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Simple Summary: The impact of parasitic plants on invasive plants varies depending on the parasitism time and species. Cuscuta australis is a common parasitic plant, while Xanthium spinosum and Xanthium italicum are invasive plants. The impact of parasitism on the competitive ability of invasive plants has been rarely reported. Therefore, in this study, we aim to investigate the impact of southern dodder parasitism on the competitive ability of X. spinosum and X. italicum. At the same time, we found that parasitism of southern dodder increased the competitive ability of X. spinosum and weakened the competitive ability of X. italicum. It is worth noting that invasive plants also provide a medium for the spread of southern dodder. Based on the research results, we suggest trying to prevent the same domain distribution of the two as much as possible to reduce the harm to local plants and crops. The competitive ability of invasive plants is a key factor in their successful invasion, and research on this ability of invasive plants can provide a theoretical basis for the prevention and control of invasive plants. This study used Cuscuta australis, Xanthium spinosum, and Xanthium italicum as research materials and conducted outdoor controlled pot experiments to compare and study the changes in the biomass, competitiveness, and growth cycle of X. spinosum and X. italicum parasitized by C. australis at different growth stages. The results showed that (1) parasitism by C. australis increased the biomass of X. spinosum and decreased that of X. italicum, but under parasitism, the root cap ratio of X. spinosum and X. italicum increased, and the fruit biomass ratio decreased, indicating that X. spinosum and X. italicum reduced the energy input for reproduction and increased the energy input for nutrient growth to resist the impact of C. australis parasitism; (2) the relative competitive intensity calculated based on the total biomass of a single plant showed a negative value for X. spinosum during parasitism at the flowering and fruit stages, indicating an increase in competitive ability, and X. italicum showed a positive value during parasitism at the seedling and flowering stages, indicating a decrease in competitive ability; and (3) the parasitism of C. australis significantly shortened the fruit stage of X. spinosum and X. italicum, leading to a significant advance in their flowering, fruiting, and fruit ripening times. Simultaneously, it significantly reduced the morphological indicators of biomass, plant height, and crown width. Thus, C. australis parasitism has a certain inhibitory effect on the competitive ability of some invasive plants and can shorten their growth cycle, the latter of which has an important impact on their reproduction and diffusion. [ABSTRACT FROM AUTHOR]

Transgenerational plasticity (TGP) allows a plant to acclimate to external variable environments and is a potential mechanism that explains the range expansion and invasion success of some exotic plants. Most studies explored the traits of TGP associated with the success of exotic plant invasions by comparison studies among exotic, native, invasive, and noninvasive species. However, studies on the TGP of invasive plants in different resource environments are scarce, and the biological mechanisms involved are not well understood. This study aimed to determine the role of TGP in the invasiveness of Xanthium strumarium in northeast China. We measured the plant morphology of aboveground parts and the growth of three generations of the invader under different environmental conditions. The results showed that the intergenerational plasticity of X. strumarium was stronger under stress conditions. We found that the X. strumarium parent generation (F0) grown under water and/or nutrient deficiency conditions transferred the environmental information to their offspring (F1 and F2). The F1 generation grown under high‐resource conditions has greater height with larger crown sizes, thicker basal diameters, and higher biomass. Both water and nutrients can affect the intergenerational transmission of plant plasticity, nutrients play a more important role compared with water. The high morphological intergenerational plasticity of X. strumarium under a pressure environment can help it quickly adapt to the new environment and accelerate the rapid expansion of the population in the short term. The root:shoot ratio and reproductive and nutrient distribution of the X. strumarium F0 and F1 generations showed high stability when the growth environment of the F0 generation differed from that of the F1 generation. The stable resource allocation strategy can ensure that the obtained resources are evenly distributed to each organ to maintain the long‐term existence of the community. Therefore, the study of intergenerational transmission plasticity is of great significance for understanding the invasion process, mechanism, and prevention of invasive plants. [ABSTRACT FROM AUTHOR]

