TY  - JOUR
A1  - Aarts, Alexander A.
A1  - Anderson, Joanna E.
A1  - Anderson, Christopher J.
A1  - Attridge, Peter R.
A1  - Attwood, Angela
A1  - Axt, Jordan
A1  - Babel, Molly
A1  - Bahnik, Stepan
A1  - Baranski, Erica
A1  - Barnett-Cowan, Michael
A1  - Bartmess, Elizabeth
A1  - Beer, Jennifer
A1  - Bell, Raoul
A1  - Bentley, Heather
A1  - Beyan, Leah
A1  - Binion, Grace
A1  - Borsboom, Denny
A1  - Bosch, Annick
A1  - Bosco, Frank A.
A1  - Bowman, Sara D.
A1  - Brandt, Mark J.
A1  - Braswell, Erin
A1  - Brohmer, Hilmar
A1  - Brown, Benjamin T.
A1  - Brown, Kristina
A1  - Bruening, Jovita
A1  - Calhoun-Sauls, Ann
A1  - Callahan, Shannon P.
A1  - Chagnon, Elizabeth
A1  - Chandler, Jesse
A1  - Chartier, Christopher R.
A1  - Cheung, Felix
A1  - Christopherson, Cody D.
A1  - Cillessen, Linda
A1  - Clay, Russ
A1  - Cleary, Hayley
A1  - Cloud, Mark D.
A1  - Cohn, Michael
A1  - Cohoon, Johanna
A1  - Columbus, Simon
A1  - Cordes, Andreas
A1  - Costantini, Giulio
A1  - Alvarez, Leslie D. Cramblet
A1  - Cremata, Ed
A1  - Crusius, Jan
A1  - DeCoster, Jamie
A1  - DeGaetano, Michelle A.
A1  - Della Penna, Nicolas
A1  - den Bezemer, Bobby
A1  - Deserno, Marie K.
A1  - Devitt, Olivia
A1  - Dewitte, Laura
A1  - Dobolyi, David G.
A1  - Dodson, Geneva T.
A1  - Donnellan, M. Brent
A1  - Donohue, Ryan
A1  - Dore, Rebecca A.
A1  - Dorrough, Angela
A1  - Dreber, Anna
A1  - Dugas, Michelle
A1  - Dunn, Elizabeth W.
A1  - Easey, Kayleigh
A1  - Eboigbe, Sylvia
A1  - Eggleston, Casey
A1  - Embley, Jo
A1  - Epskamp, Sacha
A1  - Errington, Timothy M.
A1  - Estel, Vivien
A1  - Farach, Frank J.
A1  - Feather, Jenelle
A1  - Fedor, Anna
A1  - Fernandez-Castilla, Belen
A1  - Fiedler, Susann
A1  - Field, James G.
A1  - Fitneva, Stanka A.
A1  - Flagan, Taru
A1  - Forest, Amanda L.
A1  - Forsell, Eskil
A1  - Foster, Joshua D.
A1  - Frank, Michael C.
A1  - Frazier, Rebecca S.
A1  - Fuchs, Heather
A1  - Gable, Philip
A1  - Galak, Jeff
A1  - Galliani, Elisa Maria
A1  - Gampa, Anup
A1  - Garcia, Sara
A1  - Gazarian, Douglas
A1  - Gilbert, Elizabeth
A1  - Giner-Sorolla, Roger
A1  - Glöckner, Andreas
A1  - Göllner, Lars
A1  - Goh, Jin X.
A1  - Goldberg, Rebecca
A1  - Goodbourn, Patrick T.
A1  - Gordon-McKeon, Shauna
A1  - Gorges, Bryan
A1  - Gorges, Jessie
A1  - Goss, Justin
A1  - Graham, Jesse
A1  - Grange, James A.
A1  - Gray, Jeremy
A1  - Hartgerink, Chris
A1  - Hartshorne, Joshua
A1  - Hasselman, Fred
A1  - Hayes, Timothy
A1  - Heikensten, Emma
A1  - Henninger, Felix
A1  - Hodsoll, John
A1  - Holubar, Taylor
A1  - Hoogendoorn, Gea
A1  - Humphries, Denise J.
A1  - Hung, Cathy O. -Y.
A1  - Immelman, Nathali
A1  - Irsik, Vanessa C.
