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Arable plant species diversity has been on a decline, with many species dependent on arable land becoming threatened. At the same time, attempts at defining the drivers of arable plant diversity have proven difficult and results are often contradictory. Much of the available data come from surveys that are small-scale and with great variability in methodology, leading to difficulties comparing them. In this study, I have used survey data from Gotland to examine how arable plant diversity is influenced by management, field size, soil texture and standing crop. I found a negative trend of diversity with increasing field size, and a suggested effect of management and soil texture on the presence of red listed arable plants. This study also evaluates the use of small datasets when examining plant diversity, and the limitations associated with it. It shows that while a small dataset cannot be analysed to the extent a more comprehensive one can, it is possible to identify trends and patterns with it, which may inform further studies.

Arable plant species diversity has been on a decline, with many species dependent on arable land becoming threatened. At the same time, attempts at defining the drivers of arable plant diversity have proven difficult and results are often contradictory. Much of the available data come from surveys that are small-scale and with great variability in methodology, leading to difficulties comparing them. In this study, I have used survey data from Gotland to examine how arable plant diversity is influenced by management, field size, soil texture and standing crop. I found a negative trend of diversity with increasing field size, and a suggested effect of management and soil texture on the presence of red listed arable plants. This study also evaluates the use of small datasets when examining plant diversity, and the limitations associated with it. It shows that while a small dataset cannot be analysed to the extent a more comprehensive one can, it is possible to identify trends and patterns with it, which may inform further studies.

Weeds in agricultural landscapes can serve as alternate hosts for phytopathogenic fungi and promote the spatial and long-term distribution of these fungi. Especially, semi-natural habitats such as kettle holes are considered as a source of fungal pathogens because they are a permanent habitat for various weed species in arable lands. In our study, we investigated the suitability of nine different weed species and families at the edges of 18 kettle holes in two consecutive autumn/winter seasons as alternate hosts for Fusarium and Alternaria. We detected a fungal infestation with both genera on every weed species investigated with significantly higher abundances of these fungi in the second, notably wetter season. Eight weed species were described as non-host plants for Fusarium and Alternaria in agricultural landscapes in Brandenburg, Germany for the first time. In both autumn/winter periods, weeds harbored more Alternaria than Fusarium. The study revealed a high Fusarium species diversity in weeds and a community structure of up to 12 Fusarium species at the edges of kettle holes. Grasses showed the highest diversity and often the highest fungal abundances compared to herbaceous plants. Therefore, these habitats in arable lands can act as ecosystem disservice and promote the spread of fungal diseases in the surrounding crop fields., Peer Reviewed

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 ar

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?, Postprint (published version)

Weeds in agricultural landscapes can serve as alternate hosts for phytopathogenic fungi and promote the spatial and long-term distribution of these fungi. Especially, semi-natural habitats such as kettle holes are considered as a source of fungal pathogens because they are a permanent habitat for various weed species in arable lands. In our study, we investigated the suitability of nine different weed species and families at the edges of 18 kettle holes in two consecutive autumn/winter seasons as alternate hosts for Fusarium and Alternaria. We detected a fungal infestation with both genera on every weed species investigated with significantly higher abundances of these fungi in the second, notably wetter season. Eight weed species were described as non-host plants for Fusarium and Alternaria in agricultural landscapes in Brandenburg, Germany for the first time. In both autumn/winter periods, weeds harbored more Alternaria than Fusarium. The study revealed a high Fusarium species diversity in weeds and a community structure of up to 12 Fusarium species at the edges of kettle holes. Grasses showed the highest diversity and often the highest fungal abundances compared to herbaceous plants. Therefore, these habitats in arable lands can act as ecosystem disservice and promote the spread of fungal diseases in the surrounding crop fields., Peer Reviewed

“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.