Cenchrus spinifex is one of the invasive plant species in China, which seriously affects the animal husbandry and ecological environment in China.In order to predict the change of suitable distribution area of C. spinifex under future climate change scenarios, based on the MaxEnt model, this study used 103 geographical distribution data of C. spinifex and 19 climatic and environmental factors to analyze and predict the suitable distribution area of C. spinifex in China under two climate change scenarios of RCP2.6 and RCP8.5 in the 2050s and 2070s. The results were as follows:(1)The current suitable distribution area of C. spinifex occupied 4.00% of the study area, which was mainly distributed in Northeast China borderline by Inner Mongolia, Jilin and Liaoning.(2)Under the two future climate change scenarios, the suitable distribution areas for each grade of C. spinifex will expand to a certain extent compared with the current, and the medium suitable areas will expand the most, reaching 38.26%.(3)Annual mean temperature, standard deviation of seasonal temperature variation, and precipitation in the wettest season were the main climatic factors affecting the distribution of C. spinifex.(4)In the future, the distribution centroid of C. spinifex will generally move westward. The above results indicate that the current invaded areas of C. spinifex in China are far smaller than the potential invaded areas, and it may further spread to the arid and semi-arid regions in China. In order to prevent the harm caused by the widespread spread of C. spinifex in northern China, we need to focus on its preventive measures and invasion situation in the future. The results of this study provide important theoretical basis and control methods for the prevention and control of invasive plants in China. [ABSTRACT FROM AUTHOR]

Effective management of invasive plants conserves biodiversity values, reduces economic costs, and minimizes negative impacts on human health. Fostering people's awareness of invasive plants is one of the most cost-effective approaches in preventing the spread and introduction of invasive plants. Therefore, this study aims to understand (1) people's knowledge and risk perceptions, (2) associations between risk perceptions and demographics, and (3) people's willingness to support current management strategies in the Metro Vancouver region, British Columbia, Canada. An online survey was carried out and received 356 responses across the region. We found that people's knowledge and risk perceptions of invasive plants were ecologically oriented. Older respondents perceived higher risks of invasive plants. Among respondents of the same age, annual income higher than $50,000 was associated with higher levels of risk perception. Respondents who had professional and/or recreational group memberships perceived higher economic risks. Respondents highly supported activities that they could take part in directly, such as community invasive pulls and native species planting. Overall, our findings aid managers in allocating appropriate funding or tailoring outreach efforts to different aspects of invasive plants as well as groups/communities where people's knowledge and risk perceptions of invasive plants are low. Highlights: People's knowledge and risk perceptions of invasive plants were ecologically oriented. Age and income were positively associated with perceived risks of invasive plants. Respondents who had professional/recreational group memberships perceived higher risks of invasive plants. Respondents supported local governments to spend funds on active management activities. [ABSTRACT FROM AUTHOR]

Summary: The perennial shrub Siam Weed (Chromolaena odorata (L.) R. M. King & H. Rob.), a native of the rainforests of central and southern America, is predicted to invade most countries between the Tropics of Cancer and Capricorn. Subsequent to its discovery in northern Queensland, Australia in 1994, it was unsuccessfully targeted for eradication, with early control efforts restricted to manual removal and foliar spraying with triclopyr/picloram. A chemical trial involving five herbicides and three application methods (foliar, basal bark and cut stump) was undertaken in northern Queensland to identify effective chemicals to control this weed. Of the foliar herbicides tested, fluroxypyr (70 g/100 L) provided 99% mortality, triclopyr/picloram (105/35 g/100 L) 95%, while metsulfuron‐methyl (9 g/100 L) killed 85% of the treated plants. The herbicides fluroxypyr (300 g/100 L), picloram (43 g/1 kg) and triclopyr/picloram (400/200 g/100 L) killed greater than 98% of the plants when applied as basal bark or cut stump. The integration of fire into the management strategy either as a primary or secondary control option could have a major role, given that in this study, 99% of the Siam Weed soil seed bank was located on the soil surface. [ABSTRACT FROM AUTHOR]

