Integrating phosphorus management and cropping technology for sustainable maize production

Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize production.Increasing plant density is considered an effective approach for achieving high maize yields.However,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant densities.In this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant densities.The application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium phosphate.Our scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize production.These findings offer strategic,synergistic options for achieving sustainable agricultural development.

Relationship between multi-scale climate factors and performance of ecological engineering on the Loess Plateau, China

The long-term “Grain-to-Green Program” (GGP) on China’s Loess Plateau is a major global ecological engineering project which has significantly boosted vegetation renewal. Some studies have found that the rate of restoration is quite rapid during the implementation of ecological engineering, however, the influence of multi-scale climatic conditions on the performance of ecological engineering is unclear. In this study, multiple sources of remote sensing data were used to estimate the dynamics of vegetation structural and functional indicators, water-related local climatic factors, and atmospheric circulation factors. These datasets were also used to detect possible causes for vegetation restoration on the Loess Plateau over the past 20 years. The results show that widespread increases in rates of normalized difference vegetation indexes (NDVI), leaf area indexes (LAI), gross primary production (GPP), and aboveground biomass carbon (ABC) during 2000–2016 were significantly higher than before 2000. GPP was significantly correlated with rainfall and surface runoff on a monthly scale, and there were significant positive correlations between GPP and atmospheric circulation. Our results demonstrate that both vegetation structural and functional indicators rapidly increase, and ecological engineering greatly accelerated vegetation restoration after 2000. Local climatic conditions and atmospheric circulation patterns enhance vegetation growth and impact of ecological engineering.

Achievements,challenges,and recommendations for waterbird conservation in China's coastal wetlands

China’s coastal wetlands provide breeding,migration stopover,and wintering habitats for about 230 waterbird species,which is more than a quarter of all waterbirds in the world.Large-scale and high intensity human activities have resulted in serious loss and degradation of coastal wetlands over the past half century,causing population declines in many waterbirds.Through a literature review and expert surveys,this article reviews conservation measures taken in recent decades to protect waterbirds in China’s coastal wetlands and provides recommendations for future conservation action from three aspects:policy and administration,habitat conservation and management,and multiparty participation.Over the past decades,many conservation legislation,regulations and action plans at the national level and more site-specific measures and interventions have been implemented,with notable improvement in the effectiveness in policy making and multi-stakeholder participation.Accordingly,some threats to waterbirds have been mitigated and many key sites for waterbirds have been designated as strictly protected nature reserves.However,some critical issues still remain,mostly related to habitat conservation and management,such as coastal wetland restoration,control of invasive Spartina alterniflora,control of environmental pollution,and improvement of artificial habitat quality.We highlight that protecting natural tidal wetlands and improving habitat quality are critical for the conservation of coastal waterbirds,especially those highly dependent on the intertidal wetlands.China has demonstrated strong commitment to ecological conservation and restoration for the future,in terms of both funding and policies for biodiversity and wetland ecosystems.It is important that this commitment to conserve coastal waterbirds is supported continuously by science-and evidence-based decisions and actions.

Corrigendum to“Achievements,challenges,and recommendations for waterbird conservation in China's coastal wetlands”[Avian Res.14(2023)100123]

The authors regret that Fig.1 and its caption should be replaced as below.

Diverse foraging strategies of breeding Swinhoe's Storm-petrel in the productive marginal sea of the Northwest Pacific

Understanding the foraging behavior is essential for investigating seabird ecology and conservation,as well as monitoring the well-being of the marine environment.Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance.Such tradeoff may stem from the heterogeneity of food resources and the constraints of central place foraging.Nevertheless,abundant marine productivity could alleviate the energy limitation for seabirds,resulting in a consistent foraging approach.Here,we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird,Swinhoe’s Storm-petrel(Hydrobates monorhis),in the Yellow Sea,a productive marginal sea of the Northwest Pacific.Using GPS tracking,we evaluated habitat preference,quantified the foraging strategy,and tested if environmental conditions and individual traits influence foraging trips.We found that Swinhoe’s Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips.Distinctive southeastward and southwestward strategies emerged when combining trip metrics,including foraging direction,duration,and maximum distance.The bathymetry,proximity to the coastline,and sea surface temperature differed in two foraging strategies.Foraging strategies exhibited flexibility between individuals,potentially explained by wing morphology,in which longer-winged birds are more likely to embark on longer-distance foraging trips.These findings highlight the impact of environmental factors and individual traits on seabirds’foraging decisions in productive marginal sea ecosystems.Our study also provides valuable insights into the foraging ecology of this Asian endemic storm-petrel.

