Spatial variability of diploptene δ13C values in thermokarst lakes: the potential to analyse the complexity of lacustrine methane cycling
Biogeosciences Discuss., 12, 12157-12189, doi:10.5194/bgd-12-12157-2015, 2015
Phototrophic pigment diversity and picophytoplankton abundance in permafrost thaw lakes
Summary: Permafrost thaw lakes are a subject of increasing research interest given their abundance across the northern landscape. Our aim in the present study was to characterize the photosynthetic communities in a range of subarctic thaw lakes using a combination of HPLC analysis of algal and bacterial pigments, flow cytometry and molecular analysis. Our results showed that the thaw lakes contain diverse phototrophic communities and are a previously unrecognized habitat for abundant picophotoautotrophs.
Biogeosciences Discuss., 12, 12121-12156, doi:10.5194/bgd-12-12121-2015, 2015
Metagenomic analyses of the late Pleistocene permafrost – additional tools for reconstruction of environmental conditions
Summary: A comparative analysis of the metagenomes from two 30,000 year-old permafrost samples, one of lake-alluvial origin and the other from late Pleistocene Ice Complex sediments, revealed significant differences within microbial communities. The late Pleistocene Ice Complex sediments (which have been characterized by the absence of methane with lower values of redox-potential and Fe2+ content) showed both a low abundance of methanogenic archaea and enzymes from the carbon, nitrogen and sulfur cycles.
Biogeosciences Discuss., 12, 12091-12119, doi:10.5194/bgd-12-12091-2015, 2015
Nitrogen export from a boreal stream network following forest harvesting: seasonal nitrate removal and conservative export of organic forms
Summary: The key findings of this study are the following: The mobilization of inorganic forms of nitrogen from the terrestrial environment to streams was increased by ~15 fold following forest harvesting. These concentrations combined with the higher discharge from harvested streams enhanced the loads into the stream network. A major fraction, ~70%, of the nitrate load was removed within the network before reaching the outlet; removal was seasonal. Organic N forms were exported close-to conservative.
Biogeosciences Discuss., 12, 12061-12089, doi:10.5194/bgd-12-12061-2015, 2015
A parameterization of respiration in frozen soils based on substrate availability
Summary: Respiration in frozen soils is limited to within the thin water films surrounding soil particles. We parameterize volumetric water content (VWC) in frozen soil to represent the fraction of thawed carbon to simulate substrate availability. Simulated VWC and respiration match in situ and soil incubation data. The parameterization is most applicable when simulating carbon dynamics in permafrost for time scales of 100 years or greater.
Biogeosciences Discuss., 12, 12027-12059, doi:10.5194/bgd-12-12027-2015, 2015
Model aided quantification of dissolved carbon and nitrogen release after windthrow disturbance in an Austrian karst system
Summary: We consider the time period before and after a wind disturbance in an Austrian karst system. Using a process-based flow and solute transport simulation model we estimate impacts on DIN and DOC. We show that DIN increases for several years while DOC remains within its pre-disturbance variability. Simulated transit times indicate that impact passes through the hydrological system within some months but with a small fraction exceeding transit times of even a year.
Biogeosciences Discuss., 12, 11987-12026, doi:10.5194/bgd-12-11987-2015, 2015
Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles
Summary: We present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types, and use the model to quantitatively assess the relative roles of iron versus grazing in determining phytoplankton biomass in the Southern Ocean. Our results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation.
Biogeosciences Discuss., 12, 11935-11985, doi:10.5194/bgd-12-11935-2015, 2015
Sun-induced Chlorophyll fluorescence and PRI improve remote sensing GPP estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem
Summary: Sun-induced Chlorophyll fluorescence and Photochemical reflectance index revealed controls of climate and nutrient availability on photosynthesis (GPP). Meteo-driven models (MM) were unable to describe nutrient-induced effects on GPP. Important implication can be derived from these results and uncertainties in the prediction of global GPP still remain when MM do not account for plant nutrient availability.
Biogeosciences Discuss., 12, 11891-11934, doi:10.5194/bgd-12-11891-2015, 2015
Microbial nutrient limitation in arctic lakes in a permafrost landscape of southwest Greenland
Summary: This study investigates microbial nutrient limitation patterns across a region of southwest Greenland in relation to environmental factors. Using microbial enzyme activities to infer nutrient limitation patterns, we determined most lakes are P limited. Further, P limitation was tightly controlled by lake dissolved organic carbon (DOC) concentration.
Biogeosciences Discuss., 12, 11863-11890, doi:10.5194/bgd-12-11863-2015, 2015
Modelling anomalies in the spring and autumn land surface phenology of the European forest
Biogeosciences Discuss., 12, 11833-11861, doi:10.5194/bgd-12-11833-2015, 2015
Nonlinear thermal and moisture dynamics of high Arctic wetland polygons following permafrost disturbance
Summary: Bowl shaped ice-wedge polygons in permafrost regions can retain snowmelt water and moisture in their centre. At Bylot Isl. (NU, CA), those undisturbed polygons were homogeneous in their centre (ground temperature and moisture, plant cover and species). A rapidly developing thermal erosion gully breached polygons ridges, disturbing and changing the aforementioned elements in the ground. Eroded polygons had a varying response following the breach, heterogeneity being their new equilibrium state.
Biogeosciences Discuss., 12, 11797-11831, doi:10.5194/bgd-12-11797-2015, 2015
Controls on microalgal community structures in cryoconite holes upon high Arctic glaciers, Svalbard
Summary: The diversity of microalgae and cyanobacteria in cryoconites on three high Arctic glaciers was investigated. Possible bottom-up controls via nutrient limitation, wind dispersal, and hydrological stability were measured. Grazer populations were quantified to estimate the effect of top-down controls. Nutrient limitation appeared to be the most important control on the diversity and competition outcomes of microalgae and cyanobacteria.
Biogeosciences Discuss., 12, 11751-11795, doi:10.5194/bgd-12-11751-2015, 2015
Carbon dynamics in highly heterotrophic subarctic thaw ponds
Biogeosciences Discuss., 12, 11707-11749, doi:10.5194/bgd-12-11707-2015, 2015
Modern to millennium-old greenhouse gases emitted from freshwater ecosystems of the eastern Canadian Arctic
Summary: We report on greenhouse gas (GHG) emissions in permafrost aquatic systems of the Eastern Canadian Arctic. We found strikingly different ages, sources and emission rates depending on aquatic system types. Small and shallow ponds generally emitted young (modern to a few centuries old) GHG, whereas larger and deeper lakes released much older GHG, in particular millennium-old CH4 from lake central areas. To our knowledge, this work is the first to report on GHG age from Canadian Arctic lakes.