Spartina alterniflora has become the main invasive plant along the Chinese coast and now threatens the local ecological environment. Accurately monitoring the distribution of S. alterniflora is urgent and essential for developing cost-effective control strategies. In this study, we applied the One-Class Classification (OCC) methods of Maximum entropy (Maxent) and Biased Support Vector Machine (BSVM) based on Landsat time-series imagery to detect the species on the middle coast of Jiangsu in east China. We conducted four experimental setups (i.e., single-scene analysis, time-series analysis, Normalized Difference Vegetation Index (NDVI) time-series analysis and a compressed time-series analysis), using OCC methods to recognize the species. Then, we tested the performance of a compressed time-series model for S. alterniflora detection and evaluated the expansibility of this approach when it was applied to a larger region. Our principal findings are as follows: (1) Maxent and BSVM performed equally well, and Maxent appeared to have a more balanced performance over the summer months; (2) the Maxent model with the Default Parameter Set (Maxent-DPS) showed a slightly higher accuracy and more overfitting than Maxent with the Akaike Information Criterion corrected for small samples sizes (AICc)-selected parameter set model, but a t-test found no significant difference between these two settings; (3) April and December were deemed to be important periods for the detection of S. alterniflora; (4) a compressed time-series analysis model--including only three variables (December NDVI, March green and the third Principal Component in January, PC3)--yielded higher accuracy than single-scene analyses, which indicated that time-series analysis can better detect S. alterniflora than single-scene analyses; and (5) the Maxent model using the reconstructed optimal variables and 70 training samples over a larger region produced encouraging results with an overall accuracy of 90.88% and a Kappa of 0.78. The one-class classification method combined with a phenology-based detection strategy is therefore promising for the application of the long-term detection of S. alterniflora over extended areas. [ABSTRACT FROM AUTHOR]

South Africa has a major problem with invasive plant species. Many species have long residence times, are well established, and have large invasive ranges, whereas others are still in the early stages of invasion. Predicting the full extent of invasions for species that have only recently started spreading is important for guiding management strategies. Ailanthus altissima is a widespread invasive species in many parts of the world. Although it has had a long residence time in South Africa, it is yet to replicate the extent of invasiveness and major impacts reported for the species in other parts of its adventive range. We mapped the countries in which A . altissima has been reported and evaluated the invasion status of the species in each (i.e. the position of the species on the introduction-naturalization-invasion continuum as conceptualized by Richardson and Pyšek, 2012). We then mapped the current distribution in more detail for South Africa. The species is known to be present in at least 51 countries and is invasive in 23 countries. Ailanthus altissima is present in all South African provinces except Limpopo and is most common and abundant in the Western Cape, Gauteng, Eastern Cape, and the Free State. We applied species distribution modelling using global distribution data to determine parts of the world, and in particular regions within South Africa, that are climatically suitable for the species. Large parts of Africa are potentially invasible by this species. Seven regions in South Africa were identified as high-risk areas for invasion by A . altissima . The species is already far too widespread in South Africa for eradication at the national scale to be feasible. A national strategy for managing the species should focus on: 1) early detection and rapid response in areas identified as climatically suitable and where the species is not already present; and 2) local and regional-scale initiatives based on objective prioritization in terms of feasibility of management success and asset protection. [ABSTRACT FROM AUTHOR]

Invasive alien plants that have seeds with innate dormancy, and thus large, persistent soil-stored seed banks, are particularly difficult to manage. Dormant seeds typically require specific stimuli as cues for germination, resulting in mass recruitment. Sound understanding of germination stimuli may provide options to aid the management of invasives. We investigated the response of two invasive trees, Acacia mearnsii and A. melanoxylon , and an indigenous ecological analogue, Virgilia divaricata , to different germination stimuli (chipped (manually), hot water exposure, dry heat pulse, smoke, and no treatment) at two temperature regimes (winter ~ 12 °C and summer ~ 20 °C) to explore how their germination requirements may be used to favour V. divaricata in areas cleared of the invasives. Chipped and hot water exposure resulted in the highest germination in all three species. Virgilia divaricata responded marginally better than the invasives to the dry heat pulse, particularly at 20 °C. However, the three species mostly responded comparably to the stimulus–temperature combinations, suggesting that manipulation of stimuli is not a feasible option for management of the invasives at a large scale. In the absence of any stimulus (~ akin to conditions associated with aboveground clearing of alien vegetation cover), germination was poorer in V. divaricata than in the invasive species especially at 20 °C, providing motivation for focusing Acacia management operations in cooler seasons in areas where V. divaricata seed banks occur. Another option is to sow V. divaricata seeds that have been chipped or exposed to hot water in areas cleared of the invasives of which the seeds would not have received stimuli. [ABSTRACT FROM AUTHOR]

