@article{AllanBossdorfDormannetal.2014, author = {Allan, Eric and Bossdorf, Oliver and Dormann, Carsten F. and Prati, Daniel and Gossner, Martin M. and Tscharntke, Teja and Bl{\"u}thgen, Nico and Bellach, Michaela and Birkhofer, Klaus and Boch, Steffen and B{\"o}hm, Stefan and B{\"o}rschig, Carmen and Chatzinotas, Antonis and Christ, Sabina and Daniel, Rolf and Diek{\"o}tter, Tim and Fischer, Christiane and Friedl, Thomas and Glaser, Karin and Hallmann, Christine and Hodac, Ladislav and H{\"o}lzel, Norbert and Jung, Kirsten and Klein, Alexandra-Maria and Klaus, Valentin H. and Kleinebecker, Till and Krauss, Jochen and Lange, Markus and Morris, E. Kathryn and M{\"u}ller, J{\"o}rg and Nacke, Heiko and Pasalic, Esther and Rillig, Matthias C. and Rothenwoehrer, Christoph and Schally, Peter and Scherber, Christoph and Schulze, Waltraud X. and Socher, Stephanie A. and Steckel, Juliane and Steffan-Dewenter, Ingolf and T{\"u}rke, Manfred and Weiner, Christiane N. and Werner, Michael and Westphal, Catrin and Wolters, Volkmar and Wubet, Tesfaye and Gockel, Sonja and Gorke, Martin and Hemp, Andreas and Renner, Swen C. and Sch{\"o}ning, Ingo and Pfeiffer, Simone and K{\"o}nig-Ries, Birgitta and Buscot, Francois and Linsenmair, Karl Eduard and Schulze, Ernst-Detlef and Weisser, Wolfgang W. and Fischer, Markus}, title = {Interannual variation in land-use intensity enhances grassland multidiversity}, series = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {111}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, number = {1}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.1312213111}, pages = {308 -- 313}, year = {2014}, abstract = {Although temporal heterogeneity is a well-accepted driver of biodiversity, effects of interannual variation in land-use intensity (LUI) have not been addressed yet. Additionally, responses to land use can differ greatly among different organisms; therefore, overall effects of land-use on total local biodiversity are hardly known. To test for effects of LUI (quantified as the combined intensity of fertilization, grazing, and mowing) and interannual variation in LUI (SD in LUI across time), we introduce a unique measure of whole-ecosystem biodiversity, multidiversity. This synthesizes individual diversity measures across up to 49 taxonomic groups of plants, animals, fungi, and bacteria from 150 grasslands. Multidiversity declined with increasing LUI among grasslands, particularly for rarer species and aboveground organisms, whereas common species and belowground groups were less sensitive. However, a high level of interannual variation in LUI increased overall multidiversity at low LUI and was even more beneficial for rarer species because it slowed the rate at which the multidiversity of rare species declined with increasing LUI. In more intensively managed grasslands, the diversity of rarer species was, on average, 18\% of the maximum diversity across all grasslands when LUI was static over time but increased to 31\% of the maximum when LUI changed maximally over time. In addition to decreasing overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation.}, language = {en} } @article{PenoneAllanSoliveresetal.2019, author = {Penone, Caterina and Allan, Eric and Soliveres, Santiago and Felipe-Lucia, Maria R. and Gossner, Martin M. and Seibold, Sebastian and Simons, Nadja K. and Schall, Peter and van der Plas, Fons and Manning, Peter and Manzanedo, Ruben D. and Boch, Steffen and Prati, Daniel and Ammer, Christian and Bauhus, Juergen and Buscot, Francois and Ehbrecht, Martin and Goldmann, Kezia and Jung, Kirsten and Mueller, Joerg and Mueller, Joerg C. and Pena, Rodica and Polle, Andrea and Renner, Swen C. and Ruess, Liliane and Schoenig, Ingo and Schrumpf, Marion and Solly, Emily F. and Tschapka, Marco and Weisser, Wolfgang W. and Wubet, Tesfaye and Fischer, Markus}, title = {Specialisation and diversity of multiple trophic groups are promoted by different forest features}, series = {Ecology letters}, volume = {22}, journal = {Ecology letters}, number = {1}, publisher = {Wiley}, address = {Hoboken}, issn = {1461-023X}, doi = {10.1111/ele.13182}, pages = {170 -- 180}, year = {2019}, abstract = {While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above- and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation.}, language = {en} } @article{FischerAndersSaalfrank2022, author = {Fischer, Eric Wolfgang and Anders, Janet and Saalfrank, Peter}, title = {Cavity-altered thermal isomerization rates and dynamical resonant localization in vibro-polaritonic chemistry}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {156}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {15}, publisher = {American Institute of Physics}, address = {Melville, NY}, issn = {0021-9606}, doi = {10.1063/5.0076434}, pages = {16}, year = {2022}, abstract = {It has been experimentally demonstrated that reaction rates for molecules embedded in microfluidic optical cavities are altered when compared to rates observed under "ordinary" reaction conditions. However, precise mechanisms of how strong coupling of an optical cavity mode to molecular vibrations affects the reactivity and how resonance behavior emerges are still under dispute. In the present work, we approach these mechanistic issues from the perspective of a thermal model reaction, the inversion of ammonia along the umbrella mode, in the presence of a single-cavity mode of varying frequency and coupling strength. A topological analysis of the related cavity Born-Oppenheimer potential energy surface in combination with quantum mechanical and transition state theory rate calculations reveals two quantum effects, leading to decelerated reaction rates in qualitative agreement with experiments: the stiffening of quantized modes perpendicular to the reaction path at the transition state, which reduces the number of thermally accessible reaction channels, and the broadening of the barrier region, which attenuates tunneling. We find these two effects to be very robust in a fluctuating environment, causing statistical variations of potential parameters, such as the barrier height. Furthermore, by solving the time-dependent Schrodinger equation in the vibrational strong coupling regime, we identify a resonance behavior, in qualitative agreement with experimental and earlier theoretical work. The latter manifests as reduced reaction probability when the cavity frequency omega(c) is tuned resonant to a molecular reactant frequency. We find this effect to be based on the dynamical localization of the vibro-polaritonic wavepacket in the reactant well.}, language = {en} } @article{SoliveresMaestreUlrichetal.2015, author = {Soliveres, Santiago and Maestre, Fernando T. and Ulrich, Werner and Manning, Peter and Boch, Steffen and Bowker, Matthew A. and Prati, Daniel and Delgado-Baquerizo, Manuel and Quero, Jose L. and Sch{\"o}ning, Ingo and Gallardo, Antonio and Weisser, Wolfgang W. and M{\"u}ller, J{\"o}rg and Socher, Stephanie A. and Garcia-Gomez, Miguel and Ochoa, Victoria and Schulze, Ernst-Detlef and Fischer, Markus and Allan, Eric}, title = {Intransitive competition is widespread in plant communities and maintains their species richness}, series = {Ecology letters}, volume = {18}, journal = {Ecology letters}, number = {8}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1461-023X}, doi = {10.1111/ele.12456}, pages = {790 -- 798}, year = {2015}, abstract = {Intransitive competition networks, those in which there is no single best competitor, may ensure species coexistence. However, their frequency and importance in maintaining diversity in real-world ecosystems remain unclear. We used two large data sets from drylands and agricultural grasslands to assess: (1) the generality of intransitive competition, (2) intransitivity-richness relationships and (3) effects of two major drivers of biodiversity loss (aridity and land-use intensification) on intransitivity and species richness. Intransitive competition occurred in >65\% of sites and was associated with higher species richness. Intransitivity increased with aridity, partly buffering its negative effects on diversity, but was decreased by intensive land use, enhancing its negative effects on diversity. These contrasting responses likely arise because intransitivity is promoted by temporal heterogeneity, which is enhanced by aridity but may decline with land-use intensity. We show that intransitivity is widespread in nature and increases diversity, but it can be lost with environmental homogenisation.