Biogeosciences Discuss., 12, 11661-11705, doi:10.5194/bgd-12-11661-2015, 2015
Organically fertilized tea plantation stimulates N2O emissions and lowers NO fluxes in subtropical China
Biogeosciences Discuss., 12, 11625-11659, doi:10.5194/bgd-12-11625-2015, 2015
Technical Note: An improved guideline for rapid and precise sample preparation of tree-ring stable isotope analysis
Biogeosciences Discuss., 12, 11587-11623, doi:10.5194/bgd-12-11587-2015, 2015
Structural and functional study of the nematode community from the Indian western continental margin with reference to habitat heterogeneity and oxygen minimum zone
Biogeosciences Discuss., 12, 11537-11585, doi:10.5194/bgd-12-11537-2015, 2015
Annual South American forest loss estimates based on passive microwave remote sensing (1990–2010)
Biogeosciences Discuss., 12, 11499-11535, doi:10.5194/bgd-12-11499-2015, 2015
Mercury in coniferous and deciduous upland forests in Northern New England, USA: implications from climate change
Summary: Our study investigated the effect of coniferous and deciduous vegetation on Hg cycling in forest soil. We quantified Hg in aboveground vegetation and soil horizons at eight paired forest sites. Organic horizons at coniferous stands had greater Hg concentrations and pools than at deciduous stands. Mineral soil Hg pools did not vary with vegetation type but varied with soil chemical properties. Our simple box model estimates Hg retention is significantly longer in soils at coniferous stands.
Biogeosciences Discuss., 12, 11463-11498, doi:10.5194/bgd-12-11463-2015, 2015
Seagrass beds as ocean acidification refuges for mussels? High resolution measurements of pCO2 and O2 in a Zostera marina and Mytilus edulis mosaic habitat
Biogeosciences Discuss., 12, 11423-11461, doi:10.5194/bgd-12-11423-2015, 2015
Trend and climatic sensitivity of vegetation phenology in semiarid and arid ecosystems in the US Great Basin during 1982–2011
Summary: We found that changes in wintertime and springtime precipitation played a more important role in the interannual variability of mean vegetation greenness while climate warming was mainly responsible for the 30-year positive trend in the magnitudes of mean vegetation greenness in the dryland ecosystems in the U.S. Great Basin during 1982-2011.
Biogeosciences Discuss., 12, 11387-11422, doi:10.5194/bgd-12-11387-2015, 2015
Effect of sporadic destratification, seasonal overturn and artificial mixing on CH4 emissions at the surface of a subtropical hydroelectric reservoir (Nam Theun 2 Reservoir, Lao PDR)
Biogeosciences Discuss., 12, 11349-11385, doi:10.5194/bgd-12-11349-2015, 2015
Low methane (CH4) emissions downstream of a monomictic subtropical hydroelectric reservoir (Nam Theun 2, Lao PDR)
Biogeosciences Discuss., 12, 11313-11347, doi:10.5194/bgd-12-11313-2015, 2015
Carbon dynamics in boreal peat-lands of the Yenisey region, Western Siberia
Biogeosciences Discuss., 12, 11279-11311, doi:10.5194/bgd-12-11279-2015, 2015
Concentration maxima of volatile organic iodine compounds in the bottom layer water and the cold, dense water over the Chukchi Sea in the western Arctic Ocean: a possibility of production related to degradation of organic matter
Biogeosciences Discuss., 12, 11245-11278, doi:10.5194/bgd-12-11245-2015, 2015
The abiotic contribution to total CO2 flux for soils in arid zone
Biogeosciences Discuss., 12, 11217-11244, doi:10.5194/bgd-12-11217-2015, 2015
Soil resources and climate jointly drive variations in microbial biomass carbon and nitrogen in China's forest ecosystems
Summary: Soil microbial biomass carbon (Cmic) and nitrogen (Nmic) and microbial quotient varied substantially across China’s forest ecosystems (CV 61–96%). Soil resources and climate together explained 24–41% of the variations. Cmic:Nmic ratio declined slightly with soil C:N ratio and changed with latitude and climate, suggesting a plastic homeostasis of microbial C-N stoichiometry. Divergent responses of microbial quotient of C and N to environment imply different mechanisms regulating Cmic and Nmic.
Biogeosciences Discuss., 12, 11191-11216, doi:10.5194/bgd-12-11191-2015, 2015
Quantifying importance and scaling effects of atmospheric deposition of inorganic fixed nitrogen for the eutrophic Black Sea
Biogeosciences Discuss., 12, 11159-11190, doi:10.5194/bgd-12-11159-2015, 2015
The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics
Summary: We found that regional warming promotes widespread deepening of soil thaw in the pan-Arctic area and continued warming will most likely promote permafrost degradation in the warm permafrost areas. We also found that deeper snow pack enhances soil respiration from deeper soil carbon pool more than temperature does, particularly in the cold permafrost areas, where a large amount of soil carbon is stored in deep perennial frozen soils but potentially vulnerable to mobilization from climate change.
Biogeosciences Discuss., 12, 11113-11157, doi:10.5194/bgd-12-11113-2015, 2015
Chlorophyll a specific Δ14C, δ13C and δ15N values in stream periphyton: implications for aquatic food web studies
Summary: We determined the isotopic composition of chlorophyll a in periphytic algae attached to a streambed substrate (periphyton). Although the bulk isotopic composition of periphyton is recognized as a surrogate for the photosynthetic algal community, our results indicate that the bulk periphyton matrix at the study site consists of 89%–95% algal carbon and 5%–11% terrestrial organic carbon. We also discuss how the compound-specific isotope analysis can contribute to the development of stream ecology.
Biogeosciences Discuss., 12, 11089-11111, doi:10.5194/bgd-12-11089-2015, 2015
Trichodesmium and nitrogen fixation in the Kuroshio
Summary: The high abundance of Trichodesmium and active nitrogen fixation in the Kuroshio were not explained by the nutrient distributions (nitrate, phosphate, and iron). We observed a Trichodesmium bloom and high nitrogen fixation near islands situated along the Kuroshio. Numetical experiments demonstrated that Trichodesmium around the islands could be generally delivered to the Kuroshio. These results suggest that the island mass effect is likely important for determining diazotrophy in the Kuroshio.
