Organic matter quality of deep permafrost carbon – a study from Arctic Siberia
Summary: To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic matter quality for future decomposition of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits. Missing depth trends reveal that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter independently from its age. We conclude that this permafrost organic matter is susceptible to future decomposition.
Multi-isotope labelling (13C, 18O, 2H) of fresh assimilates to trace organic matter dynamics in the plant-soil system
Summary: We present a new technique to label organic matter (OM) at its place of formation by the application of 13C, 18O and 2H through the gaseous phase. The label diffused into leaves, was incorporated into assimilates and was detected in plant tissues. This technique can be applied in soil sciences, e.g. to trace the decomposition pathways of soil OM inputs, or in plant physiology and paleoclimatic reconstruction, e.g. to further investigate the origin of the 18O and 2H signal in tree ring cellulose.
Environmental factors controlling lake diatom communities: a meta-analysis of published data
Summary: I re-analyze information published during the last decades concerning the effect of different environmental predictors on the structure of benthic diatom communities in world lakes, providing a scientific basis for the implementation of new paleoenvironmental inference models. I consider highly relevant the publication of this article in a widely known journal, provided the noticeable demand on paleolimnological meta-studies supporting the use of such biological proxies at a pancontinental scale
Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin
Summary: This study looks at the combined impacts of hypoxia and acidification, two major environmental stressors affecting coastal systems, in a seasonally stratified basin. Here, the surface water experiences less seasonality in pH than the bottom water despite higher process rates. This is due to a substantial reduction in the acid-base buffering capacity of the bottom water as it turns hypoxic in summer. This highlights the crucial role of the buffering capacity as a modulating factor in pH dynamics.
Heterotrophic prokaryote distribution along a 2300 km transect in the North Pacific subtropical gyre during strong La Niña conditions: relationship between distribution and hydrological conditions
Summary: This study focuses on the distribution of three heterotrophic prokaryote groups in relation with the environmental conditions met in the western part of NPSG. Our results showed that the high variability between the various heterotrophic prokaryote cluster abundances depend both on the mesoscale structures and the oligotrophic gradient. To the best of our knowledge, this study is the first report of the heterotrophic prokaryotes distribution under La Niña conditions in the western part of NPSG.
M. Girault, H. Arakawa, A. Barani, H. J. Ceccaldi, F. Hashihama, and G. Gregori Biogeosciences Discuss., 11, 15793-15826, 2014 AbstractDiscussion Paper (PDF, 3784 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
14 Nov 2014
Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands
Summary: Carbon dioxide exchange between the atmosphere and forested subtropical wetlands is quantified at three locations for one year. Each forested wetland showed net carbon uptake (retained in the soil and biomass or transported laterally via overland flow) from the atmosphere monthly and annually. Changes in carbon dioxide exchange were a function of seasonality in solar insolation, air temperature and water availability from rainfall.
Phytoplankton community structure in the North Sea: coupling between remote sensing and automated in situ analysis at the single cell level
Summary: Phytoplankton community structure at a high spatial resolution (<3 km) was studied in the North Sea during a cruise in May 2011. A first comparison with PHYSAT reflectance anomalies enable the extrapolation of the community structure rather than a dominant type at the North Sea scale and was interpreted with its hydrological characteristics. This will seriously improve our understanding of the influence of community structure on biogeochemical processes at the daily and the basin scales.
M. Thyssen, S. Alvain, A. Lefèbvre, D. Dessailly, M. Rijkeboer, N. Guiselin, V. Creach, and L.-F. Artigas Biogeosciences Discuss., 11, 15621-15662, 2014 AbstractDiscussion Paper (PDF, 1733 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
07 Nov 2014
Carbon dioxide transport across the hillslope–riparian–stream continuum in a boreal headwater catchment
Summary: Carbon dioxide transport between the terrestrial and aquatic systems was dominated by export from the near-stream riparian zone. Over the year, riparian export was highest during autumn storms and the spring snow melt event. This resulted in high downstream export during these periods with vertical evasion from the stream surface accounting for 60% of the total stream water export, highlighting the importance of evasion to carbon export via the aquatic conduit.
F. I. Leith, K. J. Dinsmore, M. B. Wallin, M. F. Billett, K. V. Heal, H. Laudon, M. G. Öquist, and K. Bishop Biogeosciences Discuss., 11, 15585-15619, 2014 AbstractDiscussion Paper (PDF, 1648 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
07 Nov 2014
Trends and drivers in global surface ocean pH over the past three decades
Technical Note: Artificial coral reef mesocosms for ocean acidification investigations
Summary: The design and evaluation of artificial mesocosms are presented in the context of a thirteen months experiment on the effects of ocean acidification on tropical coral reefs. Physico-chemical parameters (i.e. pH, pO2, total alkalinity, alkaline earth metals and nutrients) were successfully controlled. Daily pH variations were applied to approach field conditions. Artificial reef mesocosms leave enough degrees of freedom to the studied ecosystem to change and to acclimate to contrasted conditions.
Continuous and discontinuous variation in ecosystem carbon stocks with elevation across a treeline ecotone
Summary: Here we investigate how ecosystem carbon stocks vary with elevation shifting from the closed forest to open alpine tundra, in the mountains of Southern Norway. Aboveground carbon stocks decreased with elevation, with a clear breakpoint at the forest line, while the organic horizon soil carbon stocks increase linearly with elevation. Overall, ecosystem carbon stocks increased with elevation above, and decreased with elevation below the treeline, demonstrating the importance of the treeline.
J. D. M. Speed, V. Martinsen, A. J. Hester, Ø. Holand, J. Mulder, A. Mysterud, and G. Austrheim Biogeosciences Discuss., 11, 15435-15461, 2014 AbstractDiscussion Paper (PDF, 1020 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG
07 Nov 2014
Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry
Summary: Mean monthly fluxes of carbon and nutrients to the surface layer of the Iceland Sea are presented. From these fluxes we estimate primary production based on newly added nitrate (i.e. new production) and net community production (NCP). The annual new production in the Iceland Sea is estimated to 0.23±0.7 mol N/m2/yr, and the net annual NCP to 6.1±0.9 mol C/m2/yr. The estimated C:N ratio during biological uptake is in the range 10-12, challenging Redfield C:N as conversion factor in the area.
E. Jeansson, R. G. J. Bellerby, I. Skjelvan, H. Frigstad, S. R. Ólafsdóttir, and J. Ólafsson Biogeosciences Discuss., 11, 15399-15433, 2014 AbstractDiscussion Paper (PDF, 803 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG
06 Nov 2014
Amelioration of marine environments at the Smithian–Spathian boundary, Early Triassic
Summary: The Smithian-Spathian boundary was a key event in the recovery of marine environments and ecosystems following the end-Permian mass extinction, ~1.5 million years earlier. Our analysis of the Shitouzhai section in South China reveals major changes in oceanographic conditions at the SSB—intensification of oceanic circulation leading to enhanced upwelling of nutrient- and sulfide-rich deepwaters, coinciding with an abrupt cooling that terminated the Early Triassic hothouse climate.
L. Zhang, L. Zhao, Z.-Q. Chen, T. J. Algeo, J. Chen, R. Wang, L. Chen, J. Hou, Y. Li, H. Qiu, X. Feng, Z. Lu, X. Wang, and Y. Huang Biogeosciences Discuss., 11, 15361-15398, 2014 AbstractDiscussion Paper (PDF, 6697 KB)Supplement (156 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
06 Nov 2014
Spatial variability and hotspots of soil N2O fluxes from intensively grazed grassland
Summary: The spatial variability of N2O fluxes measured at the field scale were investigated using a high precision closed loop dynamic chamber. The results highlight the large and often unpredictable variation in N2O flux magnitude measured from agricultural soils at a relatively small scale. Available nitrogen content of the soils accounts for some of the variability in N2O emissions. The study suggests animal waste is an important source of N2O emissions released from livestock farms.
N. J. Cowan, P. Norman, D. Famulari, P. E. Levy, D. S. Reay, and U. M. Skiba Biogeosciences Discuss., 11, 15327-15360, 2014 AbstractDiscussion Paper (PDF, 1029 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
04 Nov 2014
Size-fractionated dissolved primary production and carbohydrate composition of the coccolithophore Emiliania huxleyi
Experimental drought induces short-term changes in soil functionality and microbial community structure after fire in a Mediterranean shrubland
Summary: This manuscript reports the results of an experimental field study in which the joint effect of both fire and drought is tested. Drought modifies the short-term post-fire soil functionality and microbial community, in a fire-prone xeric ecosystem in which drought is projected to increase with climate change. This study allows to make a step forward on our integrated understanding of the processes underlying impacts of climate extremes in the recovery of ecosystems after fire.