A1  - Jahn, Georg
A1  - Jaekel, Frank
A1  - Jekel, Marc
A1  - Johannesson, Magnus
A1  - Johnson, Larissa G.
A1  - Johnson, David J.
A1  - Johnson, Kate M.
A1  - Johnston, William J.
A1  - Jonas, Kai
A1  - Joy-Gaba, Jennifer A.
A1  - Kappes, Heather Barry
A1  - Kelso, Kim
A1  - Kidwell, Mallory C.
A1  - Kim, Seung Kyung
A1  - Kirkhart, Matthew
A1  - Kleinberg, Bennett
A1  - Knezevic, Goran
A1  - Kolorz, Franziska Maria
A1  - Kossakowski, Jolanda J.
A1  - Krause, Robert Wilhelm
A1  - Krijnen, Job
A1  - Kuhlmann, Tim
A1  - Kunkels, Yoram K.
A1  - Kyc, Megan M.
A1  - Lai, Calvin K.
A1  - Laique, Aamir
A1  - Lakens, Daniel
A1  - Lane, Kristin A.
A1  - Lassetter, Bethany
A1  - Lazarevic, Ljiljana B.
A1  - LeBel, Etienne P.
A1  - Lee, Key Jung
A1  - Lee, Minha
A1  - Lemm, Kristi
A1  - Levitan, Carmel A.
A1  - Lewis, Melissa
A1  - Lin, Lin
A1  - Lin, Stephanie
A1  - Lippold, Matthias
A1  - Loureiro, Darren
A1  - Luteijn, Ilse
A1  - Mackinnon, Sean
A1  - Mainard, Heather N.
A1  - Marigold, Denise C.
A1  - Martin, Daniel P.
A1  - Martinez, Tylar
A1  - Masicampo, E. J.
A1  - Matacotta, Josh
A1  - Mathur, Maya
A1  - May, Michael
A1  - Mechin, Nicole
A1  - Mehta, Pranjal
A1  - Meixner, Johannes
A1  - Melinger, Alissa
A1  - Miller, Jeremy K.
A1  - Miller, Mallorie
A1  - Moore, Katherine
A1  - Möschl, Marcus
A1  - Motyl, Matt
A1  - Müller, Stephanie M.
A1  - Munafo, Marcus
A1  - Neijenhuijs, Koen I.
A1  - Nervi, Taylor
A1  - Nicolas, Gandalf
A1  - Nilsonne, Gustav
A1  - Nosek, Brian A.
A1  - Nuijten, Michele B.
A1  - Olsson, Catherine
A1  - Osborne, Colleen
A1  - Ostkamp, Lutz
A1  - Pavel, Misha
A1  - Penton-Voak, Ian S.
A1  - Perna, Olivia
A1  - Pernet, Cyril
A1  - Perugini, Marco
A1  - Pipitone, R. Nathan
A1  - Pitts, Michael
A1  - Plessow, Franziska
A1  - Prenoveau, Jason M.
A1  - Rahal, Rima-Maria
A1  - Ratliff, Kate A.
A1  - Reinhard, David
A1  - Renkewitz, Frank
A1  - Ricker, Ashley A.
A1  - Rigney, Anastasia
A1  - Rivers, Andrew M.
A1  - Roebke, Mark
A1  - Rutchick, Abraham M.
A1  - Ryan, Robert S.
A1  - Sahin, Onur
A1  - Saide, Anondah
A1  - Sandstrom, Gillian M.
A1  - Santos, David
A1  - Saxe, Rebecca
A1  - Schlegelmilch, Rene
A1  - Schmidt, Kathleen
A1  - Scholz, Sabine
A1  - Seibel, Larissa
A1  - Selterman, Dylan Faulkner
A1  - Shaki, Samuel
A1  - Simpson, William B.
A1  - Sinclair, H. Colleen
A1  - Skorinko, Jeanine L. M.
A1  - Slowik, Agnieszka
A1  - Snyder, Joel S.
A1  - Soderberg, Courtney
A1  - Sonnleitner, Carina
A1  - Spencer, Nick
A1  - Spies, Jeffrey R.
A1  - Steegen, Sara
A1  - Stieger, Stefan
A1  - Strohminger, Nina
A1  - Sullivan, Gavin B.
