Non-Indigenous Woody Invasive Plants in a Rural New England Town

We investigated the abundance of non-indigenous woody invasive plants in Farmington, Maine, a rural New England town in a forested landscape. We found 12 invasive species and more than 7 patches per km from surveys on 33 transects (54.3 km) along field edges, abandoned railroad right-of-ways, roadsides, and riparian zones. Invasive abundance was apparently lower than for more developed areas of the northeastern US, where, in contrast to western Maine, invasives have extensively penetrated forest interiors. Invasive abundance increased with the amount of landscaping and proximity to town, suggesting a close association between local horticulture and the spread of woody invasives. Invasive abundance and diversity were highest in riparian areas, probably due to relatively high levels of propagule pressure. Species differed in the extent of invasiveness, ranging from those still dependent on planted parent trees to fully invasive populations. The invasive species recorded in this study have caused environmental and economic damage elsewhere. The lower levels of invasiveness in Farmington are likely a result of the isolation, small human population, and forested landscape rather than low levels of invasibility. This suggests the potential for future risks, and the importance of intervention while populations can still be eradicated or controlled.     

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。     

Effects of resource supplies on the structure and function of microbial communities

The supplies of nutrients, and their elemental stoichiometry, can have significant impacts upon the structure and function of microbial communities. This review focuses on the effects of nutrient supplies on the biodegradation of organic matter, and on the dynamics of host-pathogen interactions. Analyses of data from the literature suggest significant effects of nitrogen:phosphorus supply ratios on the microbial decomposition of organic matter, and it is argued that these stoichiometric effects may have important implications for the fate and fluxes of carbon in natural ecosystems. In addition, it is shown that the supplies of nitrogen and phosphorus to the host can strongly influence the outcome of infections in both terrestrial and aquatic plants, suggesting that resource availability and resource supply ratios potentially may have significant effects on the health of many plant communities. This revised version was published online in August 2006 with corrections to the Cover Date.     

丛枝菌根真菌在外来植物入侵演替中的作用与机制

外来植物入侵不仅是环境、经济和社会问题,也是一个生理学和生态学问题,尤其是入侵植物与本地植物、入侵植物和本地土壤生物之间的相互作用决定外来植物入侵程度。丛枝菌根真菌（AMF）作为土壤中一类极为重要的功能生物,在外来植物入侵演替过程中发挥多种不同作用。文章系统总结了AMF对入侵植物个体和群体的影响,入侵植物与本地植物竞争中AMF发挥的促进和抑制作用;探讨了AMF与入侵植物的相互作用关系,以及环境因子对AMF一入侵植物关系的影响：对AMF在外来植物入侵演替中的作用机制进行了讨论。旨在为探索控制生物入侵的新途径、为我国开展外来植物入侵研究与防控实践提供新思路。     

Invasive Ornamental Plants: Problems,Challenges, and Molecular Tools to Neutralize Their Invasiveness

The spread of invasive plants is one of the most challenging ecological problems in the 21st Century, causing a $35 billion loss per year to the economy in the United States alone. More than 50% of all invasive plants and 85% of invasive woody species were introduced originally for ornamental and landscape use. Because many nonnative plants are commercially important and widely utilized for various purposes, completely banning their use and prohibiting their imports are unpractical solutions for control. On the other hand, the methods currently used to control the spread of nonnative plants are ineffective, expensive, or environmentally problematic. Recent advances in plant biotechnology may enable us to create sterile cultivars of these nonnative ornamental crops of commercial value. The use of sterile cultivars should reduce or eliminate the undesirable spread of some nonnative invasive plants into natural areas.     

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.     

