@article{AllanWeisserFischeretal.2013, author = {Allan, Eric and Weisser, Wolfgang W. and Fischer, Markus and Schulze, Ernst-Detlef and Weigelt, Alexandra and Roscher, Christiane and Baade, Jussi and Barnard, Romain L. and Bessler, Holger and Buchmann, Nina and Ebeling, Anne and Eisenhauer, Nico and Engels, Christof and Fergus, Alexander J. F. and Gleixner, Gerd and Gubsch, Marlen and Halle, Stefan and Klein, Alexandra-Maria and Kertscher, Ilona and Kuu, Annely and Lange, Markus and Le Roux, Xavier and Meyer, Sebastian T. and Migunova, Varvara D. and Milcu, Alexandru and Niklaus, Pascal A. and Oelmann, Yvonne and Pasalic, Esther and Petermann, Jana S. and Poly, Franck and Rottstock, Tanja and Sabais, Alexander C. W. and Scherber, Christoph and Scherer-Lorenzen, Michael and Scheu, Stefan and Steinbeiss, Sibylle and Schwichtenberg, Guido and Temperton, Vicky and Tscharntke, Teja and Voigt, Winfried and Wilcke, Wolfgang and Wirth, Christian and Schmid, Bernhard}, title = {A comparison of the strength of biodiversity effects across multiple functions}, series = {Oecologia}, volume = {173}, journal = {Oecologia}, number = {1}, publisher = {Springer}, address = {New York}, issn = {0029-8549}, doi = {10.1007/s00442-012-2589-0}, pages = {223 -- 237}, year = {2013}, abstract = {In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 \% of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.}, language = {en} } @article{ScherberEisenhauerWeisseretal.2010, author = {Scherber, Christoph and Eisenhauer, Nico and Weisser, Wolfgang W. and Schmid, Bernhard and Voigt, Winfried and Fischer, Markus and Schukze, Ernst-Detlef and Roscher, Christiane and Weigelt, Alexandra and Allan, Eric and Beßler, Holger and Bonkowski, Michael and Buchmann, Nina and Buscot, Fran{\c{c}}ois and Clement, Lars W. and Ebeling, Anne and Engels, Christof and Halle, Stefan and Kertscher, Ilona and Klein, Alexandra-Maria and Koller, Robert and K{\"o}nig, Stephan and Kowalski, Esther and Kummer, Volker and Kuu, Annely and Lange, Markus and Lauterbach, Dirk}, title = {Bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment}, issn = {0028-0836}, year = {2010}, language = {en} } @article{FischerPfistererJoshietal.2004, author = {Fischer, Markus and Pfisterer, A. and Joshi, Jasmin Radha and Schmid, Bernhard}, title = {Rapid decay of diversity-productivity relationships after invasion of experimental plant communities}, year = {2004}, language = {en} } @misc{PratHajnýGrunewaldetal.2018, author = {Pr{\´a}t, Tom{\´a}š and Hajny', Jakub and Grunewald, Wim and Vasileva, Mina and Moln{\´a}r, Gergely and Tejos, Ricardo and Schmid, Markus and Sauer, Michael and Friml, Jiř{\´i}}, title = {WRKY23 is a component of the transcriptional network mediating auxin feedback on PIN polarity}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1123}, issn = {1866-8372}, doi = {10.25932/publishup-44633}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-446331}, pages = {20}, year = {2018}, abstract = {Auxin is unique among plant hormones due to its directional transport that is mediated by the polarly distributed PIN auxin transporters at the plasma membrane. The canalization hypothesis proposes that the auxin feedback on its polar flow is a crucial, plant-specific mechanism mediating multiple self-organizing developmental processes. Here, we used the auxin effect on the PIN polar localization in Arabidopsis thaliana roots as a proxy for the auxin feedback on the PIN polarity during canalization. We performed microarray experiments to find regulators of this process that act downstream of auxin. We identified genes that were transcriptionally regulated by auxin in an AXR3/IAA17-and ARF7/ARF19-dependent manner. Besides the known components of the PIN polarity, such as PID and PIP5K kinases, a number of potential new regulators were detected, among which the WRKY23 transcription factor, which was characterized in more detail. Gain-and loss-of-function mutants confirmed a role for WRKY23 in mediating the auxin effect on the PIN polarity. Accordingly, processes requiring auxin-mediated PIN polarity rearrangements, such as vascular tissue development during leaf venation, showed a higher WRKY23 expression and required the WRKY23 activity. Our results provide initial insights into the auxin transcriptional network acting upstream of PIN polarization and, potentially, canalization-mediated plant development.}, language = {en} } @article{PratHajnyGrunewaldetal.2018, author = {Prat, Tomas and Hajny, Jakub and Grunewald, Wim and Vasileva, Mina and Molnar, Gergely and Tejos, Ricardo and Schmid, Markus and Sauer, Michael and Friml, Jiř{\´i}}, title = {WRKY23 is a component of the transcriptional network mediating auxin feedback on PIN polarity}, series = {PLoS Genetics : a peer-reviewed, open-access journal}, volume = {14}, journal = {PLoS Genetics : a peer-reviewed, open-access journal}, number = {1}, publisher = {PLoS}, address = {San Fransisco}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1007177}, pages = {18}, year = {2018}, abstract = {Auxin is unique among plant hormones due to its directional transport that is mediated by the polarly distributed PIN auxin transporters at the plasma membrane. The canalization hypothesis proposes that the auxin feedback on its polar flow is a crucial, plant-specific mechanism mediating multiple self-organizing developmental processes. Here, we used the auxin effect on the PIN polar localization in Arabidopsis thaliana roots as