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Combined list of the recent articles of the journal Biogeosciences and the recent discussion forum Biogeosciences Discussions



 



How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils? Implications from a study of a 10-year-old soil–plant system

Thu, 23 Nov 2017 18:39:18 +0100

How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils? Implications from a study of a 10-year-old soil–plant system
Daniel Puppe, Axel Höhn, Danuta Kaczorek, Manfred Wanner, Marc Wehrhan, and Michael Sommer
Biogeosciences, 14, 5239-5252, https://doi.org/10.5194/bg-14-5239-2017, 2017
We quantified different biogenic Si pools in soils of a developing ecosystem and analyzed their influence on short-term changes of the water soluble Si fraction. From our results we concluded small (< 5 µm) and/or fragile phytogenic Si structures to have the biggest impact on short-term changes of water soluble Si. Analyses of these phytogenic Si structures are urgently needed in future as they seem to represent the most important driver of Si cycling in terrestrial biogeosystems in general.



Calcium content and high calcium adaptation of plants in karst areas of southwestern Hunan, China

Thu, 23 Nov 2017 18:39:18 +0100

Calcium content and high calcium adaptation of plants in karst areas of southwestern Hunan, China
Xiaocong Wei, Xiangwen Deng, Wenhua Xiang, Pifeng Lei, Shuai Ouyang, Hongfang Wen, and Liang Chen
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-392,2017
Manuscript under review for BG (discussion: open, 0 comments)
Karst is a kind of typical calcium rich environment, which is widely distributed. We measured the Ca2+ content of 41 plant species, as well as soil total Ca2+ and exchange Ca2+. We found out that different plants have different ways to high Ca2+ adaptation. According to the different high Ca2+ adaptation of the 17 dominant species, we divided them into 3 categories: Ca-indifferent plants, high-Ca plants and low-Ca plants. Our results can provide a theoretical basis for vegetation restoration.



Modeling seasonal and vertical habitats of planktonic foraminifera on a global scale

Wed, 22 Nov 2017 18:39:18 +0100

Modeling seasonal and vertical habitats of planktonic foraminifera on a global scale
Kerstin Kretschmer, Lukas Jonkers, Michal Kucera, and Michael Schulz
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-429,2017
Manuscript under review for BG (discussion: open, 0 comments)
The fossil shells of planktonic foraminifera are widely used to reconstruct past climate conditions. To do so, information about their seasonal and vertical habitat are needed. Here we present an updated version of a planktonic foraminifera model to better understand species-specific habitat dynamics under climate change. This model produces spatially and temporally coherent distribution patterns, which agree well with available observations, and can thus aid the interpretation of proxy records.



Physico-chemical and biological factors influencing dinoflagellate cyst production in the Cariaco Basin

Wed, 22 Nov 2017 18:39:18 +0100

Physico-chemical and biological factors influencing dinoflagellate cyst production in the Cariaco Basin
Manuel Bringué, Robert C. Thunell, Vera Pospelova, James L. Pinckney, Oscar E. Romero, and Eric J. Tappa
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-497,2017
Manuscript under review for BG (discussion: open, 0 comments)
We document 2.5 yrs of dinoflagellate cyst production in the Cariaco Basin using a sediment trap record. Each species' production pattern is interpreted in the context of the physico-chemical (e.g., temperature, nutrients) and biological (other planktonic groups) environment. Most species respond positively to upwelling, but seem to be negatively impacted by an El Niño event with a 1 year lag. This works helps understanding dinoflagellate ecology and interpreting fossil assemblages in sediments.



Year-round CH4 and CO2 flux dynamics in two contrasting freshwater ecosystems of the subarctic

Tue, 21 Nov 2017 18:39:18 +0100

Year-round CH4 and CO2 flux dynamics in two contrasting freshwater ecosystems of the subarctic
Mathilde Jammet, Sigrid Dengel, Ernesto Kettner, Frans-Jan W. Parmentier, Martin Wik, Patrick Crill, and Thomas Friborg
Biogeosciences, 14, 5189-5216, https://doi.org/10.5194/bg-14-5189-2017, 2017
The quantitative importance of northern lakes in terrestrial carbon budgets is uncertain, as year-round observations of carbon fluxes are rare. We measured CH4 and CO2 fluxes from a subarctic lake and nearby fen during 2.5 years with one eddy covariance system. We identified drivers of seasonal variability in lake fluxes and show the importance of winter and spring for annual carbon exchange in both ecosystems. The lake as a source of atmospheric carbon partially compensates the fen carbon sink.



Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

Tue, 21 Nov 2017 18:39:18 +0100

Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania
Paula Conde Pardo, Bronte Tilbrook, Clothilde Langlais, Thomas William Trull, and Stephen Rich Rintoul
Biogeosciences, 14, 5217-5237, https://doi.org/10.5194/bg-14-5217-2017, 2017
The carbon content of the water masses of the Southern Ocean south of Tasmania has increased over the period 1995–2011, leading to a general decrease in pH. An enhancement in the upwelling of DIC-rich deep waters is the main plausible cause of the increase in carbon in surface waters south of the Polar Front. North of the Polar Front, strong winds favor the ventilation of surface to intermediate layers, where the DIC increase is explained by the uptake of atmospheric CO2.



Straw incorporation increases crop yield and soil organic carbon sequestration but varies under different natural conditions and farming practices in China: a system analysis

Tue, 21 Nov 2017 18:39:18 +0100

Straw incorporation increases crop yield and soil organic carbon sequestration but varies under different natural conditions and farming practices in China: a system analysis
Xiao Han, Cong Xu, Jennifer A. J. Dungait, Roland Bol, Xiaojie Wang, Wenliang Wu, and Fanqiao Meng
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-493,2017
Manuscript under review for BG (discussion: open, 0 comments)
Loss of soil organic carbon (SOC) from agricultural soils is a key indicator of soil degradation associated with reductions in net primary productivity in crop production systems worldwide. Simple technical and locally appropriate solutions are required for farmers to increase SOC and to improve cropland management. In the last 30 years, straw incorporation has gradually been implemented across China in the context of agricultural intensification and rural livelihood improvement. A meta-analysis of data published before the end of 2016 was undertaken to investigate the effects of straw incorporation on crop production and SOC sequestration. The results of 68 experimental studies throughout China in different edaphic, climate regions and under different farming regimes were analyzed. Compared with straw removal, straw incorporation significantly sequestered SOC (0–20 cm depth) at the rate of 0.35 (range 0.31–0.40) Mg C ha−1 yr−1, increased crop grain yield by 13.4 % (range 9.3 %–18.4 %) and had a conversion efficiency of the applied straw-C as 16 % ± 2 % across the whole of China. The combined straw incorporation at the rate of 3 Mg C ha−1 yr−1 with mineral fertilizer of 200–400 kg N ha−1 yr−1 was demonstrated to be the best combination for farmers to use with crop yield increased by 32.7 % (range 17.9 %–56.4 %) and SOC sequestrated by the rate of 0.85 (range 0.54–1.15) Mg C ha−1 yr−1. Straw incorporation achieved higher SOC sequestration rate and crop yield increment when applied to clay soils, under high cropping intensities, and in areas like Northeast China where the soil is being degraded. SOC responses were the greatest in the initial starting phase of straw incorporation and then declined and finally were negligible after 28–62 years, however, crop yield responses were initially low and then increased reaching their highest level at 11–15 years after straw incorporation. Overall, our study confirmed that straw incorporation did create a positive feedback loop of SOC enhancement together with increased crop production, and this is of great practical significance to straw management as agricultural intensifies in China and other regions in the world with different climate conditions.



