天然杂交与遗传渐渗对植物入侵性的影响

生物入侵给全球生态环境与社会经济都带来了严重危害, 对其入侵机制的研究非常重要。生物入侵是一个适应性进化的过程, 天然杂交与遗传渐渗可以改变外来物种对环境的适应性并提高其入侵能力, 使其进化成为入侵种。因此了解杂交-渐渗在促进生物入侵过程中的遗传作用, 将有助于我们采取有效措施来控制生物入侵及其危害。本文从杂交-渐渗对生物适应性进化和物种形成影响的角度, 阐明外来种如何通过杂交-渐渗在新的生境中改变其适应性、生存竞争能力和入侵能力。杂交-渐渗可以导致物种发生多倍体水平和同倍体水平的进化, 虽然二者的进化过程不尽相同, 但均能使杂种群体在遗传上产生较大变化, 进而影响杂种群体的适合度, 这一过程可能促使外来种在新的生境中的成功入侵进而转变为入侵种。随着转基因生物技术的迅速发展, 大量转基因作物进入环境释放和商品化种植, 具有特定功能的转基因可能通过杂交-渐渗进入野生近缘种群体, 也可能使之成为入侵性强的农田杂草, 带来难以预测的生态后果。总之, 生物入侵是一个复杂的进化和生态过程, 利用杂交-渐渗的理论来解释植物的入侵性, 仅从一个方面反映了入侵生物学的研究, 杂交-渐渗与其他理论的结合, 将从更深的层次来解释外来种的入侵机制。     

微生物入侵影响因素研究进展

探明生物入侵的影响因素能够有效防治生物入侵,减少其对生态系统的破坏,但现有的入侵研究主要集中于动植物入侵,对微生物入侵关注较少。本文综述了外来微生物自身属性、入侵地生物和非生物状况以及外来种和土著种之间差异等对微生物入侵的影响,比较了微生物入侵与动植物入侵、微生物定殖之间的差别,提出了今后需要进一步加强的研究内容。外来微生物入侵受其自身种系、形态、大小等特性,入侵地生物多样性、天敌、有效资源等生物或非生物因子,以及外来-本地种谱系距离、生态位差异、相对适应性差异等三方面因素共同影响,但不同因素之间的关联度、交互性及相对贡献仍不清楚。外来微生物入侵过程与动植物入侵过程、微生物定殖过程有诸多类似之处,但同时也存在不少差异。今后,需加强研究外来微生物独特性状(如:持留状态和群体感应等)对其入侵影响,关注微生物进入新环境的存活数量、扩散范围和影响程度,加强利用定殖研究中常用的微生物作为入侵物种验证经典入侵理论,以及注重观察全球变化下外来微生物的入侵趋势和区分微生物在不同入侵阶段的主要影响因素。     

生境持续和瞬间部分毁坏下外来种入侵动态模拟

生境毁坏与生物入侵是造成生物多样性降低的两大重要原因, 二者结合研究是当前生物入侵研究的前沿和热点。通过外来种入侵干扰模型分析了外来种在生境完好、生境瞬间部分毁坏和生境持续部分毁坏下的入侵动态及其对土著种群的影响, 得出如下结论: 1)生境完好的情况下, 不同迁移能力的外来种会出现四种不同的入侵结果: 入侵失 败、归化、震荡共存和入侵成功; 2)无论生境瞬间部分毁坏或是生境持续部分毁坏, 当外来种的迁移率较弱时, 生境毁坏抑制入侵; 反之, 生境毁坏促进入侵成功; 3)生境毁坏从无-慢-快的变化过程中, 外来种的时滞时间表现出长-短-长的变化动态。当生境完好时, 外来种本身特征及种间竞争决定了时滞时间的长短, 当生境毁坏时, 干扰程度越强, 时滞时间越长, 外来种越需要较长的时间稳定种群。     

