上海外来植物及其入侵等级划分

汇总分析了上海外来植物75科232属357种(和种下类群)基础资料,并对其入侵危害进行等级划分;其中入侵植物64种,一般或偶见外来植物293种;报道了9种上海新纪录逸生植物。上海外来植物总体呈现种类繁多、国产种类较多、分布密度大、严重危害种类较多且分布广、入侵途径集中等特征。同时对上海外来入侵植物的管理与防治提出具体措施。     

Native and alien flower visitors differ in partner fidelity and network integration

Globalisation persistently fuels the establishment of non‐native species outside their natural ranges. While alien plants have been intensively studied, little is known about alien flower visitors, and especially, how they integrate into natural communities. Here, we focus on mutualistic networks from five Galápagos islands to quantify whether alien and native flower visitors differ consistently in their pairwise interactions. We find that (1) alien flower visitors have more interaction partners and larger species strengths (i.e. plants are more connected to alien insects), (2) native insects tend to have higher partner fidelity as they deviate more from random partner utilisation, and iii) the difference between native and alien flower visitors in network integration intensifies with island degradation. Thus, native and alien flower visitors are not interchangeable, and alien establishment might have yet unforeseen consequences for the pairwise dynamics between plants and flower visitors on the Galápagos – especially on the heavily disturbed islands.     

More widespread alien tree species do not have larger impacts on regeneration of native tree species in a tropical forest reserve

There is insufficient information regarding the factors affecting the environmental impacts of alien species. In particular, little is known about whether there is any relationship between the invasiveness (establishment and spread) of an introduced species and its per capita impact. We experimentally assessed the relationship between the extent of spread of up to 29 alien plant species and their impact on recruitment of native tree species in Amani Botanical Garden, Tanzania. We also studied the effects of allelochemicals of selected alien on native plant species to assess potential mechanisms of impact. We found no relationship between the extent of spread of an alien tree species and their impact on seed germination, seedling survival, and seedling communities of native trees in their understory, and no indication that allelochemicals consistently explain their effects on recruitment of the studied species. These results suggest that extent of spread cannot be used as a proxy for impact. Hence, managers should continue assessing both the spread and the impact of alien species when prioritizing alien species for management.     

外来入侵植物和本地植物核DNA C-值的比较及其与入侵性的关系

用流式细胞仪测定了8科10属13种外来入侵植物、6种本地植物和1种外来非入侵植物的核DNAC-值。结果表明:作为整体,外来入侵植物的平均核DNAC-值显著低于本地种和外来非入侵种,但对同属不同类型植物进行比较,未发现一致的规律;在4个既包含外来入侵种又包含本地种的属中,泽兰属(Eupatorium)和鬼针草属(Bidens)外来入侵种的核DNAC-值显著低于同属本地种,莲子草属(Alternanthera)的2种外来入侵植物中仅有1个种的核DNAC-值显著低于同属本地种,而草胡椒属(Peperomia)外来入侵种的核DNAC-值显著高于同属本地种;表明核DNAC-值与外来植物入侵性无必然联系。     

Role of the vomeronasal organ in neonatal offspring recognition in sheep

Twenty-five pregnant Dorsett ewes were randomly divided into three groups to test if ewes use their vomeronasal organs for offspring recognition during nursing. One group of eight ewes (procaine) were made anosmic by irrigation of the nasal olfactory apparatus with a zinc sulphate procaine solution. The second group of nine ewes (cauterized) had their vomeronasal organs rendered nonfunctional by cauterization of the nasoincisive duct. The third group of eight ewes were the controls. Parturition was synchronized in all ewes with betamethasone on Day 145 of gestation. Maternal responsiveness was tested two separate times with 1- to 2-day-old alien lambs. Each alien lamb trial was conducted 24 h apart. Cauterized ewes allowed alien lambs to suckle and they were unable to distinguish alien lambs from their own lambs, whereas the ewes in both groups with functional vomeronasal organs (procaine and control) violently rejected any alien lamb's attempt to suckle. Thus, female sheep use their vomeronasal organs for neonatal offspring recognition.     

