BackgroundIntensively cultivated agricultural landscapes often suffer from substantial pollinator losses, which may be leading to decreasing pollination services for crops and wild flowering plants. Conservation measures that are easy to implement and accepted by farmers are needed to halt a further loss of pollinators in large areas under intensive agricultural management. Here we report the results of a replicated long-term study involving networks of mostly perennial flower strips covering 10% of a conventionally managed agricultural landscape in southwestern Germany.ResultsWe demonstrate the considerable success of these measures for wild bee and butterfly species richness over an observation period of 5 years. Overall species richness of bees and butterflies but also the numbers of specialist bee species clearly increased in the ecological enhancement areas as compared to the control areas without ecological enhancement measures. A three to five-fold increase in species richness was found after more than 2 years of enhancement of the areas with flower strips. Oligolectic bee species increased significantly only after the third year.ConclusionsIn our long-term field experiment we used a large variety of seed mixtures and temporal variation in seeding time, ensured continuity of the flower-strips by using perennial seed mixtures and distributed the measures over c. 10% of the landscape. This led to an increase in pollinator abundance, suggesting that these measures may be instrumental for the successful support of pollinators. These measures may ensure the availability of a network of diverse habitats and foraging resources for pollinators throughout the year, as well as nesting sites for many species. The measures are applied in-field and are suitable for application in areas under intensive agriculture. We propose that flower strip networks should be implemented much more in the upcoming CAP (common agricultural policy) reform in the European Union and promoted more by advisory services for farmers.Electronic supplementary materialThe online version of this article (10.1186/s12898-018-0210-z) contains supplementary material, which is available to authorized users.

Extreme summertime flood events are expected to become more frequent in European rivers due to climate change. In temperate areas, where winter floods are common, extreme floods occurring in summer, a period of high physiological activity, may seriously impact floodplain ecosystems. Here we report on the effects of the 2002 extreme summer flood on flora and fauna of the riverine grasslands of the Middle Elbe (Germany), comparing pre- and post-flooding data collected by identical methods. Plants, mollusks, and carabid beetles differed considerably in their response in terms of abundance and diversity. Plants and mollusks, displaying morphological and behavioral adaptations to flooding, showed higher survival rates than the carabid beetles, the adaptation strategies of which were mainly linked to life history. Our results illustrate the complexity of responses of floodplain organisms to extreme flood events. They demonstrate that the efficiency of resistance and resilience strategies is widely dependent on the mode of adaptation.

Extreme environmental events are predicted to increase in future due to global climate change. However, their effects on biodiversity still remain insufficiently understood because of the rarity and consequently the difficulty of studying the effects of extreme events. Here, we investigate the impacts on ground beetles of an unpredictable catastrophic flood event of the Elbe River in Germany in the year 2002 using pre-and post-flood data. We analysed the response of grassland communities differentially exposed to flooding and focused on the question of how long their response lagged behind this extreme flood.Ground beetles were sampled from 1998 to 1999 (pre-flood period) and from 2002 to 2006 (post-flood period) on 48 floodplain grassland plots with a stratified randomized sampling design. Community resilience was quantified by calculating changes in species richness, species abundances, Simpson diversity and beta diversity of ground beetle assemblages.Ground beetles showed low resistance but high resilience to the extreme flood. Species richness decreased strongly immediately after the flood but reached pre-flood values 2 years later. However, beta diversity remained relatively high in the subsequent years indicating persistent shifts in species composition and abundances. Contrary to our expectation, assemblages inhabiting plots prone to flooding, expected to be less sensitive to floods, did not recover faster than those on rarely inundated plots.We considered both the timing and the long duration of the flood as main reasons for the low community resistance to the flood. Strategies related to dispersal and habitat generality are identified to be crucial for the quick community recovery following the extreme flood. Our results endorse that extreme floods are integral parts of functioning floodplain ecosystems and that species can cope well even with such unpredictable extreme events, although recovery time tends to be longer than after normal floods.

The relationship of carabid beetle species occurrence patterns and environmental variables characterising the hydrological regime has been studied at the River Elbe in Central Germany. Both flood duration and groundwater depth had major influence on species assemblages as the ordination of study plots mainly followed a gradient along these two variables. The simultaneous ordination of the plots according to species occurrence and environmental parameters showed a highly significant joint structure with the first two axes of a co-inertia analysis, explaining >98% of the variance. A total of 27 species out of 129 caught fulfilled criteria of fidelity and specificity to the plots of the five clusters revealed by their abiotic conditions and were sufficiently abundant to be suitable indicators for one or a combination of clusters of plots. IntroductionNatural features of European floodplains are the result of dynamic geomorphological processes that lead to a high habitat diversity of these ecosystems (GERKEN, 1981;GERKEN, 1992a;WARD, 1998;WOLFERT et al., 2001). Due to their heterogeneity in space (habitat mosaics) and time (habitat change), natural riverine landscapes are characterised by a highly adapted and diverse flora and fauna (ROBINSON et al., 2002). However, in recent decades Central European floodplains were affected by a severe decline in biodiversity (GODREAU et al., 1999), due to loss of habitats (and thus species) mainly caused by changed water regimes and increased land use pressure on these ecosystems. Hence, floodplains are considered as landscapes with high conservation value and protection needs and have become a focus of conservation research (FOECKLER and BOHLE 1991;GERKEN, 1992b;AMOROS and PETTS, 1993;YOUNG, 2001;JESSEL, 2005;SCHOLZ et al., 2005).Floodplain management and conservation requires a sound understanding of species-environment relationships and suitable bioindicators to assess and monitor ecological conditions, since parameters characterising the hydrological regime are time consuming to measure and

No abstract