Biogeosciences Discuss., 12, 11061-11087, doi:10.5194/bgd-12-11061-2015, 2015
Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium
Biogeosciences Discuss., 12, 11019-11059, doi:10.5194/bgd-12-11019-2015, 2015
Landscape-scale changes in forest canopy structure across a partially logged tropical peat swamp
Biogeosciences Discuss., 12, 10985-11018, doi:10.5194/bgd-12-10985-2015, 2015
Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems
Biogeosciences Discuss., 12, 10939-10983, doi:10.5194/bgd-12-10939-2015, 2015
Air–water fluxes and sources of carbon dioxide in the Delaware Estuary: spatial and seasonal variability
Summary: Due to its extensive geographic size, one may conceptually model the Delaware Estuary as being a funnel-shaped estuarine systems. In this case, air-water CO2 fluxes in the heterotrophic upper estuary are significantly influenced by intense river-borne CO2 degassing akin to river-dominated estuarine systems. On the other hand, the more dominant autotrophic lower estuary is governed by water column biological processes and seasonal temperature cycles akin to marine-dominated estuarine systems.
Biogeosciences Discuss., 12, 10899-10938, doi:10.5194/bgd-12-10899-2015, 2015
Comparing models of microbial-substrate interactions and their response to warming
Summary: Simple microbial decomposition models show distinct responses to warming under different assumptions of how complex organic matter is broken down. If there are limitations other than microbial enzyme availability, the short term respiration response is dampened, and the decomposition dynamics resembles traditional first order decay used in most biogeochemistry models. Further, microbial adjustment to respiratory cost for enzyme production reduces overall sensitivity to temperature.
Biogeosciences Discuss., 12, 10857-10897, doi:10.5194/bgd-12-10857-2015, 2015
Quantifying regional, time-varying effects of cropland and pasture on vegetation fire
Summary: People worldwide use fire to manage agriculture, but often also suppress fire in the landscape surrounding their fields. Here, we estimate the net result of these effects of cropland and pasture on fire at a regional, monthly level. Pasture is shown, for the first time, to contribute strongly to global patterns of burning. Our results could be used to improve representations of burning in global vegetation and climate models, improving our understanding of how people affect the Earth system.
Biogeosciences Discuss., 12, 10817-10855, doi:10.5194/bgd-12-10817-2015, 2015
Reviews and Syntheses: Effects of permafrost thaw on arctic aquatic ecosystems
Summary: In this review we give an overview of the current state of knowledge regarding how permafrost thaw affects aquatic systems. We describe the general impacts of thaw on aquatic ecosystems, pathways of organic matter and contaminant release and degradation, resulting emissions and burial, and effects on ecosystem structure and functioning. We conclude with an overview of potential climate feedbacks and recommendations for future research.
Biogeosciences Discuss., 12, 10719-10815, doi:10.5194/bgd-12-10719-2015, 2015
Sharp ecotones spark sharp ideas: comment on "Structural, physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents – how different are co-occurring savanna and forest formations?" by Veenendaal et al. (2015)
Summary: Remote sensing studies indicate that tropical forest and savanna can be alternative stable states maintained by a feedback between tree cover and fire. Veenendaal et al. (2015) attempted to refute this hypothesis with an extensive field study of the vegetation structure and soil conditions at forest-savanna transition zones. With a re-analysis of their data and a conceptual model we show that in fact the results agree with the idea of forest-savanna bistability.
Biogeosciences Discuss., 12, 10707-10717, doi:10.5194/bgd-12-10707-2015, 2015
Impacts of prescribed burning on soil greenhouse gas fluxes in a suburban native forest of south-eastern Queensland, Australia
Biogeosciences Discuss., 12, 10679-10706, doi:10.5194/bgd-12-10679-2015, 2015
Permafrost coverage, watershed area and season control of dissolved carbon and major elements in western Siberian rivers
Summary: The governing parameter of DOC and major element concentrations and fluxes in western Siberia is latitude. High fluxes in the continuous permafrost zone of frozen peat bogs stem from the fact that the underlining mineral layer is not reactive, protected by the permafrost so that the major part of the active layer is located within the organic (peat) matrix and not the mineral matrix. Possible changes in export fluxes of DOC and major river water components under permafrost thaw are quantified.
Biogeosciences Discuss., 12, 10621-10677, doi:10.5194/bgd-12-10621-2015, 2015
The organic sea surface microlayer in the upwelling region off Peru and implications for air–sea exchange processes
Biogeosciences Discuss., 12, 10579-10619, doi:10.5194/bgd-12-10579-2015, 2015
Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River Basin
Summary: Two large floodplains retain the peak flows in the Zambezi River System – the dam-impacted Kafue Flats and the rather pristine Barotse Plains. Here we show that the inputs of organic matter and nutrients from such floodplains to the river are strongly affected by the presence of hydropower dams. Environmental assessments of dam impacts should therefore consider changes in water quality.
Biogeosciences Discuss., 12, 10545-10578, doi:10.5194/bgd-12-10545-2015, 2015
Application of clustering techniques to study environmental characteristics of microbialite-bearing aquatic systems
Summary: Microbialites (rocks formed by the activity of microbes) are important geobiologic structures with a ~3.5 billion year record. Despite this, the formation of microbialites is still poorly understood. This study provides a statistical treatment of the geochemistry of several microbialite-forming environments, as well as ‘control’ environments that do not form microbialtes. It is the aim of this manuscript to discern what characteristics are integral to the formation of microbialites.
Biogeosciences Discuss., 12, 10511-10544, doi:10.5194/bgd-12-10511-2015, 2015
Water use strategies of a young Eucalyptus urophylla forest in response to seasonal change of climatic factors in South China
Summary: a) More dramatically decreased hydralic conductivity when stomatal conductance was decreasing may shed some light on the mechanism of the high WUE of Eucalyptus when exposed to drought conditions. b) As tree grows, ks is more sensitive to water loss. c) The decrease in stomatal sensitivity of GSref to D along the radiation gradient accounted for an important aspect of “plastic characteristics” for E. urophylla.
