Using molecular methods to determine the origin of weed populations of Pereskia aculeata in South Africa and its relevance to biological control

New biological control agents are required in order to reach and sustain an adequate level of control of the declared environmental weed Pereskia aculeata Miller (Cactaceae) in South Africa. Identifying the origin of weed genotypes has been important in a number of biological control programmes and is likely to be of importance for the control of P. aculeata due to its disjunct native distribution and morphological polymorphisms between plants from different regions of the native and introduced distribution. DNA sequencing of the trnL chloroplastic intron and the phyC nuclear gene indicate that the South African weed population’s origin was in the southern region of native distribution. Inter-Simple Sequence Repeats (ISSRs) confirmed this result and added resolution to the analysis indicating that the native plants with the closest genetic distance to the South African weed population were found in Rio de Janeiro Province, Brazil. The relationship between the South African weed population and garden variety plants as well as the large genetic distance between the South African plants and the native plants suggests that the South African population may be the progeny of escaped garden variety plants that have been cultivated and possibly hybridized. The low levels of genetic variation within the South African population and the monophyly of the South African plants indicates that these plants are the progeny of a single introduction or multiple introductions from the same source. Rio de Janeiro Province in Brazil is the most appropriate region in which to survey for new biological control agents.     

Ecological niche modelling of an invasive alien plant and its potential biological control agents

Invasive alien plants are of concern in South Africa. Pompom weed (Campuloclinium macrocephalum) is currently invading the Grassland and Savannah biomes of South Africa and is likely to continue spreading in the southern African sub- region. Two possible biological control agents (Liothrips tractabilis and Cochylis campuloclinium) have been identified for control of pompom weed. We used ecological niche modelling to predict which areas in southern Africa are likely to be suitable for pompom weed and the two potential biological control agents. The overlap between areas predicted to be highly suitable for pompom weed and areas suitable for the biological control agents was assessed. Methods of reducing sampling bias in a data set used for calibrating models were also compared. Finally, the performance of models calibrated using only native range data, only invaded range data and both were also compared. Models indicate that pompom weed is likely to spread across a greater region of southern Africa than it currently occupies, with the Savannah and Grassland biomes being at greatest risk of invasion. Poor overlap was found between the areas predicted to be highly suitable for pompom weed and those areas predicted to be suitable for the biological control agents. However, models of the potential distribution of the biological control agents are interpreted with caution due to the very small sample size of the data set used to calibrate the models. Models calibrated using both native range and invaded range data were found to perform best whilst models calibrated using only native range data performed the worst. There was little difference found between models that were calibrated using spatially reduced (selecting only one record per 30 min grid cell) and randomly reduced (randomly selecting 50% of available records) biased data sets.     

Synergies between research organisations and the wider community in enhancing weed biological control in South Africa

Biological control offers a cost effective and ecologically sustainable tool for the management of invasive alien plants. Its implementation, however, has historically been slow and poorly co-ordinated. In South Africa, as in many other countries, most aspects of biological control programmes were done by researchers, but from 1995 onwards, with the advent of the Working for Water Programme, a more inclusive approach to biological control has been adopted. In this paper, we report on the development of community-based biological control implementation programmes in South Africa, after 1995, and highlight a number of initiatives, including employing persons with disabilities at mass-rearing facilities and in particular, we outline a suite of educational and outreach programmes for the general public and for schools, which have increased capacity, education and employment in the field of weed biological control.     

入侵植物的生理生态特性对碳积累的影响

随着国际贸易的发展和人们交往的增加以及全球环境的变化,生物种类在全球扩散的机会也大大增加,从而为生物入侵创造了机会。生物入侵不仅给农林牧生产造成损失,而且具有长期的生态学效应。外来种的成功入侵不是其自身某一个特性决定的,而是其特性与新的生境综合作用的结果。外来入侵种生理生态特性的研究对其预测和防治具有重要的意义。目前对入侵种生理生态特性的研究较少。已有的研究表明,与本地种相比入侵种可能通过提高光合能力、资源利用率、表型可塑性、化感作用,以及降低繁殖成本等增加植株碳积累,促进其入侵。但并不是所有的入侵种都同时具有这些特性。生境不同限制性资源不同,入侵机制就不同。成功的入侵种应该能够高效地利用生境中的限制性资源,并且能够较快地调节自身的生理特性以适应波动的资源环境。     