Predicting Invasive Plants: Prospects for a General Screening System Based on Current Regional Models

Screening systems for predicting invasive plants have been independently developed for the non-indigenous floras of North America, the South African fynbos, and Australia. To evaluate the performance of these screening systems outside the regions for which they were developed, we tested them for the non-indigenous flora of the Hawaiian Islands. When known invasive plant species in the Hawaiian Islands were evaluated using the North American and Australian systems, 82% and 93% of the species were predicted to be invasive, respectively, and the remainder were classified as requiring further study. The South African fynbos system correctly predicted only 60% of the invasive species in the Hawaiian Islands. All three screening systems correctly classified a majority of the non-invaders as non-invasive. The Australian system has several advantages over the other systems, including the highest level of correct identification of invaders (>90%), ability to evaluate non-woody plants, and ability to evaluate a species even when the answers to some questions are unknown. Nevertheless, with the Australian system, a large fraction of species known not to be invasive were recommended for further study before importing, so there remains room for improvement in identifying non-invasive species. Based on our results for the Hawaiian Islands and a previous evaluation in New Zealand, the Australian system appears to be a promising template for building a globally applicable system for screening out invasive plant introductions. This revised version was published online in July 2006 with corrections to the Cover Date.     

红河流域的外来人侵植物

红河流域是中国生物多样性最为丰富的地区,植物区系起源古老,生态系统类型复杂多样.本文论述了红河流域外来入侵植物的现状,列举了73种红河流域外来入侵物的种类,对危害比较严重的紫茎泽兰、飞机草、马樱丹、肿柄菊、凤眼莲和空心莲子草6种植物作了具体介绍.对外来入侵植物的控制对策,入侵植物本身的生物学特性的研究、保护生物多样性和退化生态系统的恢复以及路域生态系统管理等几方面作了论述.结果表明,减少人类对生态系统的干扰和破坏,恢复本地植被是防止外来入侵植物入侵的有效途径.     

红河流域的外来入侵植物

红河流域是中国生物多样性最为丰富的地区,植物区系起源古老,生态系统类型复杂多样.本文论述了红河流域外来入侵植物的现状,列举了73种红河流域外来入侵物的种类,对危害比较严重的紫茎泽兰、飞机草、马樱丹、肿柄菊、凤眼莲和空心莲子草6种植物作了具体介绍.对外来入侵植物的控制对策,入侵植物本身的生物学特性的研究、保护生物多样性和退化生态系统的恢复以及路域生态系统管理等几方面作了论述.结果表明,减少人类对生态系统的干扰和破坏,恢复本地植被是防止外来入侵植物入侵的有效途径.     

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。     

Risk Assessment and Invasion Characteristics of Alien Plants in and Around the Agro-Pastoral Ecotone of Northern China

Two risk assessment protocols were adopted to assess the risks posed by alien plants that naturalized or non-naturalized in the agro-pastoral ecotone of northern China (AGENC). In this study the Risk Assessment for Central Europe method revealed that more than two-thirds of the 19 naturalized and four-fifths of the 17 non-naturalized alien plants presented high or moderate risk, and all 36 alien plants were considered to be rejected for their potential agricultural and environmental risks under the Australian Weed Risk Assessment system. On the characteristics of plant invasions, more attention should be given to disturbed habitats rather than these relative natural or closed ecosystems, and also be prudent and careful of the alien plants that are introduced as useful plants from North or South America and unintentional introduction from Europe. Moreover, annuals needed special attention: three-quarters of the alien plants were annual species, only a few were biennial (8.3%), perennial (11.1%), liana and tree plants (2.8%). Plant invasions are not extremely serious in the AGENC, but there are several alien plants that have naturalized and spread themselves in the region. However, attention should be given in the future to predicting and preventing plant invasions in this fragile region.     

Biological Control as a Tool for Ecosystem Management

Biological control is proposed as a tool useful for ecosystem management and compatible with the goals of often competing interests regarding the restoration and maintenance of ecosystems. We summarize the effects of introduced species on ecosystems in three broad groups: insects, vertebrates, and weeds. We then discuss the role of biological control for each of these groups in the context of ecosystem management and realistic outcomes. Of the three groups, we show that biological control of weeds appears to have the best chance for success in ecosystem management. We provide two case studies to support our ideas and finally discuss future needs and trends including fiscal considerations, cost/benefits associated with biological weed control, and potential funding sources.     