A1  - Talhelm, Thomas
A1  - Tapia, Megan
A1  - te Dorsthorst, Anniek
A1  - Thomae, Manuela
A1  - Thomas, Sarah L.
A1  - Tio, Pia
A1  - Traets, Frits
A1  - Tsang, Steve
A1  - Tuerlinckx, Francis
A1  - Turchan, Paul
A1  - Valasek, Milan
A1  - Van Aert, Robbie
A1  - van Assen, Marcel
A1  - van Bork, Riet
A1  - van de Ven, Mathijs
A1  - van den Bergh, Don
A1  - van der Hulst, Marije
A1  - van Dooren, Roel
A1  - van Doorn, Johnny
A1  - van Renswoude, Daan R.
A1  - van Rijn, Hedderik
A1  - Vanpaemel, Wolf
A1  - Echeverria, Alejandro Vasquez
A1  - Vazquez, Melissa
A1  - Velez, Natalia
A1  - Vermue, Marieke
A1  - Verschoor, Mark
A1  - Vianello, Michelangelo
A1  - Voracek, Martin
A1  - Vuu, Gina
A1  - Wagenmakers, Eric-Jan
A1  - Weerdmeester, Joanneke
A1  - Welsh, Ashlee
A1  - Westgate, Erin C.
A1  - Wissink, Joeri
A1  - Wood, Michael
A1  - Woods, Andy
A1  - Wright, Emily
A1  - Wu, Sining
A1  - Zeelenberg, Marcel
A1  - Zuni, Kellylynn
T1  - Estimating the reproducibility of psychological science
JF  - Science
N2  - Reproducibility is a defining feature of science, but the extent to which it characterizes current research is unknown. We conducted replications of 100 experimental and correlational studies published in three psychology journals using high-powered designs and original materials when available. Replication effects were half the magnitude of original effects, representing a substantial decline. Ninety-seven percent of original studies had statistically significant results. Thirty-six percent of replications had statistically significant results; 47% of original effect sizes were in the 95% confidence interval of the replication effect size; 39% of effects were subjectively rated to have replicated the original result; and if no bias in original results is assumed, combining original and replication results left 68% with statistically significant effects. Correlational tests suggest that replication success was better predicted by the strength of original evidence than by characteristics of the original and replication teams.
Y1  - 2015
U6  - https://doi.org/10.1126/science.aac4716
SN  - 1095-9203
SN  - 0036-8075
VL  - 349
IS  - 6251
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Aldoretta, E. J.
A1  - St-Louis, N.
A1  - Richardson, N. D.
A1  - Moffat, Anthony F. J.
A1  - Eversberg, T.
A1  - Hill, G. M.
A1  - Shenar, Tomer
A1  - Artigau, E.
A1  - Gauza, B.
A1  - Knapen, J. H.
A1  - Kubat, Jiří
A1  - Kubatova, Brankica
A1  - Maltais-Tariant, R.
A1  - Munoz, M.
A1  - Pablo, H.
A1  - Ramiaramanantsoa, T.
A1  - Richard-Laferriere, A.
A1  - Sablowski, D. P.
A1  - Simon-Diaz, S.
A1  - St-Jean, L.
A1  - Bolduan, F.
A1  - Dias, F. M.
A1  - Dubreuil, P.
A1  - Fuchs, D.
A1  - Garrel, T.
A1  - Grutzeck, G.
A1  - Hunger, T.
A1  - Kuesters, D.
A1  - Langenbrink, M.
A1  - Leadbeater, R.
A1  - Li, D.
A1  - Lopez, A.
A1  - Mauclaire, B.
A1  - Moldenhawer, T.
A1  - Potter, M.
A1  - dos Santos, E. M.
A1  - Schanne, L.
A1  - Schmidt, J.
A1  - Sieske, H.
A1  - Strachan, J.
A1  - Stinner, E.
A1  - Stinner, P.
A1  - Stober, B.
A1  - Strandbaek, K.
A1  - Syder, T.
A1  - Verilhac, D.
A1  - Waldschlaeger, U.
A1  - Weiss, D.
A1  - Wendt, A.