The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N2O emissions from an intensively managed vegetable field in southeastern China
Summary: New nitrification inhibitor CP application caused a significant decrease in yield-scaled N2O emissions in the intensively managed vegetable field while biochar amendment had no significant influence on cumulative N2O emissions, whereas this amendment significantly decreased soil pH and yield-scaled N2O emissions. Overall, taking environmental and economic benefits into consideration, CP application in the vegetable field was the best procedure for reducing the yield-scaled N2O emissions.
Pyrogenic carbon from tropical savanna burning: production and stable isotope composition
Summary: Around half of all pyrogenic carbon (charcoal and soot) derived from wildfires comes from semi-annual burning of tropical savannas. This pyrogenic carbon is significant because is a component of global aerosols capable of modulating the greenhouse effect and is resistant to degradation. We use controlled field burns in northern Australian savannas to determine how much pyrogenic carbon is formed, how much of this is recalcitrant and how it is partitioned between ground residues and airborne soot
G. Saiz, J. G. Wynn, C. M. Wurster, I. Goodrick, P. N. Nelson, and M. I. Bird Biogeosciences Discuss., 11, 15149-15183, 2014 AbstractDiscussion Paper (PDF, 3032 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
28 Oct 2014
Organic N and P in eutrophic fjord sediments – rates of mineralization and consequences for internal nutrient loading
Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of Central European forests
S. Bischoff, M. T. Schwarz, J. Siemens, L. Thieme, W. Wilcke, and B. Michalzik Biogeosciences Discuss., 11, 15087-15107, 2014 AbstractDiscussion Paper (PDF, 801 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
24 Oct 2014
Microbial iron uptake in the naturally fertilized waters in the vicinity of Kerguelen Islands: phytoplankton–bacteria interactions
Summary: In this manuscript, we present the results of iron uptake measured in the naturally iron-fertilized area during the Kerguelen Ocean and Plateau compared Study 2 cruise (KEOPS2). Iron uptake by bulk community and several size-fractions (microplankton, pico-nanoplankton, and bacteria) are presented, compared and discussed in the present paper. This work also presents first investigations on the potential competition between bacteria and phytoplankton for the access to iron.
Microbial respiration per unit microbial biomass depends on soil litter carbon-to-nitrogen ratio
Summary: Soil microbial respiration is a central process in the terrestrial carbon (C) cycle. In this study I tested the effect of the carbon-to-nitrogen (C:N) ratio of soil litter layers on microbial respiration in absolute terms and per unit microbial biomass C. For this purpose, a global dataset on microbial respiration per unit microbial biomass C - termed the metabolic quotient (qCO2) - was compiled form literature data. It was found that the qCO2 in the soil litter layers was positively correlated
Technical Note: Hyperspectral lidar time series of pine canopy physiological parameters
Summary: A hyperspectral LIDAR produces a pointcloud with multiple spectral channels (colors) for each point. We measured a pine and used the spectral content to estimate biophysiological parameters, such as chlorophyll content. We validated these results using chemical laboratory analysis of needles taken from the pine. Our prototype has limitations, but still shows the great potential of colored point clouds. Potential applications include forestry, security, archaeology and city modelling.
Drivers of long-term variability in CO2 net ecosystem exchange in a temperate peatland
Summary: The CO2 sink strength of a temperate peatland in SE Scotland exhibited large inter-annual variability which was well-correlated to the length of the growing season. Mean winter air temperature explained 87% of the inter-annual variability in the sink strength of the following summer, indicating a phenological memory-effect. Autotrophic respiration is thought to be dominant but heterotrophic processes might have been enhanced during dry spells increasing the loss of CO2 to the atmosphere.