The Global Biodiversity Information Facility (GBIF) is at the moment one of the largest and most widely used biodiversity databases. Nevertheless, there are still some limitations, e.g. in terms of plant species status (native vs. non-native) and geographic resolution of records. At the same time, it is well known that alien plant invasions in inland freshwaters can alter community structure, ecosystem functions and services with significant negative impacts on biodiversity and human activities. We assessed if the GBIF database has a geospatial homogeneous information for native and non-native aquatic plant species for South America and whether or not literature resources not yet digitalized (floras, checklists and other papers) could provide additional information. We selected a set of 40 native and 40 non-native aquatic species. These 80 species included a sub-set of 40 alien species previously evaluated with the USAqWRA scheme (US Aquatic Weed Risk Assessment). Species with non-reliable identification, duplicates of the same collection, records poorly georeferenced were removed from the dataset. New records were manually compiled through classical literature research. All the georeferenced records (GBIF + literature) were used for the mapping and the comparative analysis. As a result, we can conclude that the two datasets provide quite significantly different information and the combination of the two offers new information that would not exist in a single data source. Nevertheless, a careful [ABSTRACT FROM AUTHOR]

Managing intentional species introductions requires evaluating potential ecological risks. However, it is difficult to weigh costs and benefits when data about interactions between novel species and the communities they are introduced to are scarce. In anticipation of expanded cultivation of perennial biomass crops, we experimentally introduced Miscanthus sinensis and Miscanthus x giganteus (two non-native candidate biomass crops) into two different non-crop habitats (old field and flood-plain forest) to evaluate their establishment success and impact on ambient local communities. We followed these controlled introductions and the composition dynamics of the receiving communities over a 5-year period. Habitats differed widely in adult Miscanthus survival and reproduction potential between species, although seed persistence and seedling emergence were similar in the two biomass crops in both habitats. Few introductions survived in the floodplain forest habitat, and this mortality precluded analyses of their potential impacts there. In old field habitats, proportional survival ranged from 0.3 to 0.4, and plant survival and growth increased with age. However, there was no evidence of biomass crop species effects on community richness or evenness or strong impacts on the resident old field constituents across 5 years. These results suggest that Miscanthus species could establish outside of cultivated fields, but there will likely be a lag in any impacts on the receiving communities. Local North American invasions by M. sinensis and M. sacchariflorus display the potential for Miscanthus species to develop aggressively expanding populations. However, the weak short-term community-level impacts demonstrated in the current study indicate a clear management window in which eradicating species footholds is easily achieved, if they can be detected early enough. Diligent long-term monitoring, detection, and eradication plans are needed to successfully minimize harmful invasions from these biomass crops. [ABSTRACT FROM AUTHOR]

[Display omitted] • Urban riparian corridors have a positive effect on the spread of spontaneous plants. • The functional traits of plants responded significantly to the landscape structure. • The dispersal ability is related to the scale of plant response to landscape pattern. The loss of biodiversity due to rapid urbanization can be mitigated by urban riparian corridors. As an important component of urban biodiversity, spontaneous herbaceous plants play an essential role in the ecological functions of urban river corridors. Currently, the influence of the landscape structure within corridors on plant diversity has been poorly understood. In this study, we investigated the species and functional diversity, especially the functional traits of origin, pollination, and dispersal, of spontaneous herbaceous plants in the Wenyu River-North Canal riparian corridor in Beijing. The results showed that urban riparian corridors have a positive effect on the spread of alien and invasive plants as well as increasing the native plant diversity. No significant differences in diversity indicators but significant differences in the composition of functional traits between habitat types. Plants with long pollination and dispersal distances tended to be more closely related to the landscape structure indices at larger scales. Invasive plants were more common in patches with significant connectivity, while native plants were positively correlated with water and road connectivity. Anemophilous and anemochores were more common in habitats with sinuous edges. Ant-dispersed plants were closely related to the water bodies. Autochores were positively correlated with the connectivity of habitat patches. Plants dispersed by birds and mammals were weakly correlated with landscape structure. Our study underlines that emphasis should be placed on the support for plant pollination and dispersal, together with the prevention and control of invasive plants in the construction and management of future urban ecological corridors. [ABSTRACT FROM AUTHOR]

A personal narrative is presented which explores the author's experiences of traveling to Singapore, Malaysia and Hong Kong, China as part of her collection trip to find insects that can be used to stop the increase of invasive plants.