Biogeosciences Discuss., 12, 10469-10510, doi:10.5194/bgd-12-10469-2015, 2015
Effects of a windthrow disturbance on the carbon balance of a broadleaf deciduous forest in Hokkaido, Japan
Summary: Using the eddy covariance and biometrical methods, the carbon budget was measured in a deciduous broadleaf forest in Japan, where accidental damage by a strong typhoon damaged 40% of trees. Before the disturbance, the forest was an evident carbon sink, and it subsequently transformed to net a carbon source. GPP only decreased by 6% just after the disturbance. On the other hand, Re increased by 39%. Undergrowth dwarf bamboo has an important role in the carbon budget.
Biogeosciences Discuss., 12, 10425-10468, doi:10.5194/bgd-12-10425-2015, 2015
Lateral carbon fluxes and CO2 outgassing from a tropical peat-draining river
Summary: Tropical peatlands are an important source of organic carbon to rivers. However, due to the remoteness of these ecosystems, data are scarce. We present the first combined assessment of both lateral organic carbon fluxes and CO2 emissions from an undisturbed tropical peat-draining river. Compared to the organic carbon concentrations, CO2 fluxes to the atmosphere were actually relatively moderate, which we attributed to the short water residence time.
Biogeosciences Discuss., 12, 10389-10424, doi:10.5194/bgd-12-10389-2015, 2015
Responses of soil microbial communities and enzyme activities to nitrogen and phosphorus additions in Chinese fir plantations of subtropical China
Summary: We examined how N and P addition influenced soil microbial community composition and enzyme activities in subtropical China. The results showed that C and N cycling enzymes were more sensitive to nutrient additions than P cycling enzymes and Gram positive bacteria were most closely related to soil nutrient cycling enzymes. Combined additions of N and P fertilizer were recomoned to promote soil fertility and microbial activity in this kind of plantation.
Biogeosciences Discuss., 12, 10359-10387, doi:10.5194/bgd-12-10359-2015, 2015
Two-dimensional distribution of living benthic foraminifera in anoxic sediment layers of an estuarine mudflat (Loire Estuary, France)
Summary: We present a new rapid and accurate protocol to simultaneously sample benthic living foraminifera in two dimensions in a centimeter scale vertical grid and dissolved iron in high resolution (200µm). The main characteristics of A. tepida distribution are interpreted as a combination of passive downward transport by biomixing into deeper suboxic sediment layers and a subsequent mobility driven by a sensitivity to geochemical gradients.
Biogeosciences Discuss., 12, 10311-10358, doi:10.5194/bgd-12-10311-2015, 2015
Net ecosystem production in a Little Ice Age moraine: the role of plant functional traits
Summary: Vegetation growth after glaciers retreat can be an important feedback to increasing atmospheric CO2. We monitored, with transparent and opaque chambers, the carbon fluxes of two vegetation communities on an alpine glacier forefield over two growing seasons. We showed that different plant physiology determines the sign of the net carbon exchange. A C3 grassland, having higher assimilation rates, was a net CO2 sink, while CAM rosettes were a net source.
Biogeosciences Discuss., 12, 10271-10310, doi:10.5194/bgd-12-10271-2015, 2015
Co-occurrence patterns in aquatic bacterial communities across changing permafrost landscapes
Summary: Bacterial co-occurrence patterns were non-random, with evidence of habitat preferences. Co-occurrence networks revealed complex interdependencies within the bacterioplankton communities and showed contrasting linkages to environmental conditions among the main bacterial phyla. The thaw ponds and lakes networks were composed of a limited number of highly connected taxa, which render these communities more resilient to environmental change, but sensitive to the loss of these keystone species.
Biogeosciences Discuss., 12, 10233-10269, doi:10.5194/bgd-12-10233-2015, 2015
Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes
Biogeosciences Discuss., 12, 10195-10232, doi:10.5194/bgd-12-10195-2015, 2015
Differences between coastal and open ocean distributions of N2O in the oxygen minimum zone off Peru
Biogeosciences Discuss., 12, 10167-10193, doi:10.5194/bgd-12-10167-2015, 2015
An inversion approach for determining production depth and temperature sensitivity of soil respiration
Summary: This study examines an inversion approach for estimating Q10 and depth of production using a physically based soil model, constrained by observed high-frequency surface fluxes and/or 5 concentrations. Inversions using exclusively surface flux measurements were successful, but using multiple shallow subsurface CO2 measurements yielded the best results. This work is a first step toward building a reliable computing framework for removing physical artifacts from high frequency soil CO2 data.
Biogeosciences Discuss., 12, 10137-10166, doi:10.5194/bgd-12-10137-2015, 2015
Soil carbon sequestration by three perennial legume pastures is greater in deeper soil layers than in the surface soil
Biogeosciences Discuss., 12, 10115-10135, doi:10.5194/bgd-12-10115-2015, 2015
A process-based model for ammonia emission from urine patches, GAG (Generation of Ammonia from Grazing): description, validation and sensitivity analysis
Summary: We have been developed a process-based, weather-driven model for ammonia emission from a urine patch and assessed its sensitivity to various factors. The model can simulate the ammoniacal nitrogen content, pH and the water content of the soil under a urine patch. The validation showed that the simulated parameters are well captured by the model. The sensitivity analysis highlighted the vital role of temperature in ammonia exchange. The model is potentially suitable for larger scale application.
Biogeosciences Discuss., 12, 10059-10113, doi:10.5194/bgd-12-10059-2015, 2015
Annual litterfall dynamics and nutrient deposition depending on elevation and land use at Mt. Kilimanjaro
Biogeosciences Discuss., 12, 10031-10057, doi:10.5194/bgd-12-10031-2015, 2015
Changing nutrient stoichiometry affects phytoplankton production, DOP build up and dinitrogen fixation – a mesocosm experiment in the eastern tropical North Atlantic
Biogeosciences Discuss., 12, 9991-10029, doi:10.5194/bgd-12-9991-2015, 2015
Composition and sources of sedimentary organic matter in the deep Eastern Mediterranean Sea
Biogeosciences Discuss., 12, 9935-9989, doi:10.5194/bgd-12-9935-2015, 2015
Thermocline mixing and vertical oxygen fluxes in the stratified central North Sea
Biogeosciences Discuss., 12, 9905-9934, doi:10.5194/bgd-12-9905-2015, 2015
Speciation and distribution of P associated with Fe and Al oxides in aggregate-sized fraction of an arable soil
Biogeosciences Discuss., 12, 9879-9903, doi:10.5194/bgd-12-9879-2015, 2015
Earth system responses to cumulative carbon emissions
Biogeosciences Discuss., 12, 9839-9877, doi:10.5194/bgd-12-9839-2015, 2015
Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation
Summary: This study investigates how sunlight, dissolved organic matter (DOM) concentration and composition, and hydrology interact to control DOM degradation in headwater streams. In Imnavait Creek, a shallow, low-relief stream in the Arctic, DOM degradation by sunlight was limited by light under all conditions. Study results were used to synthesize controls on DOM degradation by sunlight for a river reach, expressed as a function of light attenuation and water residence times.