基于现代物种共存理论的入侵生态学概念框架

在入侵生态学60多年的发展历程中, 生态学家提出了多种多样的假说来解释生物入侵的机制。这些纷繁复杂的假说在丰富我们对生物入侵认知的同时, 也给入侵生态学概念的整合带来了困难。其中, 外来种和土著种是否存在生态学差异, 以及这种差异如何影响生物入侵, 是入侵生态学研究和争论的焦点问题。现代物种共存理论通过将外来种和土著种的生态学差异划分为生态位差异和适合度差异, 为入侵生态学概念的整合提供了新的视角。依据该理论, 外来种可以通过两种策略实现成功入侵: 一是扩大与土著种的生态位差异, 二是提高自身相较于土著种的适合度优势。因此, 外来种-土著种的生态位差异和适合度差异共同决定了入侵的成败与危害程度。通过对经典入侵假说进行梳理, 我们发现大部分假说都可以在该理论框架下进行解读, 不同假说的主要差别在于强调不同生态学过程对生态位和适合度差异的影响。同时, 这一理论框架很好地解释了为什么外来种-土著种的亲缘关系和性状差异会对生物入侵产生复杂的影响, 为达尔文归化谜团的和解以及外来种-土著种功能性状的比较研究提供了新的思路。目前, 现代物种共存理论还处于快速发展的阶段, 依旧存在很多不足, 但将其运用到生物入侵的实证研究中将是入侵生态学今后一个重要的发展方向。     

可利用资源波动对外来种入侵的抵抗性

生物入侵带来的生态和经济危害引起了人们的广泛关注。在入侵生态学研究方面,生物多样性与生物入侵之间的关系长久以来成为群落可入侵性探讨的焦点。Elton经典假说认为,物种多样性越高对外来种入侵的抵抗能力越强,许多模型或野外试验都支持这一假说。但现在越来越多的试验对此提出了异议,各种假说纷纷出现。究竟生物多样性会不会影响外来种的入侵?假设两种不同的群落结构(功能群),设计6种外来种入侵土著群落的情景分析不同多样性及相同多样性下外来种的入侵状况。结果发现,在多样性相同的情况下,两种群落对外来种入侵的抵抗力不同。外来种成功入侵等比群落,却被倍数群落排斥在系统之外。进一步分析表明这主要是由于可利用资源的波动引起的,即Davis提出的"资源机遇假说"。在相同的物种多样性下,由于倍数群落的特殊结构,整个群落所占有资源远远大于等比群落资源比率。因此,外来种在等比群落中更易找到合适的入侵机会。而在物种多样性不同的情况下,由于物种多样性与已占有资源的变化是成正比的,因此,混淆了多样性与剩余资源可利用性对外来种入侵的影响。     

海洋外来物种入侵生态学研究

海洋外来物种入侵已成为最为严重的全球性环境问题之一。海洋生态系统类型多样、环境复杂,其生物入侵的监测、控制与管理难度相对较大。我国对陆地外来生物的入侵已开展了较为深入的研究,但对于海洋外来生物的入侵研究仍处于起步阶段,对其入侵监测、入侵机制、入侵危害的程度以及防治等问题缺乏基础数据。本文在分析国内外海洋外来生物入侵现状的基础上,概述其入侵生态学研究形势及相关成果,包括海洋外来物种的入侵途径、入侵过程、入侵生态效应以及全球变化对入侵的影响等。海洋外来生物的入侵可能对海洋生态系统造成直接或间接的影响,如种间竞争破坏生态环境、与土著种杂交造成遗传污染、病原生物及有毒藻类导致海洋生态灾害加剧等。此外,从政策和法规、入侵风险评估、监测和公共宣传教育、生物信息系统和有效管理机制等方面提出对我国海洋外来物种入侵的防治策略。本研究为我国海洋外来物种的进一步研究提供了参考。     

外来种入侵的不确定性动态模拟

外来种的入侵性和生境的可入侵性是研究生物入侵机制的两个关键因素。总结多数学者的研究成果,认为外来种的拓殖率(迁移率或繁殖率)、死亡率及在新生境中的竞争力是衡量外来种能否入侵成功的内在实质。从全新的角度出发,将引入的外来种看作是对原有生态系统的一种干扰,并在此基础上结合Tilman的多物种共存模型提出了外来种干扰模型。模拟发现外来种在入侵时具有明显的不确定性。拓殖率小的外来种在新的生态系统中由于不能适应环境无法成功定殖,被排斥在系统之外;相反,拓殖率足够大的话,外来种由于自身优势具有很强的入侵性,在几年或几十年的时间内就会成功地在新的环境中建立种群并拓殖入侵,影响了当地物种的生存及原有生态系统的稳定。研究还发现,物种入侵也存在一定的不确定性,入侵不一定会一直持续下去,或许在百年或几百年的时间内入侵种会突然灭绝,原生态系统又恢复到原来的水平。     