The regulation and management of alien species can be contentious, particularly when the stakeholders who benefit from alien species are different from those who suffer the costs. We propose a consultative process involving relevant stakeholders in invasive species management decisions. The process involves (1) the identification of relevant stakeholders, (2) assessing their perceptions, (3) enhancing interaction between stakeholders, (4) assessing changes in stakeholders' perceptions following interactions with other stakeholders, and (5) developing management recommendations in collaboration with stakeholders. We demonstrate the application of the process using the family Cactaceae ('cacti') in South Africa. Many species of cacti have been introduced to the country over the past two centuries, mostly for horticulture, food and fodder, and hundreds of other species have been introduced in the past few decades (or are likely to be introduced soon) for horticulture. Using the proposed process enabled the negotiation and participation of all stakeholders in decision making and helped minimize contentious situations by clarifying stakeholder's beliefs and exploring consensus solutions. Consequently, management objectives were broadly supported by all stakeholders. These results will be included in a national cactus management strategy for South Africa. [ABSTRACT FROM AUTHOR]

This paper summarizes the strategies of the San Francisco Bay Area Early Detection Network (BAEDN). BAEDN coordinates and implements Early Detection of and Rapid Response to infestations of target invasive plants throughout the nine county San Francisco Bay Area. Limited-distribution invasive plant species in the Bay Area were identified by analyzing occurrence records within the Calflora database. Target species were then prioritized according to whether or not they were documented as invasive and by expert opinion. Weed Heuristics: the Invasive Population Prioritization for Eradication Tool was used to prioritize the 272 known occurrences of the 73 target priority species based on relative impact, invasiveness, and feasibility of treatment. BAEDN coordinated two years of removal of these populations. Lessons learned and next steps are reviewed. As new populations and species are identified additional funds are needed to carry out coordinated evaluation, prioritization, and control efforts. [ABSTRACT FROM AUTHOR]

Echinochloa pyramidalis (Lam.) Hitchc. & Chase is an African grass with C4 photosynthesis, high biomass production, and high vegetative propagation that is tolerant to grazing and able to grow in flooded and dry conditions. Thus, it is highly invasive in tropical freshwater marshes where it is intentionally planted by ranchers to increase cattle production. This invasion is reducing plant biodiversity by increasing the invader's aerial coverage, changing wetland hydrology and causing soil physicochemical changes such as vertical accretion. Reducing the dominance of this species and increasing the density of native wetland species is a difficult, expensive, and time-consuming process. We applied a series of disturbance treatments aimed at eliminating E. pyramidalis and recovering the native vegetation of a partially invaded freshwater marsh. Treatments included physical (cutting, soil disking, transplanting individuals of the key native species Sagittaria lancifolia subsp. media (Micheli) Bogin, and/or reducing light with shade mesh) and/or chemical (spraying Round-Up™ herbicide) disturbances. At the end of the experiment, four of the five treatments used were effective in increasing the cover and biomass of native species and reducing that of E. pyramidalis. The combination of these treatments should be used to generate a proposal for the restoration of tropical wetlands invaded by non-native grasses. A promising treatment is using soil disked to soften the soil and destroy belowground structures such as roots and rhizomes. This treatment would be more promising if combined with the use of shade cloth. If it is desirable not to impact the soil or if there is not enough budget to make an effort to include active restoration disking soil, the use of shade cloth will suffice, although the recovery of native vegetation will be slower. [ABSTRACT FROM AUTHOR]