Population genomic data reveal low genetic diversity,divergence and local adaptation among threatened Reeves's Pheasant(Syrmaticus reevesii)

Population genomic data could provide valuable information for conservation efforts;however,limited studies have been conducted to investigate the genetic status of threatened pheasants.Reeves’s Pheasant(Syrmaticus reevesii)is facing population decline,attributed to increases in habitat loss.There is a knowledge gap in understanding the genomic status and genetic basis underlying the local adaptation of this threatened bird.Here,we used population genomic data to assess population structure,genetic diversity,inbreeding patterns,and genetic divergence.Furthermore,we identified candidate genes linked with adaptation across the current distribution of Reeves’s Pheasant.The present study assembled the first de novo genome sequence of Reeves’s Pheasant and annotated 19,458 genes.We also sequenced 30 individuals from three populations(Dabie Mountain,Shennongjia,Qinling Mountain)and found that there was clear population structure among those populations.By comparing with other threatened species,we found that Reeves’s Pheasants have low genetic diversity.Runs of homozygosity suggest that the Shennongjia population has experienced serious inbreeding.The demographic history results indicated that three populations experienced several declines during the glacial period.Local adaptative analysis among the populations identified 241 candidate genes under directional selection.They are involved in a large variety of processes,including the immune response and pigmentation.Our results suggest that the three populations should be considered as three different conservation units.The current study provides genetic evidence for conserving the threatened Reeves’s Pheasant and provides genomic resources for global biodiversity management.

Population trends, threats, and conservation recommendations for waterbirds in China

Background: China is one of the countries with abundant waterbird diversity. Over the past decades, China's waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation recommendations.Methods: We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China's Vertebrates(2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in China.Results: Of the total 260 waterbird species in China, 84 species(32.3%) exhibited declining, 35 species(13.5%) kept stable, and 16 species(6.2%) showed increasing trends. Population trends were unknown for 125 species(48.1%). There was no significant difference in population trends between the migratory(32.4% decline) and resident(31.8% decline) species or among waterbirds distributed exclusively along coasts(28.6% decline), inland(36.6% decline), and both coasts and inland(32.5% decline). A total of 38 species(15.1% of the total) were listed as threatened species and 27 species(10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38(84.2%) threatened species being affected. In addition, 73.7%(28 species), 71.1%(27 species), and 57.9%(22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, respectively.Conclusions: We propose recommendations for waterbird conservation, including(1) strengthening conservation of nature wetlands and restoration of degraded wetlands,(2) enhancing public awareness on waterbird conservation,(3) improving the enforcement of Wildlife Protection Law and cracking down on illegal hunting,(4) carrying out longterm waterbird surveys to clarify population dynamics,(5) restoring populations of highly-threatened species through artificial intervention, and(6) promoting international and regional exchanges and cooperation to share information in waterbirds and their conservation.

Genome sequencing and population genomics modeling provide insights into the local adaptation of weeping forsythia

Understanding the genetic basis underlying the local adaptation of nonmodel species is a fundamental goal in evolutionary biology.In this study,we explored the genetic mechanisms of the local adaptation of Forsythia suspensa using genome sequence and population genomics data obtained from specific-locus amplified fragment sequencing.We assembled a high-quality reference genome of weeping forsythia(Scaffold N50=7.3 Mb)using ultralong Nanopore reads.Then,genome-wide comparative analysis was performed for 15 natural populations of weeping forsythia across its current distribution range.Our results revealed that candidate genes associated with local adaptation are functionally correlated with solar radiation,temperature and water variables across heterogeneous environmental scenarios.In particular,solar radiation during the period of fruit development and seed drying after ripening,cold,and drought significantly contributed to the adaptive differentiation of F.suspensa.Natural selection exerted by environmental factors contributed substantially to the population genetic structure of F.suspensa.Our results supported the hypothesis that adaptive differentiation should be highly pronounced in the genes involved in signal crosstalk between different environmental variables.Our population genomics study of F.suspensa provides insights into the fundamental genetic mechanisms of the local adaptation of plant species to climatic gradients.

