The roles of climatic factors in spatial patterns of alien invasive plants from America into China

The roles of climatic factors in plant invasions have drawn intense attention in the past. America was one of the major donors of the invasive plants in China. In this study, we investigated the roles of climatic factors in plant invasions from America into China through Akaike’s information criterion model analysis in terms of specific geographical origins, respectively. From south to north, decreasing trends of species diversity were observed on the plants from Central-South America and Mexico, while the greatest alien species diversity in mid-Chinese latitudes was observed on the invaders from North America; For the invaders from Central-South America and Mexico, climatic factors explained most of the spatial variations, while for those from North America, the roles of the climatic factors were weak. The role of the climatic factors in plant invasions may, in some extent, depend on the ecological characters inherited form the geographical origins and their accommodation to the climate of the invaded regions. If the invasive plants were introduced into the region with similar environment to their area of origin, the role of the climatic factors may be shadowed by other factors. However, for the invaders whom were introduced into the regions vastly different from their areas of origin, climatic barriers may be responsible for most of the spatial variations. The invasive plants from Central-South America and Mexico may have strong potential to invade regions at higher latitude in China in the scenario of global warming, while for the invaders from North America, the impacts of global warming may be shadowed by other factors.     

The naturalization to invasion transition: Are there introduction‐history correlates of invasiveness in exotic plants of Australia?

Of the large number of exotic plant species that become naturalized in new geographic regions, only a subset make the transition to become invasive. Identifying the factors that underpin the transition from naturalization to invasion is important for our understanding of biological invasions. To determine introduction‐history correlates of invasiveness among naturalized plant species of Australia, we compared geographic origin, reason for introduction, minimum residence time and growth form between naturalized non‐invasive species and naturalized invasive plant species. We found that more invasive species than expected originated from South America and North America, while fewer invasive species than expected originated from Europe and Australasia. There was no significant difference between invasive and non‐invasive species with respect to reason for introduction to Australia. However, invasive species were significantly more likely to have been resident in Australia for a longer period of time than non‐invasive species. Residence times of invasive species were consistently and significantly higher than residence times of non‐invasive species even when each continent of origin was considered separately. Furthermore, residence times for both invasive and non‐invasive species varied significantly as a function of continent of origin, with species from South America having been introduced to Australia more recently on average than species from Europe, Australasia and North America. We also found that fewer invasive species than expected were herbs and more invasive species than expected were primarily climbers. Considered together, our results indicate a high propensity for invasiveness in Australia among exotic plant species from South America, given that they appear in general capable of more rapid shifts to invasiveness than aliens from other regions. Furthermore, our findings support an emerging global generality that introduction‐history traits must be statistically controlled for in comparative studies exploring life‐history and ecological correlates of invasion success.     

新建川藏铁路(雅安-昌都段)沿线外来入侵植物种类及分布特征

横断山区为全球生物多样性热点地区之一, 也是全国生态屏障的重要组成部分。新建川藏铁路雅安至昌都段横跨横断山核心地区, 铁路建设形成的交通网络将沿线生物多样性热点区域与外界相连, 导致生物入侵风险陡增。为获得区域内外来入侵植物的种类及分布特征信息, 为即将开始的铁路工程建设、生态保护及生态修复等工作提供参考, 我们在雅安-昌都段内选择43个位点各进行长度1 km、宽度20 m的样线调查。研究结果显示: 雅安-昌都段共发现外来入侵植物58种, 隶属于18科42属, 其中出现频度最高的种类依次是牛膝菊(Galinsoga parviflora)、秋英(Cosmos bipinnatus)和鬼针草(Bidens pilosa)。从危害等级来看, 其中10种为恶性入侵种, 16种为严重入侵种, 8种为局部入侵种, 15种为一般入侵种, 9种为有待观察种, 超过半数种类具有明显入侵性。原产地分析结果显示美洲是该区域外来入侵植物的主要原产地。基于海拔及主要河流区段的比较研究发现: 入侵植物的种类数量呈现出明显的由东向西、由低海拔向高海拔逐渐递减的趋势, 该分布格局是环境因子和人类活动共同作用的结果。结合铁路沿线入侵现状和生境特征, 本文分析了铁路建设可能造成的外来植物入侵风险, 并针对入侵的防范提出了相应的建议。     