Dimethylsulfide dynamics in first-year sea ice melt ponds in the Canadian Arctic Archipelago

Tue, 21 Nov 2017 18:39:18 +0100

Dimethylsulfide dynamics in first-year sea ice melt ponds in the Canadian Arctic Archipelago
Margaux Gourdal, Martine Lizotte, Guillaume Massé, Michel Gosselin, Michael Scarratt, and Maurice Levasseur
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-432,2017
Manuscript under review for BG (discussion: open, 0 comments)
Melt ponds (MP) forming over first year ice (FYI) represent a potential source of the climate-relevant gas dimethylsulfide (DMS) to the atmosphere. Nine MP were sampled in the Canadian Arctic Archipelago. DMS concentrations reaching up to 6 nmol L−1, twice the world's surface oceanic mean, were measured. Seawater intrusion appeared to seed MP with DMS-producing communities. DMS flux from Arctic MP is expected to increase in response to the expanding areal and temporal trends of MP on FYI.



Ferrihydrite-associated organic matter (OM) stimulates reduction by Shewanella oneidensis MR-1 and a complex microbial consortia

Mon, 20 Nov 2017 18:39:18 +0100

Ferrihydrite-associated organic matter (OM) stimulates reduction by Shewanella oneidensis MR-1 and a complex microbial consortia
Rebecca Elizabeth Cooper, Karin Eusterhues, Carl-Eric Wegner, Kai Uwe Totsche, and Kirsten Küsel
Biogeosciences, 14, 5171-5188, https://doi.org/10.5194/bg-14-5171-2017, 2017
In this study we show increasing organic matter (OM) content on ferrihydrite surfaces enhances Fe reduction by the model Fe reducer S. oneidensis and a microbial consortia extracted from peat. Similarities in reduction rates between S. oneidensis and the consortia suggest electron shuttling dominates in OM-rich soils. Community profile analyses showed enrichment of fermenters with pure ferrihydrite, whereas OM–mineral complexes favored enrichment of Fe-reducing Desulfobacteria and Pelosinus sp.



Fungal loop transfer of N depends on biocrust constituents and N form

Mon, 20 Nov 2017 18:39:18 +0100

Fungal loop transfer of N depends on biocrust constituents and N form
Zachary T. Aanderud, Trevor B. Smart, Nan Wu, Alexander S. Taylor, Yuanming Zhang, and Jayne Belnap
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-433,2017
Manuscript under review for BG (discussion: open, 0 comments)
Besides performing multiple ecosystem services individually and collectively, biocrust constituents may also create biological networks connecting spatially and temporally distinct processes. We found evidence of fungal loops within biocrusts but only in cyanobacteria-dominated crusts for the inorganic N form NH4+. Combined with our sequencing effort, our findings suggest that minor rainfall events allow dark septate Pleosporales to rapidly translocate N in the absence of a plant sink.



Microbial Biobanking Cyanobacteria-rich topsoil facilitates mine rehabilitation

Mon, 20 Nov 2017 18:39:18 +0100

Microbial Biobanking Cyanobacteria-rich topsoil facilitates mine rehabilitation
Wendy Williams, Mel Schneemilch, Angela Chilton, Stephen Williams, and Brett Neilan
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-482,2017
Manuscript under review for BG (discussion: open, 0 comments)
Mining rehabilitation in arid landscapes requires key solutions to complex issues. The massive disturbance of topsoil can result in soil degradation. Preserving shallow topsoil scrapings appeared beneficial in microbial biobanking especially preserving cyanobacterial inoculum. Provided there is adequate cyanobacterial inoculum in the topsoil stockpiles their growth should take place largely unassisted. Ongoing monitoring of microbial recovery is an effective means of measuring soil restoration.



Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

Mon, 20 Nov 2017 18:39:18 +0100

Contextualizing time-series data: Quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data
Elizabeth N. Teel, Xiao Liu, Bridget N. Seegers, Matthew A. Ragan, William Z. Haskell, Burt H. Jones, and Naomi M. Levine
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-472,2017
Manuscript under review for BG (discussion: open, 0 comments)
Time-series sites have been instrumental in providing insight into how the ocean functions. However, to extrapolate the results from a single site to a larger region, the dynamics at the site must be placed into the context of regional scale dynamics. We develop a framework for determining the spatial domain of a time-series site using high resolution data. This framework quantifies the representativeness of the site and can be used to improve sampling to better capture the dynamics at the site.



Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Fri, 17 Nov 2017 18:39:18 +0100

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone
Susan L. Brantley, David M. Eissenstat, Jill A. Marshall, Sarah E. Godsey, Zsuzsanna Balogh-Brunstad, Diana L. Karwan, Shirley A. Papuga, Joshua Roering, Todd E. Dawson, Jaivime Evaristo, Oliver Chadwick, Jeffrey J. McDonnell, and Kathleen C. Weathers
Biogeosciences, 14, 5115-5142, https://doi.org/10.5194/bg-14-5115-2017, 2017
This review represents the outcome from an invigorating workshop discussion that involved tree physiologists, geomorphologists, ecologists, geochemists, and hydrologists and developed nine hypotheses that could be tested. We argue these hypotheses point to the essence of issues we must explore if we are to understand how the natural system of the earth surface evolves, and how humans will affect its evolution. This paper will create discussion and interest both before and after publication.



Carbon stocks and fluxes in the high latitudes: using site-level data to evaluate Earth system models

Fri, 17 Nov 2017 18:39:18 +0100

Carbon stocks and fluxes in the high latitudes: using site-level data to evaluate Earth system models
Sarah E. Chadburn, Gerhard Krinner, Philipp Porada, Annett Bartsch, Christian Beer, Luca Belelli Marchesini, Julia Boike, Altug Ekici, Bo Elberling, Thomas Friborg, Gustaf Hugelius, Margareta Johansson, Peter Kuhry, Lars Kutzbach, Moritz Langer, Magnus Lund, Frans-Jan W. Parmentier, Shushi Peng, Ko Van Huissteden, Tao Wang, Sebastian Westermann, Dan Zhu, and Eleanor J. Burke
Biogeosciences, 14, 5143-5169, https://doi.org/10.5194/bg-14-5143-2017, 2017
Earth system models (ESMs) are our main tools for understanding future climate. The Arctic is important for the future carbon cycle, particularly due to the large carbon stocks in permafrost. We evaluated the performance of the land component of three major ESMs at Arctic tundra sites, focusing on the fluxes and stocks of carbon. We show that the next steps for model improvement are to better represent vegetation dynamics, to include mosses and to improve below-ground carbon cycle processes.



Estimation of isotopologue variation of N2O during denitrification by Pseudomonas aureofaciens and Pseudomonas chlororaphis: Implications for N2O source apportionment

Thu, 16 Nov 2017 18:39:18 +0100

Estimation of isotopologue variation of N2O during denitrification by Pseudomonas aureofaciens and Pseudomonas chlororaphis: Implications for N2O source apportionment
Joshua A. Haslun, Nathaniel E. Ostrom, Eric L. Hegg, and Peggy H. Ostrom
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-463,2017
Manuscript under review for BG (discussion: open, 0 comments)
N2O δ15N and δ18O values changed non-linearly during in vitro N2O production by bacterial denitrification of NO3, an argument against their use in N2O apportionment. We present a novel approach for describing non-linear isotopic behavior, which may be applied to other multi-step reactions. We also show that the intramolecular distribution of 15N in N2O, used to apportion N2O emissions to denitrification and nitrification, is unaffected by electron donor source and electron donor concentration.



Aerobiology and passive restoration of biological soil crusts

Thu, 16 Nov 2017 18:39:18 +0100

Aerobiology and passive restoration of biological soil crusts
Steven D. Warren, Larry L. St. Clair, and Steven D. Leavitt
Biogeosciences Discuss., https//doi.org/10.5194/bg-2017-430,2017
Manuscript under review for BG (discussion: open, 1 comment)
Biological soil crusts (BSCs), common features of arid soils, are consortia of cyanobacteria, algae, fungi, lichens, and mosses. They control soil hydrology and stability, concentrate essential nutrients, and influence vascular plant survival. BSCs are easily disturbed and slow to recover. Mechanisms of recovery are poorly understood. From the field of aerobiology, we find that BSC organisms are carried airborne between areas, continents, and even hemispheres.



