Rare Weed Research Articles

Effects of habitat management on newly found populations of the endangered weed, Mummenhoffia alliacea (Brassicaceae)

AbstractGarlic pennycress (Mummenhoffia alliacea) is a rare weed of the Brassicaceae family, protected in Hungary. In 2021, three new sites of the species were discovered. In addition to these previously unknown occurrences, a detailed study of a roadside occurrence known for a longer time but not yet published was carried out. Main aim of our study was to find out how habitat management practices, such as mowing and winter‐deicing effects seed mass and germination. Seeds collected earlier had significantly lower mass than those from later collections, suggesting that late‐spring mowing would be optimal for the reproduction of M. alliacea. The type of mowing (chopping the stem into small pieces or cutting the stem at one point at few centimetres above ground) had no significant effect on seed germination but did have a significant effect on the seed mass. Seed mass deriving from whole individuals was significantly higher than seed mass of chopped individuals, suggesting, that traditional mowing methods are better than the use of modern lawnmowers for the survival of the species. The highest NaCl (used for winter‐deicing) concentration where germination was observed was 0.75 m/m% (mass percentage), which is comparable with strongly saline soils in nature. The newly discovered sites were all disturbed, one of which was located on roadsides (paved and dirt roads) and two on embankments, suggesting that anthropogenic habitats could be optimal for the species, but the long‐term survival depends on the management of these habitats.

Incidence of thermophilic, grass and rare arable weeds in cereal fields in the Czech and Slovak Republic

Our objectives were to characterise arable weeds of the Czech and Slovak Republic in cereals, especially considering important groups of species: thermophilic, weedy grasses, and rare and endangered species. The three-year phytocoenological survey was conducted from 2006 to 2008 in five climatic regions and eight different soil types. 379 relevĂŠs were recorded, and 281 weed species were found. The effects of both the climatic region and soil type were found to be statistically significant. Species richness increased with altitude. Several species were distinctly associated with soil type, from fertile chernozems to less fertile cambisols, while fluvisols were strongly associated with e.g. Calystegia sepium (L.) R. Br. The incidence of species outside their expected regions generally fit two categories: the most pervasive weeds found almost in all climate regions, such as Echinochloa crus-galli (L.) P. Beauv., or rare weeds in higher altitudes than expected, such as Lolium temulentum L. Rare and endangered species were more likely to be found in a colder climate and poorer soils, and this is linked to less intensive management; however, not all endangered arable species can tolerate such conditions. Even though this data is not recently collected, this is still valuable information on the distribution of weedy species, especially concerning the current interest in maintaining biodiversity.

Species composition of rare weeds in the south of the Far East

The results of monitoring (2016–2022) of the weed component of agrophytocenoses in the Primorsky Territory of the Russian Federation are presented. The species affiliation of rare weeds was determined, the average occurrence of which in soybeans, early grain crops and corn was less than 5% and with a maximum average abundance of 0.53 pcs/m2. A total of 58 low active weed species were identified, 29 of which were not previously found in the surveyed areas. The data on the average frequency of occurrence of rare species, the density of infestation by them of all surveyed areas and the results of monitoring of crops of individual crops are analyzed. It has been established that the species diversity and abundance of rare weeds depend on the characteristics of cultivated crops. Weed species confined to individual crops and weeds growing everywhere have been identified. Eight species were recorded in areas under all crops: Galinsoga parviflora Cav., Potentilla anserina L., Gnaphalium uliginosum L., Arctium lappa L., Crepis tectorum L., Inula salicina L., Avena fatua L. and Poa pratensis L. Exclusively in 26 rare species were noted in soybean crops. In total, 57 low-active species were recorded in soybean agrocenoses, 26 species in corn crops, and 18 species in early grain crops. The most problematic species with increased occurrence in recent years, representing a potential danger for crop production in Primorsky Krai, have been identified.