a proxy for the auxin feedback on the PIN polarity during canalization. We performed microarray experiments to find regulators of this process that act downstream of auxin. We identified genes that were transcriptionally regulated by auxin in an AXR3/IAA17-and ARF7/ARF19-dependent manner. Besides the known components of the PIN polarity, such as PID and PIP5K kinases, a number of potential new regulators were detected, among which the WRKY23 transcription factor, which was characterized in more detail. Gain-and loss-of-function mutants confirmed a role for WRKY23 in mediating the auxin effect on the PIN polarity. Accordingly, processes requiring auxin-mediated PIN polarity rearrangements, such as vascular tissue development during leaf venation, showed a higher WRKY23 expression and required the WRKY23 activity. Our results provide initial insights into the auxin transcriptional network acting upstream of PIN polarization and, potentially, canalization-mediated plant development.}, language = {en} } @article{MeyerPtacnikHillebrandetal.2017, author = {Meyer, Sebastian Tobias and Ptacnik, Robert and Hillebrand, Helmut and Bessler, Holger and Buchmann, Nina and Ebeling, Anne and Eisenhauer, Nico and Engels, Christof and Fischer, Markus and Halle, Stefan and Klein, Alexandra-Maria and Oelmann, Yvonne and Roscher, Christiane and Rottstock, Tanja and Scherber, Christoph and Scheu, Stefan and Schmid, Bernhard and Schulze, Ernst-Detlef and Temperton, Vicky M. and Tscharntke, Teja and Voigt, Winfried and Weigelt, Alexandra and Wilcke, Wolfgang and Weisser, Wolfgang W.}, title = {Biodiversity-multifunctionality relationships depend on identity and number of measured functions}, series = {Nature Ecology \& Evolution}, volume = {2}, journal = {Nature Ecology \& Evolution}, number = {1}, publisher = {Nature Publ. Group}, address = {London}, issn = {2397-334X}, doi = {10.1038/s41559-017-0391-4}, pages = {44 -- 49}, year = {2017}, abstract = {Biodiversity ensures ecosystem functioning and provisioning of ecosystem services, but it remains unclear how biodiversity-ecosystem multifunctionality relationships depend on the identity and number of functions considered. Here, we demonstrate that ecosystem multifunctionality, based on 82 indicator variables of ecosystem functions in a grassland biodiversity experiment, increases strongly with increasing biodiversity. Analysing subsets of functions showed that the effects of biodiversity on multifunctionality were stronger when more functions were included and that the strength of the biodiversity effects depended on the identity of the functions included. Limits to multifunctionality arose from negative correlations among functions and functions that were not correlated with biodiversity. Our findings underline that the management of ecosystems for the protection of biodiversity cannot be replaced by managing for particular ecosystem functions or services and emphasize the need for specific management to protect biodiversity. More plant species from the experimental pool of 60 species contributed to functioning when more functions were considered. An individual contribution to multifunctionality could be demonstrated for only a fraction of the species.}, language = {en} } @article{FischervanKleunenSchmid2004, author = {Fischer, Markus and van Kleunen, Mark and Schmid, Bernhard}, title = {Experimental life-history evolution: selection on the growth form of a clonal plant on its plasticity}, issn = {1010- 061x}, year = {2004}, abstract = {The growth form along the continuum from compact phalanx plants to more loosely packed guerilla plants is an important life-history trait in clonal plants. Prerequisite for its evolution is heritable genetic variation. Starting with 102 genotypes of the stoloniferous herb Ranunculus reptans, we performed one selection experiment on spatial spread per rosette as measure of guerillaness (broad-sense heritability 0.198) and another on plasticity in this trait in response to competition (broad-sense heritability 0.067). After two generations, spatial spread was 36.9\% higher in the high line than in the low line (realized heritability +/- SE 0.149 +/- 0.039). Moreover, compared with the low line genotypes of the high line had fewer rosettes, a lower proportion of flowering rosettes, a higher proportion of rooted rosettes, more branches per rosette, longer internodes and longer leaves. In the second experiment, we found no significant direct response to selection for high and low plasticity in spatial spread (realized heritability +/- SE - 0.029 +/- 0.063), despite a significant correlated response in plasticity in the length of the first three stolon internodes. Our study indicates a high potential for further evolution of the clonal growth form in R. reptans, but not for its plasticity, and it demonstrates that the clonal growth form does not evolve independently of other clonal life- history characteristics}, language = {en} } @article{vanKleunenFischerSchmid2005, author = {van Kleunen, Mark and Fischer, Markus and Schmid, Bernhard}, title = {Three generations under low versus high neighborhood density affect the life history of a clonal plant through differential selection and genetic drift}, year = {2005}, abstract = {We tested whether neighborhood density affects the clonal life history of the stoloniferous plant Ranunculus reptans through selection and genetic drift. After three generations of sexual reproduction of 16 low- and 16 