Corrigendum to "Comparing the influence of net and gross anthropogenic land-use and land-cover changes on the carbon cycle in the MPI-ESM" published in Biogeosciences, 11, 4817–4828, 2014
Biogeosciences, 12, 3041-3041, doi:10.5194/bg-12-3041-2015, 2015
Distribution of black carbon in ponderosa pine forest floor and soils following the High Park wildfire
Summary: Black carbon (BC) includes everything from charred wood to soot, making it difficult to measure and limiting our understanding of the amount in soils. We studied the effects of fire severity and degree of hillslope on BC quantities in forest floor and soil samples after the High Park wildfire that took place in northwestern Colorado, June 2012. Using molecular markers we found that the majority of BC remained in the litter 4 months post fire, regardless of fire intensity or degree of hillslope.
Biogeosciences, 12, 3029-3039, doi:10.5194/bg-12-3029-2015, 2015
Seasonal dynamics of organic carbon and metals in thermokarst lakes from the discontinuous permafrost zone of western Siberia
Summary: A year-around hydrochemical study (including full winter freezing and spring flood) of shallow thermokarst lakes from a discontinuous permafrost zone of western Siberia revealed conceptually new features of element concentration evolution over different seasons within a large scale of the lake size.
Biogeosciences, 12, 3009-3028, doi:10.5194/bg-12-3009-2015, 2015
Imaging tropical peatlands in Indonesia using ground-penetrating radar (GPR) and electrical resistivity imaging (ERI): implications for carbon stock estimates and peat soil characterization
Summary: We use a combination of hydrogeophysical methods and direct cores to better understand peatland thickness in Indonesia and estimate carbon storage in remote peatland systems where available information is limited. Results show that geophysical methods can help improve peat thickness accuracy (when compared to coring), and help identify certain features within the peat matrix such as organomineral horizons, wood layers or buttressed trees.
Biogeosciences, 12, 2995-3007, doi:10.5194/bg-12-2995-2015, 2015
Vegetation and elevation influence the timing and magnitude of soil CO2 efflux in a humid, topographically complex watershed
Summary: We wanted to understand how the coupling of water and carbon cycling is affected by landscape position and vegetation heterogeneity within a humid, topographically complex watershed in the Appalachian mountains of West Virginia. Over 3 years (2010-2012), we found that in low-rainfall years, shrubs had a strong effect on the magnitude of soil carbon fluxes but that in high-rainfall years, fluxes were constrained across the watershed. Highest fluxes occurred at below-average soil moisture.
Biogeosciences, 12, 2975-2994, doi:10.5194/bg-12-2975-2015, 2015
A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin
Summary: Methane hydrate may be stable at the base of the permafrost zone in sediments of the Siberian continental margin, but the sediments' depth below the sea floor precludes a fast response time (order 1-10 years) that would be required for the released methane to have a significant impact on the near-term evolution of Earth's climate. However, the Arctic could amplify anthropogenic climate change by releasing carbon on timescales of centuries or millennia.
Biogeosciences, 12, 2953-2974, doi:10.5194/bg-12-2953-2015, 2015
Structural, physiognomic and above-ground biomass variation in savanna–forest transition zones on three continents – how different are co-occurring savanna and forest formations?
Summary: When nearby forest and savanna stands are compared, they are not as structurally different as first seems. Moreover, savanna-forest transition zones typically occur at higher rainfall for South America than for Africa but with coexistence confined to a well-defined edaphic-climate envelope. With interacting soil cation-soil water storage–precipitations effects on canopy cover also observed we argue that both soils and climate influence the location of the two major tropical vegetation types.
Biogeosciences, 12, 2927-2951, doi:10.5194/bg-12-2927-2015, 2015
Assessing vegetation structure and ANPP dynamics in a grassland–shrubland Chihuahuan ecotone using NDVI–rainfall relationships
Summary: Exploration of NDVI-rainfall relationships provided ready biophysically based criteria to study the spatial distribution and dynamics of ANPP for herbaceous and shrub vegetation across a grassland-shrubland Chihuahuan ecotone (Sevilleta NWR, New Mexico). Overall our results suggest that shrub encroachment has not been particularly active for 2000-2013 in the area, although future reductions in summer precipitation and/or increases in winter rainfall may intensify the shrub-encroachment process.
Biogeosciences, 12, 2907-2925, doi:10.5194/bg-12-2907-2015, 2015
Modeling forest lines and forest distribution patterns with remote-sensing data in a mountainous region of semiarid central Asia
Biogeosciences, 12, 2893-2905, doi:10.5194/bg-12-2893-2015, 2015
Corrigendum to "Evaluating the ocean biogeochemical components of Earth system models using atmospheric potential oxygen and ocean color data" published in Biogeosciences, 12, 193–208, 2015
Biogeosciences, 12, 2891-2891, doi:10.5194/bg-12-2891-2015, 2015
Projected impacts of climate change and ocean acidification on the global biogeography of planktonic Foraminifera
Biogeosciences, 12, 2873-2889, doi:10.5194/bg-12-2873-2015, 2015
Biogeochemical indicators of peatland degradation – a case study of a temperate bog in northern Germany
Summary: Biogeochemical soil parameters are studied to detect peatland degradation along a land use gradient (intensive, extensive, near-natural). Stable carbon isotopes, radiocarbon ages and ash content confirm peat growth in the near-natural bog but also indicate previous degradation. When the bog is managed extensively or intensively as grassland, all parameters indicate degradation and substantial C loss of the order of 18.8 to 42.9 kg C m-2.
Biogeosciences, 12, 2861-2871, doi:10.5194/bg-12-2861-2015, 2015
Methane-related changes in prokaryotes along geochemical profiles in sediments of Lake Kinneret (Israel)
Summary: This study attempted to correlate between the performed geochemical and microbial profiles in lake sediments. The geochemical data suggest three main depth related zones of electron acceptor activities in the sediment: sulfate reduction, methanogenesis and a novel, deep iron-driven AOM. The prokaryotic analysis provided clues regarding the microorganisms that may be involved in this novel process and the metabolic paths that occur throughout the microbial assemblage.
Biogeosciences, 12, 2847-2860, doi:10.5194/bg-12-2847-2015, 2015
Drought-influenced mortality of tree species with different predawn leaf water dynamics in a decade-long study of a central US forest
Summary: Co-occurring tree species with varying physiologies were continuously monitored for mortality with concurrent observations of key physiological and environmental variables for a decade in a central US forest. New predictors of drought-induced mortality were developed. Time-delayed mortality was shown to be nonlinearly related to drought intensity and species’ capacities in regulating their internal hydraulic status, with elevated risk associated with extreme isohydric and anisohydric behaviors.
Biogeosciences, 12, 2831-2845, doi:10.5194/bg-12-2831-2015, 2015
Bayesian inversions of a dynamic vegetation model at four European grassland sites
Summary: We probabilistically invert the CARAIB dynamic vegetation model using a Markov chain Monte Carlo sampler, considering both homoscedastic and heteroscedastic eddy covariance residual errors with variances either fixed a priori or jointly inferred with the model parameters. A model validation experiment showed that CARAIB models calibrated considering heteroscedastic residual errors result in more robust posterior parameter distributions.
Biogeosciences, 12, 2809-2829, doi:10.5194/bg-12-2809-2015, 2015
Carbon budget estimation of a subarctic catchment using a dynamic ecosystem model at high spatial resolution
Biogeosciences, 12, 2791-2808, doi:10.5194/bg-12-2791-2015, 2015
The dynamic of the annual carbon allocation to wood in European tree species is consistent with a combined source–sink limitation of growth: implications for modelling
Summary: We provide an evaluation of the spatio-temporal dynamics of the annual C allocation to wood in French forests. Our study supports the premise that the growth of European tree species is subject to complex control processes that include both source and sink limitations. We suggest a straightforward modelling framework with which to implement these combined forest growth limitations into terrestrial biosphere models.
Biogeosciences, 12, 2773-2790, doi:10.5194/bg-12-2773-2015, 2015
Sensitivity of the air–sea CO2 exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability
Summary: The air-sea CO2 exchange is investigated in the coastal region of the Baltic Sea and Danish inner waters. The impact of short-term variability in atmospheric CO2 on the air-sea CO2 exchange is examined, and it is found that ignoring short-term variability in the atmospheric CO2 creates a significant bias in the CO2 exchange. Atmospheric short-term variability is not always included in studies of the air-sea CO2 exchange, but based on the present study, we recommend it to be so in the future.
Biogeosciences, 12, 2753-2772, doi:10.5194/bg-12-2753-2015, 2015
Dynamic C and N stocks – key factors controlling the C gas exchange of maize in heterogenous peatland
Summary: Dynamic SOC and N stocks in the aerobic zone play a key role in the regulation of plant- and microbially mediated CO2 and CH4 fluxes in drained and cultivated fen peatlands. Their interaction with the groundwater level (GWL) strongly influenced soil C gas exchange, indicating effects of GWL-dependent N availability on C formation and transformation processes in the plant--soil system. In contrast, static SOC and N stocks showed no significant effect on C gas fluxes.
