TY  - JOUR
A1  - Hemingway, Jordon Dennis
A1  - Hilton, Robert G.
A1  - Hovius, Niels
A1  - Eglinton, Timothy I.
A1  - Haghipour, Negar
A1  - Wacker, Lukas
A1  - Chen, Meng-Chiang
A1  - Galy, Valier V.
T1  - Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils
JF  - Science
N2  - Lithospheric organic carbon ("petrogenic"; OCpetro) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO2) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 +/- 11% of the OCpetro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OCpetro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO2 emission fluxes that increase with erosion rate, thereby counteracting CO2 drawdown by silicate weathering and biospheric OC burial.
Y1  - 2018
U6  - https://doi.org/10.1126/science.aao6463
SN  - 0036-8075
SN  - 1095-9203
VL  - 360
IS  - 6385
SP  - 209
EP  - +
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pauly, Maren
A1  - Helle, Gerhard
A1  - Miramont, Cecile
A1  - Buentgen, Ulf
A1  - Treydte, Kerstin
A1  - Reinig, Frederick
A1  - Guibal, Frederic
A1  - Sivan, Olivier
A1  - Heinrich, Ingo
A1  - Riedel, Frank
A1  - Kromer, Bernd
A1  - Balanzategui, Daniel
A1  - Wacker, Lukas
A1  - Sookdeo, Adam
A1  - Brauer, Achim
T1  - Subfossil trees suggest enhanced Mediterranean hydroclimate variability at the onset of the Younger Dryas
JF  - Scientific reports
N2  - Nearly 13,000 years ago, the warming trend into the Holocene was sharply interrupted by a reversal to near glacial conditions. Climatic causes and ecological consequences of the Younger Dryas (YD) have been extensively studied, however proxy archives from the Mediterranean basin capturing this period are scarce and do not provide annual resolution. Here, we report a hydroclimatic reconstruction from stable isotopes (delta O-18, delta C-13) in subfossil pines from southern France. Growing before and during the transition period into the YD (12 900-12 600 cal BP), the trees provide an annually resolved, continuous sequence of atmospheric change. Isotopic signature of tree sourcewater (delta O-18(sw)) and estimates of relative air humidity were reconstructed as a proxy for variations in air mass origin and precipitation regime. We find a distinct increase in inter-annual variability of sourcewater isotopes (delta O-18(sw)), with three major downturn phases of increasing magnitude beginning at 12 740 cal BP. The observed variation most likely results from an amplified intensity of North Atlantic (low delta O-18(sw)) versus Mediterranean (high delta O-18(sw)) precipitation. This marked pattern of climate variability is not seen in records from higher latitudes and is likely a consequence of atmospheric circulation oscillations at the margin of the southward moving polar front.
Y1  - 2018
U6  - https://doi.org/10.1038/s41598-018-32251-2
SN  - 2045-2322
VL  - 8
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - GEN
A1  - Pauly, Maren
A1  - Helle, Gerhard
A1  - Miramont, Cécile
A1  - Büntgen, Ulf
A1  - Treydte, Kerstin
A1  - Reinig, Frederick
A1  - Guibal, Frédéric
A1  - Sivan, Olivier
A1  - Heinrich, Ingo
A1  - Riedel, Frank
A1  - Kromer, Bernd
A1  - Balanzategui, Daniel
A1  - Wacker, Lukas
A1  - Sookdeo, Adam Sookdeo
A1  - Brauer, Achim
T1  - Subfossil trees suggest enhanced Mediterranean hydroclimate variability at the onset of the Younger Dryas
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Nearly 13,000 years ago, the warming trend into the Holocene was sharply interrupted by a reversal to near glacial conditions. Climatic causes and ecological consequences of the Younger Dryas (YD) have been extensively studied, however proxy archives from the Mediterranean basin capturing this period are scarce and do not provide annual resolution. Here, we report a hydroclimatic reconstruction from stable isotopes (delta O-18, delta C-13) in subfossil pines from southern France. Growing before and during the transition period into the YD (12 900-12 600 cal BP), the trees provide an annually resolved, continuous sequence of atmospheric change. Isotopic signature of tree sourcewater (delta O-18(sw)) and estimates of relative air humidity were reconstructed as a proxy for variations in air mass origin and precipitation regime. We find a distinct increase in inter-annual variability of sourcewater isotopes (delta O-18(sw)), with three major downturn phases of increasing magnitude beginning at 12 740 cal BP. The observed variation most likely results from an amplified intensity of North Atlantic (low delta O-18(sw)) versus Mediterranean (high delta O-18(sw)) precipitation. This marked pattern of climate variability is not seen in records from higher latitudes and is likely a consequence of atmospheric circulation oscillations at the margin of the southward moving polar front.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1135 
KW  - annually laminated sediments
KW  - lake Meerfelder Maar
KW  - isotopic composition
KW  - oxygen isotope
KW  - climate
KW  - cellulose
KW  - radiocarbon
KW  - temperature
KW  - record
KW  - model
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-459169
SN  - 1866-8372
IS  - 1135
ER  - 
TY  - JOUR
A1  - Hippe, Kristina
A1  - Kober, Florian
A1  - Zeilinger, Gerold
A1  - Ivy-Ochs, Susan
A1  - Maden, Colin
A1  - Wacker, Lukas
A1  - Kubik, Peter W.