Biogeosciences Discuss., 12, 9793-9838, doi:10.5194/bgd-12-9793-2015, 2015
Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda
Summary: The landscape-scale spatial pattern in the elemental and isotopic composition of organisms offers valuable information about the ecological processes operating across the landscape. When used in parallel, spatial patterns in stable isotopic composition (called isoscapes) and elemental stoichiometry (we propose the term "stoichioscapes") of seagrasses in Bermuda indicate nutrient sources and unique nitrogen cycling on this isolated oceanic platform.
Biogeosciences Discuss., 12, 9751-9791, doi:10.5194/bgd-12-9751-2015, 2015
Microbial carbon recycling: an underestimated process controlling soil carbon dynamics
Biogeosciences Discuss., 12, 9729-9750, doi:10.5194/bgd-12-9729-2015, 2015
Future fisheries yield in shelf waters: a model study into effects of a warmer and more acidic marine environment
Summary: - Effects of ocean acidification in shelf waters on fish yield can be of the same order of magnitude as climatic impacts. - Local differences in response within one shelf sea due to different governing hydrodynamic regimes and variation in importance of benthic food web. - Future fish yields in the North Sea: seasonally stratified areas show increased yield, transitional waters show decreased yield and permanently mixed waters show increased yield moderated by acidification impacts.
Biogeosciences Discuss., 12, 9695-9727, doi:10.5194/bgd-12-9695-2015, 2015
Challenges in modelling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman
Summary: Interannual variability of phytoplankton blooms in northwestern Arabian Sea and Gulf of Oman is examined. Interannual variability of the wintertime bloom is dominated by cyclonic eddies which vary in location from one year to another. We suggest that for the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies.
Biogeosciences Discuss., 12, 9651-9693, doi:10.5194/bgd-12-9651-2015, 2015
Precipitation legacy effects on dryland ecosystem carbon fluxes: direction, magnitude and biogeochemical carryovers
Summary: This simulation study found that dry legacy imposed positive impacts on net ecosystem production (NEP) whereas wet legacy had negative impacts on NEP, indicating that dry legacy can fostering more C sequestration and wet legacy more C release. The carryover of soil nitrogen was mainly responsible for the gross ecosystem production (GEP) responses while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the ecosystem respiration (Re) responses.
Biogeosciences Discuss., 12, 9613-9650, doi:10.5194/bgd-12-9613-2015, 2015
The relative contributions of forest growth and areal expansion to forest biomass carbon sinks in China
Summary: Our findings suggested that the mechanisms underlying the C sinks for natural and planted forests of China differed markedly with various effects from areal expansion and increase in carbon density. The increasing trend in the relative contribution of forest growth to C sinks for planted forests highlight that afforestation can continue to increase the C sink of China's forests in the future subject to persistently-increasing forest growth after establishment of plantation.
Biogeosciences Discuss., 12, 9587-9612, doi:10.5194/bgd-12-9587-2015, 2015
Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere
Biogeosciences Discuss., 12, 9543-9586, doi:10.5194/bgd-12-9543-2015, 2015
Ecosystem model-based approach for modelling the dynamics of 137Cs transfer to marine plankton populations: application to the western North Pacific Ocean after the Fukushima nuclear power plant accident
Biogeosciences Discuss., 12, 9497-9541, doi:10.5194/bgd-12-9497-2015, 2015
Micro-topographic variation in soil respiration and its controlling factors vary with plant phenophases in a desert-shrub ecosystem
Biogeosciences Discuss., 12, 9465-9495, doi:10.5194/bgd-12-9465-2015, 2015
Technical Note: Towards resolving in situ, centimeter-scale location and timing of biomineralization in calcareous meiobenthos – the Calcein-Osmotic pump method
Biogeosciences Discuss., 12, 9443-9463, doi:10.5194/bgd-12-9443-2015, 2015
An objective prior error quantification for regional atmospheric inverse applications
Biogeosciences Discuss., 12, 9393-9441, doi:10.5194/bgd-12-9393-2015, 2015
Insights into the transfer of silicon isotopes into the sediment record
Biogeosciences Discuss., 12, 9369-9391, doi:10.5194/bgd-12-9369-2015, 2015
The ability of atmospheric data to resolve discrepancies in wetland methane estimates over North America
Summary: We use atmospheric data from the US and Canada to examine seven wetland methane flux estimates. Our analysis indicates a wetland source that is smaller with a broader seasonal cycle than in existing estimates. Furthermore, we estimate the largest fluxes over the Hudson Bay Lowland, a spatial distribution that differs from commonly-used remote sensing estimates of wetland location.
Biogeosciences Discuss., 12, 9341-9368, doi:10.5194/bgd-12-9341-2015, 2015
Impact of forest harvesting on water quality and fluorescence characteristics of dissolved organic matter in Eastern Canadian Boreal Shield lakes
Summary: In this study, we showed that logging activities have a short-term impact (one year after the perturbation) on water quality in boreal Eastern Canadian Shield lakes. However, this effect seems to mitigate two years after the perturbation. Further, the analysis of the absorbance and fluorescence data showed that while DOC concentrations did significantly increase in perturbed lakes, the DOM quality did not measurably change.
Biogeosciences Discuss., 12, 9307-9339, doi:10.5194/bgd-12-9307-2015, 2015
C : N : P stoichiometry at the Bermuda Atlantic Time-series Study station in the North Atlantic Ocean
Biogeosciences Discuss., 12, 9275-9305, doi:10.5194/bgd-12-9275-2015, 2015
Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific
Summary: We present the first measurements of N2O across three mesoscale eddies in the eastern tropical South Pacific. Eddie's vertical structure, offshore transport, properties at the time of formation and increased primary production at the near-surface, determined the N2O distribution. Substantial depletion of N2O within the core of anticyclonic eddies suggests that although these are transient features, eddy-driven increase in N-loss processes in the Peruvian oxygen minimum zone can be significant.