}, language = {en} } @article{AllanManningAltetal.2015, author = {Allan, Eric and Manning, Pete and Alt, Fabian and Binkenstein, Julia and Blaser, Stefan and Bl{\"u}thgen, Nico and B{\"o}hm, Stefan and Grassein, Fabrice and H{\"o}lzel, Norbert and Klaus, Valentin H. and Kleinebecker, Till and Morris, E. Kathryn and Oelmann, Yvonne and Prati, Daniel and Renner, Swen C. and Rillig, Matthias C. and Schaefer, Martin and Schloter, Michael and Schmitt, Barbara and Sch{\"o}ning, Ingo and Schrumpf, Marion and Solly, Emily and Sorkau, Elisabeth and Steckel, Juliane and Steffen-Dewenter, Ingolf and Stempfhuber, Barbara and Tschapka, Marco and Weiner, Christiane N. and Weisser, Wolfgang W. and Werner, Michael and Westphal, Catrin and Wilcke, Wolfgang and Fischer, Markus}, title = {Land use intensification alters ecosystem multifunctionality via loss of biodiversity and changes to functional composition}, series = {Ecology letters}, volume = {18}, journal = {Ecology letters}, number = {8}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1461-023X}, doi = {10.1111/ele.12469}, pages = {834 -- 843}, year = {2015}, abstract = {Global change, especially land-use intensification, affects human well-being by impacting the delivery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is a major component of global change effects on multifunctionality in real-world ecosystems, as in experimental ones, remains unclear. Therefore, we assessed biodiversity, functional composition and 14 ecosystem services on 150 agricultural grasslands differing in land-use intensity. We also introduce five multifunctionality measures in which ecosystem services were weighted according to realistic land-use objectives. We found that indirect land-use effects, i.e. those mediated by biodiversity loss and by changes to functional composition, were as strong as direct effects on average. Their strength varied with land-use objectives and regional context. Biodiversity loss explained indirect effects in a region of intermediate productivity and was most damaging when land-use objectives favoured supporting and cultural services. In contrast, functional composition shifts, towards fast-growing plant species, strongly increased provisioning services in more inherently unproductive grasslands.}, language = {en} } @article{HeinzeBochFischeretal.2011, author = {Heinze, Eric and Boch, Steffen and Fischer, Markus and Hessenm{\"o}ller, Dominik and Klenk, Bernd and M{\"u}ller, J{\"o}rg and Prati, Daniel and Schulze, Ernst-Detlef and Seele, Carolin and Socher, Stephanie and Halle, Stefan}, title = {Habitat use of large ungulates in northeastern Germany in relation to forest management}, series = {Forest ecology and management}, volume = {261}, journal = {Forest ecology and management}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0378-1127}, doi = {10.1016/j.foreco.2010.10.022}, pages = {288 -- 296}, year = {2011}, abstract = {Estimating large herbivore density has been a major area of research in recent decades. Previous studies monitoring ungulate density, however, focused mostly on determining animal abundance, and did not interpret animal distribution in relation to habitat parameters. We surveyed large ungulates in the Biodiversity Exploratory Schorfheide-Chorin using faecal pellet group counts. This allowed us to explore the link between relative ungulate abundance, habitat use, and browsing damage on trees in a region with several types of forest, including unharvested and age-class beech forests, as well as age-class pine forests. Our results demonstrate that roe deer and fallow deer relative abundance is negatively correlated with large tree cover, and positively correlated with the cover of small shrubs (Rubus spec., Vaccinium spec.), and winter food supply. Habitat use of roe deer and fallow deer, as estimated by counting faecal pellet groups, revealed a preference for mature pine forests, and avoidance of deciduous forests. This differential habitat use is explained by different distributions of high quality food resources during winter. The response of deer to understory cover differed between roe deer and fallow deer at high cover percentages. The amount of browsing damage we observed on coniferous trees was not consistent with the relative deer abundance. Browsing damage was consistently higher on most deciduous trees, except for beech saplings which sustained less damage when roe deer density was low. Because roe deer is a highly selective feeder, it was reported to affect tree diversity by feeding only on trees with high nutritional value. Consequently, we propose that managing the number of all deer species by hunting is necessary to allow successful forest regeneration. Such an adjustment to deer numbers would need to account for both current tree diversity and alternative food resources. Our findings may be applicable to other forest landscapes in northeastern Germany including mature pine stands and differently harvested deciduous forests.