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18 Pág., Weed community structure, including composition, taxonomic and functional diversity, may explain variability in crop quality, adding to the variability accounted by management, climatic and genetic factors. Focusing on Mediterranean rainfed wheat crops, we sampled weed communities from 26 fields in Spain that were either organically or conventionally managed. Weed communities were characterized by their abundance and taxonomic, compositional and trait-based measures. Grain protein concentration and the glutenin to gliadin ratio were used as indicators of wheat grain quality. Linear mixed effects models were used to analyze the relationship between crop quality and weed community variables, while accounting for environmental factors. Nitrogen fertilization, previous crop and precipitation explained a large portion of the variation in wheat grain protein concentration (R2marginal = 0.39) and composition (R2marginal = 0.26). Weed community measures had limited effects on grain quality (increasing R2marginal of models by 1% on average). The weed effects were related to the composition and the functional structure of their communities, but not to their abundance. Environmental conditions promoting higher protein concentration were also selecting for weed species with competitive attributes, whereas the role of weed functional diversity depended on the functional trait and on the resource limiting crop grain quality. Understanding the mechanisms of weed effects on crop quality could aid on designing sustainable weed management practices., This research was supported by grants AGL2012-33736 and AGL2015-64130-R funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. D.J.G. was partially supported by the United States National Science Foundation (DUE 1758497 and DUE 1949969).

11 Pág., Over the last 30 years, many studies have surveyed weed vegetation on arable land. The 'Arable Weeds and Management in Europe' (AWME) database is a collection of 36 of these surveys and the associated management data. Here, we review the challenges associated with combining disparate datasets and explore some of the opportunities for future research that present themselves thanks to the AWME database. We present three case studies repeating previously published national scale analyses with data from a larger spatial extent. The case studies, originally done in France, Germany and the UK, explore various aspects of weed ecology (community composition, management and environmental effects and within-field distributions) and use a range of statistical techniques (canonical correspondence analysis, redundancy analysis and generalised linear mixed models) to demonstrate the utility and versatility of the AWME database. We demonstrate that (i) the standardisation of abundance data to a common measure, before the analysis of the combined dataset, has little impact on the outcome of the analyses, (ii) the increased extent of environmental or management gradients allows for greater confidence in conclusions and (iii) the main conclusions of analyses done at different spatial scales remain consistent. These case studies demonstrate the utility of a Europe-wide weed survey database, for clarifying or extending results obtained from studies at smaller scales. This Europe-wide data collection offers many more opportunities for analysis that could not be addressed in smaller datasets; including questions about the effects of climate change, macro-ecological and biogeographical issues related to weed diversity as well as the dominance or rarity of specific weeds in Europe., This work was made possible via the Weeds and Biodiversity working group of the European Weed Research Society. This project was funded under a Rothamsted Research and BBSRC grant number BB/W510543/1. Helen Metcalfe was partly supported by the Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) research programme NE/N018125/1 LTS-M (ASSIST). Jana Bürger's work on this project was supported by Deutsche Forschungsgemeinschaft DFG (grant number BU 3097/1-1).

Questions: Two scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot-based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis?. Location: Europe. Methods: We compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots). Results: Records from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing. Conclusion: This comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes., The work on this project was supported by Deutsche Forschungsgemeinschaft DFG (grant number BU 3097/1-1 for Jana Bürger), Czech Science Foundation (grant number 19-28491X for Milan Chytrý and Zdeňka Lososová), and by Slovenian Research Agency (research core funding No. P1-0236 for Urban Šilc and Young researcher programme for Filip Küzmič).

