The influence of herbaceous vegetaiton and its structural characteristics on sediment retention on floodplains

Sediment and nutrient retention are important ecosystem functions floodplain meadows fulfil. While it is known that the inundated floodplain vegetation purifies the water during floods, little is known about the processes behind. I investigated the effect of the vegetation structure on sedimentation at three hierarchical scales, leaf, patch, and floodplain scale and used two approaches, experiments and an in situ field study. In the leaf experiment (study 1) I inundated single leaves into sediment rich water. The results showed that leaf pubescence increased sedimentation on leaf surfaces and that for leaves without hairs, the sedimentation increased with decreasing leaf area. In the flume experiment (study 2) I investigated the effects of community characteristics of vegetation patches regarding their capacity to capture sediment. I manipulated the leaf pubescence, the community density, the community height and the structural diversity (high-high vs high-low growing species) of the patches. The results show that all four investigated community characteristics increased the sediment retention. In the second flume experiment (study 3), I investigated the effect of species richness of vegetation patches on sediment retention. The results showed the importance of the vegetation biomass and identity effects of single species, but no clear effect of species richness. For the in situ field measurements (study 4), I measured sedimentation during a real flood event along the Mulde River in Germany. With sediment traps and biomass harvests I quantified the sedimentation underneath as well as on the vegetation. The results showed that besides the vegetation biomass, the topographical parameter ‘hydrological distance’ (pathway of lowest elevation the water travels to the site) is important for sediment and especially nutrient retention. Even though sediment retention is highest close by the river, sedimentation is still reasonably high far insight the floodplain and especially nutrient retention (C, N and P) increase with hydrological distance. From the sum of results I can derive four management strategies for floodplains to increase the sediment retention. First, reduced mowing for more standing biomass during flood season, wherefore trade-offs with other ecosystem functions need to be evaluated carefully. Second, promotion of structural diversity, possible via species diversity. Third, promotion of species with characteristics that increase sediment, such as pubescent leaves. Forth, preserving or recreating topographic complexity in the floodplain. Overall, I showed that the specific structures of herbaceous vegetation are highly beneficial for sediment and nutrient retention on floodplains.:Table of contents 1. General introduction 6 1.1 The Mulde River and the “Wilde Mulde” project 7 1.2 Sediment retention on floodplains 8 1.3 Vegetation causes fine sedimentation 11 1.4 Structural characteristics 12 1.4.1 Structural identity of species 13 1.4.2 Structural identity of communities 14 1.4.3 Structural diversity of communities 15 1.5 Links between studies 17 2. Methodological features 19 2.1 Study area “Wilde Mulde” 19 2.2 Leaf roughness measurement 22 2.3 Experimental set up of the flume experiment 24 3. Original contributions 26 3.1 Paper 1 - Leaf area and pubescence drive sedimentation on leaves surfaces during flooding 26 3.2 Paper 2 – Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment 44 3.3 Paper 3 – Effects of plant species identity overrides diversity effects in explaining sedimentation within vegetation in a flume experiment 65 3.4 Paper 4 – Vegetation characteristics control sediment and nutrient retention on but not underneath vegetation in floodplain meadows 77 4. Discussion 107 4.1 Mechanistic parallels among scales 109 4.2 Effects of species diversity in relation to species identity 112 4.3 Transferability and its limitations 113 4.4 The ecosystem function of sediment retention 114 4.4.1 Floodplain management for sediment retention 115 4.4.2 Sediment retention in the context of other ecosystem functions 117 4.4.3 Floodplain management for sediment retention along the Lower Mulde River 119 5. Outlook 122 5.1 Leaf roughness 122 5.2 Diversity experiment 123 5.3 Approaches for new management strategies 124 5.4 Extrapolation with remote sensing 125 5.5 Sediment budget 126 6. Conclusion 128 7. References 130 8. Summary 143 9. Zusammenfassung 149 Acknowledgements 155 Author contribution statement 156 Curriculum vitae 164 List of publications 166 Selbstständigkeitserklärung 16

Biomass removal promotes plant diversity after short-term de-intensification of managed grasslands.

