Intensive cropping systems select for a low diversity of weeds tolerant of chemical control, leading to persistent weed‐crop competition and declining biodiversity. Crop rotation can mitigate this by ...introducing variable filters on the weed community through increasing management diversity. In this study, we investigate the effect of integrating livestock into no‐till crop rotations to complement chemical weed control.
We analysed 12 years of weed seedbank data from a trial of eight rotation systems with different crop sequence diversities, of which four included grazed forage phases. Linear mixed models and ordination were used to assess how weed abundance, diversity, and community composition responded to management filters, defined in terms of levels of disturbance strength and diversity (grazing and herbicides), and resource availability and diversity (inorganic fertilizers, legumes, and manure).
Grazed rotation systems had less herbicide applied than ungrazed rotation systems, and had the lowest weed abundance and highest weed diversity. Herbicides and grazing apply contrasting selection pressures on weeds, and this combination was more effective in reducing weed pressure than increasing herbicide quantity or mode‐of‐action diversity. Lower resource availability and higher nitrogen source diversity in grazed systems may have further reduced weed abundance and promoted diversity.
Crop sequence diversity also reduced weed abundance and promoted weed diversity, indicating that variable crop‐weed interactions can enhance weed management. In addition, yields in the main cash crop (wheat) were highest where crop diversity was highest, regardless of whether the system contained grazed phases.
Synthesis and applications. Diverse rotation systems produced high yields, and the inclusion of grazed forage phases maintained these yields at lower applications of herbicides and fertilizers: integrated livestock can therefore improve the sustainability of no‐till systems. The role of grazing as a filter imposing a contrasting selection pressure to other weed control options could be further explored to improve weed management in different farming systems.
Diverse rotation systems produced high yields, and the inclusion of grazed forage phases maintained these yields at lower applications of herbicides and fertilizers: integrated livestock can therefore improve the sustainability of no‐till systems. The role of grazing as a filter imposing a contrasting selection pressure to other weed control options could be further explored to improve weed management in different farming systems.
ABSTRACT
The number of alien plants escaping from cultivation into native ecosystems is increasing steadily. We provide an overview of the historical, contemporary and potential future roles of ...ornamental horticulture in plant invasions. We show that currently at least 75% and 93% of the global naturalised alien flora is grown in domestic and botanical gardens, respectively. Species grown in gardens also have a larger naturalised range than those that are not. After the Middle Ages, particularly in the 18th and 19th centuries, a global trade network in plants emerged. Since then, cultivated alien species also started to appear in the wild more frequently than non‐cultivated aliens globally, particularly during the 19th century. Horticulture still plays a prominent role in current plant introduction, and the monetary value of live‐plant imports in different parts of the world is steadily increasing. Historically, botanical gardens – an important component of horticulture – played a major role in displaying, cultivating and distributing new plant discoveries. While the role of botanical gardens in the horticultural supply chain has declined, they are still a significant link, with one‐third of institutions involved in retail‐plant sales and horticultural research. However, botanical gardens have also become more dependent on commercial nurseries as plant sources, particularly in North America. Plants selected for ornamental purposes are not a random selection of the global flora, and some of the plant characteristics promoted through horticulture, such as fast growth, also promote invasion. Efforts to breed non‐invasive plant cultivars are still rare. Socio‐economical, technological, and environmental changes will lead to novel patterns of plant introductions and invasion opportunities for the species that are already cultivated. We describe the role that horticulture could play in mediating these changes. We identify current research challenges, and call for more research efforts on the past and current role of horticulture in plant invasions. This is required to develop science‐based regulatory frameworks to prevent further plant invasions.
Aim
Species characteristics and cultivation are both associated with alien plant naturalization and invasiveness. Particular species characteristics are favoured for cultivation, obscuring the ...relationship between traits and naturalization success. We sought to better understand the drivers of naturalization and invasiveness by analysing relationships with species characteristics and cultivation and by disentangling the direct effects of characteristics from the indirect effects mediated by cultivation.
Location
Great Britain.
Time period
c. 1000–present.
Major taxa studied
Seed plants.
Methods
We used a comprehensive dataset of 17,396 alien plant taxa introduced to Great Britain before 1850, a country with one of the most well‐documented histories of plant introductions. We integrated this with cultivation data from historical and modern records from botanic gardens and commercial nurseries and with trait data. Accounting for time since introduction, we quantified the influences of cultivation and species characteristics on present‐day naturalization and invasiveness in Great Britain.
Results
Larger native range size, earlier flowering, long‐lived herbaceous growth form, and outdoor cultivated habitat were all associated with naturalization. However, these relationships between characteristics and naturalization largely reflected cultivation patterns. The indirect, mediating influence of cultivation on naturalization varied among species characteristics, and was relatively strong for growth form and weak for native range size. Cultivation variables, particularly availability in present‐day nurseries, best explained invasiveness, while species characteristics had weaker associations.
Main conclusions
Human influence on species introduction and cultivation is associated with increased probability of naturalization and invasiveness, and it has measurable indirect effects by biasing the distribution of species characteristics in the pool of introduced species. Accounting for human cultivation preferences is necessary to make ecological interpretations of the effects of species characteristics on invasion.
This Guidance describes a two‐phase approach for a fit‐for‐purpose method for the assessment of plant pest risk in the territory of the EU. Phase one consists of pest categorisation to determine ...whether the pest has the characteristics of a quarantine pest or those of a regulated non‐quarantine pest for the area of the EU. Phase two consists of pest risk assessment, which may be requested by the risk managers following the pest categorisation results. This Guidance provides a template for pest categorisation and describes in detail the use of modelling and expert knowledge elicitation to conduct a pest risk assessment. The Guidance provides support and a framework for assessors to provide quantitative estimates, together with associated uncertainties, regarding the entry, establishment, spread and impact of plant pests in the EU. The Guidance allows the effectiveness of risk reducing options (RROs) to be quantitatively assessed as an integral part of the assessment framework. A list of RROs is provided. A two‐tiered approach is proposed for the use of expert knowledge elicitation and modelling. Depending on data and resources available and the needs of risk managers, pest entry, establishment, spread and impact steps may be assessed directly, using weight of evidence and quantitative expert judgement (first tier), or they may be elaborated in substeps using quantitative models (second tier). An example of an application of the first tier approach is provided. Guidance is provided on how to derive models of appropriate complexity to conduct a second tier assessment. Each assessment is operationalised using Monte Carlo simulations that can compare scenarios for relevant factors, e.g. with or without RROs. This document provides guidance on how to compare scenarios to draw conclusions on the magnitude of pest risks and the effectiveness of RROs and on how to communicate assessment results.
This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2018.EN-1440/full
‘This guidance supersedes:
a) the entire Guidance on a harmonised framework for pest risk assessment and the identification and evaluation of pest risk management options by EFSA. https://doi.org/10.2903/j.efsa.2010.1495;
b) Sections 1.8 and 1.9 of Guidance on methodology for evaluation of the effectiveness of options for reducing the risk of introduction and spread of organisms harmful to plant health in the EU territory. https://doi.org/10.2903/j.efsa.2012.2755’
We identify a significant relationship between domestic market-based propagule pressure, as measured both in presence in the British horticultural market and in seed prices of ornamental plant ...species, with success in invasion. We employ a multispecies temporal approach and use a Generalized Estimation Equation model comparing ornamental non-native species introduced into Britain which started to invade with species introduced but not known outside cultivation. Historical nursery catalogues gave information on the availability and prices of seeds of 506 ornamental species in the British horticultural market every 20 years from 1885 to 1985. Higher market frequency and cheap prices of seeds were more significant and had a greater impact on the invading probability 20 years later than at the date of listing in a nursery catalogue. Our results suggest that national economic factors are an important part of the explanation for the invasiveness of ornamental plant species, and hence for the development of potential solutions.
Aim: To collect and identify the issues that may affect the future global and local management of biological invasions in the next 20-50 years and provide guidance for the prioritization of actions ...and policies responding to the management challenges of the future. Location: Global Methods: We used an open online survey to poll specialists and stakeholders from around the world as to their opinion on the three most important future issues both globally and at their respective local working level. Results: The 240 respondents identified 629 global issues that we categorized into topics. We summarized the highest rated topics into five broad thematic areas: (1) environmental change, particularly climate change, (2) the spread of species through trade, (3) public awareness, (4) the development of new technologies to enhance management and (5) the need to strengthen policies. The respondents also identified 596 issues at their respective local working levels. Management, early detection, prevention and funding-related issues all ranked higher than at the global level. Our global audience of practitioners, policymakers and researchers also elicited topics not identified in horizon scanning exercises led by scientists including potential human health impacts, the need for better risk assessments and legislation, the role of human migration and water management. Main conclusions: The topic areas identified in this horizon scan provide guidance where future policy priorities for invasive alien species should be set. First, to reduce the magnitude and speed of environmental change and its impacts on biological invasions; second, to restrict the movement of potentially invasive alien species via trade; third, to raise awareness with the general public and empower them to act; and finally, to invest in innovative technologies that can detect and mitigate adverse impacts of introduced species.
EFSA was asked for a partial risk assessment of Spodoptera frugiperda for the territory of the EU focussing on the main pathways for entry, factors affecting establishment, risk reduction options and ...pest management. As a polyphagous pest, five commodity pathways were examined in detail. Aggregating across these and other pathways, we estimate that tens of thousands to over a million individual larvae could enter the EU annually on host commodities. Instigating risk reduction options on sweetcorn, a principal host, reduces entry on that pathway 100‐fold. However, sweetcorn imports are a small proportion of all S. frugiperda host imports, several of which are already regulated and further regulation is estimated to reduce the median number entering over all pathways by approximately 10%. Low temperatures limit the area for establishment but small areas of Spain, Italy and Greece can provide climatic conditions suitable for establishment. If infested imported commodities are distributed across the EU in proportion to consumer population, a few hundreds to a few thousands of individuals would reach NUTS 2 regions within which suitable conditions for establishment exist. Although S. frugiperda is a known migrant, entry directly into the EU from extant populations in sub‐Saharan Africa is judged not feasible. However, if S. frugiperda were to establish in North Africa, in the range of thousands to over two million adults could seasonally migrate into the southern EU. Entry into suitable NUTS2 areas via migration will be greater than via commercial trade but is contingent on the establishment of S. frugiperda in North Africa. The likelihood of entry of the pest via natural dispersal could only be mitigated via control of the pest in Africa. If S. frugiperda were to arrive and become a pest of maize in the EU, Integrated Pest Management (IPM) or broad spectrum insecticides currently used against existing pests could be applied.
Sustainable strategies for managing weeds are critical to meeting agriculture’s potential to feed the world’s population while conserving the ecosystems and biodiversity on which we depend. The ...dominant paradigm of weed management in developed countries is currently founded on the two principal tools of herbicides and tillage to remove weeds. However, evidence of negative environmental impacts from both tools is growing, and herbicide resistance is increasingly prevalent. These challenges emerge from a lack of attention to how weeds interact with and are regulated by the agroecosystem as a whole. Novel technological tools proposed for weed control, such as new herbicides, gene editing, and seed destructors, do not address these systemic challenges and thus are unlikely to provide truly sustainable solutions. Combining multiple tools and techniques in an Integrated Weed Management strategy is a step forward, but many integrated strategies still remain overly reliant on too few tools. In contrast, advances in weed ecology are revealing a wealth of options to manage weeds
at the agroecosystem level
that, rather than aiming to eradicate weeds, act to regulate populations to limit their negative impacts while conserving diversity. Here, we review the current state of knowledge in weed ecology and identify how this can be translated into practical weed management. The major points are the following: (1) the diversity and type of crops, management actions and limiting resources can be manipulated to limit weed competitiveness while promoting weed diversity; (2) in contrast to technological tools, ecological approaches to weed management tend to be synergistic with other agroecosystem functions; and (3) there are many existing practices compatible with this approach that could be integrated into current systems, alongside new options to explore. Overall, this review demonstrates that integrating systems-level ecological thinking into agronomic decision-making offers the best route to achieving sustainable weed management.
Article 42 of the European Regulation (EU) 2016/2031, on the protective measures against pests of plants, introduces the concept of ‘high risk plants, plant products and other objects’ that are ...identified on the basis of a preliminary assessment to be followed by a commodity risk assessment. Following a request of the European Commission, this Guidance was developed to establish the methodology to be followed when performing a commodity risk assessment for high risk commodities (high risk plants, plant products and other objects). The commodity risk assessment performed by EFSA will be based on the information provided by the National Plant Protection Organisations of non‐EU countries requesting a lifting of import prohibition of a high risk commodity. Following international standards on pest risk analysis, this Guidance describes a two‐step approach for the assessment of pest risk associated with a specified commodity. In the first step, pests, associated with the commodity, that require risk mitigation measures are identified. In the second step, the overall efficacy of proposed risk reduction options for each pest is evaluated. A conclusion on the pest‐freedom status of the commodity is achieved. The method requires key uncertainties to be identified.
1. Ornamental horticulture is the most important pathway for plant invasions world-wide. Large numbers of non-native plants are used as ornamentals, and current policies fail to effectively address ...the continued escape of species from cultivation. Legislative measures are often limited to the listing of few high-risk species banned from sale or planting. This approach, however, may give the impression that non-listed species are not considered to be a risk and are therefore safe to use. The continued widespread use of species not yet identified as having the risk to become invasive may create a problem in the future. 2. This article argues that knowledge gained from studies designed to identify invasive traits of species and factors contributing to their invasion success can also be used to identify species with a low invasion risk that can be recommended to the horticultural trade, landscaping sector and gardeners for safer use. 3. The criteria identified for non-invading species to be listed in a green list include sufficiently long residence time, high propagule pressure, no records of invasive occurrences elsewhere and an indication of some robustness to climate change. An example is provided for a random sample of ornamental species used in Britain. 4. Synthesis and application. There is a pressing need to prevent further plant invasions resulting from ornamental horticulture. A green list of non-native ornamental species that have been assessed as having a low risk of escaping cultivation will contribute to the prevention of plant invasions. Species not yet assessed which may have the potential to become invasive in the future can then be more easily avoided. This list would be particularly useful in large-scale plantings and landscaping projects. Currently, policies often focus on (i) species that are already introduced and recognized as invasive and (ii) the prevention of potential further invasions from new introductions. This study suggests that attention to non-invasive species already present in the country and widely used in horticulture can help to advance policies for dealing with invasive ornamental species.
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