Population Dynamics and Potential for Biological Control of an Exotic Invasive Shrub in Hawaiian Rainforests

Introduction of biological control agents to reduce the abundance of exotic invasive plant species is often considered necessary but risky. I used matrix projection models to investigate the current population dynamics of Clidemia hirta (Melastomataceae), an invasive shrub, in two rainforest stands on the island of Hawaii and to predict the efficacy of hypothetical biological control agents in reducing population growth rates. Stage-structured matrix models were parameterized with field data collected over 3 years from 2906 C. hirta plants in a recently invaded forest with an open overstory (Laupahoehoe) and 600 plants in a less recently invaded forest with a closed canopy (Waiakea). Asymptotic population growth rates (λ) for both populations in all years were greater than one, demonstrating that both populations were growing. Composite elasticities were high for the seedling life-history stage and fecundity, and near-term demographic elasticities suggested that changes in seedling survival would have the largest effect on population size in the short term. However, simulations showed that almost 100% of seedlings or new recruits produced per reproductive adult would have to be destroyed to cause populations to go locally extinct under current environmental conditions. Herbivores or pathogens that decrease survival across all vegetative stages by 12% at Waiakea and 64% at Laupahoehoe were projected to cause the populations to decline. Thus, biocontrol agents that reduce survival of multiple life-history stages rather than seed production should be pursued to control C. hirta in Hawaiian rainforests.     

Towards Insecticide Free Apple Orchards: Flowering Plants to Attract Beneficial Arthropods

Tanacetum vulgare, Chrysanthemum maximum, Aster tongolensis and Achillea millefolium were planted to attract and retain predacious and parasitoid arthropods in a Quebec apple orchard. The plants covered one-third of the surface of the experimental block and provided nectar, pollen and refuge for beneficial arthropods. The parasitoid fauna increased several-fold during the study. The most important index of pest management in this study was the quality of the fruit at harvest and it attained 90.8% (clean fruit) in the fifth year of the study. The technique cannot be readily adopted into an orchard that is in full production because it would require several years to build up the beneficial arthropod fauna to an effective bio-control force. During that period, pesticides would not be applied and losses in yield would be commercially unacceptable. Habitat management should be used as a template for biological control of orchard pests over which other bio-control techniques can be superimposed to further increase the quality of the yield at harvest.     

中国外来入侵植物的学名考证

基于中国外来入侵植物的相关报道和文献,发现一些入侵植物的学名使用比较混乱,一个物种存在两个或两个以上的名称。依据最新植物志资料,对国内30种外来人侵植物学名进行了考证,包括中名、基名（若存在）、异名、原产地以及在中国的分布等。     

浙江省外来入侵植物研究

基于国内外文献资料、标本信息和野外调查,初步整理了浙江省外来入侵植物的种类组成、生活型、原产地、危害程度和入侵途径。结果表明,浙江省现有外来人侵植物46科106属166种,种数最多的是菊科、豆科和禾本科。根据原产地分析,来源于南美洲的物种最多,约占总数的32．16％,其次为北美洲,约占总数的25．63％,欧洲排第三位,约占总数的19．59％;已产生严重危害的有23种,中等危害的60种,危害较轻的83种。还有一些物种虽然没有在表里列出,但它们具有潜在的危害,必须密切关注。同时,与之前的研究相比,我们去除了一些已报道为人侵的物种,又增加了一些新的入侵种。在此基础上,对浙江省外来入侵植物的生活型、来源及危害进行了分析,并与以往的研究进行了比较,提出了针对性的管理建议。     

Biological control of waterhyacinth in Sinaloa Mexico with the weevils Neochetina eichhorniae and N. bruchi

Water hyacinth (Eichhornia crassipes (Mart.) Solms.)creates severe problems in the irrigationdistricts of Mexico, particularly in westernSinaloa. Therefore water hyacinth weevils(Neochetina eichhorniae Warner and N. bruchi Hustache), imported from the USA in1993, were used to initiate a biologicalcontrol program. Precautionary screeningrevealed that some were infected with amicrosporidian so disease-free colonies wereproduced by eliminating infected breedinglines. To demonstrate effectiveness prior toopen field releases, weevils were firstreleased in cages at field sites. Weevilintensity increased to 6.3 weevils/plant after320 days when the plants were all dead ordying. More than 8,600 N. bruchi and14,500 N. eichhorniae were then releasedat various sites during January 1995 to August1996. Waterhyacinth coverage declined atBatamote reservoir (134 ha) from 95% to <3%by 1997; at the 12-ha Hilda reservoir from100% in May 1995 to 1% by March 1998; at the42.3-ha Arroyo Prieto reservoir from 100% to1% during the same interval; and at theMariquita reservoir (492 ha), the largestreservoir in the Humaya system, from 394 ha(80%)to 98.4 ha (20%).     