}, language = {en} } @article{SoliveresvanderPlasManningetal.2016, author = {Soliveres, Santiago and van der Plas, Fons and Manning, Peter and Prati, Daniel and Gossner, Martin M. and Renner, Swen C. and Alt, Fabian and Arndt, Hartmut and Baumgartner, Vanessa and Binkenstein, Julia and Birkhofer, Klaus and Blaser, Stefan and Bl{\"u}thgen, Nico and Boch, Steffen and B{\"o}hm, Stefan and B{\"o}rschig, Carmen and Buscot, Francois and Diek{\"o}tter, Tim and Heinze, Johannes and H{\"o}lzel, Norbert and Jung, Kirsten and Klaus, Valentin H. and Kleinebecker, Till and Klemmer, Sandra and Krauss, Jochen and Lange, Markus and Morris, E. Kathryn and M{\"u}ller, J{\"o}rg and Oelmann, Yvonne and Overmann, J{\"o}rg and Pasalic, Esther and Rillig, Matthias C. and Schaefer, H. Martin and Schloter, Michael and Schmitt, Barbara and Sch{\"o}ning, Ingo and Schrumpf, Marion and Sikorski, Johannes and Socher, Stephanie A. and Solly, Emily F. and Sonnemann, Ilja and Sorkau, Elisabeth and Steckel, Juliane and Steffan-Dewenter, Ingolf and Stempfhuber, Barbara and Tschapka, Marco and T{\"u}rke, Manfred and Venter, Paul C. and Weiner, Christiane N. and Weisser, Wolfgang W. and Werner, Michael and Westphal, Catrin and Wilcke, Wolfgang and Wolters, Volkmar and Wubet, Tesfaye and Wurst, Susanne and Fischer, Markus and Allan, Eric}, title = {Biodiversity at multiple trophic levels is needed for ecosystem multifunctionality}, series = {Nature : the international weekly journal of science}, volume = {536}, journal = {Nature : the international weekly journal of science}, publisher = {Nature Publ. Group}, address = {London}, issn = {0028-0836}, doi = {10.1038/nature19092}, pages = {456 -- +}, year = {2016}, language = {en} } @article{FischerWertherBouaklineetal.2022, author = {Fischer, Eric Wolfgang and Werther, Michael and Bouakline, Foudhil and Grossmann, Frank and Saalfrank, Peter}, title = {Non-Markovian vibrational relaxation dynamics at surfaces}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {156}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {21}, publisher = {AIP Publishing}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/5.0092836}, pages = {16}, year = {2022}, abstract = {Vibrational dynamics of adsorbates near surfaces plays both an important role for applied surface science and as a model lab for studying fundamental problems of open quantum systems. We employ a previously developed model for the relaxation of a D-Si-Si bending mode at a D:Si(100)-(2 x 1) surface, induced by a "bath " of more than 2000 phonon modes [Lorenz and P. Saalfrank, Chem. Phys. 482, 69 (2017)], to extend previous work along various directions. First, we use a Hierarchical Effective Mode (HEM) model [Fischer et al., J. Chem. Phys. 153, 064704 (2020)] to study relaxation of higher excited vibrational states than hitherto done by solving a high-dimensional system-bath time-dependent Schrodinger equation (TDSE). In the HEM approach, (many) real bath modes are replaced by (much less) effective bath modes. Accordingly, we are able to examine scaling laws for vibrational relaxation lifetimes for a realistic surface science problem. Second, we compare the performance of the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) approach with that of the recently developed coherent-state-based multi-Davydov-D2 Ansatz [Zhou et al., J. Chem. Phys. 143, 014113 (2015)]. Both approaches work well, with some computational advantages for the latter in the presented context. Third, we apply open-system density matrix theory in comparison with basically "exact " solutions of the multi-mode TDSEs. Specifically, we use an open-system Liouville-von Neumann (LvN) equation treating vibration-phonon coupling as Markovian dissipation in Lindblad form to quantify effects beyond the Born-Markov approximation. Published under an exclusive license by AIP Publishing.}, language = {en} } @article{FischerWertherBouaklineetal.2020, author = {Fischer, Eric W. and Werther, Michael and Bouakline, Foudhil and Saalfrank, Peter}, title = {A hierarchical effective mode approach to phonon-driven multilevel vibrational relaxation dynamics at surfaces}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, volume = {153}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, number = {6}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/5.0017716}, pages = {15}, year = {2020}, abstract = {We discuss an efficient Hierarchical Effective Mode (HEM) representation of a high-dimensional harmonic oscillator bath, which describes phonon-driven vibrational relaxation of an adsorbate-surface system, namely, deuterium adsorbed on Si(100). Starting from the original Hamiltonian of the adsorbate-surface