Rapid removal of magnetic particles from large volumes of suspensions

Summary Two simple and rapid procedures for removal of fine magnetic particles from large volumes of suspensions are described. One of them is based on the flow of magnetic suspension through the modified glass pipette placed on a flat magnet, in the second one the magnetic suspension is poured on a plastic film covering the magnet.     

Impact of spruce forest on rainfall interception and seasonal snow cover evolution in the Western Tatra Mountains,Slovakia

The paper analyzes the impacts of the spruce forest on precipitation interception and evolution of snow cover in the mountain catchment of the Jalovecky creek, the Western Tatra Mountains, Slovakia. Both processes were monitored at the elevation of 1420 m a.s.l.. Interception was measured from the end of August 2006 until November 2008 by a network of 13 raingauges. Mean interception over the studied period in forest window was 23%. Mean values for the dripping zone under tree branches, near stems of the trees and under the young trees were 28%, 65% and 44%, respectively. With exception of forest window, the interception at the same characteristic positions was highly variable. Calculated daily precipitation thresholds needed to fulfill the storage capacity of the canopy were about 0.8–0.9 mm. Differences in snow accumulation and melt in the open area (elevation 1500 m a.s.l.) and in the forest were measured in winters 2003–2008. Snow depths (SD) and water equivalents (SWE) were typically smaller in the forest, although the differences were getting smaller towards the end of snow season. SD and SWE in the forest were higher than in the open area for a short time before the end of season in winters 2003 and 2005. The correlations between SD and SWE in the open area and in the forest explained about 90% of variability. The energy balance snow model UEB satisfactorily simulated the evolution of snow cover in the forest and in the open area.     

Bat casualties by road traffic (Brno-Vienna)

We studied the impact of road E461, Brno-Vienna, on bat mortality, with the goal to predict this impact after the road has been reconstructed and turned into highway, R52. In the Czech territory, two proposed road sections of E461 were selected, 3.5 and 4.5 km long, and divided into segments 100 m in length. Bat carcasses were picked up from emergency stopping lanes, and bat activity was recorded by ultrasound detectors along the road and 100 m away on both sides from the central strip. From May to October 2007, 25 checks of bat mortality performed at weekly intervals revealed 119 bat carcasses representing 11 or 12 species.Pipistrellus nathusii, P. pygmaeus andMyotis daubentonii were the most frequent traffic casualties. The greatest mortality was documented from early July to mid-October, with a peak in September. Monitoring bat activity by ultrasound detectors (one night per month in May, June and September) yielded 12 bat species and 3 species couples (Myotis mystacinus/brandtii, M. emarginatus/alcathoe, Plecotus auritus/austriacus), mostly the same taxa as found dead on the road. Significantly greater bat numbers were revealed in the section where the road was situated between two artificial lakes, as compared to a road section without any lakes directly adjacent to the road. In the former section, significant correlation was found between the number of carcasses found and the activity detected, according to road segments.     

Changing climate and the phenological response of great tit and collared flycatcher populations in floodplain forest ecosystems in Central Europe

This study is based on 47 years of observations (1961–2007) on two common bird species, the Great Tit (Parus major) and the Collared Flycatcher (Ficedula albicollis), and a dominant tree species in their habitat, the English Oak (Quercus robur). The study took place at four research sites in the Czech Republic located in full-grown, multi-aged floodplain forests with no forestry management. An increase in air temperature over the evaluated period clearly influenced the length of phenological phases. The full foliage date of English Oak has advanced by 8.7 days during the past 47 years. Great Tit and Collared Flycatcher populations have reacted to the changing climate in the same way, with first laying date and mean laying date advancing by between 6.0 and 9.0 days. In all cases, the trends are highly significant and consistent over all sites. Despite the ongoing shift in phenological stages toward the beginning of the year, the change does not appear to have led to mistiming in the trophic food chain. Overall, this study shows almost identical rates of change in egg laying dates for both bird species in all the floodplain forests studied, and these trends are coherent with those of English Oak and peak herbivorous caterpillar activity.     

Pollinator visitation closely tracks diurnal patterns in pollen release

Premise

Animal-pollinated plants face a high risk of pollen loss during its transfer. To limit the negative effect of pollen losses by pollen consumption and heterospecific transfer, plant species may adjust and stratify their pollen availability during the day (i.e., “schedule” their pollen presentation) and attract pollinators in specific time frames.

Methods

We investigated diurnal patterns of pollen availability and pollinator visitation in three coflowering plant species: Succisa pratensis with open flowers and accessible pollen, pollinated mainly by pollen-feeding hoverflies; Centaurea jacea with open flowers and less accessible pollen, pollinated mainly by pollen-collecting bees; and Trifolium hybridum with closed flowers and pollen accessible only after the active opening of the flower, pollinated exclusively by bees.

Results

The three plant species differed in the peak pollen availability, tracked by the visitation activity of their pollinators. Succisa pratensis released all pollen in the morning, while pollinator activity was still low and peaked with a slight delay. In contrast, C. jacea and T. hybridum had distinct pollen presentation schedules, peaking in the early afternoon. The pollinator visitation to both of these species closely matched their pollen availability.

Conclusions

Stratifying pollen availability to pollinators during the day may be one of several mechanisms that allow coflowering plants to share their pollinators and decrease the probability of heterospecific pollen transfer.