Research advances of Galliformes since 1990 and future prospects

Background: Galliformes are widely distributed throughout the world and economically important to humans as domesticated animals or gamebirds. They are at a unique position for advancing knowledge and techniques of wildlife conservation as the barometer of the status of applied ecology. Populations of many galliform species have declined mainly due to habitat loss and over-hunting. An assessment of knowledge of Galliformes could help to provide guidelines for future research and conservation strategies.Methods: Using the Web of Science search engine, we conducted a literature review of galliform-related articles published from 1990 to 2016. We used the "research area" option to filter articles focused on the zoology, environmental sciences ecology, biodiversity conservation, forestry, behavioral sciences, reproductive biology, biochemistry and molecular biology, cell biology, genetics and heredity, evolutionary biology, physiology and developmental biology. We then checked duplication based on the title, abstract and full text. In addition, we examined the reference lists of selected studies to include the publications that were missed by above searching.Results: We retained 1874 articles related to the Galliformes from the initial 243,128 publications that were found. About 91.4% focused on one or two species, and 85.0% were conducted within a short duration, typically 1–2 years. The majority of the articles concentrated on macroscopic ecology(55.5%), mainly focusing on habitat selection or habitat use. With recent advances of molecular biology, the studies of taxonomy and phylogenetics rose quickly in last two decades. The study of physiology and biochemistry was no longer limited to simple description but expanded to the mechanisms of phenotype and micro-evolutionary potential. An additional area receiving increasing attention is the conservation of Galliformes, with the assessment of the conservation status and conservation management effectiveness of Galliformes(e.g. species diversity and genetic diversity) becoming the focus.Conclusions: The studies on Galliformes have made great achievements since 1990, but there are still gaps, particularly in macroscopic ecology, molecular genetics, and conservation. There is an urgent need to enhance long-term monitoring and analysis of population dynamics, and applying different disciplines to galliform conservation. Moreover, life history information of many galliform species is still lacking, which has hindered conservation efforts and effectiveness. In addition, multidiscipline studies and new technologies are not common for galliform studies, and should be encouraged.

Changes in wintering Hooded Cranes and their habitats at Chongming Dongtan over the past 20 years

The Hooded Crane(Grus monacha)is listed as a Vulnerable species in the IUCN red list.Tidal wetland(tideland),the major habitat for wintering Hooded Cranes at East China’s Chongming Dongtan,has dramatically changed in the past two decades,but there is limited knowledge about the population and habitat changes of the Hooded Cranes.This study investigated the population size and distribution of wintering Hooded Cranes at Chongming Dongtan from 2000 to 2021.We used remote sensing images combined with a vegetation classification algorithm to analyse the distribution of saltmarsh vegetation.The quadrat method was used to investigate the density and weight of the underground corms of Sea Bulrush(Scirpus mariquter),the main food on tideland for the Hooded Cranes.From 2000 to 2021,the population number of wintering Hooded Cranes at Chongming Dongtan remained stable at approximately 100.In 2000,the area of Scirpus spp.and Common Reed(Phragmites australis)accounted for approximately half of the total saltmarsh area at Chongming Dongtan,respectively.The invasive Smooth Cordgrass(Spartina alterniflora)rapidly expanded on tideland in the 2000s while the Scirpus spp.was competed out and thus significantly reduced in area.After the implementation of an ecological project to control Smooth Cordgrass and to restore Scirpus spp.in the 2010s,the area of the Smooth Cordgrass decreased considerably while the area of Scirpus spp.increased.The corms of Sea Bulrush decreased on the southeastern tideland during the study period,which might be the cause of the northward movement of the foraging Hooded Cranes on tideland.We also found Hooded Cranes foraged crops in the nearby farmland in mid-winter,causing human-bird conflicts in the recent decade.Our results found that changes in habitat and food conditions on tideland impacted wintering Hooded Cranes.Foraging in farmland with human disturbance in the recent decade might be related to insufficient food on tideland.We suggest active intervention to accelerate the restoration of Sea Bulrush on tideland and reduce human disturbance in farmland to improve the habitat quality of the wintering Hooded Crane at Chongming Dongtan.