Seagrass as major source of transparent exopolymer particles in the oligotrophic Mediterranean coast

Wed, 15 Nov 2017 18:39:18 +0100

Seagrass as major source of transparent exopolymer particles in the oligotrophic Mediterranean coast
Francesca Iuculano, Carlos Maria Duarte, Núria Marbà, and Susana Agustí
Biogeosciences, 14, 5069-5075, https://doi.org/10.5194/bg-14-5069-2017, 2017
The role of seagrass, Posidonia oceanica, meadows as a source of transparent exopolymer particles (TEPs) to Mediterranean coastal waters was tested by comparing the TEP dynamics in two adjacent coastal waters in the oligotrophic NW Mediterranean Sea, one characterized by oligotrophic open-sea waters and the other accumulating seagrass leaf litter, together with an experimental examination of TEP release by seagrass litter. TEP concentrations ranged from 4.6 to 90.6 µg XG (xanthan gum) Eq L−1, with mean (±SE) values of 38.7 (± 2.02) µg XG Eq L−1 in the site devoid of seagrass litter, whereas the coastal beach site accumulating leaf litter had > 10-fold mean TEP concentrations of 487.02 (± 72.8) µg XG Eq L−1. Experimental evaluation confirmed high rates of TEP production by P. oceanica litter, allowing calculations of the associated TEP yield. We demonstrated that P. oceanica is an important source of TEPs to the Mediterranean Sea, contributing an estimated 76 Gg C as TEPs annually. TEP release by P. oceanica seagrass explains the elevated TEP concentration relative to the low chlorophyll a concentration in the Mediterranean Sea.



Complex controls on nitrous oxide flux across a large-elevation gradient in the tropical Peruvian Andes

Wed, 15 Nov 2017 18:39:18 +0100

Complex controls on nitrous oxide flux across a large-elevation gradient in the tropical Peruvian Andes
Torsten Diem, Nicholas J. Morley, Adan Julian Ccahuana Quispe, Lidia Priscila Huaraca Quispe, Elizabeth M. Baggs, Patrick Meir, Mark I. A. Richards, Pete Smith, and Yit Arn Teh
Biogeosciences, 14, 5077-5097, https://doi.org/10.5194/bg-14-5077-2017, 2017
Montane ecosystems in the southern Peruvian Andes were atmospheric sources of the greenhouse gas nitrous oxide, exceeding prior emissions estimates from bottom-up process models. Nitrous oxide flux originated primarily from nitrate reduction. Nitrous oxide fluxes showed an inverse trend with elevation, and only weak evidence of seasonal variability. Nitrous oxide fluxes were influenced by the availability of nitrate and soil moisture content, but were not predicted by inputs of labile carbon.



Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

Wed, 15 Nov 2017 18:39:18 +0100

Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation
Jordon D. Hemingway, Daniel H. Rothman, Sarah Z. Rosengard, and Valier V. Galy
Biogeosciences, 14, 5099-5114, https://doi.org/10.5194/bg-14-5099-2017, 2017
The balance between organic matter (OM) fixation and decay is a major control on atmospheric CO2 concentrations. Understanding the environmental, chemical, and physical mechanisms that control the distribution of OM decay rates is therefore critical for constraining the global carbon cycle. In this manuscript, we derive a method to relate OM reactivity to its isotope composition using a kinetic model and provide a novel framework to discern the controls on OM decay rates.



Differential photosynthetic responses of marine planktonic and benthic diatoms to ultraviolet radiation under various temperature regimes

Tue, 14 Nov 2017 18:39:18 +0100

Differential photosynthetic responses of marine planktonic and benthic diatoms to ultraviolet radiation under various temperature regimes
Yaping Wu, Furong Yue, Juntian Xu, and John Beardall
Biogeosciences, 14, 5029-5037, https://doi.org/10.5194/bg-14-5029-2017, 2017
Diatoms were less inhibited by UV radiation under moderately increased temperature. Benthic diatoms were more resistant to UV radiation than planktonic species under extremely high temperature as found in the intertidal zone. These differential responses were linked to repair and damage processes of photosystem II.