生物入侵的危害与防治对策

生物入侵是一个世界范围的生态学现象。入侵种通过竞争、捕食、改变生境和传播疾病等方式对本地种及其系统产生影响。生物入侵的危害表现为：造成巨大的经济损失,仅美国每年因外来种入侵造成的经济损失近1370亿美元;威胁到人类的健康和生存。成千上万的人被外来种传染疾病以致死亡;引起严重的社会恐慌和动荡,人们寝食不安;改变了生态系统的结构和功能,全球自然灾害频频爆发;导致生物多样性的急剧下降,威胁到子孙后代的生存和发展。防治生物入侵有3条途径：实行全面检疫,阻止外来种的偶然入侵;采取全面的生态评估和监测,防范引进品种的入侵灾难;对已入侵的外来种采用机械法、化学法和生物防治法进行根除和控制,应用生物防治法、筛选天敌和对其进行危害评估时要特别慎重。     

近缘种比较研究在植物入侵生态学中的应用

为什么有些物种能够成功入侵而有些物种却入侵失败？这是一直困扰入侵生态学家的问题。人们已从不同角度开展了研究, 其中包括不同物种之间的比较。然而以往对不同物种进行比较时往往忽略了亲缘关系对比较研究的影响, 使得出的结果不具可比性。将入侵种与其近缘的土著种或入侵能力不强的外来种进行比较则能够排除亲缘关系带来的影响, 使结果更加具有说服力。现有资料表明近缘种比较已广泛应用于菊科、禾本科、松科等科入侵植物的研究, 探讨与这些植物入侵有关的生物学特性以及生境的可入侵性、入侵的预测和入侵控制等入侵生态学的核心问题。本文综述了入侵种与其近缘种比较在研究生物入侵几个重要问题中的应用, 包括物种的入侵性、群落的可入侵性以及入侵种预测研究, 并分析了近缘种比较研究的发展方向。     

近20年外来生物入侵危害与风险评估文献计量分析

外来生物入侵导致全球生物多样性下降,极大地威胁着生态系统健康,已造成很大的生态损失与经济损失。近年来,随着生物入侵的加剧,全球对生物入侵的研究力度不断加大。外来入侵生物的生态危害与风险评估可以为人们提供对入侵可能性和入侵方式更直接的信息,从而为管理者制定管理策略提供依据。基于最近20年间(1995—2014年)科学文献数据库Web of Science的科学引文索引数据库扩展版(SCI-E)中数据,对外来入侵生物的生态危害与风险评估方面的研究进行了文献计量分析,旨在了解当前国际研究现状,以便推动中国的生物入侵相关研究。为了全面掌握全球外来生物入侵生态危害与风险评估方面的研究,采用Bibexcel与TDA文献计量工具,对Web of Science数据库中相关文献进行了分析,去重后共获取5492篇文献。结果表明:近20年(1995—2014年)入侵生物的生态危害与风险评估方面的研究刊文量呈现前缓后剧增的趋势,2008—2014年进入了快速发展阶段,文献数量急剧增加,2014年达到最高(511篇);美国发文量远超其它国家,占据主导地位,中国刊文量排名第5。美国、澳大利亚、法国、英国、德国的研究论文影响力较大。刊文量最多的研究机构为美国农业部(USDA),中国科学院发文量排名第10位。研究学科主要为昆虫学、农艺学、植物科学、生态学,研究热点集中在生物防治、风险评估、粮食作物和经济作物的病虫害防治、杂草防控,以及生物入侵与气候变化的关系等方面。有关外来入侵生物的生态危害与风险评估的研究多集中于北美、澳大利亚和欧洲,未来要加强亚洲地区,特别是中国外来生物入侵风险评估的研究;要加强气候变化对外来生物物种特性的影响研究,更多关注入侵生物的生态控制与生态恢复方面的研究,以便更好地为今后长期有效地防控入侵生物提供理论与技术指导。     

潮虫消耗木本植物凋落物的可选择性试验

近年来,越来越多的学者关注外来植物入侵对土壤生态功能的影响效应及其相应反馈机制的探索与研究,然而本地原生土壤生物群落对不同入侵程度下的外来植物种以及本地原生植物种之间是否存在消耗差异却尚不明了.通过等足目潮虫的选择性喂养试验来测试10个本地种、5个非入侵性外来种和5个强入侵性外来种之间的适口性差异,试图求证外来植物的入侵性是否与植物落叶被消耗率呈现必然联系.数据分析结果显示潮虫对本地种、非入侵性外来种和入侵性外来种的消耗并无显著差异;而潮虫对不同生活型下木本植物的取食却存在显著差异,即灌木消耗率显著高于乔木.其次,通过植物初始性状指标(包括木质素、纤维素、半纤维素、碳、氮含量)与相应消耗率的相关比较,消耗量总体上与植物凋落物的氮含量呈正相关关系(R2 =0.358).由此,研究结论强调植物落叶的降解速率并不一定与植物入侵性或入侵阶段呈绝对相互关连,但是氮含量,抑或各种形式的植物氮元素成分都可能在一定程度上参与并影响着外来植物的入侵进程.     