Sexual reproduction and short-term fitness advantage in the rotifer Brachionus calyciflorus:implications for the coexistence of sympatric clones

Large numbers of rotifer eggs from sediment resting egg banks may hatch simultaneously under appropriate conditions;therefore,natural populations are likely to be multiclonal in a growing season.A recent field investigation showed that subordinate and ephemeral clones were able to establish populations in an environment with several strongly dominant clone populations.However,it was not clear how the subordinate populations maintained their growth under these conditions where the crowding signal would induce high levels of sexual reproduction in the dominant clone populations.In the present study,we conducted a continuous passage to 60 generations for new populations at three different temperatures(15°C,25°C,and 35°C).These populations emerged from resting eggs produced by a clone population.At the first,30th,and 60th generations,the populations were sampled and fitness was assayed using the life-table method.We found a significant short-term fitness advantage for populations newly emerged from resting eggs produced by a clone population of the rotifer Brachionus calyciflorus,followed by a significant decrease in relative fitness with long-term continuous passage.Our results suggested that the early shortterm fitness advantage was important for later-hatched and subordinate clone populations in an environment with multiple sympatric clones.The early short-term fitness might also promote the coexistence of sympatric clones because it could help to offset the cost of early sexual reproduction.

Autumn migration routes of fledgling Chinese Egrets(Egretta eulophotes)in Northeast China and their implications for conservation

The Chinese Egret(Egretta eulophotes)is a globally threatened bird species living on the coast and islands of Liaoning,northeastern China,mainly in summer.To further protect the breeding population of Chinese Egrets,it is important to understand the current protection status of their distribution sites at pre-migration period and migration routes.Thirty-three individuals were tagged with satellite transmitters at Fantuo Island in Changhai and Xingren Island in Zhuanghe,Liaoning Province,northeastern China,in July of 2016,2017,and 2018,to identify important distribution sites during the pre-migration period,as well as detailed migration routes.The results showed that coastal mudflats in Liaoning and the west coast of North Korea were important feeding and roosting sites for fledgling Chinese Egrets from August to September.The home range sizes in August were significantly larger than in September.The eastern coast from Shandong to Guangdong,as well as Taiwan,China,and Manila Bay and Galileo Islands in the Philippines,were important stopover sites during fall migration.Specifically,we found that the egrets’autumn migration could be divided into four routes,i.e.,sea-crossing migration(SCM),coastal migration(CM),inland migration(IM),and mixed migration(MM).The migration distance,timing,speed,and straightness of the four routes also differed.The SCM routes were the straightest,and had the fastest migration speed and shortest travel time,while the IM routes had the lowest straightness and speed,and the longest duration.Manila Bay and Bohol Island in the Philippines,the west coast of Tanintharyi in Myanmar,and the Zengwun River Estuary in Taiwan,China,were wintering sites.Our findings on the key distribution sites along pre-migration and fall migration routes,including some stopover sites,have important implications for the conservation of and global action plan development for the vulnerable Chinese Egret.

Saltmarsh vegetation and social environment influence flexible seasonal vigilance strategies for two sympatric migratory curlew species in adjacent coastal habitats

Background:Animals need to adjust their vigilance strategies when foraging between physically contrasting veg-etated and non-vegetated habitats.Vegetated habitats may pose a greater risk for some if vegetation characteristics function as a visual obstruction but benefit others if they serve as protective shelter.Variation in group size,presence of similar species,along with variation in environmental conditions and anthropogenic disturbance can also influence vigilance investment.Methods:In this study,we quantified the vigilance behaviour of two large-bodied,sympatric migratory curlew species-Far Eastern Curlew(Numenius madagascariensis)and Eurasian Curlew(N.arquata)-in vegetated Suaeda salsa saltmarsh and non-vegetated mudflat habitat in Liaohekou National Nature Reserve,China.We used linear mixed models to examine the effects of habitat type,season,tide time,flock size(conspecific and heterospecific),and human disturbance on curlew vigilance investment.Results:Both species spent a higher percentage of time under visual obstruction in S.salsa habitat compared to mudflat habitat but in response,only Far Eastern Curlew increased their percentage of vigilance time,indicating that visual obstruction in this habitat is only a concern for this species.There was no evidence that S.salsa vegetation served as a form of cryptic background colouration since neither species decreased their vigilance effect in S.salsa habitat in spring compared to the autumn migration season.The effect of curlew social environment(i.e.flock size)was habitat dependent since percentage of vigilance time by curlews in saltmarsh increased with both the number of individual curlews and number of other birds present,but not in mudflat habitat.Conclusions:We conclude that both migratory curlew species exhibit a flexible vigilance adjustment strategy to cope with the different environmental and social conditions of adjacent and sharply contrasting coastal habitats,and that the trade-off between the risks of foraging and the abundance of prey may be a relatively common phenom-enon in these and other shorebird populations.

Multilocus phylogeography and ecological niche modeling suggest speciation with gene flow between the two Bamboo Partridges

Background:Understanding how species diversify is a long-standing question in biology.The allopatric speciation model is a classic hypothesis to explain the speciation process.This model supposes that there is no gene flow during the divergence process of geographically isolated populations.On the contrary,the speciation with gene flow model supposes that gene flow does occur during the speciation process.Whether allopatric species have gene flow during the speciation process is still an open question.Methods:We used the genetic information from 31 loci of 24 Chinese Bamboo Partridges(Bambusicola thoracicus)and 23 Taiwan Bamboo Partridges(B.sonorivox)to infer the gene flow model of the two species,using the approxi-mate Bayesian computation(ABC)model.The ecological niche model was used to infer the paleo-distribution during the glacial period.We also tested whether the two species had a conserved ecological niche by means of a back-ground similarity test.Results:The genetic data suggested that the post-divergence gene flow between the two species was terminated before the mid-Pleistocene.Furthermore,our ecological niche modeling suggested that their ecological niches were highly conserved,and that they shared an overlapping potential distribution range in the last glacial maximum.Conclusions:The allopatric speciation model cannot explain the speciation process of the two Bamboo Partridges.The results of this study supported a scenario in which speciation with gene flow occurring between the allopatric species and have contributed to our understanding of the speciation process.

Predicting the non-breeding distributions of the two Asian subspecies of Black-tailed Godwit using morphological information

Until recently,Limosa limosa melanuroides was thought to be the only subspecies of Black-tailed Godwit in the East Asian-Australasian Flyway.For this reason,all previous occurrences and counts of Black-tailed Godwits in the flyway have been assigned to melanuroides.However,a larger-bodied subspecies,bohaii,has recently been discovered in the flyway.As a result,the occurrence of Black-tailed Godwits in the flyway needs to be reconsidered such that the specific distribution of each subspecies becomes known.To this end,we developed a simple discriminant function to assign individuals to subspecies based on their bill and wing length.Cross-validation with individuals known to be bohaii or melanuroides,based on molecular analysis,showed the developed function to be 97.7%accurate.When applied to measurements of godwits captured at 22 sites across 9 countries in East-Southeast Asia and Australia,we found that bohaii and melanuroides occurred at most sites and overlapped in their distribution from Kamchatka to Australia.We examined photos from all along the flyway to verify this surprising result,confirming that both subspecies co-occur in most locations.Based on these results,we hypothesise that bohaii and melanuroides from the west of their breeding ranges mostly migrate over Chinese mainland.Birds of both subspecies from the east of their ranges are expected to migrate along the Pacific Ocean.We encourage ringing groups in East-Southeast Asia and Australia to use this simple method to keep adding knowledge about Black-tailed Godwits in the East Asian-Australasian Flyway.