A newcomer from the east: naturalisation of Gypsophila perfoliata L. around the city of Miskolc (Northeast Hungary)

Gypsophila perfoliata (Caryophyllaceae) is a rare, only casually occurring species in Central Europe. Its native range spans from western Asian to the coast of the Black Sea. Several adventive occurrences of G. perfoliata were documented in Central Europe, especially in Germany where the naturalisation of the taxon occurred during the first decades of the 20th century. As a rare weed, it is suspected to have been introduced with iron ore from the former Soviet Union via railways (Kryvyi Rih region, now Ukraine). In this paper, we gathered information on the occurrence of G. perfoliata from its adventive range. These data indicate an ongoing and fast spread of the species across Central and Eastern Europe. For instance, prior to this study, G. perfoliata have two occurrence records from Hungary. Six new and recent records from Miskolc town and its surrounding areas are presented in this paper. The studied plant occurs in former industrial areas (steel factory, transshipment yards, external slag heaps) or along transport lines (esp. road verges, railway lines). We also describe 18 phytosociological relevés taken at the location of occurrences. All occurrences were documented on heavily modified anthroposols, where the populations flourish on bare ground (esp. road verges or parking areas) or on ground with admixture of metalliferous slag debris. With the help of available orthophotos the presumed land-use history of the locations has also been reconstructed. Based on data presented here we recommend modifying the species’ adventive status in Hungary from casual to naturalised. Further expansion of the species is expected not only 172 at industrial sites but also at locations where slag material was utilised (e.g. landfill, road and rail construction). Due to its halophyte characteristics the species might expand its range along roads where de-icing salt is used.

Florisztikai adatok a Tiszántúl északi pereméről II.

Jelen dolgozatban 2006 és 2019 közötti időszakból, a Borsodi-ártér és a Sajó–Hernád-sík területéről gyűjtött florisztikai megfigyeléseinket tesszük közzé, összesen 126 fajról, és egy hibridről. Különös figyelmet fordítottunk a térségben jellemző kavicsbányákra, ezért az adataink egy jelentős része valamilyen módon összefüggésbe hozható a kavicsbányászati tevékenységek során létrejött élőhelyekkel. A dolgozatban bemutatjuk néhány országszerte ritka vagy szórványos őshonos faj (például Chenopodium murale, Ch. rubrum, Lycopsis arvensis, Chamaenerion dodonaei, Reseda luteola, Senecio viscosus, Gnaphalium luteoalbum, Cyperus glomeratus), ill. újjövevény (Lepidium densiflorum, L. virginicum) újabb előfordulásait. Védett, de nem feltétlenül ritka fajok lokális elterjedéséhez is kiegészítésekkel szolgálunk (például Pseudolysimachion longifolium, Nymphoides peltata, Epipactis tallosii, Leucanthemella serotina). Néhány faj előfordulását tiszántúli (Sherardia arvensis, Thymelaea passerina, Silene conica) vagy alföldi (Monotropa hypopitys) kitekintésben is jelentősnek tartjuk.

Temporary non-crop habitats within arable fields: The effects of field defects on carabid beetle assemblages

Landscape heterogeneity and higher complexity generally increase biodiversity in agroecosystems. Carabid beetles represent abundant and important predators of pests and weed seeds in temperate agroecosystems and are affected by landscape structure. Several studies have described the impact of permanent non-crop habitats such as woodlots, hedgerows, and grassy margins on carabid assemblages. However, temporal non-crop habitat islands within arable fields have been rarely investigated. The aim of this study was to investigate spatial distribution of carabid beetles within oilseed rape fields having temporary non-crop habitats (field defects). Field defects are areas where sown plants poorly develop due to sowing failures or extreme local conditions (soil humidity, missing nutrients). In twenty oilseed rape fields, we studied carabid assemblages collected with pitfall traps in three habitat types (field interiors, field defects, and boundaries between them) and in two sampling periods (spring and summer). Both activity-density and species richness were lower in field defects than in boundaries and field interiors during both sampling periods, indicating that field defects were not a preferred habitat for carabids. Activity-density and species richness significantly increased from spring to summer in all habitat types. Species composition of carabid assemblages significantly differed between field defects and field interiors or boundaries. Field defects were characterised by impoverished carabid assemblages and the presence of few indicator species. Interestingly, field defects with well-developed plant cover hosted carabid assemblages with species richness comparable to field interiors, indicating that re-sowing of field defects can support carabid populations within arable fields. However, the consequences of re-sowing on other arthropod taxa, e.g., insects requiring habitats with bare ground, and on populations of rare weeds need to be evaluated. The lack of effects of field defect size on carabid assemblages indicated that carabid beetles react to even very small patches with unsuitable conditions (e.g., very low humidity, high temperature or food scarcity).