T1  - An extensive spectroscopic time series of three Wolf-Rayet stars - I. The lifetime of large-scale structures in the wind of WR 134
JF  - Monthly notices of the Royal Astronomical Society
N2  - During the summer of 2013, a 4-month spectroscopic campaign took place to observe the variabilities in three Wolf-Rayet stars. The spectroscopic data have been analysed for WR 134 (WN6b), to better understand its behaviour and long-term periodicity, which we interpret as arising from corotating interaction regions (CIRs) in the wind. By analysing the variability of the He ii lambda 5411 emission line, the previously identified period was refined to P = 2.255 +/- 0.008 (s.d.) d. The coherency time of the variability, which we associate with the lifetime of the CIRs in the wind, was deduced to be 40 +/- 6 d, or similar to 18 cycles, by cross-correlating the variability patterns as a function of time. When comparing the phased observational grey-scale difference images with theoretical grey-scales previously calculated from models including CIRs in an optically thin stellar wind, we find that two CIRs were likely present. A separation in longitude of Delta I center dot a parts per thousand integral 90A degrees was determined between the two CIRs and we suggest that the different maximum velocities that they reach indicate that they emerge from different latitudes. We have also been able to detect observational signatures of the CIRs in other spectral lines (C iv lambda lambda 5802,5812 and He i lambda 5876). Furthermore, a DAC was found to be present simultaneously with the CIR signatures detected in the He i lambda 5876 emission line which is consistent with the proposed geometry of the large-scale structures in the wind. Small-scale structures also show a presence in the wind, simultaneously with the larger scale structures, showing that they do in fact co-exist.
KW  - instabilities
KW  - methods: data analysis
KW  - techniques: spectroscopic
KW  - stars: individual: WR 134
KW  - stars: massive
KW  - stars: Wolf-Rayet
Y1  - 2016
U6  - https://doi.org/10.1093/mnras/stw1188
SN  - 0035-8711
SN  - 1365-2966
VL  - 460
SP  - 3407
EP  - 3417
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Lorenz, A. A.
A1  - Kleber, B.
A1  - Büttner, Michael
A1  - Fuchs, M.
A1  - Mürbe, D.
A1  - Richter, B.
A1  - Sandel, M.
A1  - Nawka, T.
T1  - Validierung des Singing Voice Handicap Index in der deutschen Fassung
JF  - HNO
N2  - Der Singing Voice Handicap Index (SVHI) wurde zur Selbstbeurteilung einer Stimmstörung für Sänger in den USA entwickelt. Eine deutsche Übersetzung wurde erstellt und einer Reliabilitäts- und Validitätsprüfung unterzogen. Es wurden 54 dysphone Sänger (35 weiblich, 19 männlich), Patienten einer phoniatrischen Klinik, befragt. 130 stimmgesunde Opern- und Rundfunkchorsänger (74 weiblich, 56 männlich) bildeten die Kontrollgruppe. Die Reliabilität ergibt sich aus einer hochsignifikanten Test-Retest-Reliabilität (r = 0,960; p <= 0,001, Pearson-Korrelation) und einem Cronbach-? von 0,975. Eine Hauptkomponentenanalyse mit Varimaxrotation und die Ergebnisse des Screeplots legen die Interpretation des SVHI als einfaktorielle Skala nahe. Die Validität zeigt sich in einem hochsignifikanten Zusammenhang zwischen dem vom Patienten selbst eingeschätzten Schweregrad der Stimmstörung und dem SVHI-Gesamtscore. Patienten haben einen signifikant höheren SVHI-Gesamtscore als die Kontrollgruppe gesunder Sänger. Der SVHI ist als diagnostisches Instrument für den deutschsprachigen Raum geeignet.
KW  - Singing voice
KW  - Voice disorders
KW  - Diagnostics
KW  - Self-assessment
KW  - Validation studies
Y1  - 2013
U6  - https://doi.org/10.1007/s00106-013-2721-4
SN  - 0017-6192
SN  - 1433-0458
VL  - 61
IS  - 8
SP  - 699
EP  - 706
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Fuchs, Matthias
A1  - Grosse, Guido
A1  - Strauss, Jens
A1  - Günther, Frank
A1  - Grigoriev, Mikhail N.
A1  - Maximov, Georgy M.