Improving landscape connectivity through habitat restoration:application for Asian elephant conservation in Xishuangbanna Prefecture,China

Habitat restoration is an effective method for improving landscape connectivity,which can reduce habitat fragmentation.Maintaining landscape connectivity could promote connections between habitat,which is extremely essential to preserve gene flow and population viability.This study proposes a methodological framework to analyze landscape connectivity for Asian elephant habitat conservation,aiming to provide practical options for reducing habitat fragmentation and improving habitat connectivity.Our approach involved combining a species distribution model using MaxEnt and landscape functional connectivity models using graph theory to assess the impact on connectivity improvement via farmland/plantation restoration as habitat.The results showed that:(1)there were 119 suitable habitat patches of Asian elephant covering a total area of 1952.41 km^(2).(2)The connectivity between habitats improved significantly after vegetation restoration and the gain first decreased and then increased with the increase of dispersal distance.(3)The first few new habitat patches that were identified played an important role in improving connectivity,and the variation rate of connectivity gradually leveled off as the number of new habitats increased.(4)Prioritization of the 25 best new habitat patches increased connectivity from 0.54%to 5.59%as the dispersal distance increased and mainly was located between two Asian elephant distribution regions and two components.Establishment of new habitat patches was effective for improving or restoring connectivity.Our findings can be used as guidance for improving the studied fragmented Asian elephant habitats,and they can also be used as a reference for the habitat restoration of other endangered species heavily affected by habitat fragmentation.

A global synthesis of the effectiveness and ecological impacts of management interventions for Spartina species

Invasions by Spartina species pose serious threats to global coastal ecosystems.Although many studies have examined the effectiveness and ecological impacts of invasive Spartina management,no comprehensive global synthesis has been conducted to assess the effects of management on Spartina per se and on wider non-targets.Here,we conducted a global meta-analysis of 3,459 observations from 102 studies to quantify the effects of different management interventions(physical,chemical,biological,and integrated control)on Spartina per se and native biodiversity and environments.We found that physical measures quickly suppressed Spartina but that their effectiveness declined over time.By contrast,chemical measures decreased the abundance and growth of Spartina to a lesser degree in the early stage,but the effectiveness increased over time.Different management measures did not significantly decrease the diversity of native biota on the whole,but native-plant diversity significantly decreased with time after physical control.Different management measures did not affect abiotic factors differently.These results support the use of chemical measures to control invasive Spartina,although their effectiveness would depend on the time since the management intervention.Addressing the problem of Spartina regrowth following physical control requires improved techniques.We hold that initial states of invaders and subsequent environmental changes after management interventions should be weighed in evaluating control efficacy.

Characterization of Bacterial Community Structure and Diversity in Rhizosphere Soils of Three Plants in Rapidly Changing Salt Marshes Using 16S rDNA

在在长江河口的本国的 Phragmites 南极光和 Scirpus mariqueter 和相异的 Spartina alterniflora 的根围土壤的细菌的社区的结构和差异被构造 16S ribosomal 脱氧核糖核酸(rDNA ) 调查克隆图书馆。细菌的差异被把克隆放进运作的分类单位(OTU ) 确定在 】 的顺序类似的水平的组 97% 。398 克隆定序的结果的种系发生的分析在这些工厂的根围土壤显示了细菌的高差异。门 Proteobacteria 的 Alphaproteobacteria， Betaproteobacteria， Gammaproteobacteria，和 Deltaproteobacteria 的成员最充满 rhizobacteria。结合的 Chao 1 非参量的差异评估者 Simpson 的索引(1/D ) 相互被使用定序从每个图书馆获得评估全部的顺序差异和份量上的数据比较优势的水平。结果显示出那 Phragmites， Scirpus，和包含的 Spartina 根围土壤 200， 668，和 382 OTU 分别地。在 Spartina 和 Phragmites 根围土壤的细菌的社区显示了 1/D 揭示的种类优势，而在 Scirpus 根围土壤的细菌的社区有种类丰富的均匀分布。总的来说，从根围土壤的 16S rDNA 克隆图书馆的分析显示在细菌的作文的变化可以在植物群落与种类作文的移动附随地发生。