福建外来物种入侵现状及对经济社会和生态的影响

福建已成为中国遭受外来物种入侵最严重的省份之一。本文概述了福建主要入侵物种的数量、种类、地理起源、分布、引入途径和入侵特点,系统分析了福建外来物种入侵严重的原因和外来物种入侵对福建生态安全、经济及社会的影响,在此基础上提出了针对外来物种入侵的防控对策。     

中国外来入侵植物研究现状及存在的问题

生物入侵是当今各国发展的一大挑战,特别是像中国这样的发展中国家。然而,我们对外来入侵种的本底资料还很不清楚,更缺乏相关的深入调查;对生物入侵所造成的生态和经济影响还没有引起足够的重视,同时也忽视了盲目引种可能带来的各种危害。本文在文献调研的基础上,从外来植物的入侵历史和文化、中国外来入侵植物的调查现状、外来植物入侵对生态安全及经济的影响等方面进行了全面系统的总结,并提出了中国外来入侵植物研究领域存在的问题及应对措施。     

苋科(广义)入侵植物墙生藜在中国的新记录

外来物种的归化和入侵对全球环境和社会发展造成了严重影响，已成为当今各国生物多样性管理和生态保护中所面临的全球性问题。我国是遭受外来入侵危害最为严重的国家之一，在外来物种入侵的预警、管理和治理等方面形势严峻。基于野外调查和文献研究，该文报道了苋科(广义)入侵植物墙生藜[Chenopodiastrum murale(L.) S. Fuentes, Uotila&Borsch]在中国的新记录。墙生藜原产于地中海地区，现已扩散到欧洲、美洲、非洲和大洋洲的40多个国家，是一种危害较大的外来入侵植物，同时也是我国海关和检验检疫部门明确规定禁止入境的检疫性有害生物，现于云南省昆明市呈贡区发现该外来入侵植物。该文对其形态特征进行了详细描述，简要介绍了其分类历史，并提供了可供鉴定比对的野外生态照片；此外，对墙生藜可能的传入途径进行了分析，对其危害和风险作了简要评估。该物种的新发现说明我国外来入侵生物的本底调查还存在不足。     

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。     

The maximum relative growth rate of common UK plant species is positively associated with their global invasiveness

Aim An emerging consensus in invasion ecology is that faster‐growing alien plant species tend to be more invasive than slower‐growing species. However, phylogenetic non‐independence and the precision of growth‐rate measures often remain unaccounted for in comparative studies. We tested whether global invasiveness was related to mean and maximum relative growth rate of 105 plant species (101 native and 4 introduced) commonly occurring in the UK. Location Global. Methods We combined a unique experimental dataset of relative growth rates (RGR) measured under standardized experimental conditions for plant species that occur widely in the UK with our global measures of invasiveness, which were the number of references in the Global Compendium of Weeds (GCW) and the number of world regions invaded. We weighted mean RGR measures per species by including variances of RGR in our analyses, and we also conducted analyses with and without phylogenetic structure, to account for potential phylogenetic non‐independence in RGR. Results We found a positive association between global invasiveness and maximum RGR. In addition, this association was not confounded by phylogenetic correlation, or by species seed mass. Main conclusions The results from this study suggest that faster‐growing species are more widespread at a global scale, adding support to other studies that suggest faster‐growing alien plant species tend to be more invasive in the introduced range.     