天然林和人工林外来入侵和本地植物对比研究: 以弄岗国家级自然保护区为例

外来植物的入侵严重威胁了自然保护区的生物多样性。为探讨自然保护区内天然林和人工林林下外来植物入侵状况及其与本地优势植物的种间关系, 本研究以弄岗国家级自然保护区为研究区域, 结合保护区内4种生境72个样方的野外调查数据, 利用生态位宽度、生态位重叠和种间联结指数比较了不同生境中外来入侵草本植物的多样性和生态位宽度以及外来入侵草本植物与本土优势草本植物的生态位重叠和种间联结。结果表明: 弄岗国家级自然保护区4种生境共记录6种外来入侵草本植物, 隶属于3科6属, 其中菊科物种数量最多。外来入侵植物多样性呈现出秋枫(Bischofia javanica)人工林 > 麻竹(Dendrocalamus latiflorus)次生林 > 人面子(Dracontomelon duperreanum)人工林 > 广西澄广花(Orophea polycarpa)次生林的特征。除广西澄广花次生林生境的外来入侵草本植物丰富度与本土草本植物丰富度呈显著正相关外, 其余生境均无显著的相关关系。三叶鬼针草(Bidens pilosa)的生态位宽度最大, 为4种生境均有分布的外来入侵植物。4种生境的外来入侵植物与本土优势植物生态位重叠和种间联结程度均较低, 种间竞争较弱。本研究明确了弄岗国家级自然保护区天然林和人工林中外来入侵草本植物的分布及其与本土草本植物的种间关系。     

叶物候、构建消耗和偿还时间对入侵植物碳积累的影响

随着全球经济一体化进程的深入,生物入侵已成为严重的全球性问题之一.外来种入侵打破了物种生存的自然平衡,导致生态系统趋于均质化,并给社会经济发展和人类健康造成了无法估量的损失.然而,目前人们对外来种的入侵机理仍不十分清楚.叶物候如叶片发生时间、凋落时间、及由二者决定的叶寿命和叶片发育进程是植物在季节和非季节性变化的环境中为了获得碳收益所采取的适应策略.叶构建消耗是植物碳收获过程中必要的成本投入,反映了植物在叶片水平上的能量分配策略.偿还时间能在一定程度上反映叶片碳的积累情况.从叶物候、构建消耗和偿还时间入手,分析了入侵植物的资源捕获能力和成本对其碳积累的影响,并提出了今后的研究方向.     

Ecophysiological basis of the Jack-and-Master strategy: Taraxacum officinale (dandelion) as an example of a successful invader

Aims Successful invasive plants are often assumed to display significant levels of phenotypic plasticity. Three possible strategies by which phenotypic plasticity may allow invasive plant species to thrive in changing environments have been suggested: (i) via plasticity in morphological or physiological traits, invasive plants are able to maintain a higher fitness than native plants in a range of environments, including stressful or low-resource habitats: a 'Jack-of-all-trades' strategy; (ii) phenotypic plasticity allows the invader to better exploit resources available in low stress or favorable habitats, showing higher fitness than native ones: a 'Master-of-some' strategy and (iii) a combination of these abilities, the 'Jack-and-Master' strategy.Methods We evaluated these strategies in the successful invader Taraxacum officinale in a controlled experiment mimicking natural environmental gradients. We set up three environmental gradients consisting of factorial arrays of two levels of temperature/light, temperature/water and light/water, respectively. We compared several ecophysiological traits, as well as the reaction norm in fitness-related traits, in both T. officinale and the closely related native Hypochaeris thrincioides subjected to these environmental scenarios.Important findings Overall, T. officinale showed significantly greater accumulation of biomass and higher survival than the native H. thrincioides, with this difference being more pronounced toward both ends of each gradient. T. officinale also showed significantly higher plasticity than its native counterpart in several ecophysiological traits. Therefore, T. officinale exhibits a Jack-and-Master strategy as it is able to maintain higher biomass and survival in unfavorable conditions, as well as to increase fitness when conditions are favorable. We suggest that this strategy is partly based on ecophysiological responses to the environment, and that it may contribute to explaining the successful invasion of T. officinale across different habitats.     