C. Helfter, C. Campbell, K. J. Dinsmore, J. Drewer, M. Coyle, M. Anderson, U. Skiba, E. Nemitz, M. F. Billett, and M. A. Sutton Biogeosciences Discuss., 11, 14981-15018, 2014 AbstractDiscussion Paper (PDF, 3371 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for BG
22 Oct 2014
Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty
A. P. Ballantyne, R. Andres, R. Houghton, B. D. Stocker, R. Wanninkhof, W. Anderegg, L. A. Cooper, M. DeGrandpre, P. P. Tans, J. C. Miller, C. Alden, and J. W. C. White Biogeosciences Discuss., 11, 14929-14979, 2014 AbstractDiscussion Paper (PDF, 3972 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
22 Oct 2014
Numerical analysis of the primary processes controlling oxygen dynamics on the Louisiana Shelf
Summary: Our study suggests that a combination of physical processes and sediment oxygen consumption determine the spatial extent and temporal dynamics of hypoxia on the Louisiana shelf. In summer, stratification isolates oxygen-rich surface waters from hypoxic bottom waters; oxygen outgasses to the atmosphere at this time. A large fraction of primary production occurs below the pycnocline in summer but this primary production does not strongly affect the spatial extent of hypoxic bottom waters.
Analysis of water use strategies of the desert riparian forest plant community in inland rivers of two arid regions in northwestern China
Y. N. Chen, W. H. Li, H. H. Zhou, Y. P. Chen, X. M. Hao, A. H. Fu, and J. X. Ma Biogeosciences Discuss., 11, 14819-14856, 2014 AbstractDiscussion Paper (PDF, 7574 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG
22 Oct 2014
Poor correlation between phytoplankton community growth rates and nutrient concentration in the sea
Summary: We question here whether phytoplankton community growth rates respond to nutrient concentration in a similar manner to phytoplankton species composing the community, that is, following Monod's model. In situ marine community growth rates in relation to nutrient concentration and the behaviour of a simple multi-species community model show that community growth rate does not follow a Monod's model. We observed here that this can be explained as a consequence of change in size structure.
Soil organic carbon in the Sanjiang Plain of China: storage, distribution and controlling factors
Summary: The Sanjiang Plain of China, an important grain production base, is typical of ecosystems. In this study, 419 soil samples and a geostatistical method were used to estimate total SOC storage and determination of its pattern controlling factors. The results from this study provide the most updated knowledge on the storage and pattern of SOC in this Plain, and the analysis conducted here could contribute to the determination of ecosystem carbon budgets and understanding of ecosystem services.
New highlights on phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results
Summary: Phytoliths contain occluded organic compounds called phytC. The nature and location of phytC in the biogenic silica structure is poorly known. Here, we reconstructed the 3D structure of phytoliths using 3D Xray microscopy. We further evidenced a pool of phytC, continuously distributed in the silica structure, using nano-scale Secondary Ion Mass Spectrometry (NanoSIMS). Our findings allowed to re-evaluate previous suggestions regarding phytC quantification and environmental meaning.
A. Alexandre, I. Basile-Doelsch, T. Delhaye, D. Borshneck, J. C. Mazur, P. Reyerson, and G. M. Santos Biogeosciences Discuss., 11, 14699-14727, 2014 AbstractDiscussion Paper (PDF, 2754 KB)Interactive Discussion (Open, 4 Comments)Manuscript under review for BG
14 Oct 2014
Modelling forest lines and forest distribution patterns with remote sensing data in a mountainous region of semi-arid Central Asia
Vertical partitioning of phosphate uptake among picoplankton groups in the P-depleted Mediterranean Sea
Summary: Along a transect in the warm nutrient-depleted Mediterranean Sea, we found that microorganisms shared phosphate resources by using different uptake strategies. Bacteria and Archaea were dominating phosphate uptake in the upper layers while cyanobacteria were dominating uptake fluxes around the deep chlorophyll maximum depth. While Synechococcus seemed well equipped to respond to pulses of phosphate, Prochlorococcus and heterotrophs were more adapted to very low concentrations.
Natural and anthropogenic methane fluxes in Eurasia: a meso-scale quantification by generalized atmospheric inversion
A. Berchet, I. Pison, F. Chevallier, J.-D. Paris, P. Bousquet, J.-L. Bonne, M. Yu. Arshinov, B. D. Belan, C. Cressot, D. K. Davydov, E. J. Dlugokencky, A. V. Fofonov, A. Galanin, J. Lavrič, T. Machida, R. Parker, M. Sasakawa, R. Spahni, B. D. Stocker, and J. Winderlich Biogeosciences Discuss., 11, 14587-14637, 2014 AbstractDiscussion Paper (PDF, 6575 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
13 Oct 2014
The mechanisms of North Atlantic CO2 uptake in a large Earth System Model ensemble
Summary: The oceans currently take up around a quarter of the carbon dioxide (CO2) emitted by human activity. While stored in the ocean, this CO2 is not causing global warming. Here we explore high latitude North Atlantic CO2 uptake across a set of climate model simulations, and find that the models show a peak in ocean CO2 uptake around the middle of the century after which time CO2 uptake begins to decline. We identify the causes of this long-term change and interannual variability in the models.