The changing role of ornamental horticulture in alien plant invasions

The number of alien plants escaping from cultivation into native ecosystems is increasing steadily. We provide an overview of the historical, contemporary and potential future roles of ornamental horticulture in plant invasions. We show that currently at least 75% and 93% of the global naturalised alien flora is grown in domestic and botanical gardens, respectively. Species grown in gardens also have a larger naturalised range than those that are not. After the Middle Ages, particularly in the 18th and 19th centuries, a global trade network in plants emerged. Since then, cultivated alien species also started to appear in the wild more frequently than non‐cultivated aliens globally, particularly during the 19th century. Horticulture still plays a prominent role in current plant introduction, and the monetary value of live‐plant imports in different parts of the world is steadily increasing. Historically, botanical gardens – an important component of horticulture – played a major role in displaying, cultivating and distributing new plant discoveries. While the role of botanical gardens in the horticultural supply chain has declined, they are still a significant link, with one‐third of institutions involved in retail‐plant sales and horticultural research. However, botanical gardens have also become more dependent on commercial nurseries as plant sources, particularly in North America. Plants selected for ornamental purposes are not a random selection of the global flora, and some of the plant characteristics promoted through horticulture, such as fast growth, also promote invasion. Efforts to breed non‐invasive plant cultivars are still rare. Socio‐economical, technological, and environmental changes will lead to novel patterns of plant introductions and invasion opportunities for the species that are already cultivated. We describe the role that horticulture could play in mediating these changes. We identify current research challenges, and call for more research efforts on the past and current role of horticulture in plant invasions. This is required to develop science‐based regulatory frameworks to prevent further plant invasions.     

中国农业生态系统外来种入侵及其管理现状

农业生态系统极易遭受外来生物入侵。作者根据文献资料和多年工作观察统计出入侵我国农业生态系统的外来生物共计92科175属239种, 其中植物155种, 动物55种, 微生物29种, 植物多为有意引入后逸生, 而动物和微生物则主要是无意引入。外来入侵种发生数量呈现从南到北、从东到西逐渐减少的趋势。这些入侵种中, 来源于美洲的最多(占45.04%), 其次是欧洲(22.90%); 菜地(包括温室大棚)和果园入侵种最多, 分别达64.85%和66.53%, 而半年期的秋熟旱地和夏熟旱地分别占34.31%和23.85%。其中17种外来杂草、10种害虫、7种病原菌为恶性有害生物, 应作为防除的重点目标。目前农业生态系统外来入侵物种的控制以化学防治为主, 但由于长期施用化学农药, 在侵入我国农田的入侵种中, 已有51种在世界不同地区演化出抗药性生物型, 因而需重视生物防治、农业和生态防治以及检疫等的综合应用。今后外来种对农业生态系统的入侵格局、机制和趋势, 入侵途径以及生物入侵和抗药性生物型对农业生态系统中有害生物群落演替的影响、转基因作物导致的生物入侵等问题值得关注。     

Predicting plant invasiveness from native range size: clues from the Kashmir Himalaya

Aims In view of the growing interest in modelling the potential spread of invasive species, prediction of plant invasiveness on the basis of native range size holds considerable promise. Our objective was to use a simple model to evaluate whether a wider native range predisposes plant species to become invasive in non-native regions and to easily identify potential invaders on this basis. The Kashmir Himalayan alien flora, of which a large proportion is native to Europe, was used to test this model.Methods The Kashmir Himalayan alien flora comprises 436 species of vascular plants at different stages of invasion. We focussed on plant species at two critical invasion stages (sensu Colautti and MacIsaac 2004), i.e. Stage II (species that are just at the earliest phase of introduction) and Stage V (species that are widespread and dominant in the invaded region and are thus considered invasive). We used the territorial distribution in Europe (number of countries) as a surrogate for the native range size of plants of European origin.Important findings Using a subset of 88 species, for which information on the native European range was available, we showed that a large proportion (68%) of Stage II species growing in the Kashmir Valley had a relatively restricted European range (present in ≤20 countries); on the other hand, 77% of Stage V species had an extensive native range (present in>20 countries). We consequently hypothesized that 14 Kashmir Himalayan Stage II species of European origin that are distributed in>20 European countries are at risk of becoming future invaders in Kashmir. On the other hand, those Kashmir Himalayan Stage II species of European origin distributed in ≤20 European countries are less likely to become invasive. Although this analysis is quite simple, the data suggest that a wider native range is a good predictor of plant invasiveness and could be used as a simple and low-cost early warning tool in predicting potential invasive species.     