A1  - Hugelius, Gustaf
T1  - Carbon and nitrogen pools in thermokarst-affected permafrost landscapes in Arctic Siberia
JF  - Biogeosciences
N2  - Ice-rich yedoma-dominated landscapes store considerable amounts of organic carbon (C) and nitrogen (N) and are vulnerable to degradation under climate warming. We investigate the C and N pools in two thermokarst-affected yedoma landscapes - on Sobo-Sise Island and on Bykovsky Peninsula in the north of eastern Siberia. Soil cores up to 3m depth were collected along geomorphic gradients and analysed for organic C and N contents. A high vertical sampling density in the profiles allowed the calculation of C and N stocks for short soil column intervals and enhanced understanding of within-core parameter variability. Profile-level C and N stocks were scaled to the landscape level based on landform classifications from 5 m resolution, multispectral RapidEye satellite imagery. Mean landscape C and N storage in the first metre of soil for Sobo-Sise Island is estimated to be 20.2 kg C m(-2) and 1.8 kg N m(-2) and for Bykovsky Peninsula 25.9 kg C m(-2) and 2.2 kg N m(-2). Radiocarbon dating demonstrates the Holocene age of thermokarst basin deposits but also suggests the presence of thick Holoceneage cover layers which can reach up to 2 m on top of intact yedoma landforms. Reconstructed sedimentation rates of 0.10-0.57 mm yr(-1) suggest sustained mineral soil accumulation across all investigated landforms. Both yedoma and thermokarst landforms are characterized by limited accumulation of organic soil layers (peat). We further estimate that an active layer deepening of about 100 cm will increase organic C availability in a seasonally thawed state in the two study areas by similar to 5.8 Tg (13.2 kg C m(-2)). Our study demonstrates the importance of increasing the number of C and N storage inventories in ice-rich yedoma and thermokarst environments in order to account for high variability of permafrost and thermokarst environments in pan-permafrost soil C and N pool estimates.
Y1  - 2018
U6  - https://doi.org/10.5194/bg-15-953-2018
SN  - 1726-4170
SN  - 1726-4189
VL  - 15
IS  - 3
SP  - 953
EP  - 971
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - GEN
A1  - Fuchs, Matthias
A1  - Grosse, Guido
A1  - Strauss, Jens
A1  - Günther, Frank
A1  - Grigoriev, Mikhail N.
A1  - Maximov, Georgy M.
A1  - Hugelius, Gustaf
T1  - Carbon and nitrogen pools in thermokarst-affected permafrost landscapes in Arctic Siberia
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Ice-rich yedoma-dominated landscapes store con-
siderable amounts of organic carbon (C) and nitrogen (N)
and are vulnerable to degradation under climate warming.
We investigate the C and N pools in two thermokarst-affected
yedoma landscapes – on Sobo-Sise Island and on Bykovsky
Peninsula in the north of eastern Siberia. Soil cores up to 3 m
depth were collected along geomorphic gradients and anal-
ysed for organic C and N contents. A high vertical sampling
density in the profiles allowed the calculation of C and N
stocks for short soil column intervals and enhanced under-
standing of within-core parameter variability. Profile-level C
and N stocks were scaled to the landscape level based on
landform classifications from 5 m resolution, multispectral
RapidEye satellite imagery. Mean landscape C and N storage
in the first metre of soil for Sobo-Sise Island is estimated to
be 20.2 kg C m −2 and 1.8 kg N m −2 and for Bykovsky Penin-
sula 25.9 kg C m −2 and 2.2 kg N m −2 . Radiocarbon dating
demonstrates the Holocene age of thermokarst basin de-
posits but also suggests the presence of thick Holocene-
age cover layers which can reach up to 2 m on top of in-
tact yedoma landforms. Reconstructed sedimentation rates
of 0.10–0.57 mm yr −1 suggest sustained mineral soil accu-
mulation across all investigated landforms. Both yedoma and
thermokarst landforms are characterized by limited accumu-
lation of organic soil layers (peat).
We further estimate that an active layer deepening of
about 100 cm will increase organic C availability in a sea-
sonally thawed state in the two study areas by ∼ 5.8 Tg
(13.2 kg C m −2 ). Our study demonstrates the importance of
increasing the number of C and N storage inventories in ice-
rich yedoma and thermokarst environments in order to ac-
count for high variability of permafrost and thermokarst en-
vironments in pan-permafrost soil C and N pool estimates.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 654 
KW  - soil organic-carbon
KW  - Lena River Delta
KW  - ice-rich permafrost
KW  - thaw-lake basins
KW  - climate-change
KW  - northern Siberia
KW  - Late Quaternary
KW  - periglacial landscape
KW  - Tundra ecosystem
KW  - Yedoma region
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-418026
SN  - 1866-8372
VL  - 15
IS  - 654
ER  - 
TY  - JOUR
A1  - Scheiner, Ricarda
A1  - Abramson, Charles I.