Biogeosciences Discuss., 12, 9243-9273, doi:10.5194/bgd-12-9243-2015, 2015
Transpiration in an oil palm landscape: effects of palm age
Summary: The study provides first insights into hydrological consequences of the continuing oil palm expansion in the tropics. Stand transpiration rates of some studied oil palm stands compared to or even exceed values reported for tropical forests, indicating a high water use of oil palms under certain conditions. Oil palm dominated landscapes show some spatial variations in (evapo)transpiration rates, e.g. due to varying age, but the temporal variability of oil palm transpiration is rather low.
Biogeosciences Discuss., 12, 9209-9242, doi:10.5194/bgd-12-9209-2015, 2015
Soil fertility controls soil–atmosphere carbon dioxide and methane fluxes in a tropical landscape converted from lowland forest to rubber and oil palm plantations
Summary: We found that in Indonesia, oil palm displayed reduced soil CO2 fluxes compared to forest and rubber plantations, which was mainly caused by reduced litter input. Furthermore, we measured reduced soil CH4 uptake in oil palm and rubber plantations compared to forest which was due to a decrease in soil N availability in the converted land uses. Our study shows for the first time that differences in soil fertility control soil-atmosphere exchange of CO2 and CH4 in a tropical landscape.
Biogeosciences Discuss., 12, 9163-9207, doi:10.5194/bgd-12-9163-2015, 2015
Environmental controls on the greening of terrestrial vegetation across northern Eurasia
Summary: The vegetation of northern Eurasia has been observed to be greening over the last few decades and we assess how changes in temperature, precipitation, cloudiness and forest fires have affected the photosynthetic activity of the region. We find that while in most parts of northern Eurasia, increasing temperatures have lead to the increase in photosynthesis, in the south-western region, warming has lead to a decrease in the photosynthetic activity implying a comparatively higher drought stress.
Biogeosciences Discuss., 12, 9121-9162, doi:10.5194/bgd-12-9121-2015, 2015
Global assessment of Vegetation Index and Phenology Lab (VIP) and Global Inventory Modeling and Mapping Studies (GIMMS) version 3 products
Summary: We compared two new Earth observation based long-term global vegetation index products used in global change research (Global Inventory Modeling and Mapping Studies and Vegetation Index & Phenology Lab- VIP version 3). The two products showed a high level of consistency throughout the primary growing season and were less consistent during green-up and brown-down, which impacted trends in phenology. VIP was generally higher and more variable, which led to poorer correlations with in situ data.
Biogeosciences Discuss., 12, 9081-9120, doi:10.5194/bgd-12-9081-2015, 2015
Diazotroph community succession during the VAHINE mesocosms experiment (New Caledonia Lagoon)
Summary: -Shift from diatom associated diazotrophs (DDAs) to unicellular cyanobacterial group C (UCYN-C) in response to DIP fertilization was captured in a large-scale mesocosm experiment in the Noumea Lagoon (NL), a low nutrient low chlorophyll coastal environment. -First report of in situ net growth and mortality rates for unicellular diazotrophs UCYN-A2, and UCYN-C. -First quantitative abundance data for diazotrophs in NL indicates that DDAs and UCYN-A1/A2 may be important N2 fixers in this region.
Biogeosciences Discuss., 12, 9043-9079, doi:10.5194/bgd-12-9043-2015, 2015
Map-based prediction of organic carbon in headwaters streams improved by downstream observations from the river outlet
Summary: In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the total organic carbon (TOC) of headwaters, relative to models based on map information alone. Including river outlet TOC as a predictor in the models gave 5-15% lower prediction errors than using map information alone. Thus, data on water chemistry measured at river outlets offers information which can complement GIS-based modelling of headwaters chemistry.
Biogeosciences Discuss., 12, 9005-9041, doi:10.5194/bgd-12-9005-2015, 2015
The effect of warm-season precipitation on the diel cycle of the surface energy balance and carbon dioxide at a Colorado subalpine forest site
Summary: The effect of warm-season precipitation on environmental conditions and ecosystem-scale fluxes at a high-elevation subalpine forest site was investigated. As would be expected (based on the surface energy balance), precipitation caused an increase in latent heat flux (evapotranspiration) and a decrease in sensible heat flux. The evaporative component of evapotranspiration was, on average, estimated to be around 6% in dry conditions and 20% in wet conditions.
Biogeosciences Discuss., 12, 8939-9004, doi:10.5194/bgd-12-8939-2015, 2015
Reviews and synthesis: Carbon capture and storage monitoring – an integrated biological, biophysical and chemical approach
Summary: Here we review current knowledge about the impact of CO2 leaks from marine carbon capture storage sites, and use a recent case study to assess current monitoring techniques. We integrate aspects of microbiology, geophysics, chemistry and bioinformatics to suggest a future integrative monitoring technique, using metagenomics, to prevent large-scale leakages and associated consequences. This novel approach is generic and can be adapted to other systems of interest for environmental monitoring.
Biogeosciences Discuss., 12, 8909-8937, doi:10.5194/bgd-12-8909-2015, 2015
The first records of deep-sea fauna – a correction and discussion
Summary: The recovery of a basket star in 1818 from deep waters of Baffin Bay is often cited as the first organism that was brought up from the deep sea. Yet recoveries of stalked crinoids from the Caribbean and catches of several bathyal fishes occurred decades earlier. Yet these accidental catches remained largely neglected during the 19th and 20th century because the bathyal nature of these animals was not recognized.
Biogeosciences Discuss., 12, 8883-8907, doi:10.5194/bgd-12-8883-2015, 2015
Fossil invertebrates records in cave sediments and paleoenvironmental assessments: a study of four cave sites from Romanian Carpathians
Biogeosciences Discuss., 12, 8849-8881, doi:10.5194/bgd-12-8849-2015, 2015
Recycling vs. stabilisation of soil sugars – a long-term laboratory incubation experiment
Biogeosciences Discuss., 12, 8819-8847, doi:10.5194/bgd-12-8819-2015, 2015
Short-term changes in a microplankton community in the Chukchi Sea during autumn: consequences of a strong wind event
Summary: We studied short-term changes in microplankton community in the western Arctic Ocean with regards to responses to the strong wind event （SWE）during autumn (September 2013). SWE supplied sufficient nutrients to the surface layer that then enhance the small pennate diatom bloom under the weak stratification water column. SWE during autumn may have function to accelerate the seasonal succession of the microplankton community from summer to winter.