Alarcon Villora, R., Sanchez, A.M., Hernandez-Plaza, E. 2019. Management and diversity of weed communities in Mediterranean cereal steplands: new proposals under the sustainability paradigm. Ecosistemas 28(3):36-45. Doi.: 10.7818/ECOS.1821 The word weed is used to define the herbaceous plants that inhabit the cultivated fields. In rainfed crops, weeds have been considered one of the main causes of yield loss. However, works on the relationship between management practices, crop yields and weed communities in cereal steplands, are still scarce. Nonetheless, some of these works challenge the prevailing negative view on weeds, while questioning the efficacy of a weed management solely based on herbicide use. In Spain, the large extension of cereal steplands (6.5Mha) made the management of its weed diversity a question of great relevance. In this study, we summarize the state of the art on the effects of management practices on weed communities of cereal steplands. We identify knowledge gaps, and point out new research to support the development of management strategies based on the recovery of traditional crop rotations, the reduction of soil tillage and the use of organic fertilization. These will serve as the basis for the design of management strategies that permit to maintain crop yields and biodiversity.

The performance of irrigation schemes around the world has been below expectations. The assessment of irrigation performance is an essential step towards improving agricultural water use. One of the primary performance indicators is the relative irrigation supply (RIS, the ratio between the amount of water delivered and the crop net irrigation requirements). This study presents a worldwide analysis of irrigation scheme performance by evaluating key attributes that influence the RIS. The analysis was based on a review of reports and scientific papers that yielded 264 cases belonging to 25 countries in six world regions. The database was subjected to two types of statistical analysis: k-means clustering and analysis of covariance (ANCOVA). The cluster grouped irrigation schemes which were characterized by low RIS and advanced irrigation technology. The ANCOVA showed that the RIS co-varied significantly with the variation in precipitation, delivery schedule, on-farm irrigation systems, distribution network, and region, but not with the crop. The ANCOVA also showed that modern pressurized on-farm irrigation systems and on-demand distribution systems significantly improve RIS. The ANCOVA general linear model had a good capacity to predict RIS with a coefficient of determination of R2 = 0.83., The first author acknowledges the financial support of the University of Costa Rica to carry out his doctoral degree at the University of Córdoba, Spain.

Concerns about a global decline in pollinators have called for more knowledge about the factors influencing wild pollinator abundance and diversity in agroecosystems. Agricultural intensification has been identified as the main cause of this “global pollinator crisis”, particularly due to reductions in natural areas holding critical floral and nesting resources. Maintaining native wild plants in agricultural landscapes (e.g., in field margins) is often recommended as a cost-effective and efficient method for pollinator conservation. In this study, the role of common wild flowers, often considered weeds, in supporting pollinators in a Mediterranean agroecosystem was investigated. This work involved a two-year field trial to compare five native weed species common in Mediterranean cereal agroecosystems: Convolvulus arvensis L., Daucus carota L., Malva sylvestris L., Papaver rhoeas L., and Sonchus oleraceus L. The goal was to compare the attractiveness of these species, and a mixture of all five, to different flower-visiting insect groups in order to assess their value in supporting wild pollinators. Overall, D. carota had the highest number of insect visits, followed by P. rhoeas. C. arvensis, M. sylvestris, and S. oleraceus, which had lower numbers of visits. On the basis of their overall attractiveness to pollinators and low risk for invasiveness, D. carota, P. rhoeas, and M. sylvestris are the most likely to contribute positively to the conservation of pollinators in agroecosystems. Our results also suggest that it is advantageous for wild flowers sown for the purpose of pollinator conservation to be grown in clumps, rather than highly intermingled, for improved visitation rates., This work was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness (projects AGL2012-33736 and AGL2015-64130-R). The Natural Sciences and Engineering Research Council of Canada (NSERC) provided J.M. with a doctoral scholarship.

“Arable Weeds and Management in Europe” is a collection of weed vegetation records from arable fields in Europe, initiated within the Working Group Weeds and Biodiversity of the European Weed Research Society (EWRS). Vegetation-plot data from this scientific community was not previously contributed to databases. We aim to prove the usefulness of collection for large scale studies through some first analyses. We hope to assure other weed scientists who have signalled willingness to share data, and plan to construct a full data base, making the data available for easy sharing. Presently, the collection has over 60,000 records, taken between 1996 and 2015. Many more studies for potential inclusion exist. Data originate mostly from studies exploring the effect of agricultural management on weed vegetation. The database is accompanied with extensive meta-data on crop and weed management on the surveyed fields. The criteria for inclusion were a minimum amount of information on the cultivated crop, and a georeference. Most fields were surveyed repeatedly, i.e. transects, multiple random plots, or repeated visits. All surveys aimed to record the complete vegetation on the plots. Sometimes, taxa were identified only to genus level, due to survey dates very early in the vegetation period. Plant taxonomy is standardized to the Euro+Med PlantBase., B. was funded by Deutsche Forschungsgemeinschaft under the grant number BU 3097/1-1.

Agricultural field margins are often recommended as a cost-effective and efficient method for wild bee conservation, in response to the threat imposed by global pollinator declines as a result of intensive agricultural practices. In this study we compared margin characteristics and wild bee community structure from sites with landscapes of varying agricultural intensity in order to (i) investigate if field margins are valuable for wild bee conservation in all types of landscapes, and (ii) determine which biotic and abiotic margin characteristics best support wild bee abundance and community richness. Margin surveys and wild bee community sampling, comprising pan traps and observations of foraging activity, were carried out over three years at 27 cereal field margins in Catalonia, Spain. Generalized linear models indicated a strong inverse relationship between surrounding landscape diversity and wild bee abundance. The proportion of Halictidae bees (common generalists) increased with decreasing landscape complexity. Floral richness exhibited a positive association with number of foraging bees and morphospecies richness, and was positively correlated with the proportion of shrubs and trees represented in the margins. It was observed that wider margins held a higher proportion of perennial plants and a lower proportion of Halictidae bees. Our study suggests that field margins are more crucial in intensively farmed areas than in heterogeneous landscapes where foraging resources are more abundant. Maintaining wide margins with high flowering plant richness, comprising perennial and shrub species, best supports a dense and diverse bee community. In more diverse landscapes, conservation efforts focused on maintaining the quality of existing natural patches may be most effective., This work was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness grants (projects number AGL2012-33736 and AGL2015-64130-R). The Natural Sciences and Engineering Research Council of Canada (NSERC) provided J.M. with a doctoral scholarship.

© 2020 by the authors., In this work, we aimed to test whether taxonomic diversity and functional diversity and the values of functional traits of the weed seed bank varied across the field, from margins to the core, and between fields embedded in distinct landscape structures. We sampled the seed bank of 47 conventionally managed cereal fields from two Mediterranean regions in Spain. In each field, three positions were selected: Margin, edge and core, and soil properties were measured for each position. Landscape structure was quantified for each field as the percentage of arable land in the surrounding 1 km radius circular sector. Seed bank diversity was characterized at the taxonomic (species richness, exponential Shannon index, and evenness) and functional levels (Rao’s quadratic entropy index and four corner analysis). For functional diversity, eight functional traits related to the whole plant life cycle were considered. Results showed a slight response of increasing taxonomic diversity from the core of the fields to the margins. Functional diversity was extremely low, indicating high similarity among species in terms of functional traits. Species in the seed bank were mostly therophytes, shorter than the crop plants, small seeded, flowering between the herbicide application of late winter and crop harvest, and showed seed dispersal by gravity or wind. This trait syndrome allows persistence in intensively managed arable lands. The similarity between fields in terms of functional diversity of the seed bank and in species traits may suggest that the intensity of management practices was similar across the fields. Moreover, it emphasizes that an increase in landscape heterogeneity, if based on other intensively managed cropping systems, may not be sufficient to augment functional diversity of weed communities. Therefore, in these areas, the seed bank could restore weed taxonomic diversity following changes in management practices, but functional diversity would still remain limited., This work was funded by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness grants (projects AGL2012-33736 and AGL2015-64130-R). Y.P. was supported by an FPI scholarship (Spanish Ministry of Economy and Competitiveness).

Lolium rigidum Gaud. is the most prevalent and damaging grass weed of winter cereals in Spain. L. rigidum infestations are frequently treated with herbicides and, consequently, populations have evolved resistance. In 2012–2013 a random survey was conducted across cereal cropping areas of the Castilla-León and Cataluña regions to establish the distribution and frequency of herbicide resistance in L. rigidum populations to chlortoluron (Photosystem II inhibitor), chlorsulfuron (Acetolactate synthase inhibitor) and diclofop-methyl (Acetyl CoA Carboxylase inhibitor), commonly used herbicides for L. rigidum control in Spain. The results of this survey were compared with the results of a previous survey conducted in 2000–02. Resistance to PSII and ALS-inhibiting herbicides was common: 51% and 92% of the accessions collected from Castilla-León and Cataluña respectively were resistant to chlortoluron, while 75% of accessions from both regions were resistant to chlorsulfuron. Resistance to ACCase was more widespread in Cataluña, where 83% of accessions were classified as resistant, than in Castilla-León where 74% of the populations were still classified as susceptible to diclofop-methyl. These results show that resistance levels to all three herbicides had increased in Castilla-León since 2000 and to chlortoluron and chlorsulfuron in Cataluña. The accessions were also treated with the double dose (2X) of each herbicide. The percentage of L. rigidum that now exhibits multiple herbicide resistance has increased considerably, especially in Cataluña where 75% of the accessions were resistant to multiple herbicides, therefore herbicide sustainability and resistance management present a great challenge., This work was funded by the Ministerio de Economía y Competitividad (MINECO) of Spain, project AGL2011-23542.

Question: What is the role of exogenous and endogenous factors in determining fluctuations in plant populations? Methods: A total of 29 long-term time series from different plant species was analysed. Data were obtained from the literature as well as from our own surveys. For each series we calculated the autocorrelation function to identify the presence of cyclic dynamics. The existence and the order of density-dependent processes were examined by calculating the partial rate correlation function to obtain the global Lyapunov exponent to assess whether populations exhibited chaotic dynamics. To test the effect of exogenous factors on each population, we used regression analyses to relate mean annual temperature and total annual precipitation to population abundance. Finally, we employed a Mann-Whitney U-test to analyse whether populations that showed endogenous regulation occurred in less variable environments. © 2012 International Association for Vegetation Science., This work was partially funded by FEDER funds and the Spanish Ministry of Innovation and Science (Projects AGL2009-7883 and AGL2007-65698-C03-03) and Junta de Castilla-La Mancha (Project POII10-0123-5554).

Disturbances have a prominent role in structuring plant communities. However, in agroecosystems, the long-term effect of disturbances on determining trait distributions within weed communities remains little studied. We analyzed the effect of three tillage treatments, which differ in the intensity of soil disturbance, on the mean, the range and the distribution of four response traits within weed communities. We aim to test whether tillage acts as a filter restricting the range and the distribution of response traits within weed communities and leads to reduced response trait diversity or whether tilling may have a diversifying effect, creating opportunities for more phenotypes to coexist and increasing response trait diversity. To test this idea, we used data on weed abundance recorded over 24 years from an experiment in which conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) systems were compared. We selected four response traits, maximum height, specific leaf area (SLA), seed weight and seed output, and computed the community weighted mean (CWM) of each trait, as well as four multi-trait metrics related to a different aspect of functional diversity. We found that soil disturbance increases available niche opportunities for weeds especially in terms of regenerative traits. CT, the greater soil disturbance, leads to a greater range and even distribution of the studied traits and that abundant weed species from CT plots hold more divergent trait values than those from MT and NT plots. Our results may be explained by the idiosyncrasy of our disturbance treatments that affect weed seed placement in the soil layers as well as the stratification and availability of soil nutrients. We also found that NT system selected for lower CWM of seed weight (and higher seed output) than MT and CT systems. NT places weed seeds mostly on the soil surface, where having a large seed output may be necessary to avoid the risk of decay or depredation. Conversely, MT and CT systems offer some advantage to other strategies such as larger seed sizes useful to germinate from depth. CWM of SLA was higher in NT and MT than in CT plots and this could be related to greater soil nutrient content in NT systems. In addition our results showed a general trend over experimental time for weed communities to increase in height (and slightly in SLA and seed production) while reducing in seed size. These features are generally associated with intensive farming systems., This work has been funded by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness funds (Projects AGL2012-33736 and AGL2012-39929-C03-01).