Benefits of Classical Biological Control for Managing Invasive Plants

As a result of the rapid expansion in international travel and trade over the past few decades, invasive plants have become a problem of global proportions. Plant invasions threaten the existence of endangered species and the integrity of ecosystems, and their ravages cost national economies tens of billions of dollars every year. Strategies for managing the threats posed by plant invasions involve three main tactics: prevention, eradication, and control. The effectiveness of prevention, involving enactment of legislation to prohibit the entry and spread of noxious alien plants, has been questioned. Eradication of all but the smallest, most localized weed infestations generally is not regarded as economically feasible. Conventional weed control techniques, such as mechanical and chemical controls, because they are expensive, energy and labor intensive, and require repeated application, are impractical for managing widespread plant invasions in ecologically fragile conservation areas or low-value habitat, such as rangelands and many aquatic systems. In addition, mechanical means of control disturb the soil and may cause erosion; chemical herbicides have spurred the evolution of resistance in scores of weed species and, further, may pose risks to wildlife and human health. Because of drawbacks associated with conventional weed control methods, classical biological control, the introduction of selective exotic natural enemies to control exotic pests, increasingly is being considered and implemented as a safe, cost-effective alternative to address the invasive plant problem. Worldwide, biological weed control programs have had an overall success rate of 33 percent; success rates have been considerably higher for programs in individual countries. Benefits are several-fold. Biological control is permanent, energy-efficient, nonpolluting, and inexpensive relative to other methods. Economic returns on investment in biological weed control have been spectacular in some cases, and range from an estimated benefit/cost ratio of 2.3 to 4000 or more. Although the risks involved in biological control in general are considered unacceptable by some, biological weed control in particular has had an enviable safety record. Since establishment of the stringent standards and regulatory apparatus currently in place in the United States and elsewhere, there have been no reported cases of biological weed control causing significant harm to nontarget populations or to the environment at large.     

Using Life Strategies to Explore the Vulnerability of Ecosystem Services to Invasion by Alien Plants

Invasive plants can have different effects on ecosystem functioning and on the provision of ecosystem services, with the direction and magnitude of such effects depending on the service and ecosystem being considered, but also on the life strategies of the invaders. Strategies can influence invasiveness, but also key processes of host ecosystems. To address the combined effects of these various factors, we developed a methodological framework to identify areas of possible conflict between ecosystem services and alien invasive plants, considering interactions between landscape invasibility and species invasiveness. Our framework combines multi-model inference, efficient techniques to map ecosystem services, and life strategies. The latter provides a functional link between invasion, functional changes, and potential provision of services by invaded ecosystems. The framework was applied to a region in Portugal, for which we could successfully predict current patterns of plant invasion, of ecosystem service provision, and of potential conflict between alien species richness and the potential provision of selected services. Potential conflicts were identified for all combinations of plant strategy and ecosystem service, with an emphasis on carbon sequestration, water regulation, and wood production. Lower levels of conflict were obtained between invasive plant strategies and the habitat for biodiversity supporting service. The value of the proposed framework for landscape management and planning is discussed with emphasis on anticipation of conflicts, mitigation of negative impacts, and facilitation of positive effects of plant invasions on ecosystems and their services.     

Evidence for a new regime shift between floating and submerged invasive plant dominance in South Africa

Hydrobiologia - Classical biological control for the management of floating invasive plants has been highly successful in South Africa. However, restoring ecosystem services has been compromised by...     

重庆市森林生态系统服务功能价值评估

评价了重庆市近几年来森林生态系统服务功能价值,将重庆市森林生态系统服务功能划分为提供产品功能、调节功能、支持功能及文化服务功能4大类,以2006年为基准年,利用市场价值法和生产成本法等,定量评价重庆市森林生态系统服务功能的经济价值。结果表明:从2006年至2011年,森林产品提供功能由35.14亿元增加至51.24亿元,提高了45.82%。森林碳储量增长了近100万t。重庆市森林生态系统涵养水源价值增加了59.21亿元。森林生态系统的土壤保持能力与保持总量都有所提高。气候调节价值净增加了45.86亿元。2011年森林工程引发旅游业收入增加68.34亿元。从不同的服务功能类型来看,其价值量大小依次为:水源涵养气候调节景观旅游生物多样性土壤保持碳固定。从研究结果来看,重庆市森林生态系统服务功能价值巨大,该结果有利于加强人们对森林生态系统的认识,可以为生态系统管理、生态保护和生态补偿提供依据。     