Biogeosciences Discuss., 12, 8789-8817, doi:10.5194/bgd-12-8789-2015, 2015
Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin
Biogeosciences Discuss., 12, 8747-8787, doi:10.5194/bgd-12-8747-2015, 2015
Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wild fire
Biogeosciences Discuss., 12, 8723-8745, doi:10.5194/bgd-12-8723-2015, 2015
Drivers of summer oxygen depletion in the central North Sea
Summary: In stratified shelf seas, physical and biological conditions can lead to seasonal oxygen depletion when consumption exceeds supply. An ocean glider obtained a high resolution 3-day data set of biochemical and physical properties in the central North Sea. The data revealed very high oxygen consumption rates, far exceeding previously reported rates. An consumption/supply oxygen budget indicates a localised or short lived resuspension event causing rapid remineralisation of benthic organic matter.
Biogeosciences Discuss., 12, 8691-8722, doi:10.5194/bgd-12-8691-2015, 2015
Latitudinal and temporal distributions of diatom populations in the pelagic waters of the Subantarctic and Polar Frontal Zones of the Southern Ocean and their role in the biological pump
Summary: Diatom and major components of the flux collected by two sediment traps in Subantarctic and Polar Frontal Zones were studied. Despite significant differences in the composition and magnitude of the flux, POC flux was similar between sites. The development of a group of bloom-forming diatoms during summer led to the formation of aggregates and enhanced POC export. Our results suggest that high biogenic silica accumulation rates should be interpreted as a proxy for iron-limited diatom assemblages.
Biogeosciences Discuss., 12, 8615-8690, doi:10.5194/bgd-12-8615-2015, 2015
Integrated radar and lidar analysis reveals extensive loss of remaining intact forest on Sumatra 2007–2010
Summary: We integrated satellite Synthetic Aperture Radar (SAR), lidar and forest plot data to calculate the amount and loss of above ground biomass in remaining tall natural forests in a section of Sumatra, with quantified uncertainties. We estimate very high deforestation rates of 3.8% yr-1, and the loss of 11.3% remaining forest biomass in only three years. L-band SAR is valuable for penetrating cloud for deforestation analyses, and for reliably estimating the carbon emissions from land use change.
Biogeosciences Discuss., 12, 8573-8614, doi:10.5194/bgd-12-8573-2015, 2015
Comparative study of vent and seep macrofaunal communities in the Guaymas Basin
Summary: The absence of biogeographic barrier between seep and vent ecosystems in the Guaymas basin offers the opportunity to assess the role of environmental conditions on the distribution of macrofaunal communities. Our results showed that community structure was primarily shaped by common abiotic factors. In addition, a high number of common species were shared, suggesting frequent connections between the two ecosystems. Overall, this study supports the hypothesis of a continuum among vents and seeps.
Biogeosciences Discuss., 12, 8497-8571, doi:10.5194/bgd-12-8497-2015, 2015
Does Juncus effusus enhance methane emissions from grazed pastures on peat?
Biogeosciences Discuss., 12, 8467-8495, doi:10.5194/bgd-12-8467-2015, 2015
Carbonate saturation state of surface waters in the Ross Sea and Southern Ocean: controls and implications for the onset of aragonite undersaturation
Summary: We calculate the carbonate saturation state of surface water from the Ross Sea and along a transect between the Ross Sea and southern Chile using ~ 1700 total alkalinity measurements. Our results suggest that variability in surface carbonate saturation state is driven by biological productivity. We argue that in the Ross Sea the aragonite saturation state of surface water during the early spring never falls below 1.2.
Biogeosciences Discuss., 12, 8429-8465, doi:10.5194/bgd-12-8429-2015, 2015
Biodegradability of dissolved organic carbon in permafrost soils and waterways: a meta-analysis
Summary: We found that dissolved organic carbon (DOC) in arctic soils and aquatic systems is increasingly degradable with increasing permafrost extent. Also, DOC seems less degradable when moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly bioavailable DOC is lost in headwater streams. We also recommend a standardized DOC incubation protocol to facilitate future comparison on processing and transport of DOC in a changing Arctic.
Biogeosciences Discuss., 12, 8353-8393, doi:10.5194/bgd-12-8353-2015, 2015
Fate of peat-derived carbon and associated CO2 and CO emissions from two Southeast Asian estuaries
Summary: We studied organic carbon and the dissolved greenhouse gases carbon dioxide (CO2) and carbon monoxide (CO) in two estuaries in Sarawak, Malaysia, whose coast is covered by carbon-rich peatlands. The estuaries received terrestrial organic carbon from peat-draining tributaries. A large fraction was transformed to CO2 and a minor fraction to CO. Both gases were released to the atmosphere. This shows how these estuaries function as efficient filters between land and ocean in this important region.
Biogeosciences Discuss., 12, 8299-8340, doi:10.5194/bgd-12-8299-2015, 2015
Greenhouse gas balance of cropland conversion to bioenergy poplar short rotation coppice
Summary: The suitability of a land conversion from cropland to short rotation coppice (SRC) of poplar in Central Italy was investigated comparing the respective GHG budgets, including biogenic and anthropogenic CO2, CH4 and N2O fluxes, change in soil C stocks and effects of biomass use. Land conversion was suitable from a GHG perspective, saving 2358 ± 835 gCO2eq m-2, as C exports in the cropland compensated all the C taken up by plants, while in the SRC only in part. Soil non-CO2 fluxes were negligible
Biogeosciences Discuss., 12, 8035-8084, doi:10.5194/bgd-12-8035-2015, 2015
Calculating the global contribution of coralline algae to carbon burial
Summary: The ongoing increase in anthropogenic carbon dioxide (CO2) emissions is changing the marine environment. Reduction of CO2 to a sustainable level is required to avoid further change. In this manuscript, the carbon storage potential of coralline algae (CA) and their deposits is accessed. We show that CA represent an as yet unquantified significant carbon repository, storing similar amounts of carbon to seagrasses and mangroves. Critically, stored carbon will be stable at geological time scale.
