, respectively) and future climatic scenarios (29.8% vs. 20.3% for O. communa and E. strenuana, respectively). Importantly, climate change is expected to reduce the total geographic overlap of A. artemisiifolia by the two agents combined (42.9% vs. 29.8% for current and future climate conditions, respectively), with a higher reduction by O. communa than by E. strenuana. Our analyses also identified for which abiotic conditions to select in order to develop climatically adapted strains for particular regions, where A. artemisiifolia is presently unlikely to be covered.

Profound threats on global biodiversity caused by the expansion and accumulation of invasive species substantiate the urgent need to understand their invasion mechanisms. While most studies of invasive plants have focused on macro-organisms, it has become increasingly clear that microorganisms are pervasive and play central roles in successful invasion processes of exotic plants. According to studies examining soil microbes and invasive plants, we discuss the effects of invasive plants on soil microbial communities by dividing them into three separate groups, namely microbial pathogens, mutualistic microbes, and saprotrophic microbes. Roots are the primary site for interactions with microbes, and the rhizosphere is the largest reservoir of known microbial diversity. The rhizosphere provided a heterogeneity microhabitat at the root-soil interface (rhizosphere soil, rhizoplane, and endorhizosphere) and shapes the habitat into different functions. However, previous studies have tended to focus on either the single dimension or at the hole level, which fails to explain the scope and depth of the phenomenon. When examining this issue, we propose that future studies of the interactions between rhizosphere microbes and invasive plant should combine the root elaborate microhabitat and macro-functional traits. It is essential to construct a systematic and reproducible research framework by using high-throughput DNA sequencing technology and corresponding bioinformatic tools, to switch the mode of research from the description and prediction of the phenomenon into the elaboration of the mechanism in the field of plant invasion.

To determine biodiversity, 74 plant community plots were surveyed in western Inner Mongolia between 2012 and 2014. These samples were divided into four vegetation types, including temperate steppe, temperate shrub, meadow, and desert. Four biodiversity indices (Patrick index, Simpson index, Shannon-Wiener index and Pielou index) were calculated to show biodiversity differences among the four vegetation types. Climate and soil data were also collected over the course of the survey. Pearson correlation analysis was conducted to reveal the relationship between biodiversity and environmental factors and stepwise regression analysis was used to determine dominant environmental factors. Results indicated that: (1) In western Inner Mongolia, biodiversity indices were different among the four vegetation types. Temperate steppe and meadow had similar values for biodiversity indices, and were also the highest amongst all vegetation types, while the lowest biodiversity was found in the desert. (2) Pearson correlation analysis showed that the Patrick index, Shannon-Wiener index, and Simpson index were all negatively and linearly correlated with mean annual temperature and potential evapotranspiration. (3) Among all chemical properties of the soil, pH, organic carbon and total nitrogen all influenced biodiversity indices. (4) Stepwise regression analysis showed that potential evapotranspiration and soil organic carbon were the most influential factors affecting the Patrick index and Shannon-Wiener index. The only dominant factor for the Simpson index was soil organic carbon while soil total nitrogen was most important factor for the Pielou index.

Species dissimilarity mainly reflects temporal and spatial variation in community composition. Its relationship with random and deterministic factors reveals community assembly, biodiversity formation, and maintenance mechanisms. In this study, we analyzed relationships between species dissimilarity of plant communities and influencing factors in the Dulongjiang River Watershed Area. Jaccard species dissimilarity, geographic distance, difference in climate (Mean Annual Temperature and Mean Annual Precipitation), and altitude between any two communities were calculated. Results showed that the species turnover rate varied from 0.42 to 1. Species turnover significantly linearly increased with Ln-transformed geographic distance and differences in climate and altitude. Results from partial regression analysis showed that these three kinds of factors together can explain nearly 30% of species differences of vascular plant communities in the Dulongjiang River Watershed Area; independent effects of geographical distance, elevation difference, and climatic differences were 18.80%, 3.47%, and 0.10%, respectively. Species dissimilarity in the Dulongjiang Watershed Area results from the combination of environmental and dispersal limitations, which plays an important role in the conservation of plant biodiversity in the Dulongjiang Watershed Area. When biodiversity conservation is undertaken in the area, on the basis of considering the impact of environmental factors, the effects of topographical barriers and dispersal abilities of propagules should be fully considered.