污染湖泊生态系统服务净价值评估——以滇池为例

水污染是我国湖泊生态系统面临的主要环境问题,评估污染条件下湖泊生态系统服务价值对认识和恢复污染湖泊生态功能具有重要意义。针对当前湖泊生态系统服务价值评估方法中未体现水污染负面影响的问题,在传统生态系统服务功能价值评估框架的基础上,将水污染造成的经济损失内化到生态系统服务功能价值中,提出了针对污染湖泊的生态系统服务功能价值评估方法。应用该方法核算了滇池生态系统服务净价值。结果表明:2006—2015年滇池年均生态系统服务功能价值为386.55亿元/a,水污染改变了滇池的价值结构,供水价值丧失,气候调节、旅游和蓄水等成为滇池生态系统服务功能价值的主体;滇池水污染对流域内外经济社会发展造成的损失达到15.23亿元/a,主要经济损失体现在生态补水费用和蓝藻去除费用;综合湖泊生态系统服务的正向价值和水污染的负向损失,滇池的净生态系统服务价值为371.33亿元/a,占流域GDP的11.7%。将水污染损失纳入湖泊生态系统服务功能价值评估中增强了评价结果的合理性,能够更加真实地反映湖泊生态系统对人类经济社会发展的综合影响。     

华南地区外来入侵和归化植物分析

为了解华南地区外来植物现状,通过野外调查和查阅文献等,确定华南地区有外来入侵和归化植物45科141属223种,以菊科(Asteraceae,38种)、豆科(Fabaceae,36种)、禾本科(Poaceae,19种)植物为主,其中草本植物和原产美洲的植物占优势,分别有204种(占总数的91.5%)和163种(占73.1%)。广东外来入侵植物有159种,归化植物23种;广西有入侵植物135种,归化植物16种;海南有入侵植物111种,归化种15种;香港有入侵植物105种,归化植物9种;澳门有入侵植物89种,归化种4种;华南5省区共有的外来入侵和归化植物为57种(55种为入侵植物,2种为归化植物)。广东是外来植物种类最多的地区,与其他4省区共有的外来入侵和归化植物种类也最多,说明广东同时是外来植物输入和输出大省。由于气候和生态生境的相似性,各省区都面临着其他植物从周边地区入侵的风险,因此在治理入侵植物时,应建立联合防控机制对外来入侵植物的联合监测和防控,以提升外来入侵植物的治理成效和降低其对人类健康和生态安全的威胁。     

农牧交错带风蚀沙化区农业生态系统服务功能的经济价值评估

运用市场价值法、替代工程法、影子价格法和机会成本法等方法对内蒙古阴山北麓风蚀沙化区农业生态系统服务功能的价值进行了经济评估。结果表明 ,该地区农业生态系统总的服务价值为 4 6 5 4 5 381 0万元 ,其中产品服务价值为 2 9874 1万元 (占 0 0 6 % ) ,水土保持价值为 4 5 70 2 84 2万元 (占 9 7% ) ,涵养水源价值为 4 2 80 2 6万元 (占 0 0 9% ) ,气候调节价值为393411 8万元 (占 0 84 % ) ,营养物质循环价值为 4 1910 6 73 9万元 (占 89 2 7% ) ,从服务功能的价值比例来看 ,系统的环境服务价值要远远大于其产品服务的价值 ,表明该地区农业生产水平落后 ,同时也体现了在当地环境恶劣 ,农业经营粗放的前提下 ,系统环境服务价值是维系其不稳定农业生产的基础     

中国西南纵向岭谷区外来入侵植物对生物多样性的影响

论述中国西南纵向岭谷区外来入侵植物对生物多样性的影响。中国西南纵向岭谷区是我国生物多样性保护的关键地区。目前,该区域已成为外来植物入侵的重灾区,外来入侵植物种类多达70余种,其中,紫茎泽兰Ageratina adenophora（Eupatoriumadenophorum）、飞机草Chromolaena odorata（Eupatorium odoratum）和肿柄菊Tithonia diversifolia等在该区域危害严重,该区域的生态系统的结构与功能遭受破坏,本地物种面临灭绝,农、林、牧生产乃至区域的生态安全受到威胁。该区域的外来入侵植物的危害居全国之冠。研究该区域的外来入侵植物,揭示其危害规律,遏制其危害速度,最终清除该区域的外来入侵植物,恢复该区域的生态平衡,具有十分重要的现实意义和科学价值。文中详细论述了外来入侵植物对植物物种多样性、植物群落多样性、生态系统多样性、农牧业及林业的影响,最后指出消除和控制外来入侵植物的途径。     

杂草生防作用物对本土生物群落的影响

传统生物防治是治理外来入侵杂草危害切实可行的有效策略和途径,近来对传统生物防治的批评主要集注于,引进的生防作用物攻击威胁本土非靶标生物。引进的生防作用物可能对本土非靶标生物产生直接和间接影响,这类影响通过不同营养级生物之间的取食关系,以及通过同一营养级内生物间的竞争关系,而影响本土非靶标生物群落。列举若干杂草生物防治案例对以上影响方式及其发生途径进行了评述。就防范杂草生防作用物对非靶标生物的负面影响,提出了以下对策:(i)把引进天敌防治外来入侵生物作为最后的有效手段;(ii)适当增加对非靶标生物潜在影响的生态学评估;(iii)选择寄主专一性强而且能有效控制靶标杂草的天敌;(iv)加强对杂草传统生物防治的生态学研究。     

南四湖湿地外来入侵植物

南四湖是我国重要的淡水湖泊湿地之一。为阐明南四湖湿地外来植物的现状及入侵规律,为湿地生态系统的重建、生物多样性的保护和湿地资源开发等提供指导,通过野外调查和参考有关文献资料,对南四湖湿地外来植物进行了较为深入的研究,并与青岛、昆嵛山、滨州沿海三地作了比较。结果表明,南四湖湿地外来入侵植物有41种,隶属19科35属;以菊科和豆科为优势科;外来入侵物种中热带来源与温带来源比例相当,人为引入导致的外来入侵植物高达39%。南四湖与沿海三地相比,沿海三地外来入侵植物的种类均比南四湖湿地多,其中以经济最发达的青岛种类最多;青岛外来入侵植物中有35种在南四湖湿地未发现;南四湖湿地的特有外来入侵植物有5种,体现出湿地外来入侵植物水生特性。群落相似性分析表明,Jaccard指数和Sorenson指数呈现的规律一致,南四湖与滨州的相似性最高,其次为昆嵛山,与青岛的差异最大。通过分析南四湖湿地外来入侵植物种类和分布规律,提出了相应的防治对策。     

外来斑潜蝇入侵和适应机理及管理对策

重要外来斑潜蝇（美洲斑潜蝇Liriomyza sativae Blanchard,南美斑潜蝇L.huidobrensis Blanchard)已对我国蔬菜和花卉生产造成了重大的经济损失。介绍了我国外来斑潜蝇的主侵形势,入侵途径和特点及采取的防治对策;分析了外来斑潜蝇在我国与寄主植物,气候,人类活动等作用过程中的适应机理,并针对我国目前外来斑潜蝇入侵现状提出了可行的管理措施,以期对预防了管制我国外来生物入侵提供参考。     

After biocontrol: Assessing indirect effects of insect releases

Development of biological control agents for weeds has been motivated by the need to reduce the abundance and distribution of a pest plant where chemical and mechanical control were not cost effective. Primary objectives have been direct reduction in abundance of the target and, secondarily, the increase of desirable species. Recently, wildland weeds have become a focus of biological control projects. Here, desired outcomes include both reduction of the target and indirect effects of increased diversity and abundance of native species and restoration of ecosystem services. However, goals and benefits of biocontrol programs are not always well-articulated and direct and indirect impacts are not easily predicted. We evaluated the extent to which several successful biological control projects for weeds of rangelands and waterways measured indirect impacts on invaded ecosystems. We also examined biocontrol of a wildland pest tree for which the principal objective is restoration of ecosystem services. We found few quantitative assessments of the impacts of pest plant reduction on community composition or ecosystem processes. All examples documented variation in the impacts of agent(s) across the invasive range of the target plant as well as variation in impacts on the invaded ecosystem. However, without appropriate quantitative information, we cannot evaluate site characteristics that may influence vegetation responses. Most successful weed management programs integrated the use of biocontrol agents with other weed management strategies, especially modifications of disturbance and competing vegetation. Discussion and evaluation of responses of nontarget species would improve our understanding of the context-specificity of outcomes.     

我国外来入侵生物防控现状、问题和对策

外来物种入侵已经威胁全球多个国家和地区,严重影响农林牧渔业生产,威胁生态系统稳定,是当前全球生物多样性丧失的主要原因之一,开展入侵物种防控已成为生物多样性保护与农业绿色发展的重点工作。我国已经成为全球遭受生物入侵威胁与损失最为严重的国家之一,截至2018年底,入侵我国的外来物种有近800种,已确认入侵农林生态系统的有638种,全国31个省（区、市）均有外来生物入侵发生并带来危害,半数以上县域都有入侵物种分布,几乎涉及所有类型的生态系统。本文对全球主要发达国家外来入侵物种发生情况及防控进行梳理发现,从国家层面立法开展外来入侵生物防控成为主流,制定长期防控战略并增加投入是入侵物种防控成功的关键。近些年,我国在外来入侵物种防控方面初步建立了工作机制,发布了重点管理外来入侵物种名录,完成了重点入侵物种的调查监测,开展了局部地区的防控措施,积极推动立法工作。根据国外生物入侵防治经验与我国实际情况,本研究提出我国外来入侵物种防控对策建议,包括加强法制建设、开展本底调查和启动重大防控工程等,为我国外来侵入生物的防控提供借鉴。     