Biogeosciences Discuss., 12, 7845-7877, doi:10.5194/bgd-12-7845-2015, 2015
Human land uses enhance sediment denitrification and N2O production in Yangtze lakes primarily by influencing lake water quality
Biogeosciences Discuss., 12, 7815-7844, doi:10.5194/bgd-12-7815-2015, 2015
Age depth-model for the past 630 ka in Lake Ohrid (Macedonia/Albania) based on cyclostratigraphic analysis of downhole gamma ray data
Biogeosciences Discuss., 12, 7671-7703, doi:10.5194/bgd-12-7671-2015, 2015
Isotopically enriched ammonium shows high nitrogen turnover in the pile top zone of dairy manure compost
Summary: δ15N-NH4+-N of dairy manure compost piles was studied. Piles with bulking agent showed significantly higher value 17.7±1.3‰ than that of the piles without bulking agent (11.8±0.9‰) at the end of the process, reflecting significant higher nitrogen conversion and NH3 loss occurred in the pile with bulking agent. The pile top samples which showed very high NH4+-N concentrations with significantly enriched δ15N values (12.7-29.8‰) indicate extremely high nitrogen conversion occurred in this zone.
Biogeosciences Discuss., 12, 7577-7598, doi:10.5194/bgd-12-7577-2015, 2015
Detecting methane ebullition on thermokarst lake ice using high resolution optical aerial imagery
Summary: We used multi-temporal high-resolution aerial images of an Alaskan thermokarst lake acquired following freeze-up to map and characterize methane ebullition bubbles trapped in lake ice. We assessed their spatial pattern and also analyzed the spatio-temporal variability of seep occurrences. Our study helped to reveal the location and relative sizes of high- and low-flux seepage zones within the lake. A large number of seeps demonstrated spatio-temporal stability over our two-year study period.
Biogeosciences Discuss., 12, 7449-7490, doi:10.5194/bgd-12-7449-2015, 2015
Effects of nitrate and phosphate supply on chromophoric and fluorescent dissolved organic matter in the Eastern Tropical North Atlantic: a mesocosm study
Biogeosciences Discuss., 12, 7209-7255, doi:10.5194/bgd-12-7209-2015, 2015
Characterization of active and total fungal communities in the atmosphere over the Amazon rainforest
Biogeosciences Discuss., 12, 7177-7207, doi:10.5194/bgd-12-7177-2015, 2015
Two decades of inorganic carbon dynamics along the Western Antarctic Peninsula
Summary: Evaluation of a unique 20 year long timeseries of inorganic carbon and nutrient observations from the Western Antarctic Peninsula region shows that summertime biological productivity and meltwater input drive a large range of surface aragonite saturation states from values < 1 (undersaturated) up to 3.9. pCO2 measurements from fall and spring indicate a statistically significant increasing trend of up to 23 μatm decade-1, pointing towards first signs of ocean acidification.
Biogeosciences Discuss., 12, 6929-6969, doi:10.5194/bgd-12-6929-2015, 2015
Comment on "Solute specific scaling of inorganic nitrogen and phosphorus uptake in streams" by Hall et al. (2013)
Biogeosciences Discuss., 12, 5991-6001, doi:10.5194/bgd-12-5991-2015, 2015
Dynamics of air–sea CO2 fluxes in the North-West European Shelf based on Voluntary Observing Ship (VOS) and satellite observations
Biogeosciences Discuss., 12, 5641-5695, doi:10.5194/bgd-12-5641-2015, 2015
Halocarbon emissions and sources in the equatorial Atlantic Cold Tongue
Summary: This manuscript covers the first measurements of CHBr3, CH2Br2 and CH3I from the equatorial Atlantic during the Cold Tongue season, identifying this region and season as a source for these compounds. For the first time, we calculated diapycnal fluxes, and showed that the fluxes from below the mixed layer to the surface are not sufficient to balance the mixed layer budget. Hence, we conclude that mixed layer production has to take place despite a pronounced sub-mixed-layer-maximum.
Biogeosciences Discuss., 12, 5559-5608, doi:10.5194/bgd-12-5559-2015, 2015
Quantifying wind and pressure effects on trace gas fluxes across the soil–atmosphere interface
Summary: One continuing, significant source of uncertainty in global climate predictions is the combined effect of wind and pressure on trace gas fluxes. We quantified the effects of wind speed and pressure on fluxes of CO2 and CH4 within three different ecosystems. Trace gas fluxes are positively correlated with both wind speed and pressure near the soil surface but we argue that wind speed is a better proxy for general use. These results have implications for a number of global feedback mechanisms.
Biogeosciences Discuss., 12, 4801-4832, doi:10.5194/bgd-12-4801-2015, 2015
Stable isotopes in barnacles as a tool to understand green sea turtle (Chelonia mydas) regional movement patterns
Summary: We report on the oxygen isotope signatures in green sea turtle (Chelonia mydas) barnacles (Platylepas sp.) to suggest likely regional movement patterns by mapping these onto a predictive oxygen isotope map of the Pacific. Discussing barnacle proxies potential relevance as an alternative tool with which to study green sea turtle migration, we find that these could complement traditional methods of studying connectivity between turtle populations and help inform more effective conservation policy.
Biogeosciences Discuss., 12, 4655-4669, doi:10.5194/bgd-12-4655-2015, 2015
Interdependencies between temperature and moisture sensitivities of CO2 emissions in European land ecosystems
Summary: Our experiments showed that in cold areas (e.g. northern latitudes or mountain areas) warming as well as rain events will have a larger impact on CO2 emissions. Increased moisture in dry areas or drying of wet areas will largely promote CO2 emissions. Irrigation of arable lands might have a higher impact on CO2 emissions in warmer regions in the South of Europe than in the North.
Biogeosciences Discuss., 12, 4433-4464, doi:10.5194/bgd-12-4433-2015, 2015
Stable isotope paleoclimatology of the earliest Eocene using kimberlite-hosted mummified wood from the Canadian Subarctic
Summary: The recent discovery of mummified wood (non-petrified) within kimberlite diamond mines in Northwest Territories, Canada, has prompted a paleoclimatic investigation of the time in which the trees grew - the earliest Eocene (ca. 53.3 Ma). Multiple proxy records derived from these samples suggest that during greenhouse climates of the Eocene, subarctic Canada was characterized by high temperatures (+16 C above modern), and multidecadal variability in cloudiness and temperature on 20-30 year cycles.
Biogeosciences Discuss., 11, 16269-16308, doi:10.5194/bgd-11-16269-2014, 2014