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Open access

Bożena Denisow and Małgorzata Wrzesień

Abstract

Understanding the factors that have an impact on the diversity of forage flora in the agricultural landscape is a key issue in the maintenance and control of food niches for pollinators. Field margins are common linear structures in the agricultural landscape. In the present study, we evaluated the factors that exert an impact on the forage flora composition and on the diversity in field margins. The study was conducted in the 2010 - 2011 time period across the agricultural landscape on the Lublin Upland of SE Poland. Data on the forage flora were obtained while making floristic charts along 45 transect plots x 300 m; the total length being 13500 m. Multivariate ordination techniques (PCA and RDA) were employed to analyse forage-flora characteristics. Field margins represent valuable refuge areas for forage-species richness, but not for the abundance of forage species. On field margins, forage-species diversity benefits from the location of natural habitats (forests or meadows), primarily if the distance from these habitats is <1000 m or the field acreage is <10 ha. The shift from heterogeneous habitats to a more homogeneous landscape causes a reduction of forage floral diversity. Due to lack of dense forage-species patches, the promotion of sowing nectariferous and/or polleniferous species seems to be a reasonable management method to enhance the quantitative food niche on field margins and to support the conservation of pollinators in the areas surrounding farms.

Open access

Małgorzata Wrzesień and Bożena Denisow

Abstract

Plant species diversity is threatened in many agricultural landscapes due to the changes it has to undergo. Although the modification of the agricultural landscape pattern is observed across Europe, both extensive and intensive agricultural landscapes still co-exist in Poland. The objective of the study was to examine the flora in field margins in intensively and extensively managed agricultural landscapes, located across three regions in SE Poland. The flora was compared with respect to species richness, diversity, and evenness indices. Detrended correspondence analysis was employed to characterise variation in species composition. Agricultural landscape type made a higher contribution than the topography or geology to species richness and composition in field margins. Field margins function as important habitats for general vascular plant species diversity and are useful for the conservation of rare, threatened, endangered or bee plants. A significant decline in species diversity was observed over a distance of 1000 m from the habitat elements. Plants growing on field margins are mainly perennials; however participation of annuals clearly increases in intensive landscapes. The participation of wind-dispersed species decreased in an open-spaced intensive landscape. Animal-dispersed plants predominated in an extensive landscape with forest islands. Irrespective of landscape type, native species predominated. However, these habitats create the biota and corridors for alien-invasive species as well.

Open access

Małgorzata Bożek, Monika Strzałkowska-Abramek and Bożena Denisow

Abstract

Properly arranged ornamental gardens in both urban and agricultural landscapes can be of a benefit to bees. In this study, we observed the flowering phenology, nectar, and pollen production of the ornamental Hosta species and varieties (H. sieboldiana Engler, H. capitata Nakai, H. crispula Maekawa, H. fluctuans Maekawa, syn. H. sieboldiana var. fluctuans hort., H. undulata var. univittata Miquel (Hylander), syn. H. univittata). Our experiment was conducted in the 2012 - 2014 time period, at the UMCS Botanical Garden in Lublin, Poland (51° 14’ N, 21° 34’ E). The total sugar yield varied almost 5-fold among Hosta ornamentals; the lowest amount was calculated for H. fluctuans (2.31 g per 10 m2) and the highest for H. capitata (11.80 g per 10 m2). The average pollen yield was from 0.24 g per 10 m2 (H. undulata var. univittata) to 9.53 g per 10 m2 (H. capitata). Pollen grains were bilaterally symmetrical, and large-sized. In polar view, they were prolatum (shape index 1.33 - 1.61), while in equatorial view, oblatum (shape index 0.5 - 0.7). Hosta species can complete the summer pasture mainly for bumblebees. In four of the five Hosta representatives, bumblebees accounted for 60 - 70% of the total visits. The honeybee predominated only on the flowers of H. capitata (54 - 71%). Solitary bees were rarely observed (3 - 9% of visits). The phenotypic traits of Hosta flowers (the accumulation of nectar in the deep and narrow perianth tube) reduced the access to nectar reward and restricted an array of insect visitors.

Open access

Bożena Denisow, Sebastian Antoń and Grażyna Szymczak

Summary

Urban areas have a specific ecological environment and may help to sustain local pollinator populations by the cultivation of different ornamental plants with entomophilous flowers. This yearlong study examined the flowering pattern, abundance of flowering, pollen production as well as insect visitation of two cultivars of the ornamental shrub Potentilla fruticosa L. (‘Maanleys’ and ‘Blink’), grown in Lublin; a city in south-eastern Poland. P. fruticosa ‘Maanleys’ bloomed from the middle of May to the first decade of September and P. fruticosa ‘Blink’ from June until October. The pattern of diurnal flowering was similar for both cultivars and showed plasticity in the season. Flowers opened most intensively in the morning hours, and 80 - 90% of the daily installment of newly opened flowers expanded by 8.00 h GMT +2h. A delay in the peak of diurnal flowering was noted between the spring/summer and summer/autumn periods. The most intense blooming fell in the 2nd month of flowering. The mass of pollen produced per flower depended on both the number of anthers and the efficiency of archesporial tissues. The pollen output varied from 1.4 to 7.2 mg per 10 flowers (‘Maanleys’) and from 2.6 to 4.5 mg per 10 flowers (‘Blink’). The mass of pollen produced per individual shrub was substantially related to the abundance of blooming. The average estimated pollen productivity in the full flowering phase was low; 1 g (‘Maanleys’) and 1.5 g (‘Blink’) per 10 m2 of shrub crown. The flowers of Potentilla fruticosa attracted numerous insects, mainly solitary bees (33 - 43%), dipterans (31 - 42%), lepidopterans (4 - 14%), bumblebees (3 - 15%), and honey bees (3 - 4%). The Potentilla fruticosa ‘Maanleys’ and ‘Blink’ are propagated for specific ornamental arrangements and due to a long flowering period may be used in small urban courtyards for both decorative value and as a pollen delivering plants.

Open access

Bożena Denisow, Monika Strzałkowska-Abramek, Małgorzata Bożek and Anna Jeżak

Abstract

The flowering phenology and pollen production of three ornamental Centaurea species were investigated in the years 2009 and 2012-2013. The study objects, Centaurea montana L. = Cyanus montanus (L.) Hill, Centaurea mollis Waldst & Kit, and Centaurea dealbata Willd. were cultivated within an area of the UMCS Botanical Garden in Lublin, Poland (51° 14’ N, 22° 34’ E). Under the environmental conditions of SE Poland, the Centaurea species flowered continuously from mid-May to the first week of June. The mass of pollen in anthers was found to be species-related: 3.70 mg (C. montana), 4.02 mg (C. mollis), and 6.01 mg (C. dealbata) per 100 anthers. The total pollen yield was related to the mass of pollen produced in flowers and the abundance of blooming. Pollen grains were medium-sized, spheroid (C. dealbata) or prolato-spheroid (C. mollis and C. montana) in shape, and characterized by high viability (over 80% on average). The pollen provided by the plants of ornamental Centaurea species amounted to 6.0 - 7.9 g per m2 on average. The honeybee was the most frequent visitor of C. dealbata, accounting for 55.2% of the total pollinators, and bumblebee species predominated on the flowers of both C. montana (77.7%) and C. mollis (85.6%). Solitary bees and dipterans were also observed on the flowers of all species studied, but C. mollis was avoided by lepidopterans. Ornamental Centaurea species provide pollen reserves that could support communities of invertebrate pollinators, although the period of effective supply fluctuates annually due to changeable periods of blooming.

Open access

Bożena Denisow, Monika Strzałkowska-Abramek, Małgorzata Bożek and Anna Jeżak

Abstract

This study, conducted in 2008 and 2012 - 2013, evaluated the flowering pattern (seasonal and diurnal), the abundance of flowering, nectar, and pollen yield, and insect visitor activity for Corydalis solida (L.) Clairv. and C. cava Schweig. et Koerte. The populations occur in the ground layer of a deciduous forest (Fagetalia ordo, Querco-Fagetea class) in a natural gorge within the current area of the UMCS Botanical Garden in Lublin, Poland (51° 16’ N, 22° 30’ E). The phenology of Corydalis species showed distinct year-to-year plasticity (e.g., blooming period in March - April or in April - May; duration 18 - 42 days). The most intensive flower opening was noted in the early morning hours (85 - 90% of daily openings occurred between 6.00 and 10.00 h, GMT +2 h). The average sugar yield was similar at 4.6 kg/ha (C. cava) and 5.2 kg/ha (C. solida), but the average pollen production differed and reached 2.1 kg/ha (C. cava) and 4.1 kg/ha (C. solida). The flower-visitor interaction in Corydalis species involved both biological (early pattern of diurnal flowering, protandry, pollen presentation at the moment of anthesis) and morphological (nectar hidden in deep spur) features. Apis mellifera foragers predominated on both Corydalis species (mean of total visitors, 68.0% to C. solida; 62.5% to C. cava) and foraged mainly for pollen (82% of foragers), while bumblebee queens (mean of total visitors, 32.0% to C. solida; 37.5% to C. cava) collected mainly nectar (68.0% of foragers).

Open access

Małgorzata Wrzesień, Jacek Jachuła and Bożena Denisow

Abstract

In a modern agricultural landscape the assurance of food resources is a key issue in the maintaince and control of food niche for pollinators. In the present study we evaluated bee forage flora composition and diversity within railway embankments located in the agricultural landscape, SE Poland. We also analysed the abundance of pollinators that use food resources along railway embankments and recognized insect visitors preference for selected plant species. Railway embankments represent valuable refuge areas for bee forage flora (307 species, i.e. 76.1% of total flora) and pollinators (in total 4172 insect visits from 9 taxonomic groups). However, the richness and abundance of bee forage flora significantly differed between types of the railway distinguished by traffic volume. The highest diversity of bee forage flora is noted along the railway with intermediate traffic volume. Approx. 25% and 40% less bee forage species was identified along railways with low and high traffic volume. Likewise, bee forage flora differed considerably between microhabitat types, i.e. top vs. slope vs. bottom of the embankment. Providing support (e.g. mowing) seems to be an important management type in order to strengthen the native bee forage flora particularly on railway embankments along low and high traffic volume tracks. Such activity is crucial to counteract the spread of aggressive non-forage species (e.g. Calamagrostis epigejos, Artemisia vulgaris, Phragmites communis) and invasive species (e.g. Bunias orientalis, Solidago gigantea).

Open access

Bożena Denisow, Sebastian Antoń and Małgorzata Wrzesień

Abstract

During the monitoring of populations of Anemone sylvestris L. (Ranunculaceae), a protected species in Poland, we found that the seed set is impaired. The flower is considered an adaptation that has coevolved to achieve effective pollination and successful fertilization. Therefore we have focused on the morphological and anatomical characteristics of the flowers of A. sylvestris L. as a prelude to the study of the species’ pollination biology and plant breeding system. The large size of the flower (50.6 ± 16.4 mm in dimensions) and its bowl shape fulfil both the biotic pollination syndrome and the aerodynamic requirements for pollen dispersal and capture. The opening and closing of the perianth provide a shelter for beetles. The odourless perianth, absence of nectar, scarcity of pollen (approximately 200 000 pollen grains per flower) and its traits - small size (axis P = 18.52 ± 1.0 μm; E = 16.59 ± 0.9 μm), lack of balsam on the exine surface, starch accumulation in more than 95% of pollen grains correspond to the specialization in anemophily. The stigma is papillous, the dense hairs are situated between single carpels indicating adaptation to capturing dry pollen and specialization in the wind pollination syndrome. The flower of A. sylvestris is an example for an intermediate form between entomophily and anemophily, i.e. a secondary and more advanced feature among Ranunculaceae.

Open access

Jacek Jachuła, Małgorzata Wrzesień, Monika Strzałkowska-Abramek and Bożena Denisow

Abstract

There is growing evidence that food, in particular pollen, limitation is the strongest factor in pollinator decline. We have considered the potential effects of diversity in plant-community attributes as well as variations in the pollen and energy amount on the abundance and frequency of insect visitors to the Lamiaceae species Salvia pratensis L., S. verticillata L., Thymus serpyllum L., Betonica officinalis L. syn. Stachys officinalis (L.) Trevis., and Origanum vulgare L. The species were grown in two different habitat types (dry grassland vs. railway embankment) in the Lublin Upland, Poland. We found significant inter-species, inter-habitat, and inter-year disparities in the pollen mass and total energy amount per unit area. Canonical correspondence analysis (CCA) revealed that the blossom cover, species richness, and diversity noted at the plant community level significantly influenced the distribution of insect visitors to Lamiaceae species. The pollen caloric value and pollen abundance (but not the protein content in the pollen) had a considerable impact on the abundance and frequency of honeybees, bumblebees, and solitary bees in Lamiaceae flowers. Butterflies, beetles and flies did not respond to these factors. The model including all variables explained 66.4% of the observed variance. The studied Lamiaceae species, due to abundant flowering and good pollen nutritional value should be considered in the protocols to improve food resources, especially for social bees; however, disparities in pollen quantity and energy amount should not be ignored.