A1  - Brodschneider, Robert
A1  - Crailsheim, Karl
A1  - Farina, Walter M.
A1  - Fuchs, Stefan
A1  - Grünewald, Bernd
A1  - Hahshold, Sybille
A1  - Karrer, Marlene
A1  - Koeniger, Gudrun
A1  - Königer, Niko
A1  - Menzel, Randolf
A1  - Mujagic, Samir
A1  - Radspieler, Gerald
A1  - Schmickl, Thomas
A1  - Schneider, Christof
A1  - Siegel, Adam J.
A1  - Szopek, Martina
A1  - Thenius, Ronald
T1  - Standard methods for behavioural studies of Apis mellifera
JF  - Journal of apicultural research
N2  - In this BEEBOOK paper we present a set of established methods for quantifying honey bee behaviour. We start with general methods for preparing bees for behavioural assays. Then we introduce assays for quantifying sensory responsiveness to gustatory, visual and olfactory stimuli. Presentation of more complex behaviours like appetitive and aversive learning under controlled laboratory conditions and learning paradigms under free-flying conditions will allow the reader to investigate a large range of cognitive skills in honey bees. Honey bees are very sensitive to changing temperatures. We therefore present experiments which aim at analysing honey bee locomotion in temperature gradients. The complex flight behaviour of honey bees can be investigated under controlled conditions in the laboratory or with sophisticated technologies like harmonic radar or RFID in the field. These methods will be explained in detail in different sections. Honey bees are model organisms in behavioural biology for their complex yet plastic division of labour. To observe the daily behaviour of individual bees in a colony, classical observation hives are very useful. The setting up and use of typical observation hives will be the focus of another section. The honey bee dance language has important characteristics of a real language and has been the focus of numerous studies. We here discuss the background of the honey bee dance language and describe how it can be studied. Finally, the mating of a honey bee queen with drones is essential to survival of the entire colony. We here give detailed and structured information how the mating behaviour of drones and queens can be observed and experimentally manipulated.
 The ultimate goal of this chapter is to provide the reader with a comprehensive set of experimental protocols for detailed studies on all aspects of honey bee behaviour including investigation of pesticide and insecticide effects.
KW  - COLOSS
KW  - BEEBOOK
KW  - honey bee
KW  - behaviour
KW  - gustatory responsiveness
KW  - olfactory responsiveness
KW  - phototaxis
KW  - non-associative learning
KW  - associative learning
KW  - appetitive learning
KW  - aversive learning
KW  - locomotion
KW  - temperature sensing
KW  - honey bee flight
KW  - observation hive
KW  - honey bee dance
KW  - honey bee navigation
KW  - harmonic radar
KW  - BeeScan
KW  - RFID
KW  - honey bee mating
KW  - free-flying honey bees
Y1  - 2013
U6  - https://doi.org/10.3896/IBRA.1.52.4.04
SN  - 0021-8839
SN  - 2078-6913
VL  - 52
IS  - 4
PB  - International Bee Research Association
CY  - Cardiff
ER  - 
TY  - JOUR
A1  - Fuchs, Matthias
A1  - Lenz, Josefine
A1  - Jock, Suzanne
A1  - Nitze, Ingmar
A1  - Jones, Benjamin M.