P. R. Halloran, B. B. B. Booth, C. D. Jones, F. H. Lambert, D. J. McNeall, I. J. Totterdell, and C. Völker Biogeosciences Discuss., 11, 14551-14585, 2014 AbstractDiscussion Paper (PDF, 3411 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG
13 Oct 2014
Influence of aeolian activities on the distribution of microbial abundance in glacier ice
Drought in forest understory ecosystems – a novel rainfall reduction experiment
K. F. Gimbel, K. Felsmann, M. Baudis, H. Puhlmann, A. Gessler, H. Bruelheide, Z. Kayler, R. H. Ellerbrock, A. Ulrich, E. Welk, and M. Weiler Biogeosciences Discuss., 11, 14319-14358, 2014 AbstractDiscussion Paper (PDF, 2982 KB)Interactive Discussion (Open, 3 Comments)Manuscript under review for BG
07 Oct 2014
A global carbon assimilation system based on a dual optimization method
H. Zheng, Y. Li, J. M. Chen, T. Wang, Q. Huang, W. X. Huang, S. M. Li, W. P. Yuan, X. Zheng, S. P. Zhang, Z. Q. Chen, and F. Jiang Biogeosciences Discuss., 11, 14269-14317, 2014 AbstractDiscussion Paper (PDF, 1173 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for BG
02 Oct 2014
Nematode diversity, abundance and community structure 50 years after the formation of the volcanic island of Surtsey
Seasonal survey of the composition and degradation state of particulate organic matter in the Rhone River using lipid tracers
M.-A. Galeron, R. Amiraux, B. Charriere, O. Radakovitch, P. Raimbault, N. Garcia, V. Lagadec, F. Vaultier, and J.-F. Rontani Biogeosciences Discuss., 11, 14197-14237, 2014 AbstractDiscussion Paper (PDF, 2200 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG
02 Oct 2014
Divergence of above- and belowground C and N pool within predominant plant species along two precipitation gradients in north China
Nitrous oxide emission and nitrogen use efficiency in response to nitrophosphate, N-(n-butyl) thiophosphoric triamide and dicyandiamide of a wheat cultivated soil under sub-humid monsoon conditions
W. X. Ding, Z. M. Chen, H. Y. Yu, J. F. Luo, G. Y. Yoo, J. Xiang, H. J. Zhang, and J. J. Yuan Biogeosciences Discuss., 11, 13571-13603, 2014 AbstractDiscussion Paper (PDF, 573 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for BG
19 Sep 2014
Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska
Using O2 to study the relationships between soil CO2 efflux and soil respiration
A. Angert, D. Yakir, M. Rodeghiero, Y. Preisler, E. A. Davidson, and T. Weiner Biogeosciences Discuss., 11, 12039-12068, 2014 AbstractDiscussion Paper (PDF, 854 KB)Interactive Discussion (Open, 6 Comments)Manuscript under review for BG
07 Aug 2014
Tidal controls on trace gas dynamics in a seagrass meadow of the Ria Formosa lagoon (southern Portugal)
E. Bahlmann, I. Weinberg, J. V. Lavrič, T. Eckhard, W. Michaelis, R. Santos, and R. Seifert Biogeosciences Discuss., 11, 10571-10603, 2014 AbstractDiscussion Paper (PDF, 1009 KB)Interactive Discussion (Open, 7 Comments)Manuscript under review for BG
10 Jul 2014
Forests, savannas and grasslands: bridging the knowledge gap between ecology and Dynamic Global Vegetation Models
M. Baudena, S. C. Dekker, P. M. van Bodegom, B. Cuesta, S.I. Higgins, V. Lehsten, C. H. Reick, M. Rietkerk, S. Scheiter, Z. Yin, M. A. Zavala, and V. Brovkin Biogeosciences Discuss., 11, 9471-9510, 2014 AbstractDiscussion Paper (PDF, 969 KB)Supplement (121 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for BG