The intermediate distance hypothesis of biological invasions

Biological invasions are a worldwide phenomenon, but the global flows between native and alien regions have rarely been investigated in a cross‐taxonomic study. We therefore lack a thorough understanding of the global patterns of alien species spread. Using native and alien ranges of 1380 alien species, we show that the number of alien species follows a hump‐shaped function of geographic distance. We observe distinct variations in the relationship between alien species exchanges and distance among taxonomic groups, which relate to the taxa‐specific dispersal modes and their pathways of introduction. We formulate a simple statistical model, combining trade volume and biogeographic dissimilarity, which reproduces the observed pattern in good agreement with reported data and even captures variations among taxonomic groups. This study demonstrates the universality of the intermediate distance hypothesis of alien species spread across taxonomic groups, which will help to improve the predictability of new alien species arrivals.     

外来树种的耗水特征及其对环境水资源的影响

外来树种常被作为"先锋树种"广泛引种，在荒山造林和水土保持方面发挥了积极作用；然而，不少外来树种具有高耗水和强抗旱的水分利用特性，耗水量大、水分消耗快，若不加甄别地引种会影响甚至危害本土森林生态系统的健康。目前，部分被引种的外来树种已造成入侵；同时，在当前水资源缺乏的形势下，外来树种的引种安全问题已成为全球关注的生态环境问题。本文综述了外来树种在生态系统、整树、叶片及枝条水平的耗水特性，分析了外来树种对引种地水资源的影响。前期的研究结果显示，被引种的外来树种在生态系统及整树水平的耗水量普遍高于乡土树种，但对水资源的影响却因受控于多个因素如环境、气候、植物个体等而不尽相同；同时还显示，外来树种在叶片和枝条水平的耗水特性更多地体现了其应对环境变化的水分利用策略。研究还就提高外来树种耗水特性研究的准确性和提升外来树种危害风险的预警能力方面，提出了若干研究方向，旨在为森林管理者和政府部门平衡外来树种的经济效益和生态效应提供借鉴和指导，以期降低外来树种引种风险，增进生态安全。     

Maternal ‘imprinting’ or maternal ‘labelling’ in goats?

The present study on maternal ‘imprinting’ in goats initially failed to replicate previous findings that mothers discriminate between their own and alien young, accepting their own kid and rejecting alien kids. Rather, 62% of the mothers accepted both their own and alien kid. This disparity was not due to breed differences, age, or behaviour of the aliens but to length of time the alien kids had been with their own mother. When behaviour was eliminated through anaesthesia or left intact, older aliens that had had no contact with their mother were accepted by other mothers, while those aliens with more than 8 h of contact with their own mothers were rejected (whether anaesthetized or not) by other mothers. Maternal ‘imprinting’ in goats may take longer than previously reported, and mothers may ‘label’ their kids and learn to recognize the labels.     

Salinity-related distribution of alien amphipods in rivers provides refugia for native species

There are numerous papers upon the range extension, biology and the impact of alien amphipods upon the local fauna. However, there are no studies concerning the alien versus native species distribution patterns at the catchment scale of river systems. In total 125 sites were sampled: 41 in main rivers constituting the Polish section of the central invasion corridor (Bug, Vistula, Notec with canals, Oder) and 84 in their affluents. The conductivity of large rivers was much higher than in their small affluents. The number of alien species and their abundance was higher at sites with raised conductivity values. The reverse situation was noticed when native amphipods were taken into account. Moreover, large rivers were inhabited by alien fauna, whereas in smaller streams only native species were sampled. The absence of alien amphipods in small rivers may be explained by their ecological preference for a higher conductivity of water. Thus in smaller streams the native fauna is free from the pressure posed by alien amphipods. If not degraded by human activity, small affluents may function as refugia for native amphipod species. Otherwise, elevation of salinity related to improper catchment management or sewage treatment may lead to extinction of such local disjunct population of native amphipods.     

基因组学: 理解植物入侵性的重要工具

入侵植物基因组学是一个新兴的研究领域, 它利用基因组学方法研究与植物入侵性相关的分子基础和表达调控机制, 甄别入侵性基因型, 进而在基因组水平上揭示外来种入侵性产生和进化的分子机制。本文扼要综述了可用于植物入侵生物学研究的主要基因组学方法, 包括比较基因组学、群体基因组学和表观基因组学等方法; 运用基因组学技术研究入侵植物除草剂抗性和根状茎发育的分子基础已取得了重要进展。然而, 入侵植物基因组学仍处于发展初期, 选择理想的入侵植物模式种, 建立入侵性研究的模式系统, 是当前亟待解决的问题。本文还提出了入侵植物基因组学研究值得关注的几个发展方向, 包括基因组信息的完善、不同环境条件下入侵植物的分子响应机制以及入侵性的系统生物学研究等。     