A1  - Strauss, Jens
A1  - Günther, Frank
A1  - Grosse, Guido
T1  - Organic carbon and nitrogen stocks along a thermokarst lake sequence in Arctic Alaska
JF  - Journal of geophysical research : Biogeosciences
N2  - Thermokarst lake landscapes are permafrost regions, which are prone to rapid (on seasonal to decadal time scales) changes, affecting carbon and nitrogen cycles. However, there is a high degree of uncertainty related to the balance between carbon and nitrogen cycling and storage. We collected 12 permafrost soil cores from six drained thermokarst lake basins (DTLBs) along a chronosequence north of Teshekpuk Lake in northern Alaska and analyzed them for carbon and nitrogen contents. For comparison, we included three lacustrine cores from an adjacent thermokarst lake and one soil core from a non thermokarst affected remnant upland. This allowed to calculate the carbon and nitrogen stocks of the three primary landscape units (DTLB, lake, and upland), to reconstruct the landscape history, and to analyze the effect of thermokarst lake formation and drainage on carbon and nitrogen stocks. We show that carbon and nitrogen contents and the carbon-nitrogen ratio are considerably lower in sediments of extant lakes than in the DTLB or upland cores indicating degradation of carbon during thermokarst lake formation. However, we found similar amounts of total carbon and nitrogen stocks due to the higher density of lacustrine sediments caused by the lack of ground ice compared to DTLB sediments. In addition, the radiocarbon-based landscape chronology for the past 7,000years reveals five successive lake stages of partially, spatially overlapping DTLBs in the study region, reflecting the dynamic nature of ice-rich permafrost deposits. With this study, we highlight the importance to include these dynamic landscapes in future permafrost carbon feedback models. Plain Language Summary When permanently frozen soils (permafrost) contain ice-rich sediments, the thawing of this permafrost causes the surface to sink, which may result in lake formation. This process, the thaw of ice-rich permafrost and melting of ground ice leads to characteristic landforms-known as thermokarst. Once such a thaw process is initiated in ice-rich sediments, a thaw lake forms and grows by shoreline erosion, eventually expanding until a drainage pathway is encountered and the lake eventually drains, resulting in a drained thermokarst lake basin. In our study, we show that such a thermokarst-affected landscape north of Teshekpuk Lake in northern Alaska is shaped by repeated thaw lake formation and lake drainage events during the past 7,000years, highlighting the dynamic nature of these landscapes. These landscape-scale processes have a big effect on the carbon and nitrogen stored in permafrost soils. We show that large amounts of carbon (>45kg C/m(2)) and nitrogen (>2.6kg N/m(2)) are stored in unfrozen lake sediments and in frozen soil sediments. The findings are important when considering the potential effect that permafrost thaw has for the global climate through releasing carbon and nitrogen, which was frozen and therefore locked away for millennia, from the active carbon cycle.
Y1  - 2019
U6  - https://doi.org/10.1029/2018JG004591
SN  - 2169-8953
SN  - 2169-8961
VL  - 124
IS  - 5
SP  - 1230
EP  - 1247
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bizic-Ionescu, Mina
A1  - Zeder, Michael
A1  - Ionescu, Danny
A1  - Orlic, Sandi
A1  - Fuchs, Bernhard M.
A1  - Grossart, Hans-Peter
A1  - Amann, Rudolf
T1  - Comparison of bacterial communities on limnic versus coastal marine particles reveals profound differences in colonization
JF  - Environmental microbiology
N2  - Marine and limnic particles are hotspots of organic matter mineralization significantly affecting biogeochemical element cycling. Fluorescence in-situ hybridization and pyrosequencing of 16S rRNA genes were combined to investigate bacterial diversity and community composition on limnic and coastal marine particles >5 and >10m respectively. Limnic particles were more abundant (average: 1x10(7)l(-1)), smaller in size (average areas: 471 versus 2050m(2)) and more densely colonized (average densities: 7.3 versus 3.6 cells 100m(-2)) than marine ones. Limnic particle-associated (PA) bacteria harboured Alphaproteobacteria and Betaproteobacteria, and unlike previously suggested sizeable populations of Gammaproteobacteria, Actinobacteria and Bacteroidetes. Marine particles were colonized by Planctomycetes and Betaproteobacteria additionally to Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria. Large differences in individual particle colonization could be detected. High-throughput sequencing revealed a significant overlap of PA and free-living (FL) bacteria highlighting an underestimated connectivity between both fractions. PA bacteria were in 14/21 cases more diverse than FL bacteria, reflecting a high heterogeneity in the particle microenvironment. We propose that a ratio of Chao 1 indices of PA/FL<1 indicates the presence of rather homogeneously colonized particles. The identification of different bacterial families enriched on either limnic or marine particles demonstrates that, despite the seemingly similar ecological niches, PA communities of both environments differ substantially.
Y1  - 2015
U6  - https://doi.org/10.1111/1462-2920.12466
SN  - 1462-2912
SN  - 1462-2920
VL  - 17
IS  - 10
SP  - 3500
EP  - 3514
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -