Etablierung und Entwicklung der Deutschen Tamariske (Myricaria germanica) an der oberen Drau in Kärnten

Die Deutsche Tamariske (Myricaria germanica (L.) DESV.) ist eine charakteristische Begleitpflanze dynamischer Uferstandorte alpiner Fließgewässer. Infolge der anthropogenen Veränderung der Gebirgsbäche und Alpenflüsse und dem dadurch bedingten Verlust geeigneter Lebensräume gilt die Art heute alpenweit als gefährdet. In Kärnten kam die Art nur mehr auf wenigen Standorten vor, und auch an der oberen Drau galt M. germanica als ausgestorben. Die Deutsche Tamariske konnte im Zuge eines Ansiedlungsprojekts im Gebiet wieder etabliert werden, sie hat sich speziell in den revitalisierten Drauabschnitten weiter natürlich ausgebreitet. M. germanica kann neu entstandene Kies- und Schotterbänke schnell und in ausreichender Anzahl besiedeln, wenn ausreichend viele Diasporen auf günstigen „Safe Sites“ für die Keimung ausgebreitet werden bzw. die Samen entsprechend günstige Keimeigenschaften aufweisen. Damit eine Etablierung auf den Kies- und Schotterbänken in einem so dynamischen Habitat Erfolg hat, müssen sich die Keimlinge entsprechend schnell entwickeln. Ziel der Arbeit war es, grundlegende Fragen zur Biologie und Ökologie der Deutschen Tamariske als Leitart für dynamische Uferstandorte alpiner Fließgewässer zu beantworten. Dabei stehen ökophysiologische Aspekte im Vordergrund, im Speziellen wurde auf die einzelnen Lebensabschnitte und die in jeder dieser Phasen wichtigsten Schlüsselfunktionen der Art näher eingegangen. So können Aussagen über die Etablierung und die Entwicklung der Deutschen Tamariske an der oberen Drau getroffen werden. Zudem wurden phänologische Aspekte untersucht, der Blüh- und Fruchtansatz der Pflanzen wurde erhoben. Ermittelt wurde, wie viele Diasporen eine einzelne Pflanze im Schnitt produziert, und mittels Samenfallen wurde untersucht, wie weit die Diasporen transportiert werden. Des Weiteren wurde der Habitus der Pflanze näher untersucht. Freilanduntersuchungen zum Lebensraum wurden an verschiedenen Standorten durchgeführt. Detaillierte Daten wurden am Standort Kleblach zum Tamariskenbestand erhoben. Aufbauend auf diesen Informationen konnten Aussagen über die Ausbreitung der Art an der oberen Drau getroffen werden. Am Standort Kleblach wurde die Verteilung und Häufigkeit der verschiedenen Altersstadien erhoben, speziell wurde auf die Verteilung der Keimlinge und Einjährigen im Gelände eingegangen. Ergänzt wurden diese Freilandstudien durch Untersuchungen im Labor zur Keimfähigkeit von Samen im Wasser und zum Wurzelwachstum der Keimlinge unter kontrollierten Bedingungen. Altersbestimmungen ermöglichten wiederum, Aussagen über Altersstruktur und die Vegetationsdynamik in einem solchen Habitat zu treffen. Die Keimtests zeigen, dass M. germanica bereits im Wasser mit äußerst hohen Keimraten keimt und dass die Keimfähigkeit durch eine entsprechende Lagerung im Kühlschrank ausgedehnt werden kann. Die Art kann die günstigen feuchten Keimbedingungen im Wasser nutzen, vorgekeimte Sämlinge können über das Transportmedium Wasser neue Lebensräume erreichen. Zudem wird die Art anemochor verbreitet, was die Ergebnisse des Diasporeneintrags in den Samenfallen bestätigen, und zwar in einer sehr hohen Zahl in einer Distanz von über 100 m. Das Wurzelwachstum der Keimlinge ist eher gering, obwohl der Sämling in den ersten Monaten vor allem in das Wurzelwachstum investiert. Die verlangsamte Entwicklung der Keimlinge ist der Hauptgrund für die hohe Sterblichkeit und bedingt die niedrigen Etablierungsfrequenzen der Art. Die Ergebnisse zur Phänologie zeigen, dass der Blüh- bzw. Fruchtansatz und infolge die Samenproduktion mit der Größe der Tamarisken exponentiell ansteigt. Die am Standort Kleblach produzierte Diasporensumme ist überaus hoch. Altersbestimmungen zeigten, dass die Art relativ langlebig sein kann und dass der Durchmesser der Primärwurzel allein nicht auf das Alter der Pflanzen schließen lässt. Die Ergebnisse der Arbeit bestätigen, dass für die Deutsche Tamariske die Initialphase der kritischste Lebensabschnitt ist und dass die variierenden Standortbedingungen für die Etablierungschancen der Art entscheidend sind. Werden Restaurierungsmaßnahmen durchgeführt, ist vor allem darauf zu achten, dass im Gebiet genügend unterschiedliche Habitattypen vorhanden sind, die eine dauerhafte Besiedlung ermöglichen. Abhängig vom Lebensabschnitt benötigt die Art sehr unterschiedliche Standortbedingungen. Keimlinge benötigen offene, gut durchfeuchtete Standorte mit niedrigen Umlagerungsfrequenzen. Diese offenen Standorte sind aber immer ein Resultat einer zuvor sehr hohen Dynamik. Adulte Pflanzen können sich nur auf den ständig umgelagerten Standorten halten, die dadurch frei von Konkurrenten bleiben. Die Ergebnisse der Arbeit sollen als wissenschaftliche Grundlage für die Ausarbeitung mittel- bis langfristiger Schutzmaßnahmen für die Tamariske und deren Habitate verwendet werden und als Grundlage für die Erstellung von „Expertenregeln“ für ein Auenvegetations-Sukzessionsmodell dienen.The German Tamarisk (Myricaria germanica (L.) Desv.) is a characteristic species at alpine floodplains and was widespread along the river beds in the alpine region. Due to human impact M. germanica nearly lost its complete habitats, only a few suitable sites have remained. The species is nowadays national endangered. In Carinthia, the German Tamarisk was restricted to a few locations and described to be extinct at the upper Drau River. Just recently, M. germanica could be resettled in this area. Due to this initial plantation, the German Tamarisk was able to re-establish, especially at the revitalised river sections. M. germanica is a pioneer shrub which is able to recolonize recently formed gravel bars and sand banks. For the establishment of an adequate number of plants, a great number of seeds have to be dispersed in order to reach appropriate ‘Safe Sites’ for germination. Furthermore, seedlings need to develop rapidly so that establishment in such a dynamic habitat is successful. Since M. germanica is regarded as one of the most important indicator species for alpine rivers with natural dynamics, the main aim of this diploma thesis was to elucidate basic questions about biology and ecology of M. germanica, with a focus on ecophysiological aspects. The lifecycle of M. germanica, the major age states and the influence of the important key-functions during each state were analysed in order to evaluate the development and establishment of the German Tamarisk at the obere Drau River. In addition, phenological aspects were investigated. The magnitude of the infructescences per plant was determined and the number of seeds per plant was calculated. The seed rain was registered by traps to determine the distance of the seed dispersal. Furthermore, the habitus of M. germanica was reviewed. Fieldwork studies were conducted at different sites. Detailed data for the Myricaria-population at the study site Kleblach were collected to conclude on the dispersion of M. germanica at the upper Drau River. The occurrence and distribution of M. germanica was determined, i.e. the size and total number of individuals belonging to different age states were evaluated. Especially the amount and distribution of seedlings and one-year-old plants were mapped. These fieldwork results were combined with results from experiments under laboratory conditions, for instance germination tests in water and experiments dealing with the growth rate of primary roots from M. germanica. In addition, the age of some plants was estimated to conclude on the age structure and dynamic of the population in such a habitat. Germination tests in water show that M. germanica is able to germinate rapidly with a high percentage. The plant’s capability to germinate can be even expanded, if the seeds are kept in a refrigerator. M. germanica benefits from the moist conditions, and pre-germinated seeds are able to distribute via water to reach new ‘Safe Sites’. Results of the seed rain experiments verify that a great number of seeds are transported by wind, in fact over a distance more than 100 m. The growth rate of the primary roots is rather low, although the seedling invests a lot of energy in the first few months to develop a proper root system. The delayed growth rate of the primary root is probably the main reason why most seedlings are not able to settle, and as a consequence the rate of establishment is very low. The results of the phenological investigations show that M. germanica produces a remarkable amount of infructescences, and that the number of seeds rises exponentially with the plant’s size. Hence, the seed rain of the Myricaria-population at the location Kleblach is extraordinary high as well. The age determinations show that M. germanica is quite persistent. Surprisingly, there is no correlation between the age of a plant and the diameter of its primary root. The results approve that the initial phase is the most critical stage in the life cycle of this plant. Furthermore, the variable habitat conditions are important for the rate of establishment. If restorations of floodplains are realized, it would be important to provide appropriate sites with different habitat conditions which allow a colonisation and establishment of a stable population. Depending on the age stage of M. germanica, the species have different requirements to its habitat. Seedlings need open, moist sites with a low rate of redistribution. However, such a habitat is always a result of a previously high river dynamic. In contrast, adults can only survive, if the gravel bars are flooded constantly, because otherwise other shrubs will become dominant. The results obtained from this diploma work should provide basic information to elaborate medium- to long-term safety precautions for M. germanica and its habitat. These data could be used as a basis to establish so called “expert rules” for a vegetation-succession-model in floodplain

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

First measurement of the Z→μ+μ−Z\rightarrow \mu^+ \mu^- angular coefficients in the forward region of pppp collisions at s=13\sqrt{s}=13 TeV

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton

Precision measurement of forward ZZ boson production in proton-proton collisions at s=13\sqrt{s} = 13 TeV

A precision measurement of the $Z$ boson production cross-section at $\sqrt{s} = 13$ TeV in the forward region is presented, using $pp$ collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb$^{-1}$. The production cross-section is measured using $Z\rightarrow\mu^+\mu^-$ events within the fiducial region defined as pseudorapidity $2.020$ GeV/$c$ for both muons and dimuon invariant mass $60<M_{\mu\mu}<120$ GeV/$c^2$. The integrated cross-section is determined to be \begin{equation*} \sigma(Z\rightarrow\mu^+\mu^-) = 195.3 \pm 0.2 \pm 1.5 \pm 3.9~pb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions, including a prediction at next-to-next-to-leading order in perturbative quantum chromodynamics and a prediction with resummation

First measurement of the Z→μ+μ−Z\rightarrow \mu^+ \mu^- angular coefficients in the forward region of pppp collisions at s=13\sqrt{s}=13 TeV

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton