入侵植物加拿大一枝黄花和本地一枝黄花的遗传多样性比较

为了阐明加拿大一枝黄花成功入侵的机制,利用简单序列重复区间标记(ISSR)方法对加拿大一枝黄花和本地一枝黄花的遗传多样性进行比较研究。从100条引物中筛选出12条引物用于PCR扩增,利用POPGEN32软件对2种一枝黄花进行遗传多样性分析。结果表明,加拿大一枝黄花在物种水平上的多态位点百分率为95.19%,Nei’s基因多样性指数为0.308 5,Shannon’s信息指数为0.415 8;本地一枝黄花在物种水平上的多态位点百分率(89.80%)、Nei’s基因多样性指数(0.249 1)和Shannon’s信息指数(0.383 4)都比加拿大一枝黄花小。加拿大一枝黄花和本地一枝黄花居群间遗传分化系数分别为0.118 2和0.131 3,居群内变异分别为0.881 8和0.868 7,表明2个物种居群间的遗传分化不明显,遗传一致度高,且主要的遗传变异存在于居群内。入侵植物加拿大一枝黄花具有较高遗传多样性,且高于本地一枝黄花,这可能是加拿大一枝黄花成功入侵的原因之一。     

外来入侵物种的基因签名及其遗传多样性聚类分析

密码子的使用频率分布能够反映一定的生物特性,因而可作为一种基因签名。本文使用CGR方法来研究外来入侵物种不同组织序列的基因签名及遗传多样性聚类分析,首先得出了刺花莲子草(Alternanthera pungens),紫茎泽兰(Ageratina adenophora),水葫芦(Eichhornia crassipes),微甘菊(Mikania micrantha),土荆芥(Chenopodium ambrosioides),一枝黄花(Solidago canadensis)等6种外来入侵植物的31条序列核苷酸字串长k=1到k=6的情况,并选取k=3,即基因序列的密码子,作为生物特性的一个重要表达。并且构造序列间的CGR欧式距离,进而对外来入侵植物序列遗传多样性进行了聚类分析。通过对所获得的6种外来入侵植物的31条序列的基因签名,得出如下结果：CGR是一种简便且计算量小的方法,且基于CGR方法的基因签名,具有典型的生物特性;入侵植物的基因序列在密码子的使用上是非均衡的,且物种亲缘关系近的,则基因签名相似越高;而且基因签名也揭示出了密码子的第三位碱基偏好使用碱基T的现象,与一般物种密码子第三位碱基偏好G/C情况有强烈反差。此外,从获得的6个物种的31条序列聚类谱系图可以直观看出,入侵植物间存在着一定的亲缘关系,遗传多样性较丰富。由于我们所建立的基于CGR方法的基因签名,不仅能够反映植物特性和进化关系,而且能揭示序列中密码子和碱基的偏好使用情况,因而该方法有利于对外来入侵物种的遗传多样性分析、风险评估及预防控制等提供科学依据。     

土地利用变化对生物多样性的影响

土地利用变化对生物多样性影响是生物多样性受到威胁的重要因素.文章对土地利用变化对基因多样性、物种多样性、生态系统多样性影响方面的研究进行了总结分析,并提出了新的展望.土地利用变化对基因多样性的影响涉及了对物种生境的隔离、农牧业活动对物种改良和生境条件的改变方面,目前还主要集中在对少数物种繁殖过程方面影响的研究;土地利用变化对物种多样性影响包括对物种优势度和丰富度、种间关系、物种分布格局、物种入侵和灭绝方面的影响,目前对物种丰富性和多样性影响方面研究较多,对物种灭绝、物种入侵和种间关系影响方面的研究极少,且还限于大型动物和植物,对微生物和小型动植物研究却很少;土地利用变化对生态系统的影响涉及了对生态系统结构组成及分布方面的影响.另外,目前缺少土地利用变化对基因多样性、物种多样性和生态系统多样性综合影响方面的研究,难以量化和预测土地利用变化对生物多样性影响效应.未来需要综合考虑基因多样性、物种多样性和生态系统多样性方面,系统开展土地利用变化对生物多样性影响的趋势和机制方面的研究,定量预测土地利用变化对生物多样性的影响.     