Land-use intensification is one of the main drivers threatening biodiversity in managed grasslands. Despite multiple studies investigating the effect of different land-use components in driving changes in plant biodiversity, their effects are usually studied in isolation. Here, we establish a full factorial design crossing fertilization with a combined treatment of biomass removal, on 16 managed grasslands spanning a gradient in land-use intensity, across three regions in Germany. Specifically, we investigate the interactive effects of different land-use components on plant composition and diversity using structural equation modelling. We hypothesize that fertilization and biomass removal alter plant biodiversity, directly and indirectly, mediated through changes in light availability. We found that, direct and indirect effects of biomass removal on plant biodiversity were larger than effects of fertilization, yet significantly differed between season. Furthermore, we found that indirect effects of biomass removal on plant biodiversity were mediated through changes in light availability, but also by changes in soil moisture. Our analysis thus supports previous findings, that soil moisture may operate as an alternative indirect mechanism by which biomass removal may affect plant biodiversity. Most importantly, our findings highlight that in the short-term biomass removal can partly compensate the negative effects of fertilization on plant biodiversity in managed grasslands. By studying the interactive nature of different land-use drivers we advance our understanding of the complex mechanisms controlling plant biodiversity in managed grasslands, which ultimately may help to maintain higher levels of biodiversity in grassland ecosystems

Crowd Research at School: Crossing Flows

It has become widely known that when two flows of pedestrians cross stripes emerge spontaneously by which the pedestrians of the two walking directions manage to pass each other in an orderly manner. In this work, we report about the results of an experiment on crossing flows which has been carried out at a German school. These results include that previously reported high flow volumes on the crossing area can be confirmed. The empirical results are furthermore compared to the results of a simulation model which succesfully could be calibrated to catch the specific properties of the population of participants.Comment: contribution to proceedings of Traffic and Granular Flow 2013 held in J\"ulich, German

Kindliche Verhaltensauffälligkeiten im ersten Lebensjahr und mütterliche Belastung in der Zeit der COVID-19-Pandemie

Theoretischer Hintergrund: Die COVID-19-Pandemie stellte in vielen Bereichen eine Belastung für Familien dar, insbesondere durch die einschneidenden Beschränkungen zu Beginn. Fragestellung: Wie wirkte sich dies auf die Belastung von Müttern mit Kindern im ersten Lebensjahr und auf die kindliche Verhaltensregulation aus? Methode: In einer Online-Befragung schätzten 577 Mütter das Schrei-‍, Schlaf- und Fütter-/Essverhalten ihrer Kinder (M = 7.3; 0 – 12 Mon., SD = 3.25) und ihre eigene Belastung ein, zudem Stresserleben, depressive Symptomatik, Partnerschaftszufriedenheit und Bonding. Ergebnisse: Schlafprobleme traten bei 21.7 %, schwer tröstbares und häufiges Schreien bei 12.3 % und exzessives Schreien bei 1.6 % der Kinder auf. Mindestens jede fünfte Mutter fühlte sich durch Schreien oder Schlafprobleme belastet. Mehr Stress, beeinträchtigtes Bonding und weniger Partnerschaftszufriedenheit erklärten 17 – 21 % der Varianz der mütterlichen Belastung durch Schrei- und Schlafverhalten. In der Zeit der stärksten Beschränkungen zeigte sich signifikant mehr Belastung in der Gruppe von Müttern, die von vermehrtem Schreien und verlängerter Einschlaflatenz berichteten, sowie mit mindestens einem weiteren Kind im Haushalt (MANOVA). Diskussion und Schlussfolgerung: Pandemiebedingt belastend für Mütter im ersten Jahr scheinen eingeschränkter Zugang zum Versorgungssystem, die Betreuung von mehr als einem Kind sowie das Alter des Kindes zu sein, während eine gute Beziehung zum Kind (Bonding) und/oder zum Partner (Partnerschaftszufriedenheit) abmildernd wirken.Theoretical background: The COVID-19 pandemic placed a burden on families in several respects, particularly because of the severe confinement imposed at its beginning. The confinement in spring 2020 led to social disruption and a reduction of supportive structures. In the first year of an infant’s life, the psychological well-being of a mother–child dyad is particularly susceptible to external stressful changes. Research question: How did the restrictions from the pandemic affect families with children in the first year of the infant’s life, particularly infant regulatory problems and related maternal stress? Methods: In an online survey, N = 577 mothers reported on their infants’ behavior (0 – 12 months of age, M = 7.3 months, SD = 3.3) regarding their crying, sleeping, and feeding/eating behavior as well as the respective distress experienced during the restrictions. Measures of current maternal well-being included overall perceived stress, depressivity, relationship satisfaction, and maternal bonding. Frequency/duration of infantile crying, sleep latency as well as night awakenings and feeding/eating problems were surveyed following clinical criteria (DC: 0 – 5) and percentile scores, respectively. The association of infant behavior and maternal distress was examined using linear regression and MANOVA. Results: Overall, at least one in five mothers felt burdened by her child’s regulatory problems during the time of severe restrictions. More than one in four mothers reported being highly or very highly distressed by her child’s crying. Sleeping problems, such as prolonged sleep latency (> 90th percentile) or several nightly awakenings, were reported for 21.7 % of the children. Difficulty to console and frequent crying were reported for 12.3 % and excessive crying for 1.6 % of the children. Higher levels of stress as well as increased impairment in maternal bonding and less relationship satisfaction explained 17 – 21 % of the variance of maternal distress from crying and sleeping problems. Significantly more distress was evident in the group of mothers who reported increased crying and prolonged latency to fall asleep (> 45 min) and with more than one child in the household during the period of most severe restrictions (MANOVA). A lack of medical, psychotherapeutic, and other means of care was reported by nearly a quarter of the respondents and was the only restriction that was significantly related to the perception of more stressful child behavior. Discussion and conclusion: Pandemic-related stressors for first-year mothers appear to be enhanced by limited access to the care system, caring for more than one child, the increasing age of the child, while a good relationship with the child (bonding) and/or partner (relationship) satisfaction provide buffers

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

The role of adjacent vegetation on the recovery of riparian flora : Effect of upstream and upland vascular vegetation after stream restoration in a boreal catchment

Restoration of streams that were formerly channelized for timber-floating has become increasingly common. Generally, this restoration returns boulders from riparian zones to streams, leading to wider, more heterogeneous channels with slower flows. The primary goal is to enhance fish populations, but riparian vegetation is also expected to be favoured. However, increases in floristic diversity have not been observed and reasons for this slow response are still unknown. One possible explanation might be the lack of colonist pools. I therefore investigated how surrounding plant compositions influence riparian recovery. The vascular plant flora was identified in riparian sites and in adjacent upstream riparian and upland sites. Four reach types were included: unchannelized, channelized, restored and demonstration restored. Species richness and floristic similarities among types of sites and reaches were compared. Correlations with upland and upstream channel slopes were made and the importance of variation in seed floating ability was tested. The results show that unchannelized reaches were floristically similar to their adjacent upstream riparian and upland sites, whereas channelized reaches showed more different floras. Restoration created a somewhat more homogeneous flora among the three site types and demonstration restored reaches were most similar to upstream sites. Soil moisture conditions (i.e. wetland vs. forest) in the uplands had stronger impacts on species similarities than upland or upstream channel slopes. I conclude that adjacent sites are important for floristic recovery of riparian reaches and that demonstration restoration is most advantageous for riparian recovery. I recommend protection of upland sites from forestry to facilitate recovery.Local- and landscape-scale effects on biodiversity after stream restoratio

The influence of herbaceous vegetaiton and its structural characteristics on sediment retention on floodplains

Sediment and nutrient retention are important ecosystem functions floodplain meadows fulfil. While it is known that the inundated floodplain vegetation purifies the water during floods, little is known about the processes behind. I investigated the effect of the vegetation structure on sedimentation at three hierarchical scales, leaf, patch, and floodplain scale and used two approaches, experiments and an in situ field study. In the leaf experiment (study 1) I inundated single leaves into sediment rich water. The results showed that leaf pubescence increased sedimentation on leaf surfaces and that for leaves without hairs, the sedimentation increased with decreasing leaf area. In the flume experiment (study 2) I investigated the effects of community characteristics of vegetation patches regarding their capacity to capture sediment. I manipulated the leaf pubescence, the community density, the community height and the structural diversity (high-high vs high-low growing species) of the patches. The results show that all four investigated community characteristics increased the sediment retention. In the second flume experiment (study 3), I investigated the effect of species richness of vegetation patches on sediment retention. The results showed the importance of the vegetation biomass and identity effects of single species, but no clear effect of species richness. For the in situ field measurements (study 4), I measured sedimentation during a real flood event along the Mulde River in Germany. With sediment traps and biomass harvests I quantified the sedimentation underneath as well as on the vegetation. The results showed that besides the vegetation biomass, the topographical parameter ‘hydrological distance’ (pathway of lowest elevation the water travels to the site) is important for sediment and especially nutrient retention. Even though sediment retention is highest close by the river, sedimentation is still reasonably high far insight the floodplain and especially nutrient retention (C, N and P) increase with hydrological distance. From the sum of results I can derive four management strategies for floodplains to increase the sediment retention. First, reduced mowing for more standing biomass during flood season, wherefore trade-offs with other ecosystem functions need to be evaluated carefully. Second, promotion of structural diversity, possible via species diversity. Third, promotion of species with characteristics that increase sediment, such as pubescent leaves. Forth, preserving or recreating topographic complexity in the floodplain. Overall, I showed that the specific structures of herbaceous vegetation are highly beneficial for sediment and nutrient retention on floodplains.:Table of contents 1. General introduction 6 1.1 The Mulde River and the “Wilde Mulde” project 7 1.2 Sediment retention on floodplains 8 1.3 Vegetation causes fine sedimentation 11 1.4 Structural characteristics 12 1.4.1 Structural identity of species 13 1.4.2 Structural identity of communities 14 1.4.3 Structural diversity of communities 15 1.5 Links between studies 17 2. Methodological features 19 2.1 Study area “Wilde Mulde” 19 2.2 Leaf roughness measurement 22 2.3 Experimental set up of the flume experiment 24 3. Original contributions 26 3.1 Paper 1 - Leaf area and pubescence drive sedimentation on leaves surfaces during flooding 26 3.2 Paper 2 – Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment 44 3.3 Paper 3 – Effects of plant species identity overrides diversity effects in explaining sedimentation within vegetation in a flume experiment 65 3.4 Paper 4 – Vegetation characteristics control sediment and nutrient retention on but not underneath vegetation in floodplain meadows 77 4. Discussion 107 4.1 Mechanistic parallels among scales 109 4.2 Effects of species diversity in relation to species identity 112 4.3 Transferability and its limitations 113 4.4 The ecosystem function of sediment retention 114 4.4.1 Floodplain management for sediment retention 115 4.4.2 Sediment retention in the context of other ecosystem functions 117 4.4.3 Floodplain management for sediment retention along the Lower Mulde River 119 5. Outlook 122 5.1 Leaf roughness 122 5.2 Diversity experiment 123 5.3 Approaches for new management strategies 124 5.4 Extrapolation with remote sensing 125 5.5 Sediment budget 126 6. Conclusion 128 7. References 130 8. Summary 143 9. Zusammenfassung 149 Acknowledgements 155 Author contribution statement 156 Curriculum vitae 164 List of publications 166 Selbstständigkeitserklärung 16

The influence of herbaceous vegetaiton and its structural characteristics on sediment retention on floodplains

Sediment and nutrient retention are important ecosystem functions floodplain meadows fulfil. While it is known that the inundated floodplain vegetation purifies the water during floods, little is known about the processes behind. I investigated the effect of the vegetation structure on sedimentation at three hierarchical scales, leaf, patch, and floodplain scale and used two approaches, experiments and an in situ field study. In the leaf experiment (study 1) I inundated single leaves into sediment rich water. The results showed that leaf pubescence increased sedimentation on leaf surfaces and that for leaves without hairs, the sedimentation increased with decreasing leaf area. In the flume experiment (study 2) I investigated the effects of community characteristics of vegetation patches regarding their capacity to capture sediment. I manipulated the leaf pubescence, the community density, the community height and the structural diversity (high-high vs high-low growing species) of the patches. The results show that all four investigated community characteristics increased the sediment retention. In the second flume experiment (study 3), I investigated the effect of species richness of vegetation patches on sediment retention. The results showed the importance of the vegetation biomass and identity effects of single species, but no clear effect of species richness. For the in situ field measurements (study 4), I measured sedimentation during a real flood event along the Mulde River in Germany. With sediment traps and biomass harvests I quantified the sedimentation underneath as well as on the vegetation. The results showed that besides the vegetation biomass, the topographical parameter ‘hydrological distance’ (pathway of lowest elevation the water travels to the site) is important for sediment and especially nutrient retention. Even though sediment retention is highest close by the river, sedimentation is still reasonably high far insight the floodplain and especially nutrient retention (C, N and P) increase with hydrological distance. From the sum of results I can derive four management strategies for floodplains to increase the sediment retention. First, reduced mowing for more standing biomass during flood season, wherefore trade-offs with other ecosystem functions need to be evaluated carefully. Second, promotion of structural diversity, possible via species diversity. Third, promotion of species with characteristics that increase sediment, such as pubescent leaves. Forth, preserving or recreating topographic complexity in the floodplain. Overall, I showed that the specific structures of herbaceous vegetation are highly beneficial for sediment and nutrient retention on floodplains.:Table of contents 1. General introduction 6 1.1 The Mulde River and the “Wilde Mulde” project 7 1.2 Sediment retention on floodplains 8 1.3 Vegetation causes fine sedimentation 11 1.4 Structural characteristics 12 1.4.1 Structural identity of species 13 1.4.2 Structural identity of communities 14 1.4.3 Structural diversity of communities 15 1.5 Links between studies 17 2. Methodological features 19 2.1 Study area “Wilde Mulde” 19 2.2 Leaf roughness measurement 22 2.3 Experimental set up of the flume experiment 24 3. Original contributions 26 3.1 Paper 1 - Leaf area and pubescence drive sedimentation on leaves surfaces during flooding 26 3.2 Paper 2 – Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment 44 3.3 Paper 3 – Effects of plant species identity overrides diversity effects in explaining sedimentation within vegetation in a flume experiment 65 3.4 Paper 4 – Vegetation characteristics control sediment and nutrient retention on but not underneath vegetation in floodplain meadows 77 4. Discussion 107 4.1 Mechanistic parallels among scales 109 4.2 Effects of species diversity in relation to species identity 112 4.3 Transferability and its limitations 113 4.4 The ecosystem function of sediment retention 114 4.4.1 Floodplain management for sediment retention 115 4.4.2 Sediment retention in the context of other ecosystem functions 117 4.4.3 Floodplain management for sediment retention along the Lower Mulde River 119 5. Outlook 122 5.1 Leaf roughness 122 5.2 Diversity experiment 123 5.3 Approaches for new management strategies 124 5.4 Extrapolation with remote sensing 125 5.5 Sediment budget 126 6. Conclusion 128 7. References 130 8. Summary 143 9. Zusammenfassung 149 Acknowledgements 155 Author contribution statement 156 Curriculum vitae 164 List of publications 166 Selbstständigkeitserklärung 16