Anthropogenic fires increase alien and native annual species in the Chilean coastal matorral

Aim We tested the hypothesis that anthropogenic fires favour the successful establishment of alien annual species to the detriment of natives in the Chilean coastal matorral. Location Valparaíso Region, central Chile. Methods We sampled seed rain, seedbank emergence and establishment of species in four paired burned and unburned areas and compared (using GLMM) fire resistance and propagule arrival of alien and native species. To assess the relative importance of seed dispersal and seedbank survival in explaining plant establishment after fire, we compared seed rain and seedbank structure with post‐fire vegetation using ordination analyses. Results Fire did not change the proportion of alien species in the coastal matorral. However, fire increased the number of annual species (natives and aliens) of which 87% were aliens. Fire reduced the alien seedbank and not the native seedbank, but alien species remained dominant in burned soil samples (66% of the total species richness). Seed rain was higher for alien annuals than for native annuals or perennials, thus contributing to their establishment after fire. Nevertheless, seed rain was less important than seedbank survival in explaining plant establishment in burned areas. Main conclusions Anthropogenic fires favoured alien and native annuals. Thus, fire did not increase the alien/native ratio but increased the richness of alien species. The successful establishment of alien annuals was attributable to their ability to maintain rich seedbanks in burned areas and to the greater propagule arrival compared to native species. The native seedbank also survived fire, indicating that the herbaceous community has become highly resilient after centuries of human disturbances. Our results demonstrate that fire is a relevant factor for the maintenance of alien‐dominated grasslands in the matorral and highlight the importance of considering the interactive effect of seed rain and seedbank survival to understand plant invasion patterns in fire‐prone ecosystems.     

Determinants of data deficiency in the impacts of alien bird species

To identify the factors that influence the availability of data on the negative impacts of alien bird species, in order to understand why more than 70% are currently classified as Data Deficient (DD) by the Environmental Impact Classification of Alien Taxa (EICAT) protocol. Information on factors hypothesised to influence the availability of impact data were collated for 344 alien bird species (107 with impact data and 237 DD). These data were analysed using mixed effects models accounting for phylogenetic non‐independence of species (MCMCglmm). Data deficiency in the negative impacts of alien birds is not randomly distributed. Residence time, relative brain size and alien range size were found to be strongly related to the availability of data on impacts. The availability of data on the negative impacts of alien birds is mainly influenced by the spatial and temporal extents of their alien ranges. The results of this study suggest that the impacts of some DD alien birds are likely to be minor (e.g. species with comparatively long residence times as aliens, such as the common waxbill Estrilda astrild and the Java sparrow Padda oryzivora). However, the results also suggest that some DD alien birds may have damaging impacts (e.g. species from orders of alien birds known for their impacts to biodiversity but with comparatively small alien ranges, such as the New Caledonian crow Corvus moneduloides). This implies that at least some DD alien birds may have impacts that are being overlooked. Studies examining the traits that influence the severity of alien bird impacts are needed to help to predict which DD species are more likely to impact upon biodiversity.     

A plant‐traits approach to assessing the success of alien weed species in irrigated Mediterranean orchards

In addition to their impact on natural habitats, invasive alien plants can have a significant negative effect on agricultural systems and cause economic losses. Flood‐irrigated orchards in the Mediterranean Basin are vulnerable to the invasion of alien weeds, primarily because of the traditional management practices used in the orchards, which are characterized by high soil moisture during the dry summer period, nutrient availability and high levels of disturbance. This study sought to determine whether their biological traits can explain the success of alien weed species. To answer this question, 408 floristic relevés were conducted in 136 flood‐irrigated orchards on the Plains of Lleida (Catalonia, NE of Spain). Richness and cover of native and alien weeds were compared. Furthermore, a set of biological traits were compared between successful and non‐successful weeds for the whole data and separately between native and alien weeds using logistic regression and classification trees. In flood‐irrigated orchards, alien species covered most of their area, even though the richness of alien species was lower than that of the native species. The most important species were C4 species with seeds dispersed by water, and on the other hand, rosulate and caespitose‐reptant hemicryptophytes with long flowering period. Most of these traits fitted with those of the invasive alien weeds, which were mostly C4 species with seeds dispersed by water. Perennial life form characterized successful native weeds. In this study, we discuss how the traditional management of flood irrigation in fruit‐tree orchards favours invasive alien weeds that have specific traits, acting as a reservoir for the spread of alien weeds into other crops and surrounding riparian habitats. We also propose changing management practices in order to avoid the selection of alien weeds and to promote native species.     

Influence of settlement time, human population, park shape and age, visitation and roads on the number of alien plant species in protected areas in the USA

Abstract. I examined a data set of 77 protected areas in the USA (including national and state parks) to determine which of the following variables most strongly influence alien plant species richness: park area, climate (temperature and precipitation), native species richness, visitation rate, local human population size, total road length, park shape and duration of European settlement. Many of these predictor variables are intercorrelated, so I used multiple regression to help separate their effects. In support of previous studies, native species richness was the best single predictor of alien species richness, probably because it was a good estimator of both park area and habitat diversity available for establishment of alien species. Other significant predictors of alien species richness were years of occupation of the area by European settlers and the human population size of adjacent counties. Climate, visitation rate, road length and park shape did not influence alien species richness. The proportion of alien species (alien richness/native richness) is inversely related to park area, in agreement with a previous study. By identifying which variables are most important in determining alien species richness, such findings suggest ways to reduce alien species establishment.     

Alien plant species favoured over congeneric natives under experimental climate warming in temperate Belgian climate

Climate warming and biological invasions by alien species are two key factors threatening the world’s biodiversity. To date, their impact has largely been studied independently, and knowledge on whether climate warming will promote invasions relies strongly on bioclimatic models. We therefore set up a study to experimentally compare responses to warming in native and alien plant species. Ten congeneric species pairs were exposed to ambient and elevated temperature (+3°C) in sunlit, climate-controlled chambers, under optimal water and nutrient supply to avoid interaction with other factors. All species pairs combined, total plant biomass reacted differently to warming in alien versus native species, which could be traced to significantly different root responses. On average, native species became less productive in the warmer climate, whereas their alien counterparts showed no response. The three alien species with the strongest warming response (Lathyrus latifolius, Cerastium tomentosum and Artemisia verlotiorum) are currently non-invasive but all originate from regions with a warmer climate. Still, other alien species that also originate from warmer regions became less or remained equally productive. Structural or ecophysiological acclimation to warming was largely absent, both in native and alien species, apart from light-saturated photosynthetic rate, where warming tended to restrain the native but not the alien species. A difference in the capacity to acclimate photosynthetic rates to the new climate may therefore have caused the contrasting biomass response. Future experiments are needed to ascertain whether climate warming can effectively tip the balance between native and alien competitors.     

Relative abundance of an invasive alien plant affects native pollination processes

One major characteristic of invasive alien species is their occurrence at high abundances in their new habitat. Flowering invasive plant species that are visited by native insects and overlap with native plant species in their pollinators may facilitate or disrupt native flower visitation and fertilisation by forming large, dense populations with high numbers of flowers and copious rewards. We investigated the direction of such a proposed effect for the alien invasive Rhododendron ponticum in Irish habitats. Flower visitation, conspecific and alien pollen deposition, fruit and seed set were measured in a self-compatible native focal plant, Digitalis purpurea, and compared between field sites that contained different relative abundances of R. ponticum. Flower visitation was significantly lower at higher alien relative plant abundances than at lower abundances or in the absence of the alien. Native flowers experienced a significant decrease in conspecific pollen deposition with increasing alien abundance. Heterospecific pollen transfer was very low in all field sites but increased significantly with increasing relative R. ponticum abundance. However, lower flower visitation and lower conspecific pollen transfer did not alter reproductive success of D. purpurea. Our study shows that indirect interactions between alien and native plants for pollination can be modified by population characteristics (such as relative abundance) in a similar way as interactions among native plant species. In D. purpurea, only certain aspects of pollination and reproduction were affected by high alien abundances which is probably a result of high resilience due to a self-compatible breeding system. Native species that are more susceptible to pollen limitation are more likely to experience fitness disadvantages in habitats with high relative alien plant abundances.     

安徽省外来入侵植物的分布格局及其等级划分

区域性外来入侵植物的研究及其入侵等级划分在地方入侵植物管理与防治对策的制定上具有重要的指导意义。本文基于文献报道、标本记录和必要的分类学考证,特别是通过2013-2015年对安徽省外来入侵植物的全面调查,统计分析了安徽省外来入侵植物的物种组成、生活型、原产地、区系组成和水平分布格局,并对其入侵危害进行等级划分。结果显示,安徽省有外来入侵植物37科86属132种,总体上呈现种类丰富、原产于美洲的种类多、泛热带起源的种类多、危害严重的种类多、区域分化明显、入侵途径集中等特征。提出在外来入侵植物的防控中应重点警惕起源于美洲的、泛热带分布属的植物和关注人类活动频繁的热点区域。还对中国外来入侵植物研究中存在的问题进行了探讨,澄清了几个长期以来被忽视的关于外来入侵物种认知的问题。     

中国外来入侵生物的空间分布格局及其影响因素

不同地理区域影响生物分布格局的因子不同,对外来入侵物种也是如此。在区域尺度上分析外来入侵生物的空间分布格局及其影响因子对预测生物入侵的影响及入侵种的控制管理具有重要意义。本研究应用中国外来入侵物种数据库、自然环境数据库和社会人文环境数据库,分析了我国外来入侵动植物的空间格局;并运用主成分分析（PCA）和典范对应分析（CCA）探讨了自然环境和人类活动等因素对外来入侵动植物分布格局的影响;同时研究了外来入侵物种多样性与本地物种多样性之间的关系。结果表明,我国现有外来入侵动物138种、入侵植物384种,其数量和密度都呈现出由东南沿海向西北内陆减少的趋势,且入侵动物和入侵植物空间格局基本一致;降水（MAP）是决定我国外来入侵动植物分布格局的主要自然环境因子,国民生产总值（GDP）是主要社会经济影响因子。在全国尺度上,外来入侵物种多样性与本地物种多样性之间呈显著的正相关关系,但地域间存在较大差异。不同区域外来入侵物种与本土物种多样性的相关关系表现出不同,与研究尺度有密切关系。     

Ecological traits and environmental affinity explain Red Sea fish introduction into the Mediterranean

Alien species are considered one of the prime threats to biodiversity, driving major changes in ecosystem structure and function. Identifying the traits associated with alien introduction has been largely restricted to comparing indigenous and alien species or comparing alien species that differ in abundance or impact. However, a more complete understanding may emerge when the entire pool of potential alien species is used as a control, information that is rarely available. In the eastern Mediterranean, the marine environment is undergoing an unparalleled species composition transformation, as a flood of aliens have entered from the Red Sea following the opening of the Suez Canal in 1869. In this study, we compile data on species traits, geographical distribution, and environmental affinity of the entire pool of reef‐associated fish species in the Red Sea and more generally across the Indo‐Pacific. We use this extensive data to identify the prime characteristics separating Red Sea species that have become alien in the Mediterranean from those that have not. We find that alien species occupy a larger range of environments in their native ranges, explaining their ability to colonize the seasonal Mediterranean. Red Sea species that naturally experience high maximum temperatures in their native range have a high probability of becoming alien. Thus, contrary to predictions of an accelerating number of aliens following increased water temperatures, hotter summers in this region may prevent the establishment of many alien species. We further find that ecological trait diversity of alien species is substantially more evenly spaced and more divergent than random samples from the pool of Red Sea species, pointing at additional processes, such as competition, promoting ecological diversity among alien species. We use these results to provide a first quantitative ranking of the potential of Red Sea species to become established in the eastern Mediterranean.     

Knowledge,perceptions and willingness to control designated invasive tree species in urban household gardens in South Africa

Many biological invasions result in negative impacts on the environment and human livelihoods, but simultaneously some also provide benefits that are valued differently by various stakeholders. To inform policy and management of invasive species it is important to assess landowners’ and broader society’s knowledge and perceptions of invasive species, something which is lacking in many contexts, especially in urban settings. In this study we interviewed 153 householders living in a medium-sized South African town who had declared invasive alien trees in their gardens. Less than half of the respondents could identify the invasive tree on their property and only one-third knew that it was an invasive alien species. There was a positive association between income and education levels with exposure to media about invasive alien species and respondents’ ability to identify the species and name any other invasive alien tree species. Knowledge levels were unequal across species. Amongst those who knew the tree was an invasive alien species, reasons why they retained it in their gardens included that it would be costly or too much effort to remove, they liked the tree, that it was not causing any harm and that the property was rented and so its removal was not their responsibility. However, the majority of people (83 %) were willing to have it removed from their garden if done for free by appropriate agencies, which is promising for compliance with new regulations on invasive species implemented at the end of 2014 in South Africa. The results also highlight the need for targeted and appropriate education and awareness programs amongst urban householders on invasive alien species, relevant legislation and their obligations.