Biogeosciences, 12, 2737-2752, doi:10.5194/bg-12-2737-2015, 2015
Autonomous profiling float observations of the high-biomass plume downstream of the Kerguelen Plateau in the Southern Ocean
Summary: Four bio-profilers were deployed in the high-biomass plume downstream of the Kerguelen Plateau (KP; Southern Ocean) to examine the conditions favouring phytoplankton accumulation. Regions of very high Chla accumulation were mainly associated with surface waters from the northern KP. Light limitation seems to have a limited influence on production. A cyclonic eddy was associated with a significant export of organic matter and a subsequent dissolved inorganic carbon storage in the ocean interior.
Biogeosciences, 12, 2707-2735, doi:10.5194/bg-12-2707-2015, 2015
Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of central European forests
Biogeosciences, 12, 2695-2706, doi:10.5194/bg-12-2695-2015, 2015
Scaling from individual trees to forests in an Earth system modeling framework using a mathematically tractable model of height-structured competition
Summary: We present a model, LM3-PPA, which simulates vegetation dynamics and biogeochemical processes by explicitly scaling from individual plants to ecosystems using the perfect plasticity approximation. It includes height-structured competition for light- and root-allocation-dependent competition for belowground resources. Because of the tractability of the PPA, the coupled LM3-PPA model is able to retain computational tractability, as well as close linkages to mathematically tractable special cases.
Biogeosciences, 12, 2655-2694, doi:10.5194/bg-12-2655-2015, 2015
Peruvian upwelling plankton respiration: calculations of carbon flux, nutrient retention efficiency, and heterotrophic energy production
Summary: Ocean carbon flux, seafloor respiration, and seafloor carbon burial are calculated from plankton respiration. Based on this respiration, a new parameter, the heterotrophic energy production - the rate of ATP generated in seawater, is calculated, and a new concept, the nutrient retention efficiency (NRE), and its ocean variability, is developed and demonstrated. Finally, the curvature of the respiration profile is discovered to be the control - key for NRE and carbon flux.
Biogeosciences, 12, 2641-2654, doi:10.5194/bg-12-2641-2015, 2015
Effects of low-pH stress on shell traits of the dove snail, Anachis misera, inhabiting shallow-vent environments off Kueishan Islet, Taiwan
Summary: This was the first study to compare snail’s morphological traits under varying shallow-vent stresses using populations previously classified by protein expression profiles. Anachis snails were classified as V-South (pH 7.78-7.82) and V-Rest (pH 7.31-7.83). There was a difference in shell width : length, with vent populations being more globular. Vent Anachis snails had thinner body whorl (56%) and penultimate whorl (29%) shells than non-vent Euplica sp.
Biogeosciences, 12, 2631-2639, doi:10.5194/bg-12-2631-2015, 2015
Modelling coral calcification accounting for the impacts of coral bleaching and ocean acidification
Summary: Coral reefs are diverse ecosystems threatened by rising CO2 levels through increases in sea surface temperature and ocean acidification. This study presents a new unified model, based on experimental and observational data, that links changes in temperature and carbonate chemistry to coral health. We show that, despite the implicit complexity of the coral reef environment, our simple model can give important insights into how corals respond to changes in temperature and ocean acidification.
Biogeosciences, 12, 2607-2630, doi:10.5194/bg-12-2607-2015, 2015
Open ocean dead zones in the tropical North Atlantic Ocean
Summary: This study is the first report of the formation of dead zones in the open ocean. A combination of multiple ocean observing system elements (mooring, floats, satellites, ships) allowed us to reconstruct the generation of the dead zones and to connect the formation to enhanced respiration within mesoscale ocean eddies. The dead zones present specific threats to the ecosystem, such as the interruption of the diurnal migration of zooplankters.
Biogeosciences, 12, 2597-2605, doi:10.5194/bg-12-2597-2015, 2015
Soil moisture and land use are major determinants of soil microbial community composition and biomass at a regional scale in northeastern China
Biogeosciences, 12, 2585-2596, doi:10.5194/bg-12-2585-2015, 2015
Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty
Biogeosciences, 12, 2565-2584, doi:10.5194/bg-12-2565-2015, 2015
Eutrophication mitigation in rivers: 30 years of trends in spatial and seasonal patterns of biogeochemistry of the Loire River (1980–2012)
Summary: Based on large, long-term and high-quality data sets, this study describes the mitigation of eutrophication in the Loire River basin since 1980. Reducing direct phosphate inputs in the early 1990s has led to a significant decrease in algal biomass although Corbicula spp. clams invaded the river during this period and have probably played a significant role in phytoplankton decline. A powerful trend and seasonality analysis showed that these changes considerably affected river biogeochemistry.
Biogeosciences, 12, 2549-2563, doi:10.5194/bg-12-2549-2015, 2015
Large-eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics
Summary: We used large-eddy simulations to test the sensitivity of roughness parameters to characteristics of canopy structure. We found that displacement height scaled with maximum canopy height, aerodynamic canopy height with maximum canopy height and leaf area index, and eddy-penetration depth with gap fraction. Using a decade of observations, we found that fixed parameterizations of roughness performed well but that empirical approaches that incorporated canopy structure preformed even better.