system, the HEM representation is constructed via iterative orthogonal transformations, which are efficiently implemented with Householder matrices. The detailed description of the HEM representation and its construction are given in the second quantization representation. The hierarchical nature of this representation allows access to the exact quantum dynamics of the adsorbate-surface system over finite time intervals, controllable via the truncation order of the hierarchy. To study the convergence properties of the effective mode representation, we solve the time-dependent Schrodinger equation of the truncated system-bath HEM Hamiltonian, with the help of the multilayer extension of the Multiconfigurational Time-Dependent Hartree (ML-MCTDH) method. The results of the HEM representation are compared with those obtained with a quantum-mechanical tier-model. The convergence of the HEM representation with respect to the truncation order of the hierarchy is discussed for different initial conditions of the adsorbate-surface system. The combination of the HEM representation with the ML-MCTDH method provides information on the time evolution of the system (adsorbate) and multiple effective modes of the bath (surface). This permits insight into mechanisms of vibration-phonon coupling of the adsorbate-surface system, as well as inter-mode couplings of the effective bath.}, language = {en} } @phdthesis{Fischer2022, author = {Fischer, Eric Wolfgang}, title = {Quantum vibrational dynamics in complex environments: from vibrational strong coupling in molecular cavity QED to phonon-induced adsorbate relaxation}, doi = {10.25932/publishup-56721}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-567214}, school = {Universit{\"a}t Potsdam}, pages = {viii, 171}, year = {2022}, abstract = {Molecules are often naturally embedded in a complex environment. As a consequence, characteristic properties of a molecular subsystem can be substantially altered or new properties emerge due to interactions between molecular and environmental degrees of freedom. The present thesis is concerned with the numerical study of quantum dynamical and stationary properties of molecular vibrational systems embedded in selected complex environments. In the first part, we discuss "strong-coupling" model scenarios for molecular vibrations interacting with few quantized electromagnetic field modes of an optical Fabry-P{\´e}rot cavity. We thoroughly elaborate on properties of emerging "vibrational polariton" light-matter hybrid states and examine the relevance of the dipole self-energy. Further, we identify cavity-induced quantum effects and an emergent dynamical resonance in a cavity-altered thermal isomerization model, which lead to significant suppression of thermal reaction rates. Moreover, for a single rovibrating diatomic molecule in an optical cavity, we observe non-adiabatic signatures in dynamics due to "vibro-polaritonic conical intersections" and discuss spectroscopically accessible "rovibro-polaritonic" light-matter hybrid states. In the second part, we study a weakly coupled but numerically challenging quantum mechanical adsorbate-surface model system comprising a few thousand surface modes. We introduce an efficient construction scheme for a "hierarchical effective mode" approach to reduce the number of surface modes in a controlled manner. In combination with the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) method, we examine the vibrational adsorbate relaxation dynamics from different excited adsorbate states by solving the full non-Markovian system-bath dynamics for the characteristic relaxation time scale. We examine half-lifetime scaling laws from vibrational populations and identify prominent non-Markovian signatures as deviations from Markovian reduced system density matrix theory in vibrational coherences, system-bath entanglement and energy transfer dynamics. In the final part of this thesis, we approach the dynamics and spectroscopy of vibronic model systems at finite temperature by formulating the ML-MCTDH method in the non-stochastic framework of thermofield dynamics. We apply our method to thermally-altered ultrafast internal conversion in the well-known vibronic coupling model of pyrazine. Numerically beneficial representations of multilayer wave functions ("ML-trees") are identified for different temperature regimes, which allow us to access thermal effects on both electronic and vibrational dynamics as well as spectroscopic properties for several pyrazine models.}, language = {en} }