Evaluating the ecotoxicity of nitrification inhibitors using terrestrial and aquatic test organisms

BackgroundThe increasing demand for food and animal fodder worldwide has led to an intensified agriculture with an increasing use of nitrogen fertilizers. More recently, nitrate leaching and gaseous nitrogen emissions have become the focus of environmental discussions and climate politics. One approach to reduce such negative impacts is the use of nitrification inhibitors (NIs) that have shown to effectively reduce nitrogen losses to the groundwater and the air. However, ecotoxic effects of NIs have been studied to a limited extent only. Therefore, two commercial NIs (Piadin and Vizura) and an active ingredient of another NI, dicyandiamide (DCD), were assayed using various ecotoxicological biotests and test species: the Lemna Growth Inhibition Test (Lemna gibba), the Seed Germination/Root Elongation Toxicity Test (Agrostemma githago, Fagopyrum esculentum, Glycine max, Hordeum vulgare, Lunaria annua, Zea mays), the Seedling Emergence and Seedling Growth Test (A. githago, F. esculentum, Z. mays) and the marine Luminescent Bacteria Test (Aliivibrio fischeri). The fresh water L. gibba and the bacterium A. fischeri were exposed to different test concentrations in liquid growth media, whereas the terrestrial plants were exposed to the test substances diluted/dissolved in deionized water and added to the solid growth medium.ResultsDicyandiamide did not show ecotoxic effects in any test conducted. Piadin and Vizura showed ecotoxic effects throughout all experiments. Frond number and frond area of L. gibba were inhibited with increasing concentrations of both substances with Piadin leading to an earlier inhibition and therefore lower EC50 values. In the Seed Germination Test, Vizura generally inhibited seed germination and root development more effectively than Piadin. Regarding both substances, the endpoint root length was much more sensitive than the endpoint germination. In the Seedling Emergence Test, Z. mays was the least sensitive and the rare weed species A. githago the most sensitive species with regard to the tested endpoints and both substances. A. fischeri was strongly inhibited by Vizura, whereas Piadin had barely effects on the bacteria.ConclusionAll findings indicate ecotoxic effects of Piadin and Vizura, especially on the aquatic species L. gibba and on the root development of several terrestrial plant species. However, the origins of the ecotoxic properties remain unclear as both substances contain a mixture of—to some extent unknown—chemical compounds.

Species but not genotype diversity strongly impacts the establishment of rare colonisers

Summary Understanding species coexistence and regulation of biodiversity are major research challenges, yet there is no consensus on the effects of diversity on diversity, including their mediation through plant–plant interactions. We examined how the diversity of recipient communities impacted on the establishment of colonising species. We ran a greenhouse‐based community experiment, creating artificial arable crop communities with varying levels of barley genotype and weed species diversity, analysed with structural equation modelling of responses across trophic levels. Colonising arable weed species establishment was significantly reduced when the recipient communities’ weed species richness, but not barley genotype richness, increased. Recipient plant communities with higher species richness occupied more total niche space and showed stronger competition with colonising species. In contrast, recipient plant communities with higher genotype richness, even though they had slightly greater niche space occupancy, had no significant effects on the colonisation of additional species. Responses were species specific: colonising common weed species establishment was less affected by the recipient plant communities than that of colonising rare weed species. Strong responses of colonising rare species were related to the abiotic rather than the biotic environment created by the recipient communities. The stronger response of colonising rare species suggests greater niche overlap with and competitive inferiority to the recipient plant community, whereas the relative independence of colonising common species indicates less niche overlap and/or competitive equality or superiority. We observed a negative species diversity effect on colonising species, with the effect size increasing with increasing rarity of the colonising species. This differential responsiveness of colonising rare and common arable weed species to the presence of and diversity in the recipient arable plant communities may be crucial in understanding rarity and may result from differential evolutionary pathways in response to interactions.

A Gagea minima és a Dictamnus albus újrafelfedezése a Dél-Tiszántúlon, valamint további florisztikai adatok az Alföldről

A szerzők a 2011 és 2017 közötti időszakban az Alföldről gyűjtött floriszti­kai adataik közül az érdekesebbeket adják közre. A cikkben 49 faj, illetve hibridfaj előfordu­lását, élőhelyi körülmé­nyeit, esetenként a térségből ismert történetét mutatjuk be. További 13 faj esetében – azok természet­védelmi jelentősége miatt – a Magyarország edényes nö­vényfajainak elterjedési atlaszához (Bartha et al. 2015, a továbbiakban: „Flóraatlasz”) meg­jegyzések nélküli kiegészítéseket is közlünk. A tárgyalt adatok többsége a Gyula, Békéscsaba és Doboz térségében elterülő keményfás ligeterdőkből származik, emellett további szór­ványadatokat közlünk az Alföld számos pontjáról. Eredményeink közül legjelentő­sebbek a Dél-Tiszántúlról kipusztultnak vélt Dictamnus albus, illetve az „elfeledett” Gagea minima újra­felfedezése. Emellett több, az Alföld, illetve az adott közép- vagy kistáj flórájára új (pél­dául Draba muralis, Nicandra physalodes, Cystopteris fragilis), illetve regionálisan veszélyez­tetett faj adatát (például Inula helenium, Ophioglossum vulgatum) ismertetjük. Bemutatunk továbbá ritka gyomnövényeket (pél­dául Calepina irregularis, Cardamine impatiens), terjedő­ben lévő adventív fajokat (Chorispora tenella, Euphorbia maculata, Phytolacca americana, Ph. esculenta, Sicyos angulata), illetve az adott térségben feltűnően alultérképezett fajokat (pl.: Loranthus europaeus, Arabis hirsuta, Rumex confertus).

New measurements of thousand-seed weights of species in the Pannonian flora

For understanding local and regional seed dispersal and plant establishment processes and for considering the ecotypes and other forms of specific variability, hard data of locally or regionally measured traits are necessary. We provided newly measured seed weight data of 193 taxa, out of which 24 taxa had not been represented in the SID, LEDA or BiolFlor databases. Our new measurements and formerly published data of locally collected seed weight records together covers over 70% of the Pannonian flora. However, there is still a considerable lack in seed weight data of taxonomically problematic genera, even though they are represented in the Pannonian flora with a relatively high number of species and/or subspecies (e.g. Sorbus, Rosa, Rubus, Crataegus and Hieracium). Our regional database contains very sporadic data on aquatic plants (including also numerous invasive species reported from Hungary and neighbouring countries) and some rare weeds distributed in the southwestern part of the country. These facts indicate the necessity of further seed collection and measurements.

Effect of landscape structure on agrobiodiversity in western Iran (Gilan-E Gharb)

ABSTRACTThe widespread transition into intensive agroecosystems has led to a considerable decline in plant biodiversity especially for organisms in the field boundaries. The aim of this study was to survey the vegetation of fields and field boundary types located in an agricultural landscape. We provided the structural map of the landscape and classified it into field boundary types nested in three main groups of natural and seminatural elements. Species recorded in all habitat types were categorized into two emergent groups based on their response to land use intensification: 1) agrotolerant species (AT) and 2) high nature-value species (NV). We analyzed the effect of landscape structure and soil physicochemical properties on species richness of these groups. We found both landscape structure and soil properties significant in explaining variation among AT and NV species richness both at 2-m-×-2-m and landscape scales. The most overall species richness was recorded for agricultural fields (43 species) followed by non-crop field edges (37). Woody green veins and permanent ditches were the elements providing high NV species richness clearly, while fields and other field boundary types were mostly supporters of AT species richness. Diversity of AT species increased along nitrogen and clay content gradients of the soil, while NV species benefited where phosphorus and soil moisture content were high. We recommend agricultural landscapes to be more specified with (semi-)natural habitats which embed high a proportion of rare weeds as nature-value plant species.