The cobblers stick to their lasts: pollinators prefer native over alien plant species in a multi-species experiment

The majority of plant species rely, at least partly, on animals for pollination. Our knowledge on whether pollinator visitation differs between native and alien plant species, and between invasive and non-invasive alien species is still limited. Additionally, because numerous invasive plant species are escapees from horticulture, the transition from human-assisted occurrence in urbanized habitats to unassisted persistence and spread in (semi-)natural habitats requires study. To address whether pollinator visitation differs between native, invasive alien and non-invasive alien species, we did pollinator observations for a total of 17 plant species representing five plant families. To test whether pollinator visitation to the three groups of species during the initial stage of invasion depends on habitat type, we did the study in three urbanized habitats and three semi-natural grasslands, using single potted plants. Native plants had more but smaller flower units than alien plants, and invasive alien plants had more but smaller flowers than non-invasive alien plants. After accounting for these differences in floral display, pollinator visitation was higher for native than for alien plant species, but did not differ between invasive and non-invasive alien plant species. Pollinator visitation was on average higher in semi-natural than in urbanized habitats, irrespective of origin or status of the plant species. This might suggest that once an alien species has managed to escape from urbanized into more natural habitats, pollinator limitation will not be a major barrier to establishment and invasion.     

The global invasion success of Central European plants is related to distribution characteristics in their native range and species traits

Aim Determining which traits predispose a species to become invasive is a fundamental question of invasion ecology, but traits affect invasiveness in concert with other factors that need to be controlled for. Here, we explore the relative effects of biological traits of plant species and their distributional characteristics in the native range on invasion success at two stages of invasion. Location Czech Republic (for native species); and the world (for alien species). Methods The source pool of 1218 species of seed plants native to Central Europe was derived from the flora of the Czech Republic, and their occurrence in 706 alien floras all over the world was recorded, distinguishing whether they were listed as an ‘alien’ or a ‘weed’ in the latest version of Randall’s ‘Global compendium of weeds’ database. The latter type of occurrence was considered to indicate species ability to invade and cause economic impact, i.e. a more advanced stage of invasion. Using the statistical technique of regression trees, we tested whether 19 biological traits and five distributional characteristics of the species in their native range can be used to predict species success in two stages of invasion. Results The probability of a species becoming alien outside its native distribution range is determined by the size of its native range, and its tolerance of a wide range of climates acquired in the region of origin. Biological traits play only an indirect role at this stage of invasion via determining the size of the native range. However, the ability of species to become a weed is determined not only by the above characteristics of native distribution, but also directly by biological traits (life form and strategy, early flowering, tall stature, generative reproduction, number of ploidy levels and opportunistic dispersal by a number of vectors). Species phylogenetic relatedness plays only a minor role; it is more important at the lowest taxonomic levels and at the later stage of invasion. Main conclusion The global success of Central European species as ‘weeds’ is determined by their distributional characteristics in the native ranges and by biological traits, but the relative importance of these determinants depends on the stage of invasion. Species which have large native ranges and are common within these ranges should be paid increased attention upon introductions, and the above biological traits should be taken into account in screening systems applied to evaluate deliberate introductions of alien plants to new regions.     

Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success: a hypothesis

Our understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource‐acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource uptake and competitive ability compared to native species in the alien range, and compared to plants of the invader in its native range. Such root‐trait changes could be ecological or evolutionary in nature. I explain how shifts in root traits could occur as a consequence of enemy release and contribute to invasion success of alien plants, and how they could be interrelated with other potential belowground drivers of invasion success (allelopathy, mutualist enhancement). Finally, I outline the approaches that could be taken to test whether belowground enemy release results in increased competitive ability and nutrient uptake by invasive alien plants, via changes in root traits in the alien range.     

