Warmer temperatures advance flowering in a spring plant more strongly than emergence of two solitary spring bee species.

Climate warming has the potential to disrupt plant-pollinator interactions or to increase competition of co-flowering plants for pollinators, due to species-specific phenological responses to temperature. However, studies focusing on the effect of temperature on solitary bee emergence and the flowering onset of their food plants under natural conditions are still rare. We studied the effect of temperature on the phenology of the two spring bees Osmia cornuta and Osmia bicornis, by placing bee cocoons on eleven grasslands differing in mean site temperature. On seven grasslands, we additionally studied the effect of temperature on the phenology of the red-list plant Pulsatilla vulgaris, which was the first flowering plant, and of co-flowering plants with later flowering. With a warming of 0.1°C, the abundance-weighted mean emergence of O. cornuta males advanced by 0.4 days. Females of both species did not shift their emergence. Warmer temperatures advanced the abundance-weighted mean flowering of P. vulgaris by 1.3 days per 0.1°C increase, but did not shift flowering onset of co-flowering plants. Competition for pollinators between P. vulgaris and co-flowering plants does not increase within the studied temperature range. We demonstrate that temperature advances plant flowering more strongly than bee emergence suggesting an increased risk of pollinator limitation for the first flowers of P. vulgaris.

Forest roadsides harbour less competitive habitats for a relict mountain plant (Pulsatilla vernalis) in lowlands.

The long-term survival of relict populations depends on the accessibility of appropriate sites (microrefugia). In recent times, due to the mass extinction of rare species that has resulted from the loss of natural habitats, the question is - Are there any human-made sites that can act as refugial habitats? We examined forest roadside populations of the mountain plant Pulsatilla vernalis in the last large lowland refugium in Central Europe. We compared the habitat conditions and community structure of roadsides with P. vernalis against the forest interior. Light availability and bryophyte composition were the main factors that distinguished roadsides. Pulsatilla occurred on sites that had more light than the forest interior, but were also more or less shaded by trees, so more light came as one-side illumination from the road. Roadsides had also a lower coverage of bryophytes that formed large, dense carpets. At the same time, they were characterised by a greater richness of vascular plants and 'small' bryophytes, which corresponds to a higher frequency of disturbances. In a warming and more fertile Anthropocene world, competition plays the main role in the transformation of forest communities, which is why relict populations have found refugia in extensively disturbed human-made habitats.

Redistribution pattern of fetal liver circulation in intrauterine growth restriction.

OBJECTIVE. Fetal liver blood supply is an important determinant of fetal growth and adaptation. Most fetal liver blood supply is from the umbilical vein, but the portal vein contributes 14-20% and studies of low-risk pregnancies suggest the splanchnic arteries are also involved in the homeostasis of fetal liver perfusion. Here we determine the circulatory pattern of the fetal liver in intrauterine growth restriction (IUGR). DESIGN. Cross-sectional study. POPULATION. Thirty-one IUGR fetuses (estimated fetal weight <5th centile). METHODS. Pulsatility index (PI) measurements of the umbilical, middle cerebral, splenic, hepatic, and superior mesenteric arteries were compared with a reference population and related to umbilical venous flow, umbilico-caval pressure gradient (assessed by ductus venosus peak velocity) and venous distribution within the liver (assessed by flow velocity in the left portal vein). RESULTS. Thirteen of 31 IUGR fetuses had umbilical artery PI > 97.5 centile and 13 showed a middle cerebral artery brain-sparing pattern (PI Z-score < - 2). In IUGR, umbilical venous flow was lower and less umbilical blood was distributed to the right liver lobe, while the umbilico-caval pressure gradient was kept normal. The hepatic and splenic arteries, but not the superior mesenteric artery, had low PI compared with the reference population. CONCLUSIONS. IUGR fetuses with increased or normal umbilical artery PI maintained venous perfusion pressure to the liver while distributing less umbilical blood to the right liver lobe. They showed regional splanchnic arterial redistribution with low splenic and hepatic artery PI, implying increased portal venous flow and direct arterial contribution to hepatic perfusion, respectively.