Invasion success of non-indigenous aquatic and semi-aquatic plants in their native and introduced ranges. A comparison between their invasiveness in North America and in France

Aquatic and semi-aquatic plants comprise few species worldwide, yet the introduction of non-indigenous plants represents one of the most severe examples of biological invasions. My goal is to compare the distribution and the biology of aquatic and semi-aquatic plants in their introduced ranges and in their native ranges. The primary objective of this study is to test the hypothesis that invasive species have evolved traits likely to increase their success in the new range. I made two reciprocal comparisons, i.e. I compared European species in France and in North America, and North American species in France and in North America. Twenty-seven species were classified according to their invasiveness in their introduced area. I␣found six invasive macrophyte species in France native to North America and 17 invasive species in North America native to Europe. Four species are invasive in both areas. There is no general tendency for macrophytes to be more vigorous in their introduced ranges. Most non-indigenous aquatic and semi-aquatic species are potentially invasive or widespread and well-established in their introduced country, while few species seem to be restricted in their distribution.     

Resource quality and stoichiometric constraints on stream ecosystem functioning

1. Resource quality and stoichiometric imbalances in carbon : nutrient ratios between consumers and resources can influence key ecosystem processes. In many streams, this has important implications for food webs that are based largely upon the utilization of terrestrial leaf‐litter, which varies widely among litter types in its value as a food source for detritivores and as a substrate for microbial decomposers. 2. We measured breakdown rates and macroinvertebrate colonization of leaf‐litter from a range of native and exotic plants of differing resource quality and palatability to consumers [e.g. carbon : nitrogen : phosphorus (C : N : P) ratios, lignin and cellulose content], in a field experiment. We also measured C : N : P ratios of the principal leaf‐shredding invertebrates, which revealed strong stoichiometric imbalances across trophic levels: C : N and C : P ratios typically differed by at least one order of magnitude between consumers and resources, whereas N : P imbalances were less marked. Application of the threshold elemental ratio approach, which integrates animal bioenergetics and body elemental composition in examining nutrient deficiency between consumers and resources, revealed less marked C : P imbalances than those based on the simpler arithmetic differences described above. 3. Litter breakdown rates declined as nutrient imbalances widened and resource quality fell, but they were independent of whether resources were exotic or native. The principal drivers of total, microbial and invertebrate‐mediated breakdown rates were lignin : N, lignin : P and fungal biomass, respectively. However, multiple regression using orthogonal predictors yielded even more efficient models of litter breakdown, as consumers responded to more than one aspect of resource quality. For example, fungal biomass and litter C : N both influenced invertebrate‐mediated breakdown. 4. Large stoichiometric imbalances and changes in resource quality are likely to have serious consequences for stream ecosystem functioning, especially when riparian zones have been invaded by exotic plant species whose chemical composition differs markedly from that of the native flora. Consequently, the magnitude and direction of change in breakdown rates and, thus, resource depletion, will be driven to a large extent by the biochemical traits (rather than taxonomic identity per se) of the resident and invading flora.     

The Principles of Data Formalization for Building Biological Model of Shoot Development in Flowering Plants

Shoot system of a plant can be divided into elementary molecules composed of phyllome, internode, and meristem of the lateral bud. The capacity of plants for open growth is manifested as multiple reproductions of the modules. These main principles of plant structural organization can be used to formalize and integrate the data from various disciplines studying shoot development—genetics of development, morphology, etc. At the example of a model species Arabidopsis thaliana we show that the data on genetic control of shoot development can be considered in terms of rearrangement of individual modules. Several variants of the module structural reorganization are allowed: reduction or transformation of phyllome, change in the internode length, and triggering active/inactive status of the lateral shoot meristem. Each variant of module structure corresponds to specific pattern of genes activity. Such integration of the data on genetic and structural aspects of morphogenesis can form a basis for mathematical modeling of plant development.