147 - Cross-Talk between Two Antioxidants, Thioredoxin Reductase 1 and Heme Oxygenase-1 and Therapeutic Implications in Multiple Myeloma

The intensification of agricultural management has caused some weed species to become rare in arable farming systems. It is difficult to disentangle which management practices are the least harmful for the conservation of rare arable weeds because of their sparse presence. In this research, we overcame the limitations of previous analyses of rare weeds by analyzing them in a large number of plots (1957) at the edges of multiple organic fields (304), which maximized the probability of detecting these species. We evaluated the relationships between farming practices and local site conditions and the presence of rare arable species that are characteristic of cereal fields.We detected 46 of the 65 rare weeds that are known to inhabit the study area, but their frequency was very low. Cereal crops, either alone or in mixtures with legumes, enhanced the probability of finding rare weed species, while fertilization had a detrimental effect. Other management practices that were considered had no effect on the presence of rare arable weeds. However, selected rare species tended to fare better under particular local conditions and to be favored by specific management practices. In contrast, a significant amount of the variance of the rare weed presence was explained by farm-related and field-related random factors. Thus, the occurrence of rare arable species is apparently determined by stochastic factors that may be related to the local species pool that likely depends on the history of fields and farms. Therefore, conservation efforts should be focused on areas currently inhabited by rare arable species.

Which conditions determine the presence of rare weeds in arable fields?

The intensification of agricultural management has caused some weed species to become rare in arable farming systems. It is difficult to disentangle which management practices are the least harmful for the conservation of rare arable weeds because of their sparse presence. In this research, we overcame the limitations of previous analyses of rare weeds by analyzing them in a large number of plots (1957) at the edges of multiple organic fields (304), which maximized the probability of detecting these species. We evaluated the relationships between farming practices and local site conditions and the presence of rare arable species that are characteristic of cereal fields.We detected 46 of the 65 rare weeds that are known to inhabit the study area, but their frequency was very low. Cereal crops, either alone or in mixtures with legumes, enhanced the probability of finding rare weed species, while fertilization had a detrimental effect. Other management practices that were considered had no effect on the presence of rare arable weeds. However, selected rare species tended to fare better under particular local conditions and to be favored by specific management practices. In contrast, a significant amount of the variance of the rare weed presence was explained by farm-related and field-related random factors. Thus, the occurrence of rare arable species is apparently determined by stochastic factors that may be related to the local species pool that likely depends on the history of fields and farms. Therefore, conservation efforts should be focused on areas currently inhabited by rare arable species.

Response of the two rare arable weed species Lithospermum arvense and Scandix pecten-veneris to climate change conditions

Rare weeds are currently under pressure due to intensifying arable management practices, and as a consequence of climate change, these practices will likely become even more intensive, together with a greater uniformity of land use. As a result, ecological stresses will increase for most species of rare weeds, in some cases leading to their further decline or even extinction. Moreover, climate change will alter the suitability of the environment for many plants, since average temperatures are predicted to increase and precipitation extremes to become more common. For most arable weed species it is unclear, whether the anticipated changes in environmental conditions are disadvantageous or beneficial. Little is known about specific biological responses of rare weeds to climate changes, and this study attempts to close some of these knowledge gaps. Here, the rare arable weed Lithospermum arvense and the endangered arable species Scandix pecten-veneris were investigated with regard to the effects of higher temperature and different crop densities on flowering time, shoot development, plant height, dry mass and seed production. Semi-field experiments were conducted with winter wheat crop for 3 years, involving 48 climate cages, in which every second was a variant of warmer temperature and contrasting crop density. We observed that S. pecten-veneris flowered earlier under warmer conditions and had fewer seeds and less biomass in the dense wheat crop compared to control conditions, while L. arvense grew taller, it produced fewer seeds in the high density crop. We suggest that such data concerning the biological responses of weeds can improve the precision of bioclimatic distribution models. Finally, we discuss strategies, such as relocation or non-intrusive management practices, for preventing further disappearances of rare arable weeds. Our results should be of considerable interest for the fields of plant ecology, biodiversity research and conservation.

Reintroduction of a rare arable weed: Competition effects on weed fitness and crop yield

Arable weeds have severely declined due to intensification of farming during the past decades, and some of them are close to extinction in large parts of western and central Europe. Recent conservation strategies suggest reintroduction of rare arable weeds to suitable types of land use, for example organic fields. To test the feasibility of this conservation option we investigated the effects of spring wheat and a common weed (Stellaria media) on growth and reproduction of a rare weed (Legousia speculum-veneris) in a semi-open glasshouse experiment. Additionally, the impact of the weeds on crop yield was assessed. Aboveground biomass and seed production of L. speculum-veneris were significantly reduced under competition with the crop and the common arable weed. With increasing competition L. speculum-veneris allocated disproportionally more resources to seeds. Wheat yield was not affected by the arable weeds. We conclude that L. speculum-veneris is a subordinate species that is negatively affected by more competitive plants. In the presence of wheat the addition of other weeds does not further harm the species. Enhanced allocation to reproduction might be a specific strategy of the species to maintain populations under competition. Reduced crop densities would help reintroducing the species, while yield losses due to reintroduction of that rare arable weed are unlikely.

Refining rare weed trait syndromes along arable intensification gradients.

QuestionHow does the conservation (rarity) value of arable weed communities differ along intensification gradients? Which functional traits best distinguish the weed communities of more and less extensively managed fields? Can the same traits predict the rarity of individual weed species?LocationHungary.MethodsUsing relevé data from 60 cereal and 70 stubble fields, together with weed trait data, we characterized community responses to arable intensification using functional trait analyses based on trait‐convergence and trait‐divergence assembly patterns. We also examined how well the broad‐scale rarity status of species predicts their occurrence along intensification gradients, and how it maps onto our functional classifications describing intensification responses.ResultsThe response of weeds to intensification in cereal fields was best described by a functional classification based on species' flowering duration, maximum height and seed weight: weeds of extensively managed fields have short flowering seasons (2–5 mo) and particularly large or small seeds. The highest proportions of rare species also happen to be found in these groups. The rarest weeds among these species tend to be late‐winter and early‐summer annuals, while the rare species of stubble fields tend to be broad‐leaved with low nitrogen requirements, small seeds and short height. Stubble fields showed a decline in weed cover with increasing application of fertilizer and distance from the field edge, but we could detect no strong associations of management factors with trait composition, perhaps because the intensification gradient across these fields was shorter.ConclusionsMany rare Hungarian weeds are associated with traditional extensive farming practices. They are particularly characterized by short, midsummer flowering periods and by preference for low nitrogen levels, but a range of trait syndromes must be considered to understand their ecology and conservation. Analyses based on trait‐divergence patterns, rather than trait‐convergence patterns, provide better insights into the functional composition of weed communities, emphasizing the importance of disruptive filters in weed community assembly and the need for improved methods to detect such effects.

Segetal Weed Vegetation Database of Greece

The Segetal Weed Vegetation Database of Greece (GIVD ID EU-GR-004) attempts to document the vanishing plants and vegetation of segetal fields used in a traditional manner without herbicide application. At present it includes chiefly unpublished records of southern mainland Greece and recently published data from the island of Crete. Its focus is on the documentation of rare weed species occurrences and on the option of monitoring plants, vegetation and land use.