上海崇明岛人工林群落对加拿大一枝黄花入侵的影响

加拿大一枝黄花(Solidago canadensis)是华东地区危害最大的入侵植物之一,也是侵入人工林最重要的外来杂草。为了解人工林群落对加拿大一枝黄花入侵性的影响,选择上海崇明岛的水杉(Metasequoia glyptostroboides)群落、复羽叶栾树(Koelreuteria paniculata)群落、香樟(Cinnamomum camphora)群落、梧桐(Firmiana platanifolia)群落和重阳木(Bischofia polycarpa)群落,调查分析加拿大一枝黄花在不同群落的入侵和分布状况。结果表明,加拿大一枝黄花在各群落中重要值由大到小为重阳木群落复羽叶栾树群落香樟群落梧桐群落水杉群落。通过分析不同群落林下草本植物生态位,发现加拿大一枝黄花在5个群落中生态位宽度与生态位重叠结果趋于一致,依次为重阳木群落梧桐群落香樟群落复羽叶栾树群落水杉群落。群落乔木层郁闭度越大,加拿大一枝黄花入侵程度越小。     

攀枝花市入侵植物马缨丹群落的物种组成与多样性研究

采用样地调查法,对攀枝花市5种生境中的马缨丹入侵群落的物种组成、生活型谱、物种多样性、丰富度、均匀度进行了调查分析。结果表明,(1)马缨丹入侵群落中,植物种类共有71种,隶属34科67属,以菊科、豆科、大戟科植物居多,且外来植物多达31种,约占调查植物种类的44%。(2)不同群落中植物生活生活型均以高位芽植物为主(平均达58%),其中矿山迹地人工促进自然恢复地的高位芽植物比例高达68%,而四旁地块中高位芽植物比例最低,为44%;一年生植物所占比例平均达30%,这类植物主要是以入侵的菊科植物为代表的一年生草本植物;地上芽、地面芽和地下芽植物所占比例平均均低于10%。群落植物的生活型组成,一方面反映了植被所处环境的干热特征;另一方面也反映了群落受干扰的程度,干扰程度越低,高位芽植物所占的比例越大。(3)马缨丹入侵群落的物种多样性与群落所处的生境有明显的相关性:矿山迹地人工促进自然恢复地的各指数最高,荒山撂荒地的各生物多样性指数最低,二者各多样性指数均呈现显著性差异,矿山迹地人工开荒的柑橘园、芒果园,以及四旁的各指数居于中间,且柑橘园与芒果园的各指数间无显著差异。研究表明,人工干预程度增加的情况下(如Ⅱ和Ⅲ矿山迹地人工开荒果园),打破了马缨丹占绝对优势的状况,新物种的增加产生了新的种间关系,进而引起生物多样性发生改变。由于该区外来入侵物种种类较多,且多种外来入侵植物和当地乡土物种共同挤占生存空间的前提下,研究外来入侵植物对原生生态系统的影响将变得更为复杂,必须加强相关方面的研究。     

中国生物入侵的现状与趋势

采用文献调研、实地考察与专家咨询相结合的方式,对中国境内森林、湿地、草原、荒漠、内陆水域和海洋等生态系统的外来入侵物种进行调查,共查明488种外来入侵物种并收集其详细信息,包括名称、分类地位、分布、起源、首次发现或引入的地点和时间、入侵途径、危害、营养和环境条件等.在这488种外来入侵物种中,植物265种,动物171种,菌物26种,病毒12种,原核生物11种,原生生物3种.对有较明确入侵时间记载的392种外来入侵物种入侵年代的分析结果表明,1850年以前,仅出现31种外来人侵物种,自1850年起,新的外来入侵物种种数总体呈逐步上升趋势,特别是1950年后的60a间,新出现209种.外来入侵物种首次发现的地点集中在沿海地区及云南和新疆等边疆地区,但首次发现地点有逐步北移的趋势.有意引进与无意引进的外来入侵物种种数所占比例十分接近,近年来无意引进成为首要途径.美洲、欧洲和亚洲其他地区是中国外来入侵物种的主要来源地.外来入侵物种的分布呈现由沿海向内陆逐步减少的趋势.     

从管理角度辨析外来入侵物种的概念和内涵

外来入侵物种是造成全球生物多样性丧失的主要威胁因素,我国是世界上受外来入侵物种危害最严重的国家之一。外来入侵物种的界定是一个富有争议的话题,准确界定外来入侵物种,明确防控对象,是开展外来入侵物种防控的首要条件。综合分析了各类国际公约以及不同国家和地区对外来入侵物种的定义方法,并从表述方式、空间范围、时间范围、影响和层次性5个角度分析界定了外来入侵物种的相关主要问题。通过辨析外来入侵物种的概念与内涵,探讨外来入侵物种的相关重要问题,为我国未来制定外来入侵物种的专门性法规提供新的参考思路。     