Background There are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. Competitive crops may provide potent management tools against invasive plants. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-aminute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. The trial incorporated seven ratios of sweet potato and mile-a-minute plants in 25 m2 plots. Results In monoculture, the total biomass, biomass of adventitious root, leafstalk length, and leaf area of sweet potato were all higher than those of mile-a-minute, and in mixed culture the plant height, branch, leaf, stem node, adventitious root, flowering and biomass of mile-a-minute were suppressed significantly (P < 0.05). The relative yield (RY) of mile-a-minute and sweet potato was less than 1.0 in mixed culture, indicating that intraspecific competition was less than interspecific competition. The competitive balance index of sweet potato demonstrated a higher competitive ability than mile-a-minute. Except pH, other soil nutrient contents of initial soil (CK) were significantly higher than those of seven treatments. The concentrations of soil organic matter, total N, total K, available N, available P, available K, exchange Ca, exchange Mg, available Mn, and available B were significantly greater (P < 0.05) in mile-aminute monoculture soil than in sweet potato monoculture soil, and were reduced by the competition of sweet potato in the mixture. Conclusions Evidently sweet potato has a competitive advantage in terms of plant growth characteristics and greater absorption of soil nutrients. Thus, planting sweet potato is a promising technique for reducing infestations of mile-a-minute, providing weed management benefits and economic returns from harvest of sweet potatoes. This study also shows the potential value of replacement control methods which may apply to other crop-weed systems or invaded natural ecosystems. [ABSTRACT FROM AUTHOR]

The article presents a study which was focused on identifying plant species that are prone to become invasive in California because of the horticultural trade. More than 774 species has been invasive in the Mediterranean climates out of which 186 species are expected to become invasive in California. It further mentions that 47 percent plant species are not naturalized in California.

Results of studies conducted in the Institute of Animal Science of the Republic of Cuba with an integral and multidisciplinary approach are presented. The topic developed is related with the applied strategies to control the degradation of grasslands invaded by wire grass (Sporobolus indicus). Other researches conducted with this weed in different tropical and subtropical regions considering the biological characteristics of this species are also considered. Reproduction methods of wiregrass and of seeds production are also dealt with. The negative effect of this weed on the economy and biomass production of an improved grassland is analyzed. The infestation level of wiregrass and the pureness percentage of the improved pasture are considered, as well as the application of recovery alternatives throughout new sowings or rehabilitation. It is proved that planting species of the Pennisetum genus by the plowing method or the traditional method are effective ways of control that also favor the recovery of completely damaged grasslands. The recovery or rehabilitation with the use of plowing plus harrowing, in combination with the chemical and organic fertilization, is a promising alternative to recover the energy of the grassland and an option to minimize the population of this weed and reestablish the productivity of the agroecosystem. A good animal and agrotechnical management is suggested after these labours, in order to achieve the sustainability of the improved pastures. The knowledge described will make possible to design a program for the integral control of the weed and the recovery of improved grasslands ecosystems invaded by wiregrass. [ABSTRACT FROM AUTHOR]

Invasive plants have invaded swathes of grasslands in Lake Nakuru National Park thus necessitating the Park management to institute measures to control them. Despite this, information on the status and impact of invasive plants in these grasslands is lacking. Six grassland types were identified and assigned random numbers. Five study sites were then randomly selected from each grassland type. The Point-Centre Quarter method was used to determine the distribution and density of seven major invasive plants, whilst their impact was assessed by comparing biomass and crude protein content of important forage grasses in invaded and noninvaded grasslands. Results show that the distribution of invasive plants did not differ among the grasslands ( F = 1.47, P = 0.229) but their densities differed among the plants ( F = 20.99, P < 0.001). The mean biomass in invaded and noninvaded grasslands (22 g m versus 37.2 g m) was significantly different ( t-test, P < 0.05), while crude protein content of grasses in invaded (7.73, % DM) and noninvaded (9.3, % DM) patches was not significantly different ( t-test; P > 0.05). Our results suggest that invasive plants lower grass production and hence might reduce food availability to grazers. [ABSTRACT FROM AUTHOR]