China’s previous zoogeographical regionalization designations were delineated according to expert knowledge and experience. However, these previous designations have limited application in wildlife conservation and management because of a lack of quantitative footing. Additionally, there are still significant differences in the ecological components of some of the basic units. In order to meet the needs of wildlife protection and management, especially the needs of the Second National Survey on Terrestrial Wildlife Resources in China, we carried out national wildlife survey unit zoning, based on Zhang Rongzu’s “Zoogeographical Regions of China”. In this study, hierarchical clustering was applied to a 5 km × 5 km grid of faunistic and environmental components, based on a comprehensive species distribution dataset, consisting of 262 amphibians, 358 reptiles, 814 birds, and 350 mammals. Our results delineated China into 2 realms, 7 regions, 19 sub-regions, 54 zoogeographical provinces, 239 eco-geographical units, and 310 survey units. Compared to Zhang’s scheme, the number of realms, regions, sub-regions, and zoogeographical provinces are the same and most of the boundaries are broadly consistent, however, some discrepancies also emerge. To meet the needs of wildlife conservation and management, two hierarchical levels of zoogeographical units were added, namely eco-geographical units and survey units.

The watershed of the Wuyi-Xianxialing Mountains comprises the Poyang Lake water system of the Yangtze River basin and independent coastal rivers of eastern China, including the Qiantang River, Oujiang River, Minjiang River, and Hanjiang River. It is a key area for the conservation of biodiversity in Chinese ecosystems. In this study, fish surveys were conducted in 111 upstream sections of five river basins draining the Wuyi-Xianxialing Mountains and over 13,000 specimens were collected. The fish fauna of this area, on the basis of our investigations and records from historical literature, included 282 species, of which 239 were freshwater fishes, belonging to 101 genera, 23 families, and 6 orders. The orders of Cypriniformes, Perciformes, and Siluriformes supported the majority of fish composition in this area, with 181, 29, and 22 species, respectively, accounting for 75.73%, 12.13%, and 9.21% of total freshwater fish found. There were 109 fish species that were the major component of fish composition of the river plains of East Asia and 51 species of warm water fish with Southeast Asian origin, accounting for 45.61% and 21.34% of the total freshwater fishes, respectively. There were many species shared among the five river basins, and the average faunal resemblance of any two rivers was more than 50%. For the four substantive rivers in the eastern region, from north to south, the proportion of endemic fishes in the river plains of East Asia gradually decreased, and the proportion of warm water fishes of Southeast Asian origin gradually increased. Clustering analysis of fish fauna demonstrates that Poyang Lake, Qiantang River, Oujiang River, and Minjiang River are clustered into one class, while Hanjiang River forms the other class. This analysis indicates that the Wuyi-Xianxialing Mountains do not form a strong barrier for freshwater fishes, and that the whole district of the Wuyi-Xianxialing Mountains should be a component of the Oriental Region. In view of the differences between the north and the south, this paper argues that Hanjiang River in the southeast belongs to the South China Area of the South-east Asiatic Subregion, while Poyang Lake, Qiantang River, Oujiang River, and Minjiang River belong to the East China Area.

The temperate coniferous and broadleaf mixed forest (TCBMF) in Northeastern China is the contact zone between southern warm-temperate forests and northern cool-temperate forests, and is a key region for studying the influence of Quaternary climate changes on genetic patterns. Vegetation reconstructions have shown the TCBMF has retreated southward to 25°-30° N during the last glacial maximum (LGM). However, phylogeographic studies indicated plants of TCBMF could have survived in one refugium or multiple refugia at 35° N during the LGM. The Mt. Changbai and Korean Peninsula are the two most important refugia for the TCBMF, and other refugia may also exist, of which the northernmost ones would reach the Xiaoxing’an Range and Russian Far East. The interglacial or postglacial expansion from refugia resulted in complicated distribution patterns with respect to genetic diversity. The northward population expansion from one southern refugium does not necessarily cause a significant decrease in inter-population genetic diversity as latitude increases. Inter-population genetic diversity always shows a uniform distribution in plants which have multiple refugia. Although previous studies have shown the influence of the quaternary, especially the LGM, on the evolutionary history of plants in the TCBMF, these studies have concentrated on tree species and mainly focused on one species. Therefore, adaptive evolution of closely-related species or sibling species between Northeast and South China, and the mechanisms driving community assembly are two directions for future studies.