Browsing by Subject "pollination"

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  • Boulanger-Lapointe, Noemie; Järvinen, Antero; Partanen, Rauni; Herrmann, Thora Martina (2017)
    Annual fluctuations in the abundance of wild berries have repercussions on animals and humans who depend on this important resource. Although studies have tried to disentangle the effect of climate and herbivores on inter-annual berry yield, there are still many uncertainties as to which factors are driving productivity. In this research, we evaluated the effect of climate and predation by rodents and moths on the abundance of bilberry (Vaccinium myrtillus) flowers and berries at the Kilpisjarvi Biological Station in northwest Finnish Lapland. The data were collected from 1973 to 2014 in a forest and an alpine site, both undisturbed by human activities. This dataset is unique due to the length of the sampling period, the availability of flower, berry, and rodent abundance data as well as the undisturbed nature of the habitat. Previous summer temperatures, the abundance of rodents, and the presence of a moth outbreak were complementary factors explaining the abundance of flowers. Herbivores had a larger impact on flower production than climate, but both variables were important to understand reproductive effort. Contrary to results from experimental studies, warmer winters did not significantly influence reproductive success. The abundance of fruits was strongly correlated with pollinator activity; the forest site, with a larger pollinator network, had a higher reproductive success and spring conditions were linked to inter-annual variability in fruit production. Our results illustrate the importance of the location of the population within the species distribution range to understand plant sensitivity to climatic fluctuations with fruit production only influenced by current year summer temperatures at the alpine site. Finally, we observed a general increase in flower and fruit production at the alpine site, which was driven by large yields since the early 1990s. Fruit production at the forest site was comparatively stable throughout the study period.
  • Tiusanen, Mikko; Huotari, Tea; Hebert, Paul D. N.; Andersson, Tommi; Asmus, Ashley; Bety, Joel; Davis, Emma; Gale, Jennifer; Hardwick, Bess; Hik, David; Körner, Christian; Lanctot, Richard B.; Loonen, Maarten J. J. E.; Partanen, Rauni; Reischke, Karissa; Saalfeld, Sarah T.; Senez-Gagnon, Fanny; Smith, Paul A.; Sulavik, Jan; Syvanpera, Ilkka; Urbanowicz, Christine; Williams, Sian; Woodard, Paul; Zaika, Yulia; Roslin, Tomas (2019)
    Pollination is an ecosystem function of global importance. Yet, who visits the flower of specific plants, how the composition of these visitors varies in space and time and how such variation translates into pollination services are hard to establish. The use of DNA barcodes allows us to address ecological patterns involving thousands of taxa that are difficult to identify. To clarify the regional variation in the visitor community of a widespread flower resource, we compared the composition of the arthropod community visiting species in the genus Dryas (mountain avens, family Rosaceae), throughout Arctic and high-alpine areas. At each of 15 sites, we sampled Dryas visitors with 100 sticky flower mimics and identified specimens to Barcode Index Numbers (BINs) using a partial sequence of the mitochondrial COI gene. As a measure of ecosystem functioning, we quantified variation in the seed set of Dryas. To test for an association between phylogenetic and functional diversity, we characterized the structure of local visitor communities with both taxonomic and phylogenetic descriptors. In total, we detected 1,360 different BINs, dominated by Diptera and Hymenoptera. The richness of visitors at each site appeared to be driven by local temperature and precipitation. Phylogeographic structure seemed reflective of geological history and mirrored trans-Arctic patterns detected in plants. Seed set success varied widely among sites, with little variation attributable to pollinator species richness. This pattern suggests idiosyncratic associations, with function dominated by few and potentially different taxa at each site. Taken together, our findings illustrate the role of post-glacial history in the assembly of flower-visitor communities in the Arctic and offer insights for understanding how diversity translates into ecosystem functioning.
  • Tiusanen, Mikko; Kankaanpää, Tuomas; Schmidt, Niels Martin; Roslin, Tomas (2020)
    When plant species compete for pollinators, climate warming may cause directional change in flowering overlap, thereby shifting the strength of pollinator-mediated plant-plant interactions. Such shifts are likely accentuated in the rapidly warming Arctic. Targeting a plant community in Northeast Greenland, we asked (a) whether the relative phenology of plants is shifting with spatial variation in temperature, (b) whether local plants compete for pollination, and (c) whether shifts in climatic conditions are likely to affect this competition. We first searched for climatic imprints on relative species phenology along an elevational gradient. We then tested for signs of competition with increasing flower densities: reduced pollinator visits, reduced representation of plant species in pollen loads, and reduced seed production. Finally, we evaluated how climate change may affect this competition. Compared to a dominant species,Dryas integrifolia x octopetala, the relative timing of other species shifted along the environmental gradient, withSilene acaulisandPapaver radicatumflowering earlier toward higher elevation. This shift resulted in larger niche overlap, allowing for an increased potential for competition for pollination. Meanwhile,Dryasemerged as a superior competitor by attracting 97.2% of flower visits. HigherDryasdensity resulted in reduced insect visits and less pollen ofS. acaulisbeing carried by pollinators, causing reduced seed set byS. acaulis. Our results show that current variation in climate shifts the timing and flowering overlap between dominant and less-competitive plant species. With climate warming, such shifts in phenology within trophic levels may ultimately affect interactions between them, changing the strength of competition among plants.
  • Toivonen, Marjaana; Herzon, Irina; Toikkanen, Jenni; Kuussaari, Mikko (Enviroquest, 2021)
    Journal of Pollination Ecology 28, 153-166
    Uncultivated field margins are important refugia for pollinating insects in agricultural landscapes. However, the spill-over of pollination services from field margins to adjacent crops is poorly understood. This study (i) examined the effects of landscape heterogeneity on pollinator occurrence in permanent field margins and pollinator visitation to adjacent mass-flowering turnip rape (Brassica rapa ssp. oleifera) in boreal agricultural landscapes, and (ii) tested whether pollinator abundance and species richness in field margins predict abundance and species richness of crop visitors. Pollinators visiting the crop were more affected by landscape heterogeneity than pollinators in adjacent margins. Species richness, total abundance, and the abundance of syrphid flies visiting the crop increased with increasing landscape heterogeneity, whereas, in field margins, landscape heterogeneity had little effect on pollinators. In field-dominated homogeneous landscapes, wild pollinators rarely visited the crop even if they occurred in adjacent margins, whereas in heterogeneous landscapes, differences between the two habitats were smaller. Total pollinator abundance and species richness in field margins were poor predictors of pollinator visitation to adjacent crop. However, high abundances of honeybees and bumblebees in margins were related to high numbers of crop visitors from these taxa. Our results suggest that, while uncultivated field margins help pollinators persist in boreal agricultural landscapes, they do not always result in enhanced pollinator visitation to the adjacent crop. More studies quantifying pollination service delivery from semi-natural habitats to crops in different landscape settings will help develop management approaches to support crop pollination.
  • Mustalahti, Aino-Maija (Helsingfors universitet, 2011)
    Insect pollination increases seed production and improves the quality of the yield of various crop plants. In berry plants, such as strawberry and raspberry, the size and the quality of the fruits increase by successful insect pollination. Strawberry flowers are mainly not attractive to honeybees but raspberry is one of the main yield crops for honeybees. The aim of the study was to find out, how efficiently honeybees visit strawberry and raspberry flowers, concentrating on the honey bee visits on a single flower during one hour. Honey bees can be used as vectors of Gliocladium catenulatum to control Botrytis cinerea in strawberry and raspberry. The success of vector dissemination and its sufficiency to control Botrytis cinerea is evaluated based on flower visits. The data was collected from six farms in Eastern-Finland near to Suonenjoki, in the summer 2007. The flower visits were calculated during the flowering season of strawberry and raspberry in different weather conditions, times of the day and distances from the bee hives. Flowers were chosen randomly and they had to be open to be selected for observation. The observation time varied according to bee activity on the field. In average, honeybees visited on single strawberry flower 1.75 times per hour, and on single raspberry flower 4.27 times per hour. In both plants there were no significant differences in the flower visits according to the stage of the flowering. Time of the day (hour) correlated negatively with flower visits in both plants and temperature correlated positively to flower visits in both plants. Challenging weather conditions restricted the collecting of the data and the summer was rainy. Despite of that, honeybees visited the flowers of the both plants so that the pollination was proper and the control of Botrytis cinerea was sufficient. When planning the vector dissemination, especially in strawberry, the placement and the adequate number of bee hives should be taken into consideration. The need of nutrition should be great in the hives, to maximize the flower visits. Open brood can be inserted to hives or pollen storages can be removed from the hives to stimulate pollen collection. More information is needed on the effect of hive placement, competing plants and attractiveness of different Finnish strawberry cultivars to flower visits. It could be necessary to determine the nectar and pollen secretion of Finnish strawberry and raspberry cultivars.