Evaluating differences in the shape of native and alien plant trait distributions will bring new insights into invasions of plant communities

Failure to quantify differences in the shape of inter‐specific trait distributions (e.g., skew, kurtosis) when comparing co‐occurring alien and native plants hinders the integration of biological invasions and plant community ecology. Within a plant community, understanding the circumstances that lead to the shape of the inter‐specific distribution of one or more functional plant traits being unimodal, bimodal, multimodal or skewed has the potential to shed new light on community vulnerability to invasion, subsequent ecosystem impacts and the selection pressures (e.g., stabilizing, directional or disruptive) acting upon native and alien species. Ignoring differences in the shape of inter‐specific trait distributions of alien and native species could miss important insights into plant invasions, including: the existence of unsaturated native plant communities, empty niches, shifting trait optima of species as a result of environmental change and incomplete colonization–extinction processes following invasion. Future comparisons of functional trait differences between native and alien species should include assessment of the shapes of inter‐specific trait distributions since these may differ even when the mean values of traits are similar for native and alien species. The infrequent application of such approaches may explain the limited generalizations regarding the drivers and consequences of plant invasions in plant communities.     

西双版纳外来入侵植物及其共存种叶片氮、磷化学计量特征

诊断外来植物和本地种的资源利用方式是入侵生态学研究的热点问题。叶片氮(N)、磷(P)含量和化学计量特征可以反映受侵地区植物的N、P吸收能力和限制状况, 为把握外来植物的入侵能力、为本地植物共存或消失的机制提供基础科学依据。该研究以我国西南地区典型外来入侵植物(飞机草(Chromolaena odorata)、紫茎泽兰(又叫破坏草, Ageratina adenophora))及其共存的本地植物为对象, 探讨不同入侵条件下入侵种及其共存的本地植物的N、P利用策略。在云南西双版纳孔明山研究区, 调查了无入侵条件下和飞机草与紫茎泽兰的不同入侵程度(按入侵种生物量比例划分)下的物种数量和生物量, 分析了主要植物的叶片N、P含量和N:P值。结果显示: 尽管群落地上生物量随飞机草和紫茎泽兰入侵程度增加而增加, 但本地植物种数随飞机草和紫茎泽兰入侵程度增加而显著减少。飞机草与紫茎泽兰的叶片N、P平均含量无显著差异, 但均显著高于无入侵条件下的本地植物以及与其共存的本地植物。两种入侵植物的N、P含量均随它们所占样方总生物量的比例增大而升高, 本地植物N含量也有相似的变化趋势。当对比入侵和无入侵两类样方的同种植物N、P和N:P变化时发现多数本地种叶片P含量呈降低趋势, N含量和N:P呈升高趋势。根据叶片N、P绝对含量和N:P值及其随入侵的变化规律, 推测入侵可能提高了植物的N可利用性, 但本地植物仍然受N限制; 入侵植物N:P值总体小于10与其具有相对于N吸收的较高的P吸收能力有关。该研究揭示了西南典型外来入侵植物具有较强的N、P吸收富集能力。     

Foliar nitrogen and phosphorus stoichiometry of alien invasive plants and co-occurring natives in Xishuangbanna

Aims How alien invasive plants and co-occurring native plants utilize nutrients is one of major issues in invasion ecology. Foliar nitrogen (N) and phosphorus (P) contents and stoichiometry can elucidate the uptake ability and limitation status of nutrients in plants, which provides basic knowledge for understanding the invading ability and co-occurrence or disappearance of plants.
Methods Based on typical alien invasive plants (Chromolaena odorata, Ageratina adenophora) and native plants in southwestern China, this study focused on strategies of N and P utilization among invasive plants and native plants under different invasion conditions. The species compositions, aboveground biomass, leaf N and P contents and leaf N:P were investigated for plants in plots with no invasion and with different invasion extents (estimated by the plot-based percentage of invaders’ biomass in total community) at Mt. Kongming in Xishuangbanna region, Yunnan Province, China.
Important findings The species number decreased significantly with the invasion extent of both C. odorata and A. adenophora, although the aboveground biomass was greatly enhanced. Leaf N and P contents did not differ between the two studied invaders, but they showed significantly higher N and P levels than both co-occurring and only native species (p < 0.05). Besides, leaf N and P contents of invaders increased with the invasion extent, and leaf N of native plants also showed an increasing trend with the invasion extent. When the influence of invasion was checked for the same species, leaf P contents decreased, whereas leaf N and N:P increased for most native plants under invasion. Based on the absolute foliar N and P contents, N:P values, we inferred that native plants were still limited by N, although N availability might be enhanced by invasion. Both invasive plants had leaf N:P values lower than 10, suggesting a higher P uptake relative to N uptake. All above results highlighted a higher N and P uptake of typical alien invasive plants in southwestern China.