[ES] Se cuantificaron e identificaron las semillas de malas hierbas presentes en muestras de 200 g de las cosechas de cereal (trigo duro, trigo blando y triticale) obtenidas en 2017 en 182 parcelas de cultivo convencional, distribuidas en 20 términos municipales de las campiñas de Huelva y del occidente de Sevilla. Se identificaron 68 especies pertenecientes a 19 familias de angiospermas. Las especies más frecuentes y abundantes fueron Polygonum aviculare (73%, 3558 semillas), Phalaris minor (47%, 1476 semillas), Chrysanthemum coronarium (46%, 2369 semillas) y Lolium rigidum (36%, 6165 semillas). La mayoría de muestras (59%) registró entre 11 y 100 semillas y el valor máximo de abundancia fue de 4215 semillas. En términos de riqueza en especies, la mayoría de muestras analizadas (43%) presentó 4-6 especies, aunque un 6% registró al menos 10. Se analizó mediante modelos lineales el efecto de los factores ambientales (clima, evaluado por la longitud geográfica) y de uso agrícola (fecha de recolección, tamaño de la parcela, distancia de la parcela a un hábitat no agrícola) en los valores medios ponderados a nivel de comunidad (CWM) de diversos caracteres con significación funcional: altura de las plantas, peso de las semillas, inicio y duración de la floración, representación de dicotiledóneas y afinidad por los nutrientes (valores indicadores de Ellenberg para el N). La mayoría de los caracteres respondió a alguno de los factores analizados, indicando que las semillas de malas hierbas que acompañan al grano cosechado llevan la firma de la respuesta funcional de las comunidades arvenses a los filtros ambientales y de manejo., [EN] We quantified and identified the weed seeds present in 200 g samples of cereal grain (durum wheat, bread wheat and triticale) harvested in 2017 in 182 conventionallymanaged fields distributed in 20 municipalities of the cereal areas of Huelva and Seville provinces, in south-western Spain. We identified 68 species from 19 families of flowering plants. The most frequent and abundant species were Polygonum aviculare (73%, 3558 seeds), Phalaris minor (47%, 1476 seeds), Chrysanthemum coronarium (46%, 2369 seeds) and Lolium rigidum (36%, 6165 seeds). Most of the samples (59%) exhibited 11-100 weed seeds and the highest abundance recorded was 4215 seeds. In terms of species richness, most of the analyzed samples (43%) showed 4-6 species, although 6% of the samples exhibited at least 10. Linear models were used to test for effects of environmental (climate, using geographical longitude as a proxy) and agricultural factors (harvest date, field size, distance to the nearest non-agricultural habitat) in community-weighted mean values (CWM) of different functional traits: plant height, seed weight, onset and extent of flowering, representation of forbs and nutrient affinity (Ellenberg’s indicator values for N). Most of the traits were responsive to some of the analyzed factors, thus indicating that the weed seeds accompanying harvested cereal grain exhibit the fingerprint of the functional response of cereal weed communities to environmental and management filters.

Time of seedling emergence is an important step in the life cycle of annual plants because it may determine subsequent performance and success. Timing of emergence is especially critical to plant performance in habitats like arable fields which are subject to frequent disturbances. Within-season variation in timing of germination in the range of only a few days is typical for many arable weeds. However, since it is unclear whether such small deviations in germination date translate into fitness differences in the course of the life cycle, the aim of this paper was to quantify the effects of short germination delays on plant performance. We conducted two generalized randomized block experiments in an unheated greenhouse to study the impact of delayed germination (1, 2, 3 and 7 d) with and without competition, respectively, on the fitness of the arable weed species Agrostemma githago (L.). We expected that delayed germination significantly reduces fitness in terms of several life-history traits, and that the decrease of fitness is higher in the presence of competition. Under realistic conditions with competition through barley, Agrostemma plants with delayed germination of 7 d produced 54% fewer shoots, 57% less biomass, 52% fewer flowers, 36% lighter seeds and were 23% shorter as compared to control plants without delayed germination. Without additional stress through competition with barley this pattern was less pronounced. Thus, in the situation of interspecific competition, early emerging seedlings have biologically significant fitness advantages over later emerging seedlings of the same species.

El trabajo analiza la importancia de la diversidad vegetal en los agroecosistemas y los efectos de la intensificación de las prácticas agrícolas y del paisaje sobre la diversidad vegetal. La revisión de diversos estudios llevados a cabo por el equipo de investigación permite destacar que la intensificación agrícola, tanto a escala de campo como de paisaje, afecta negativamente la abundancia y la riqueza específica de la flora. La comparación de la flora arvense de los cultivos cerealistas de secano mediterráneos entre los años 50 y la actualidad refleja la reducción de la flora arvense, especialmente de la flora propia de las mieses y la disminución de la abundancia de grupos funcionales como las leguminosas y las plantas entomófilas. El efecto de las prácticas agrícolas y de la complejidad del paisaje varía en función de la flora estudiada. Así, la complejidad del paisaje es el principal factor que afecta la configuración de la vegetación de los márgenes, mientras que la intensidad de las prácticas agrícolas es el principal factor para explicar las diferencias en la flora arvense en el centro de los campos. Por último, el artículo analiza diversas propuestas para la gestión de los agrosistemas con el objetivo de conciliar la producción agrícola y la conservación de la biodiversidad en la región mediterránea., The paper analyses the importance of plant diversity in agroecosystems and the effects of the intensification of agricultural practices and the complexity of the landscape on plant diversity. A review of several studies conducted by the research team shows that agricultural intensification, at field and landscape scales, negatively affects the abundance and richness of the flora. The comparison of weed communities from the 50s to the present reflects the reduction of weed flora, especially characteristic arable weeds, and the decline in abundance of functional groups such as legumes and insect-pollinated species. The effect of both agricultural practices and landscape complexity depends on the studied flora. Thus, landscape complexity is the main factor shaping vegetation of field boundaries whereas the intensity of agricultural practices is the most important factor in explaining differences in the weed flora in the centre of the fields. Finally, the paper discusses several proposals for farmland management aiming at reconciling crop production and biodiversity conservation in the Mediterranean region.

El trabajo analiza la importancia de la diversidad vegetal en los agroecosistemas y los efectos de la intensificación de las prácticas agrícolas y del paisaje sobre la diversidad vegetal. La revisión de diversos estudios llevados a cabo por el equipo de investigación permite destacar que la intensificación agrícola, tanto a escala de campo como de paisaje, afecta negativamente la abundancia y la riqueza específica de la flora. La comparación de la flora arvense de los cultivos cerealistas de secano mediterráneos entre los años 50 y la actualidad refleja la reducción de la flora arvense, especialmente de la flora propia de las mieses y la disminución de la abundancia de grupos funcionales como las leguminosas y las plantas entomófilas. El efecto de las prácticas agrícolas y de la complejidad del paisaje varía en función de la flora estudiada. Así, la complejidad del paisaje es el principal factor que afecta la configuración de la vegetación de los márgenes, mientras que la intensidad de las prácticas agrícolas es el principal factor para explicar las diferencias en la flora arvense en el centro de los campos. Por último, el artículo analiza diversas propuestas para la gestión de los agrosistemas con el objetivo de conciliar la producción agrícola y la conservación de la biodiversidad en la región mediterránea., The paper analyses the importance of plant diversity in agroecosystems and the effects of the intensification of agricultural practices and the complexity of the landscape on plant diversity. A review of several studies conducted by the research team shows that agricultural intensification, at field and landscape scales, negatively affects the abundance and richness of the flora. The comparison of weed communities from the 50s to the present reflects the reduction of weed flora, especially characteristic arable weeds, and the decline in abundance of functional groups such as legumes and insect-pollinated species. The effect of both agricultural practices and landscape complexity depends on the studied flora. Thus, landscape complexity is the main factor shaping vegetation of field boundaries whereas the intensity of agricultural practices is the most important factor in explaining differences in the weed flora in the centre of the fields. Finally, the paper discusses several proposals for farmland management aiming at reconciling crop production and biodiversity conservation in the Mediterranean region.

With the recent appearances of a new and well-documented classification of the Dutch plant communities (Schaminee el al. 1995a,b; 1996) and a database on the seed longevity of plant species of North West Europe (Thompson et al. 1997a) it was possible to investigate patterns of seed longevity in Dutch plant communities, considering the frequencies of plant species in various communities. This study revealed that arable weed communities have long-lived seeds compared to the transient seed bank of deciduous woodland; species-rich grassland communities tend to have a short-lived soil seed bank, intermediate between the latter two communities. Moreover, the present study showed that significant differences in community longevity exist between weed communities as well as between grassland communities. The approach based on soil seed bank spectra of plant communities gives support to existing phytosociological theories on different strategies of plant communities sensu Stortelder (1992) and Schaminee & Stortelder (1996). The information on seed longevity of communities is essential to the practice of nature conservation and nature development because it reveals the possible vulnerability of plant communities to extinction, including their soil seed banks, the necessity of their conservation and their possibilities for regeneration.

Vegetation composition in contrasting field boundary plots was analysed by means of transects perpendicular to the arable field 3 years after establishment. Plots were established on the outer meters of an arable field next to a pre-existing field boundary and sown with (1) a mixture of 30 forbs, (2) Lolium perenne * and (3) plots left regenerating naturally. Tall, competitive species concentrated biomass production in a zone within 1 m from the arable field, while small, stress tolerant species were predominantly found in a zone m from the field. The tall species were able to increase total vegetation biomass production significantly in the zone bordering the arable field, probably by means of capturing nutrients from the arable field. The two major arable weeds found in the boundary plots, Elymus repens and Cirsium arvense, colonized the plots with different strategies but both were seriously reduced in vigour when plots were sown with Lolium perenne or with forbs at the onset of the experiment. Species richness in the forbs-plots was relatively high but rather low in the grass- and regeneration-plots caused by a very limited colonization of potential field boundary species; only two species colonizing the boundary plots were new to the original field boundary, while 30% of the species from the original field boundary were not found in the boundary plots after 3 years. This limited colonization ability may seriously hamper efforts to restore field boundary diversity.