中国外来入侵植物的分布格局及其与环境因子和人类活动的关系

认识区域尺度上外来入侵植物的分布格局及其成因对预测入侵的影响和入侵种的管理具有重要意义。该文采用聚类分析和排序的方法分析了我国外来入侵植物的空间格局,并利用多元线性逐步回归和典范对应分析探讨了自然环境因子和人类活动强度对中国32个省级空间单位(省市自治区,不包括香港和澳门)中外来入侵植物分布的影响。结果表明,中国各省外来入侵植物物种数从南到北逐渐减少,导致这一格局的主要因子为无霜期;各省外来入侵植物物种密度由东南海岸向内陆递减,造成这一趋势的主要影响因素为交通密度;纬度是解释中国各省外来入侵植物物种组成变异的主要因子,因此中国32个省区可归为低、中、高纬度区3大类型。在此基础上预测中国东南部地区有遭受更多外来植物入侵的可能;此外,交通发达的区域也将成为外来植物入侵的热点区,应该引起有关部门的重视。     

Alien woody plant invasions in natural forests across China

外来木本植物在我国天然林中的入侵 外来植物入侵已经成为一个主要的全球性环境问题，造成了严重的经济和生态破坏。中国区域内部分地区已有关于严重入侵情况的报道，但是大多是小尺度上的研究，全国范围天然林中的外来植物入侵情况仍不清楚。本文基于全国天然林的3573个样方数据，绘制了外来木本植物入侵在我国各地天然林中的空间分布格局，探究了可能的环境和社会经济控制因素。研究结果显示，只有271个样方被外来木本植物入侵，占样方总数的7.58%；在所有调查的2825种木本植物中，只有5个外来物种(占比0.177%)。人类活动和气候因素都对入侵格局产生影响。由于我国天然林多位于偏远山区，人为干扰较轻，外来木本植物入侵的报道少于北美森林和欧洲林地。然而，随着交通运输的发展和山区经济活动的增加，在不久的将来可能会有更多。因此，需要积极的管理和政策制定来防止或减缓入侵进程，降低人类活动的干扰，监测外来物种的入侵情况并及时做出应对。     

Invasions by alien plant species of the agro-pastoral ecotone in northern China: Species-specific and environmental determinants

The establishment, reproduction, dispersal, and distribution of alien plants are affected by various factors during the transition from being newly introduced in a habitat to being invasive. In the agro-pastoral ecotone of northern China, comprising farmlands and natural grasslands, the biological characteristics of alien plant species were the key intrinsic factors (propagation characteristics and competitive ability), followed by such extrinsic factors as human interference and environmental heterogeneity. Among biological characteristics, the life form may be an important and useful indicator of the invasive ability of a species, and the risk of invasion is greater from alien species that are poisonous, inedible, and have traits that facilitate wide dispersal. Farmlands may serve as initial shelters for alien species, from which they spread into neighbouring habitats, whereas natural grassland may act as a barrier to plant invasions. Management practices detrimental to grasslands, including overgrazing, reclamation, and road construction, often facilitate the invasions; therefore, counter measures such as reseeding and a ban on grazing need special attention. Environmental factors including precipitation, nutrients, prevailing winds, fires, and topography may be other factors that promote or block the process of invasion. In studying ways of preventing or controlling such invasions, alien plants with short life cycle, prolific seed production, and strong competitiveness, deserve particular attention and so do human activities that may damage the environment and fragile habitats.     

湛江市外来植物入侵状况

[目的]了解湛江市外来入侵植物的种类特征、生活型、起源和危害情况等,对制定预防和控制管理措施提供参考。[方法]以野外调查为主,结合文献资料、网络资源以及标本数据,确定湛江市外来入侵植物的种类、生活型、原产地、引入途径,并进行评估及划分危害等级。[结果]湛江市现有外来入侵植物共112种(含变种),隶属于37科89属,其中,菊科(21种)、禾本科(13种)和豆科(13种)为种类较多的3个科,三者合计占湛江市外来入侵植物总种数的41.96%。湛江市外来入侵植物中以草本植物居多(98种),占入侵植物总数的87.50%。入侵植物主要来源于美洲,共82种,占总种数的73.21%;且55.36%(62种)的入侵植物为有意引入。从危害等级看,外来入侵植物中恶性入侵种(1级)23种,严重入侵种(2级)35种,局部入侵种(3级)21种,一般入侵种(4级)15种,有待观察种(5级)18种。[结论]湛江市的外来入侵植物种类繁多,这与湛江独特的地理位置以及日趋频繁的人类活动息息相关,应当加强监管与防范,及时对外来物种进行治理。     

Arbuscular Mycorrhizas: Drivers or Passengers of Alien Plant Invasion

Observational and manipulative studies have revealed that alien plant invasions are an outcome of interplay between a myriad of biotic and abiotic factors operating at various spatio-temporal stages and scales. Despite the salient role of ubiquitous arbuscular mycorrhizal (AM) fungi in plant interactions, studies exploring the role of such symbionts in invasiveness of alien species and invasibility of communities are limited, in part because of difficult-culturablilty of AM fungi on artificial media and apparent complexities in manipulations of AM-plant interactions in field and laboratory experiments. Moreover, analysis of the AM-plant invasion studies conducted so far have yielded contradictory results with some indicating facilitation of invasion by AM fungi and others its inhibition. Other studies have indicated that arbuscular mycorrhizal symbiosis has no effect on invasiveness of alien plants. While arbuscular mycorrhizas may facilitate invasiveness of some alien plants, such plants may also potentially impact mycorrhizal community structure and functions in the invaded habitats in different ways. The present review addresses these paradoxically conflicting observations in the context of mutualism-commensalism-parasitism gradient that characterizes the relationship between AM fungi and their alien vs. native hosts and also discusses the influence of alien invasive plants on mycorrhizal community structure of invaded ecosystems. Through critical analysis of costs and benefits for invasive plants that associate with AM fungi in their introduced range, invasion-induced shifts in AM mutualism are evaluated in the context of their impact on native biodiversity. Underlining limitations of methodologies and experimental designs usually employed to understand AM-mediated plant invasiveness, we proposes herein some alternative frameworks and experimental approaches to overcome these limitations.     

A functional trait perspective on plant invasion

Background and Aims

Global environmental change will affect non-native plant invasions, with profound potential impacts on native plant populations, communities and ecosystems. In this context, we review plant functional traits, particularly those that drive invader abundance (invasiveness) and impacts, as well as the integration of these traits across multiple ecological scales, and as a basis for restoration and management.

Scope

We review the concepts and terminology surrounding functional traits and how functional traits influence processes at the individual level. We explore how phenotypic plasticity may lead to rapid evolution of novel traits facilitating invasiveness in changing environments and then ‘scale up’ to evaluate the relative importance of demographic traits and their links to invasion rates. We then suggest a functional trait framework for assessing per capita effects and, ultimately, impacts of invasive plants on plant communities and ecosystems. Lastly, we focus on the role of functional trait-based approaches in invasive species management and restoration in the context of rapid, global environmental change.