Plant structural diversity alters sediment retention on and underneath herbaceous vegetation in a flume experiment

Sediment retention is a key ecosystem function provided by floodplains to filter sediments and nutrients from the river water during floods. Floodplain vegetation is an important driver of fine sediment retention. We aim to understand which structural properties of the vegetation are most important for capturing sediments. In a hydraulic flume experiment, we investigated this by disentangling sedimentation on and underneath 96 vegetation patches (40 cm x 60 cm). We planted two grass and two herb species in each patch and conducted a full-factorial manipulation of 1) vegetation density, 2) vegetation height, 3) structural diversity (small-tall vs tall-tall species combinations) and 4) leaf pubescence (based on trait information). We inundated the vegetation patches for 21 h in a flume with silt- and clay-rich water and subsequently measured the amount of accumulated sediment on the vegetation and on a fleece as ground underneath it. We quantified the sediment by washing it off the biomass and off the fleece, drying the sediment and weighting it. Our results showed that all manipulated vegetation properties combined (vegetation density and height, and the interaction of structural diversity and leaf pubescence) explained sedimentation on the vegetation (total R2 = 0.34). The sedimentation underneath the vegetation was explained by the structural diversity and the leaf pubescence (total R2 = 0.11). We further found that vegetation biomass positively affected the sedimentation on and underneath the vegetation. These findings are crucial for floodplain management strategies with the aim to increase sediment retention. Based on our findings, we can identify management strategies and target plant communities that are able to maximize a floodplain’s ability to capture sediments.</p

Effects of plant species identity override diversity effects in explaining sedimentation within vegetation in a flume experiment

During floods, sediments suspended in river water deposit on floodplains. Thus, floodplains are a key to improving river water quality. Yet, the factors that determine the amount of fine sediment that deposits on floodplains are largely unknown. Plant diversity typically increases structural diversity, whereas the vegetation structure and the structural characteristics of individual species are known to influence sedimentation. We hypothesised that species diversity, in addition to species identity, may promote sediment retention. Our study aimed to disentangle the effects of species richness and species identity, via differences in vegetation structure, on sediment retention within herbaceous vegetation patches. In a flume experiment, we investigated sedimentation on 30 vegetation patches (40 × 60 cm2). We created patches with five different species-richness levels (3, 4, 6, 8, and 11 species), each replicated six times. Species were randomly selected from 14 common floodplain species. We inundated the patches with silt- and clay-rich water and measured the amount of accumulated sediment on the vegetation and on the ground underneath it. Species richness significantly increased sedimentation underneath the vegetation (R2 = 0.17). However, including species identity effects in a structural equation model, we showed that individual species' presence largely drove these effects. Alopecurus pratensis had a direct negative effect on sedimentation on the vegetation, whereas Bromus inermis and Elymus repens had indirect positive effects through an increase in total biomass (R2 = 0.42). Elymus repens had a direct negative, and Urtica dioica a direct positive effect on sedimentation underneath the vegetation (R2 = 0.38). Our results indicate that selecting the most effective species, rather than as many species as possible, may have the greatest benefits for promoting sedimentation. Overall, we conclude that floodplain management that aims to increase sediment retention should alter the vegetation structure of meadows by increasing vegetation biomass.</p