In 2009, a previously undescribed disease was found on the nonnative invasive annual grass Microstegium vimineum (Japanese stiltgrass). Diseased plants exhibited foliar lesions, wilting, and in some cases, death of entire plants. We identified the causal agent as a Bipolaris sp. similar to B. zeicola. We observed spores and associated structures characteristic of Bipolaris spp. growing from leaf lesions on field collected plants. Pure cultures of the fungus were made and spore suspensions were applied to laboratory-reared M. vimineum seedlings in growth chamber and greenhouse experiments. Initial symptoms appeared on seedlings in the growth chamber experiment within 72 h of inoculation, and seedlings exhibited characteristic lesions within 10 days. The fungus was reisolated from lesions, and the internal transcribed spacer (ITS) region was sequenced to confirm its identity. In the greenhouse experiment, inoculated plants displayed characteristic lesions, and relatively greater spore loads increased disease incidence. Disease reduced seed head production by 40% compared to controls. This is the first report of a Bipolaris sp. causing disease on invasive M. vimineum. Following further analysis, including assays with co-occurring native species, this Bipolaris sp. may be considered as a biocontrol agent for invasive M. vimineum. [ABSTRACT FROM AUTHOR]

1. Although habitat fragmentation and species invasions are widely recognized threats to biodiversity, few empirical studies have examined both threats together. Here we test the hypothesis that habitat fragmentation may limit the spread of invasive species across landscapes. 2. In central Texas, patches of herbaceous vegetation become increasingly fragmented (e.g. smaller and more isolated) as landscapes undergo woody plant encroachment. However, during this process, fragmentation and loss of herbaceous habitat are not completely correlated, which allowed us to separate the effects of fragmentation from the effects of habitat loss. 3. At three sites in central Texas, we recorded the occurrence of the invasive bunchgrass Bothriochloa ischaemum in randomly-located plots in herbaceous patches. We measured fragmentation of the herbaceous habitat around these plots at five scales, using aerial photographs. 4. Bothriochloa ischaemum occurrence was significantly negatively related to most aspects of fragmentation. These negative relationships were stronger after the effects of habitat loss were removed from the effects of fragmentation per se. 5. The strength of the negative relationship between B. ischaemum occurrence and fragmentation varied among sites, probably reflecting the influence of grazing and other management practices. 6. Synthesis and applications. Our results indicate that fragmentation, separated from habitat loss, can have positive as well as negative conservation effects. Fragmentation, if wisely used, could be a useful tool in the management of invasive plant species like B. ischaemum. Increasing the degree of habitat fragmentation may slow the spread of invasive species across landscapes. [ABSTRACT FROM AUTHOR]

1. Identifying the mechanisms that facilitate invasion is crucial for the design of preventative measures and understanding the invasion process, but not necessarily for the design of effective control strategies. 2. When a novel disturbance is identified as facilitating invasion, the intuitive control strategy is to restore the previous disturbance regime. This recommendation is implicitly based on traditional models of succession, which explain the dynamics of few natural ecosystems. We investigate whether the application and/or manipulation of novel disturbances designed explicitly under an alternative states model are more effective for restoration. 3. Using a field trial, we manipulated a relatively new disturbance (ungulate grazing), a facilitator of invasion, to determine its effects on the invasive grass species, Eragrostis curvula and the rest of the plant community. The split-plot design used excluded and permitted grazing and was combined with reductions in the biomass of the invader using mowing and selective application of herbicides. We also altered soil nutrient conditions and monitored responses over two growing seasons characterized by different rainfall patterns. 4. We found that the control strategy based implicitly on traditional successional models (removing the causal disturbance and killing the invasive grass) was not the most effective option for restoring a desirable native community. While this control strategy reduced the abundance of the invader and increased native grasses, it led to an increase in the abundance of an undesirable exotic forb, Verbena tenuisecta. The most effective control strategy was based on alternative states models and involved the maintenance of grazing and the use of fertilizers to increase the palatability of the invader. With this strategy, the abundance of the invader decreased because grazing pressure increased, native grasses increased and the exotic forb was maintained at low levels. 5. Synthesis and applications. The control strategy based on the alternative states models initially appears at odds with restoration efforts, because livestock grazing and nutrient addition are associated with the degradation of plant communities worldwide. However, for effective restoration, we found approaches that take into consideration the dynamics of the novel invader-dominated system were the most effective in the short term. [ABSTRACT FROM AUTHOR]