high- density lines, we studied traits related to growth form and reproduction in a common competition free environment. A 7.7\% lower branching frequency and slightly longer internodes indicated an evolutionary shift towards a less compact growth form under high neighborhood density, but because stolons grew also more vertically, horizontal spread per ramet was slightly decreased. Neighborhood density had no directional effects on the evolution of allocation to sexual and vegetative reproduction in R. reptans. Variation among replicated high-density lines was significantly lower than among replicated low-density lines in both growth form and reproductive characteristics, indicating less pronounced genetic drift under high neighborhood density. This study demonstrates that a clonal plant can respond to selection imposed by neighborhood density. Moreover, it shows that the effect of random genetic drift increases with decreasing neighborhood density. In a declining species, such as R. reptans in central Europe, this may lower the potential for adaptive evolutionary change and increase extinction risk}, language = {en} } @article{RuehlmannBuecheleOstermannetal.2018, author = {R{\"u}hlmann, Madlen and B{\"u}chele, Dominique and Ostermann, Markus and Bald, Ilko and Schmid, Thomas}, title = {Challenges in the quantification of nutrients in soils using laser-induced breakdown spectroscopy}, series = {Spectrochimica Acta Part B: Atomic Spectroscopy}, volume = {146}, journal = {Spectrochimica Acta Part B: Atomic Spectroscopy}, publisher = {Elsevier}, address = {Oxford}, issn = {0584-8547}, doi = {10.1016/j.sab.2018.05.003}, pages = {115 -- 121}, year = {2018}, abstract = {The quantification of the elemental content in soils with laser-induced breakdown spectroscopy (LIBS) is challenging because of matrix effects strongly influencing the plasma formation and LIBS signal. Furthermore, soil heterogeneity at the micrometre scale can affect the accuracy of analytical results. In this paper, the impact of univariate and multivariate data evaluation approaches on the quantification of nutrients in soil is discussed. Exemplarily, results for calcium are shown, which reflect trends also observed for other elements like magnesium, silicon and iron. For the calibration models, 16 certified reference soils were used. With univariate and multivariate approaches, the calcium mass fractions in 60 soils from different testing grounds in Germany were calculated. The latter approach consisted of a principal component analysis (PCA) of adequately pre-treated data for classification and identification of outliers, followed by partial least squares regression (PLSR) for quantification. For validation, the soils were also characterised with inductively coupled plasma optical emission spectroscopy (ICP OES) and X-ray fluorescence (XRF) analysis. Deviations between the LIBS quantification results and the reference analytical results are discussed.}, language = {en} } @article{CaselFernauGaspersetal.2020, author = {Casel, Katrin and Fernau, Henning and Gaspers, Serge and Gras, Benjamin and Schmid, Markus L.}, title = {On the complexity of the smallest grammar problem over fixed alphabets}, series = {Theory of computing systems}, volume = {65}, journal = {Theory of computing systems}, number = {2}, publisher = {Springer}, address = {New York}, issn = {1432-4350}, doi = {10.1007/s00224-020-10013-w}, pages = {344 -- 409}, year = {2020}, abstract = {In the smallest grammar problem, we are given a word w and we want to compute a preferably small context-free grammar G for the singleton language {w} (where the size of a grammar is the sum of the sizes of its rules, and the size of a rule is measured by the length of its right side). It is known that, for unbounded alphabets, the decision variant of this problem is NP-hard and the optimisation variant does not allow a polynomial-time approximation scheme, unless P = NP. We settle the long-standing open problem whether these hardness results also hold for the more realistic case of a constant-size alphabet. More precisely, it is shown that the smallest grammar problem remains NP-complete (and its optimisation version is APX-hard), even if the alphabet is fixed and has size of at least 17. The corresponding reduction is robust in the sense that it also works for an alternative size-measure of grammars that is commonly used in the literature (i. e., a size measure also taking the number of rules into account), and it also allows to conclude that even computing the number of rules required by a smallest grammar is a hard problem. On the other hand, if the number of nonterminals (or, equivalently, the number of rules) is bounded by a constant, then the smallest grammar problem can be solved in polynomial time, which is shown by encoding it as a problem on graphs with interval structure. However, treating the number of rules as a parameter (in terms of parameterised complexity) yields W[1]-hardness. Furthermore, we present an O(3(vertical bar w vertical bar)) exact exponential-time algorithm, based on dynamic programming. These three main questions are also investigated for 1-level grammars, i. e., grammars for which only the start rule contains nonterminals on the right side; thus, investigating the impact of the "hierarchical depth" of grammars on the complexity of the smallest grammar problem. In this regard, we obtain for 1-level grammars similar, but slightly stronger results.}, language = {en} }