吉林省外来物种入侵特征的初步研究

通过大量的野外实地调查和文献资料分析，总结了吉林省外来物种入侵的主要特征。研究表明，目前对吉林省造成危害的外来物种共计51种，分别为外来杂草38种、外来害虫10种和外来病菌3种。其中危害性较强的丰要有7种，分别为稻水象甲(Lissorhoptrus oryzophilus)、美洲斑潜蝇(Liriomyza sativae)、日本松干蚧(Matsucoccrs matsumurae)、栗山天牛(Mallambyx raddei)、菜豆象(Acanthoscelides obtectus)、松针红斑病菌(Dorhistroma pimi Hulbary)。这些外来物种的传播和扩散速度较快，传播途径多以无意引入为主，对吉林省的经济和生态环境危害严重。外来物种入侵地多为生态系统结构单一的农田或人工林系统；入侵地多为吉林省气候温暖湿润的东中部，且生物多样性比较丰富的地区。     

城市化影响下北京市外来入侵植物特征及其分布

通过文献资料分析和实地调查相结合的方法,对北京市外来入侵植物的种类、生活型、起源地、引入途径和分布等特征进行了分析,结果表明:该地区共有48种外来入侵植物,隶属39属19科,其中菊科、禾本科、苋科和大戟科植物为优势科,占到了所有入侵植物总数的60.4%.除火炬树外,其余47种植物均为草本植物,以起源于美洲的居多(70.8%),多为伴随种子苗木运输无意引进.入侵植物分布受城市化水平和人口密度影响显著,城市功能扩展区分布有最多的入侵植物,就入侵种分布密度而言,城市功能拓展区和城市核心区均明显高于近郊区和远郊区.目前北京入侵植物主要分布于农田、绿地、花圃等半人工生态系统,尚处于可控范围之内,但北京的自然地理条件及城市化进程使其仍存在较高的入侵风险,在将来的防治工作中应采取更加严格的检疫措施.     

上海滨岸带生态环境问题及调控对策

结合长江口上海滨岸带资源与环境现状,重点分析了上海滨岸地区在经济快速发展过程中面临的主要生态环境问题;指出上海滨岸地区面临风暴潮、海平面上升、地面沉降等主要自然灾害;滨岸水环境质量恶化,重金属等污染物的生态风险不容忽视;潮滩过渡围垦导致湿地生态系统破坏严重。探讨了污水排放等人类活动对滨岸带生态环境的影响。此外,从战略环境评价、污染控制、生态恢复、行政法规和管理等方面,提出了相应的调控对策。     

Are soil mite assemblages structured by the identity of native and invasive alien grasses?

Associations between plants and animals in aboveground communities are often predictable and specific. This has been exploited for the purposes of estimating the diversity of animal species based on the diversity of plant species. The introduction of invasive alien plants into an ecosystem can result in dramatic changes in both the native plant and animal assemblages. Few data exist at the species level to determine whether belowground animal assemblages share the same degree of association to plants. The hypotheses that soil mites (Acari) form assemblages specifically associated with different native grass species in an unmanipulated natural ecosystem and that invasive alien grasses will impact soil mite assemblage composition in this setting were tested. Soil mites sampled beneath five native and two invasive alien species of grasses at the Konza Prairie Biological Station, Kansas, USA, were similarly abundant, species rich, diverse, and taxonomically distinct. No mite species had affinities for a specific grass species. There was no evidence from analysis of similarity, canonical correspondence analysis, or a nonparametric assemblage analysis that the assemblage composition of soil mites was specific to grass species. Results suggest that soil mite assemblages were more related to characteristics of the plant assemblage as a whole or prevailing soil conditions. The most recent invasive alien grass did not support a successionally younger mite fauna, based on the ratio of mesostigmatid to oribatid mites, and neither of the two invasive grasses influenced mite assemblage structure, possibly because they had not yet substantially altered the soil environment. Our results suggest that extrapolations of soil mite diversity based on assumptions of plant specificity would be invalid.     

河岸缓冲带对氮磷的截留转化及其生态恢复研究进展

河岸缓冲带是河岸生态系统的重要组成部分,对农业非点源污染物起到有效的截留转化作用。对河岸缓冲带的定义、生态结构特性和功能,河岸缓冲带对氮和磷的截留转化作用以及河岸缓冲带的生态修复现状进行了综合评述。结果表明：草地和森林类型河岸缓冲带均能有效地控制氮和磷向水体中迁移;河岸缓冲带的宽度、水文特征、土壤性质、季节变化以及人为活动等是影响其截留效率的因素;加强退化河岸缓冲带的恢复重建工程,可以保证河岸生态系统的健康。针对目前研究中的不足,提出今后的研究方向,认为应进行长期的大尺度的野外实践研究,并从生态学的角度出发,建立合理的河岸缓冲带健康指标,为退化河岸缓冲带恢复重建提供科学依据。     

二氧化碳浓度升高对植物入侵的影响

从入侵植物和入侵植物群落两个方面,综述了大气二氧化碳浓度升高对植物入侵的影响。二氧化碳浓度升高,可以增加C3植物的入侵性,提高入侵植物的生物量、资源利用率以及繁殖能力,直接影响植物入侵;还可以通过改变土壤水分、氮循环、干扰体系等其它环境因子间接地影响植物入侵。此外,二氧化碳浓度升高,对入侵群落的初级生产量、组成与结构以及群落动态产生重要影响,改变群落的可入侵性。今后应当着重从群落水平,结合其它全球变化因子的共同作用研究二氧化碳浓度升高对植物入侵的影响,同时深入探讨其作用机制以及不同植物类群对二氧化碳的响应,为入侵种的预防和控制提供理论指导。     

Effects of Weed-Management Burning on Reptile Assemblages in Australian Tropical Savannas

Abstract: Fire is frequently used for land management purposes and may be crucial for effective control of invasive non‐native plants. Nevertheless, fire modifies environments and may affect nontarget native biodiversity, which can cause conflicts for conservation managers. Native Australian reptiles avoid habitat invaded by the alien plant rubber vine (Cryptostegia grandiflora) and may be susceptible to the impacts of burning, a situation that provides a model system in which to examine possible conservation trade‐offs between managing invasive plants and maintaining native biodiversity. We used replicated, experimental fire treatments (unburned, dry‐season burned, and wet‐season burned) in 2 habitats (riparian and adjacent open woodland) to examine the short‐ (within 12 months of fire) and longer‐term (within 3 years of fire) changes of reptile assemblages in response to wet‐ and dry‐season burning for weed management in tropical savannas of northern Australia. Within 12 months of fire, abundances of the skink Carlia munda (Scincidae) were higher in the burned sites, but overall reptile composition was structured by habitat type rather than by effects of burning. Within 3 years of a fire, the effects of fire were evident. Reptiles, especially the gecko Heteronotia binoei (Gekkonidae), were least abundant in dry‐season burned sites; litter‐associated species, including Carlia pectoralis (Scincidae), were rarely observed in burned habitat; and there were fewer species in the wet‐season burned sites. Reptile abundance was associated with vegetation structure, which suggests that fire‐induced changes detrimentally altered the availability of resources for some reptiles, particularly leaf‐litter species. Invasive alien plants, such as rubber vine, have severe effects on native biodiversity, and control of such species is a fundamental land management objective. Nevertheless, fire management of invasive alien plants may adversely affect native biodiversity, creating a conservation conundrum. In such scenarios, land managers will need to identify the most desired conservation goal and consider the consequences for native biota.     

薇甘菊入侵对深圳湾红树林生态系统碳储量的影响

外来植物入侵对生态系统碳过程的影响已经成为入侵生态学研究的热点问题。采用比较研究的方法分析了薇甘菊（MikaniamicranthaH．B．K．）入侵对深圳湾红树林生态系统碳储量的影响,分别设置红树林（Kandelia candel）群落、红树林．薇甘菊群落、薇甘菊群落以及光滩等样地,采集植被、凋落物和土壤剖面样品,分析生态系统各组分的碳储量变化。结果表明,薇甘菊入侵对红树林生态系统碳储量有着显著的影响,碳储量从未被入侵下215．73tC／hm^2减少到轻、高度入侵下的197．56tC／hm2和166．70tC／hm2,分别减少8．42％和22．72％。其中植被和土壤碳储量显著减少,凋落物碳储量显著增加。薇甘菊入侵一方面导致红树林枯萎,减少植被生物量,增加凋落物量,另一方面促进了土壤微生物活动,使土壤有机碳分解释放,降低土壤碳储量。薇甘菊入侵后红树林碳储量的降低将大大削弱生态系统的碳汇功能。     