Intercropping of rice varieties increases the eff iciency of blast control through reduced disease occurrence and variability

Creating a crop-heterogeneous system by intraspecific mixtures of different rice varieties can substantially reduce blast diseases. Such variety mixtures provide an ecological approach for effective disease control, maintaining high yields with the minimum fungicide applications. Whether such an approach is universally applicable for random rice variety combinations and what is the variation pattern of the diseases under intercropping still remains unclear. We conducted two-year large-scale field experiments involving 47 rice varieties/lines and 98 variety-combinations to compare the occurrence of rice blast in monoculture and intercropping plots at multiple sites. In the experiments, the plant height of the selected tradi- tional varieties was about 30 cm taller, and their life cycle was 10 days longer, than that of the improved rice varieties. The monoculture included either traditional or modern rice varieties grown in separate plots. The intercropping included both traditional and modern rice varieties planted together in the same plots. Results from the field experiments under natural disease conditions demonstrated significant reduction for rice blast disease in intercropping plots, compared with that in monoculture plots. For traditional varieties, the average blast incidence reduced from -26% in monoculture to -10% in intercropping, and the disease severity reduced from -17 in monoculture to -5 in intercropping. For modern varieties, the average blast incidence reduced from -19% in monoculture to -10% in intercropping, and the severity from -10 in mono- culture to -4 in intercropping. Traditional rice varieties （-72%） had a much greater increase in the efficiency of disease control than modern varieties （-60%）. In addition, substantially lower values of variance in the blast incidence and severity was detected among the variety combinations in intercropping plots than in monoculture plots. Based on these results, we conclude that the intercropping or mixture of rice varieties greatly reduces the occurrence and variation of rice blast disease in particular variety combinations, which makes the intercropping system more stable and consistent for disease suppression on a large scale of rice cultivation.

Chemical composition and phytotoxic activity of the volatile oil of invasive Xanthium italicum Moretti from Xinjiang,China

Aerial parts of Xanthium italicum in an air tight container greatly inhibited root elongation of radish, implying that this invasive plant could release biologically active volatile organic compounds （VOCs） into the environment to affect other plants＇ growth. This phenomenon was further studied by evaluating the phytotoxic effects of X. italicum essential oil against two dicot plants, amaranth （Amaranthus mangostanus L.） and lettuce （Lectuca sativa L.）, and two monocot plants, wheat （Triticum aestivum Linn） and ryegrass （Lolium multiforum）, and analyzing the chemical composition of the oil. Among the 4 test species, amaranth was the most sensitive plant, 0.5μl/mL essential oil application resulted in a 50% reduction on root elongation, and 2.5 μl/mL essential oil almost completely inhibited its seedling growth. Wheat was the least sensitive species, whose root growth was reduced to 36% of control by 5 μl/mL essential oil. The essential oil exerted moderate inhibitory effect on both lettuce and ryegrass. Compared to a commercial herbicide-Harness, X. italicum oil exhibited stronger phytotoxicity on amaranth, lettuce and wheat, but weaker activity on ryegrass. The chemical composition of the essential oil isolated by hydrodistillation from the aerial parts of X. italicum Moretti was analyzed by GC/MS. Thirty two compounds were identified, representing 94.89% of total oil, which was found to be rich in monoterpene hydrocarbons （60.71%）. The main constituents of the oil were limonene （51.61%）, germacrene B （6.98%）, 6-cadinol （5.94%）, β-pinene （5.23%）, α-caryophyllene （5.1%） and bornyl acetate （3.15%）. Bioassay revealed the dominant constituent-limonene, was unlikely the responsible phytotoxic compound due to its low biological activity; rather, there might be other oil constituent（s） that either act alone, or work together, and possibly assisted by synergistic effect, to display the phytotoxic activity. Our results suggested that X. italicum might produce allelopathic VOCs to facilitate its invasion success. This is the first report on the phytotoxic activity and the chemical composition of the essential oil of X. itaficum Moretti from China.