1. Matrix population models are widely used to describe population dynamics, conduct population viability analyses and derive management recommendations for plant populations. For endangered or invasive species, management decisions are often based on small demographic data sets. Hence, there is a need for population models which accurately assess population performance from such small data sets. 2. We used demographic data on two perennial herbs with different life histories to compare the accuracy and precision of the traditional matrix population model and the recently developed integral projection model (IPM) in relation to the amount of data. 3. For large data sets both matrix models and IPMs produced identical estimates of population growth rate (λ). However, for small data sets containing fewer than 300 individuals, IPMs often produced smaller bias and variance for λ than matrix models despite different matrix structures and sampling techniques used to construct the matrix population models. 4. Synthesis and applications. Our results suggest that the smaller bias and variance of λ estimates make IPMs preferable to matrix population models for small demographic data sets with a few hundred individuals. These results are likely to be applicable to a wide range of herbaceous, perennial plant species where demographic fate can be modeled as a function of a continuous state variable such as size. We recommend the use of IPMs to assess population performance and management strategies particularly for endangered or invasive perennial herbs where little demographic data are available. [ABSTRACT FROM AUTHOR]

For a given invasive plant species and control method, effective invasive plant eradication requires regular monitoring and management. While most previous studies characterize invasive plant species, develop appropriate control methods, or prioritize species for management using aggressiveness and other considerations, few study why some forestland owners are less likely than others to regularly remove invasive plant species. Such information is useful in prioritizing and targeting forestland owners who are at greater risk for invasion, with the stands threatening adjacent forestlands. Towards this end, we surveyed 1800 forestland owners in Virginia and Texas. We use data on forestland owners’ socioeconomics and forestland features—such as acreage, forestland ownership objectives, and forest management activities—to determine how these factors affect the regularity of invasive-plant removal. For these purposes, we used the Cochran–Armitage trend test, the Cochran–Mantel–Haenszal regression, odds ratio estimates, and partition-analysis techniques. Our results suggest that female forestland owners, owners with smaller forestlands, and forestland owners without written forest-management plans are less likely than others to regularly remove invasive plant species. Forest-management activities, such as building/maintaining roads in the forestland, partially harvesting stands, and wildlife- and fisheries-improvement projects, also significantly predict a more regular invasive-plant-removal tendency. However, since these activities are potential pathways for the spread of invasive plant species, we controlled for the other significant covariates and measured the relationship between frequent practice of the given forest-management activities and having a tendency to regularly remove invasive plant species. The results suggest that forestland owners that regularly practiced the said forest-management activities have higher odds for tending to remove invasive plant species regularly, suggesting that, despite their demonstrated effort at removing invasive plant species from their forest, their management activities may be inadvertently contributing to the spread of invasive plant species. These results highlight the importance of integrating invasive-plant-removal plans with forest-management plans as well as forestland owners’ educational and outreach needs. [ABSTRACT FROM AUTHOR]

Mikania micrantha (Asteraceae: Eupatorieae), widely called mile-a-minute, has been a persistent problem to forestry, plantations and biodiversity conservation in southwestern and northeastern India, as well as in Andaman and Nicobar islands. To supplement the previously imported Trinidad-originating Puccinia spegazzinii (Pucciniales: Pucciniaceae), a different pathotype (IMI 393076) was imported from Peru, South America, after obtaining the import permit from the Plant Protection Advisor to the Government of India. The Peruvian pathotype was held in the National Containment-cum-Quarantine Facility for Transgenic Planting Material at ICAR-National Bureau of Plant Genetic Resources in New Delhi as a quarantine organism for pre-release evaluation. Screening of M. micrantha populations from Andaman and Nicobar islands (12), Assam (15) and Kerala (3) indicated their complete susceptibility to the Peruvian pathotype. In the host-specificity tests, the rust could not infect any of the 25 plant species in ten tribes within Asteraceae, which confirmed its safety to non-target plant species. Further, none of the 31 sunflower cultivars/accessions screened were infected. [ABSTRACT FROM AUTHOR]

The author discusses the important role of the use of carefully screened host-specific arthropods or pathogens, combined with quarantine and spread-prevention measures to control gamba grass and other invasive weeds in Australia.