Alien invasive plants in China: risk assessment and spatial patterns

With a wide range of habitats and exploding development of international trade, China is facing escalating risk of the plant invasion. Research on the risk assessment of alien invasive plants may help us manage the invasive with priority, and is imperatively needed in China. However, until now, few studies have been conducted for the risk of alien invasive plants and its spatial patterns in China, especially with a regard to ecosystem conservation and biodiversity protection. In this paper, we assessed the risk of invasive plants and its spatial patterns. We focused on the following basic questions: Which alien invasive plants are the most noxious, and which of them are mild? How are the spatial patterns of alien invasive plants at different risk ranks? In the present study, the risk of 100 major alien invasive plants in China was assessed based on a revised risk assessment system and an extensive consult with literatures. The results indicated that there were 18 species of rank 1st, 29 of rank 2nd, 33 of rank 3rd and 20 of rank 4th. Although, there was high richness of alien invasive plants in South China, most of them were of low risk. By contrast, low richness of alien invasive plants was observed in North China and the regions in high altitude, but most of the invasive were of high risk. Compared with previous studies, our study appears to have delivered credible results and may play an early warning function, and also further our understanding of the risk of invasive plants and its spatial patterns in China, though we acknowledged that the risk assessment may have some potential weakness, and appealed timely and further investigations in future.     

The current status of biological control of weeds in southern China and future options

China has become one of the countries most seriously affected by invasive alien weeds in the world. Weeds impact agriculture, the environment and human health, and conventional control methods such as herbicides are expensive, damaging to human health and unsustainable. As the impacts and costs of weed control in China increase, there is an urgent need to manage some of the more important weeds through more sustainable methods. Classical biological control of invasive alien weeds is environmentally-friendly and sustainable. Biological control in China began in the 1930s with the introduction of two agents into Hong Kong for the control of Lantana camara. Since then, a further seven biological control agents have been introduced into China to control four weed species. In addition, 11 biological control agents targeting seven weed species have naturally spread into China. Together, these biological control agents are helping to control some of China's worst weeds. However, these efforts are only a small portion of the weeds that could be targeted for weed biological control. This paper reviews the current status of weed biological control efforts against introduced weeds in ten provinces and regions in southern China and provides a platform to identify the most effective and appropriate weed biological control opportunities and programmes to pursue in the future. Introducing additional safe and effective biological control agents into China to help manage some of the worst weeds in the region should reduce the use of herbicides and impacts on human health and the environment, while increasing productivity and food security.     

Cross-fertilizing weed science and plant invasion science to improve efficient management: A European challenge

Both weed science and plant invasion science deal with noxious plants. Yet, they have historically developed as two distinct research areas in Europe, with different target species, approaches and management aims, as well as with diverging institutions and researchers involved. We argue that the strengths of these two disciplines can be highly complementary in implementing management strategies and outline how synergies were created in an international, multidisciplinary project to develop efficient and sustainable management of common ragweed, Ambrosia artemisiifolia. Because this species has severe impacts on human health and is also a crop weed in large parts of Europe, common ragweed is one of the economically most important plant invaders in Europe. Our multidisciplinary approach combining expertise from weed science and plant invasion science allowed us (i) to develop a comprehensive plant demographic model to evaluate and compare management tools, such as optimal cutting regimes and biological control for different regions and habitat types, and (ii) to assess benefits and risks of biological control. It further (iii) showed ways to reconcile different stakeholder interests and management objectives (health versus crop yield), and (iv) led to an economic model to assess invader impact across actors and domains, and effectiveness of control measures. (v) It also led to design and implement management strategies in collaboration with the various stakeholder groups affected by noxious weeds, created training opportunities for early stage researchers in the sustainable management of noxious plants, and actively promoted improved decision making regarding the use of exotic biocontrol agents at the national and European level. We critically discuss our achievements and limitations, and list and discuss other potential Old World (Afro-Eurasian) target species that could benefit from applying such an integrative approach, as typical invasive alien plants are increasingly reported from crop fields and native crop weeds are invading adjacent non-crop land, thereby forming new source populations for further spread.