Conclusions

To understand how the abundance and impacts of invasive plants will respond to rapid environmental changes it is essential to link trait-based responses of invaders to changes in community and ecosystem properties. To do so requires a comprehensive effort that considers dynamic environmental controls and a targeted approach to understand key functional traits driving both invader abundance and impacts. If we are to predict future invasions, manage those at hand and use restoration technology to mitigate invasive species impacts, future research must focus on functional traits that promote invasiveness and invader impacts under changing conditions, and integrate major factors driving invasions from individual to ecosystem levels.     

中国外来入侵植物的等级划分与地理分布格局分析

基于文献报道、野外调查、标本记录和必要的分类学考证, 整理出我国外来入侵植物72科285属515种。根据外来入侵种的生物学与生态学特性、自然地理分布、入侵范围以及所产生的危害, 将其划分为5类: 即恶性入侵类(34种)、严重入侵类(69种)、局部入侵类(85种)、一般入侵类(80种)和有待观察类(247种)。通过地理分布格局分析, 中国外来入侵植物主要分布在我国西南及东部沿海地区, 并进一步扩散到内陆各省。中国外来入侵等级划分和地理分布格局可以作为外来入侵植物风险防范和管理的依据。本工作提供我国外来入侵植物的本底资料的同时, 还对主要外来入侵植物的管理提出了具体建议。     

Multiple introductions,admixture and bridgehead invasion characterize the introduction history of Ambrosia artemisiifolia in Europe and Australia

Admixture between differentiated populations is considered to be a powerful mechanism stimulating the invasive success of some introduced species. It is generally facilitated through multiple introductions; however, the importance of admixture prior to introduction has rarely been considered. We assess the likelihood that the invasive Ambrosia artemisiifolia populations of Europe and Australia developed through multiple introductions or were sourced from a historical admixture zone within native North America. To do this, we combine large genomic and sampling data sets analysed with approximate Bayesian computation and random forest scenario evaluation to compare single and multiple invasion scenarios with pre‐ and postintroduction admixture simultaneously. We show the historical admixture zone within native North America originated before global invasion of this weed and could act as a potential source of introduced populations. We provide evidence supporting the hypothesis that the invasive populations established through multiple introductions from the native range into Europe and subsequent bridgehead invasion into Australia. We discuss the evolutionary mechanisms that could promote invasiveness and evolutionary potential of alien species from bridgehead invasions and admixed source populations.     

What drives invasibility? A multi‐model inference test and spatial modelling of alien plant species richness patterns in northern Portugal

Understanding and predicting biological invasions can focus either on traits that favour species invasiveness or on features of the receiving communities, habitats or landscapes that promote their invasibility. Here, we address invasibility at the regional scale, testing whether some habitats and landscapes are more invasible than others by fitting models that relate alien plant species richness to various environmental predictors. We use a multi‐model information‐theoretic approach to assess invasibility by modelling spatial and ecological patterns of alien invasion in landscape mosaics, and by testing competing hypotheses of environmental factors that may control invasibility. Because invasibility may be mediated by particular characteristics of invasiveness, we classified alien species according to their C‐S‐R plant strategies. We illustrate this approach with a set of 86 alien species in northern Portugal. We first focus on predictors influencing species richness and expressing invasibility, and then evaluate whether distinct plant strategies respond to the same or different groups of environmental predictors. We confirmed climate as a primary determinant of alien invasions, and as a primary environmental gradient determining landscape invasibility. The effects of secondary gradients were detected only when the area was sub‐sampled according to predictions based on the primary gradient. Then, multiple predictor types influenced patterns of alien species richness, with some types (landscape composition, topography and fire regime) prevailing over others. Alien species richness responded most strongly to extreme land management regimes, suggesting that intermediate disturbance induces biotic resistance by favouring native species richness. Land‐use intensification facilitated alien invasion, whereas conservation areas hosted few invaders, highlighting the importance of ecosystem stability in preventing invasions. Plants with different strategies exhibited different responses to environmental gradients, particularly when the variations of the primary gradient were narrowed by sub‐sampling. Such differential responses of plant strategies suggest using distinct control and eradication approaches for different areas and alien plant groups.