A1  - Wieler, Rainer
T1  - Quantifying denudation rates and sediment storage on the eastern Altiplano, Bolivia, using cosmogenic Be-10, Al-26, and in situ C-14
JF  - Geomorphology : an international journal on pure and applied geomorphology
N2  - Denudation processes and sediment transfer are investigated in a high-elevation, low-relief environment (eastern Altiplano, Bolivia) using Be-10, Al-26, and in situ C-14 analysis in fluvial sediments. Concentrations of the long-lived nuclides Be-10 and Al-26 yield consistently low catchment-wide denudation rates of similar to 3-29 mm ky(-1) (integrating over 21-194 ky), which reflect the low geomorphic gradients and the discontinuity of fluvial transport along the eastern Altiplano margin. No significant correlation is recorded between denudation rates of individual catchments and morphological basin parameters (slope, area, elevation). This is attributed to the overall little variability in morphology. The agreement between the denudation rates and published modern sediment discharge data suggests steady landscape evolution of the eastern Altiplano from the latest Pleistocene until today. While Be-10 and Al-26 provide long-term estimates on sediment production, in situ cosmogenic C-14 is used to trace short-term sediment storage. In situ C-14 concentrations are comparatively low indicating that C-14 decayed during alluvial storage over at least the past similar to 11-20 ky. We assume storage at shallow depth (2 m) and consider the influence of soil-mantled hillslopes on the in situ C-14 concentration. Our results illustrate the importance of sediment storage even over short distances and demonstrate the potential of in situ C-14 to study sediment routing and transfer times within drainage systems. However, this study also demonstrates that the long-lived Be-10 and Al-26 nuclides can provide adequate estimates on long-term denudation rates even if sediment transport is not fast but interrupted by several thousands of years of storage.
KW  - Cosmogenic nuclides
KW  - Denudation
KW  - Sediment storage
KW  - In situ C-14
KW  - Altiplano
Y1  - 2012
U6  - https://doi.org/10.1016/j.geomorph.2012.07.031
SN  - 0169-555X
VL  - 179
IS  - 22
SP  - 58
EP  - 70
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Hector, Andy
A1  - Hautier, Yann
A1  - Saner, Philippe
A1  - Wacker, Lukas
A1  - Bagchi, Robert
A1  - Joshi, Jasmin Radha
A1  - Scherer-Lorenzen, Michael
A1  - Spehn, Eva M.
A1  - Bazeley-White, Ellen
A1  - Weilenmann, Markus
A1  - Caldeira, Maria da Conceição Brálio de Brito
A1  - Dimitrakopoulos, Panayiotis G.
A1  - Finn, John A.
A1  - Huss-Danell, Kerstin
A1  - Jumpponen, Ari
A1  - Mulder, Christa P. H.
A1  - Palmborg, Cecilia
A1  - Pereira, J. S.
A1  - Siamantziouras, Akis S. D.
A1  - Terry, Andrew C.
A1  - Troumbis, Andreas Y.
A1  - Schmid, Bernhard
A1  - Loreau, Michel
T1  - General stabilizing effects of plant diversity on grassland productivity through population asynchrony and overyielding
N2  - Insurance effects of biodiversity can stabilize the functioning of multispecies ecosystems against environmental variability when differential species' responses lead to asynchronous population dynamics. When responses are not perfectly positively correlated, declines in some populations are compensated by increases in others, smoothing variability in ecosystem productivity. This variance reduction effect of biodiversity is analogous to the risk- spreading benefits of diverse investment portfolios in financial markets. We use data from the BIODEPTH network of grassland biodiversity experiments to perform a general test for stabilizing effects of plant diversity on the temporal variability of individual species, functional groups, and aggregate communities. We tested three potential mechanisms: reduction of temporal variability through population asynchrony; enhancement of long-term average performance through positive selection effects; and increases in the temporal mean due to overyielding. Our results support a stabilizing effect of diversity on the temporal variability of grassland aboveground annual net primary production through two mechanisms. Two-species communities with greater population asynchrony were more stable in their average production over time due to compensatory fluctuations. Overyielding also stabilized productivity by increasing levels of average biomass production relative to temporal variability. However, there was no evidence for a performance-enhancing effect on the temporal mean through positive selection effects. In combination with previous work, our results suggest that stabilizing effects of diversity on community productivity through population asynchrony and overyielding appear to be general in grassland ecosystems.
Y1  - 2010
UR  - http://esapubs.org/esapubs/journals/ecology.htm
SN  - 0012-9658
ER  -