DOI: 10.5061/dryad.m905qftxf
title: Dryness, wetness and temporary flooding reduce floral resources of plant communities with adverse consequences for pollinator attraction

description: 1. Climate change alters precipitation regimes worldwide and is regarded
 as a major threat for pollinators and pollination services. Yet, not much
 is known on how wetter as well as drier conditions affect food resources
 for pollinators and pollinator attraction in a multi-species community
 context. It is unclear how community shifts under changed hydrological
 conditions might affect pollinators. 2. This mesocosm study addresses
 existing research gaps by investigating effects of drought, wetness and
 temporary flooding on floral resources and pollinator attraction within a
 plant community, initially including nine insect- and six wind-pollinated
 species. Floral resources were assessed over three growing seasons
 monitoring community descriptors (percentage of herbs and herbaceous
 species richness, presence of flowering insect-pollinated individuals),
 floral traits (flower height, size and weight, floral sugar content of one
 key species) and proxies for plant fitness (pollinator attraction, seed
 and flower weight of one key species). 3. Wetness and especially dryness
 decreased the species richness and biomass proportion of insect-pollinated
 herbaceous species and flowering herbaceous plant individuals occurred
 less frequently. Permanent wetness decreased the floral sugar content of
 the key species Trifolium pratense. Consequently, wet, temporary flooded
 and especially dry communities were visited by pollinators less often, and
 active pollinators spent less time within wet and flooded communities,
 while not at all visiting dry communities. Seed and flower weight of the
 obligate xenogamous T. pratense in flooded and dry communities was
 decreased, indicating negative consequences for plant fitness caused by a
 lack of pollination. 4. Synthesis: While dryness had negative effects for
 floral resources when looking at both, community descriptors and floral
 traits, negative effects of wetness and temporary flooding were mostly
 caused by a decrease of insect-pollinated herbaceous species. The study
 thus indicates that shifts in plant community composition are decisive for
 a predictive understanding of plant-pollinator interactions under
 environmental change, but have been neglected in past research. Changing
 precipitation patterns will adversely affect floral resources and
 pollinator attraction in agriculturally used temperate grassland, which
 might have widespread negative consequences for pollination services and
 food security in coming decades.
description: Data was collected in a pot experiment with sown grassland
 communities, as described in the article.  
description: water= hydrological conditions under which plant communitis grew
 from 2016 until 2019    <br> L=waterlogged    <br> D=dry  
  <br> M=mesic<br> PL=temporary flooding
 species: herbaceous plant species     Am=
 Achillea millefolium    <br> Bp= Bellis perennis    <br> Cb=
 Crepis biennis    <br> Cj= Centaurea jacea    <br> Ga= Galium
 mollugo agg.    <br> Pl= Plantago lanceolata    <br> Td=
 Trifolium dubium    <br> Tp= Trifolium pratense    <br> Vc=
 Vicia cracca     pot    pot number    
 no. visitors    number of insects touching flowers of herbaceous
 species    <br> time spent    seconds that insect stayed on flowers
 of a certain pot    <br> time spent without rest    seconds without
 insects resting on flowers for more than 60 s    <br> visitor  
  kind of visitor: BB= bumblebee, B= bee, D=dipteran species (visitor 1-4;
 one pot was never visited by more than four pollinators, time [s] 1 refers
 to time visitor 1 spent in the pot (and so on)<br> flow    number of
 flowers touched by respective visitor    <br> species richness  
  number of different insect-pollinated species in community    <br>
 present    was plant species present in community (1=yes, 0=no)  
  <br> occurring in flowering state    did species flower in a given
 year (1=yes, 0=no)    <br> abundance [%]    abundance of herbaceous
 species in %, based on biomass production data (does not add up to 100,
 because graminoid species were present in communities as well)<br>
 biomass production [g]    total biomass production of one pot in grams  
  <br> herb weight    weight of herbaceous species from one pot  
  <br> grass weight    weight of graminoid species from one pot  
  <br> singly potted: results of floral traits for plants that grew
 singly in pots in 2018     NA means that data were not
 available or could not be measured (e.g. no floral traits could be
 measured when flowering species was not present)