The importance of climate, site and management on weed vegetation in oilseed rape in Germany

Data on the occurrence of weed species in 1463 German oilseed rape (OSR) fields were used to multivariately investigate the interactions of management practices and ecological processes with weed species composition. Partial canonical correspondence analysis (pCCA) served to quantify the relative contribution of 25 characteristics of climate, site and crop to weed species composition. According to pCCA the considerable differences in weed species composition of OSR fields were mainly associated with the crop preceding OSR, the tillage intensity and soil quality. Longitude and precipitation were the most important environmental parameters. Factors driving the occurrence of weed species differed for the categories ‘common’, ‘frequent’ and ‘rare’ weed species. Common weed species showed the strongest response to factors acting at the field scale such as crop sowing date or soil quality, while only frequent species were affected by local environment, and the occurrence of rare weeds more than the other groups depended on large-scale geographical position variables as well as cropping intensity. Cluster analyses of thematically grouped explanatory variables resulted in the identification of four farming systems with different soil properties and management, two farming systems differing in the occurrence of OSR cropping, and five ecoregions, each with characteristic and statistically verified OSR weed communities.

Effects of cultivation regimes on weed community structures in newly reclaimed sandy farmlands

The varieties, quantities, coverage rates and heights of farmland weeds were surveyed and species diversity and richness analyzed in a newly reclaimed sandy farmland located in the margin oasis of the middle reaches of Heihe River Basin, Northwest China. The aim of the study was to evaluate the effects of cultivation regimes on weed community structure characteristics in the basin. A total of 16 weed species from 10 families were identified and recorded. The most common species of weed communities in newly reclaimed sandy farmlands are Chenopodium album, Eleusine indica, Setaria viridis and Amaranthus retroflexus. Weed community compositions are largely influenced by cultivation regimes. Weed species richness, Shannon-Wiener index and Simpson in-dex are lower in conventional cultivation regimes (film mulching, autumn plowing and continuous maize planting). Those could, however, be improved under straw mulching, zero-autumn plowing and maize-soybean rotation treatments. Compared with film mulching, E. indica has a higher dominance ratio while C. album and A. retroflexus have lower dominance ration under straw mulching treatments. Compared with autumn plowing, S. viridis, A. reteroflexus, Silene conoidea and C. glaucum have a higher dominance ratio whereas E. indica has a lower dominance ratio under zero-autumn plowing treatments. Also compared with con-tinuous maize planting, S. conoidea exhibits a higher dominance ratio under maize-soybean rotation regimes. There exist random rare weed species distribution in the field, which are not significantly effected by cultivation regimes. Results further show that weed species is few and weed communities composition is single in a newly reclaimed sandy farmland, and cultivation regimes obviously influence weed species diversity and community structure in reclaimed sandy farmlands. It is recommended to conduct additional research for a non-subjective interpretation of the effects of cultivation regimes on weed growth in order to guide weed control in newly reclaimed sandy farmlands.

Using selective herbicides to manage beneficial and rare weed species in winter wheat

Weed species within arable farming systems act as a source of food and provide habitat for various taxa at higher trophic levels. Using field experiments in winter wheat, we investigated whether selective herbicides can be used as a potential tool for sustaining beneficial, less competitive weed species and rare species of high conservation value while controlling highly competitive weed species. We tested three selective herbicides with different active ingredients (amidosulfuron + iodosulfuron, fluroxypyr, mecoprop-P) at two application rates. We analysed cover of selected focal species (Centaurea cyanus and Papaver rhoeas) as well as weed species richness, winter wheat yield and weed community composition as influenced by herbicide treatments. Herbicide treatments involving fluroxypyr generally allowed for the selective retention of the regionally threatened weed species C. cyanus and P. rhoeas as a beneficial species of high value for associated trophic level and provided considerable control of the competitive species G. aparine. Herbicide treatments significantly affected weed species composition. The PRC method clearly showed the time-dependent herbicide treatment effects on weed community composition and allowed an estimate of the variance in species composition that is explained by the herbicide treatments. Our results indicated that applying selective herbicides can provide a feasible option for in-crop management of weed diversity by retention of beneficial or rare weed species occurring at moderate densities and control of highly-competitive weeds. However, weed control strategies must be tailored to site-specific conditions to account for increased abundance of competitive species.