Risk Assessment of Riparian Plant Invasions into Protected Areas

Abstract:  Protected areas are becoming increasingly isolated. River corridors represent crucial links to the surrounding landscape but are also major conduits for invasion of alien species. We developed a framework to assess the risk that alien plants in watersheds adjacent to a protected area will invade the protected area along rivers. The framework combines species- and landscape-level approaches and has five key components: (1) definition of the geographical area of interest, (2) delineation of the domain into ecologically meaningful zones, (3) identification of the appropriate landscape units, (4) categorization of alien species and mapping of their distribution and abundance, and (5) definition of management options. The framework guides the determination of species distribution and abundance through successive, easily followed steps, providing the means for the assessment of areas of concern. We applied the framework to Kruger National Park (KNP) in South Africa. We recorded 231 invasive alien plant species (of which 79 were major invaders) in the domain. The KNP is facing increasing pressure from alien species in the upper regions of the drainage areas of neighboring watersheds. On the basis of the climatic modeling, we showed that most major riparian invaders have the ability to spread across the KNP should they be transported down the rivers. With this information, KNP managers can identify areas for proactive intervention, monitoring, and resource allocation. Even for a very large protected area such as the KNP, sustainable management of biodiversity will depend heavily on the response of land managers upstream managing alien plants. We suggest that this framework is applicable to plants and other passively dispersed species that invade protected areas situated at the end of a drainage basin.     

海南鹦哥岭的外来植物与生态环境影响评价

通过对鹦哥岭外来植物的调查,以及外来植物区系的种类组成、原产地、生长型、生境和危害程度等的分析,阐明鹦哥岭的外来植物现状及其对当地生态环境的影响。分析表明:共有53种外来植物,约占鹦哥岭种子植物总数的2.73%,主要来自新大陆热带地区(35种)。其中草本(36种)和灌木(13种)占优势,藤本(3种)和小乔木(2种)相对不明显。外来种对鹦哥岭自然生态系统的影响较小,对人为干扰严重的生态系统影响较大。最后对外来植物进行评估,并提出防控措施。     

Invasive species in Europe: ecology, status, and policy

Globalization of trade and travel has facilitated the spread of non-native species across the earth. A proportion of these species become established and cause serious environmental, economic, and human health impacts. These species are referred to as invasive, and are now recognized as one of the major drivers of biodiversity change across the globe. As a long-time centre for trade, Europe has seen the introduction and subsequent establishment of at least several thousand non-native species. These range in taxonomy from viruses and bacteria to fungi, plants, and animals. Although invasive species cause major negative impacts across all regions of Europe, they also offer scientists the opportunity to develop and test theory about how species enter and leave communities, how non-native and native species interact with each other, and how different types of species affect ecosystem functions. For these reasons, there has been recent growth in the field of invasion biology as scientists work to understand the process of invasion, the changes that invasive species cause to their recipient ecosystems, and the ways that the problems of invasive species can be reduced. This review covers the process and drivers of species invasions in Europe, the socio-economic factors that make some regions particularly strongly invaded, and the ecological factors that make some species particularly invasive. We describe the impacts of invasive species in Europe, the difficulties involved in reducing these impacts, and explain the policy options currently being considered. We outline the reasons that invasive species create unique policy challenges, and suggest some rules of thumb for designing and implementing management programs. If new management programs are not enacted in Europe, it is inevitable that more invasive species will arrive, and that the total economic, environmental, and human health impacts from these species will continue to grow.     

Co-infection patterns and geographic distribution of a complex pathosystem targeted by pathogen-resistant plants

Increasingly, pathogen-resistant (PR) plants are being developed to reduce the agricultural impacts of disease. However PR plants also have the potential to result in increased invasiveness of nontarget host populations and so pose a potential threat to nontarget ecosystems. In this paper we use a new framework to investigate geographical variation in the potential risk associated with unintended release of genetically modified alfalfa mosaic virus (AMV)-resistant Trifolium repens (white clover) into nontarget host populations containing AMV, clover yellow vein virus (ClYVV), and white clover mosaic virus (WCIMV) in southeastern Australia. Surveys of 213 sites in 37 habitat types over a 300 000-km2 study region showed that T. repens is a significant weed of many high-conservation-value habitats in southeastern Australia and that AMV, ClYVV, and WClMV occur in 15-97% of nontarget host populations. However, T. repens abundance varied with site disturbance, habitat conservation value, and proximity to cropping, and all viral pathogens had distinct geographic distributions and infection patterns. Virus species frequently co-infected host plants and displayed nonindependent distributions within host populations, although co-infection patterns varied across the study region. Our results clearly illustrate the complexity of conducting environmental risk assessments that involve geographically widespread, invasive pasture species and demonstrate the general need for targeted, habitat- and pathosystem-specific studies prior to the process of tiered risk assessment.