Biogeosciences, 12, 2533-2548, doi:10.5194/bg-12-2533-2015, 2015
First on-line isotopic characterization of N2O above intensively managed grassland
Biogeosciences, 12, 2517-2531, doi:10.5194/bg-12-2517-2015, 2015
Modelling the response of yields and tissue C : N to changes in atmospheric CO2 and N management in the main wheat regions of western Europe
Biogeosciences, 12, 2489-2515, doi:10.5194/bg-12-2489-2015, 2015
Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired 14C analysis
Summary: We used measurements of radiocarbon to model the decomposition of organic matter associated with minerals in tropical rainforest soils, using contemporary and archived samples. Most organic matter decomposed over 11 to 26 years, while a smaller portion decomposed over centuries. Rates were similar among soils with strongly differing physical and chemical properties, but declined with a proxy for oxygen limitation. Previous models based on one time point may underestimate decomposition rates.
Biogeosciences, 12, 2471-2487, doi:10.5194/bg-12-2471-2015, 2015
Corrigendum to "Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry" published in Biogeosciences, 12, 1753–1763, 2015
Biogeosciences, 12, 2469-2469, doi:10.5194/bg-12-2469-2015, 2015
Changes of the CO2 and CH4 production potential of rewetted fens in the perspective of temporal vegetation shifts
Summary: In this paper, the CO2 and CH4 production due to the subaqueous decomposition of the five most abundant plant species, which are considered to be representative of different rewetting stages, will be presented. Beside continuous gas flux measurements, bulk chemical analyses of plant tissue were performed to gain insights into changing litter characteristics. With respect to temporal vegetation shifts in rewetted fens, the results provide new insights into the climate effect of these ecosystems.
Biogeosciences, 12, 2455-2468, doi:10.5194/bg-12-2455-2015, 2015
Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget
Summary: CO2 and CH4 concentrations and fluxes in the Zambezi River basin are well below the median/average values reported previously for tropical rivers, streams and reservoirs, and mainly controlled by the connectivity with floodplains and the presence of waterfalls and man-made reservoirs. The mass balance suggests that carbon transport to the ocean represents the major component (~60%) of the budget, while emissions to the atmosphere account for less than 40% of the total carbon yield.
Biogeosciences, 12, 2431-2453, doi:10.5194/bg-12-2431-2015, 2015
Reconciling single-chamber Mg / Ca with whole-shell δ18O in surface to deep-dwelling planktonic foraminifera from the Mozambique Channel
Summary: In this paper we present, for the first time, results from single-chamber Mg/Ca analyses combined with single-shell δ18O and δ13C for four planktonic foraminiferal species from a sediment trap in the Mozambique Channel. Eddy-induced hydrographic variability is reflected in test carbonate chemistry of these different species. A species-specific depth-resolved mass balance model confirms distinctive migration and calcification patterns for each species as a function of hydrography.
Biogeosciences, 12, 2411-2429, doi:10.5194/bg-12-2411-2015, 2015
Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers
Biogeosciences, 12, 2395-2409, doi:10.5194/bg-12-2395-2015, 2015
Nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance in the diatom Phaeodactylum tricornutum
Biogeosciences, 12, 2383-2393, doi:10.5194/bg-12-2383-2015, 2015
Biogeochemical variability in the central equatorial Indian Ocean during the monsoon transition
Summary: In 2010, a first-of-its-kind deployment of biological sensors on a mooring in the central Indian Ocean revealed interesting variability in chlorophyll (a proxy for ocean productivity) at timescales of about 2 weeks. Using the mooring data with satellite observations and a biogeochemical model, it was determined that local wind mixing and entrainment, rather than mixed Rossby gravity waves, were likely responsible for much of the observed variability.
Biogeosciences, 12, 2367-2382, doi:10.5194/bg-12-2367-2015, 2015
Corrigendum to "Global cropland monthly gross primary production in the year 2000" published in Biogeosciences, 11, 3871–3880, 2014
Biogeosciences, 12, 2365-2366, doi:10.5194/bg-12-2365-2015, 2015
Glacial meltwater and primary production are drivers of strong CO2 uptake in fjord and coastal waters adjacent to the Greenland Ice Sheet
Summary: The Greenland Ice Sheet releases large amounts of freshwater, which strongly influences the biogeochemistry of the adjacent fjord systems and continental shelves. Here we present seasonal observations of the carbonate system in the surface waters of a west Greenland tidewater outlet glacier fjord. Our data reveal a permanent undersaturation of CO2 in the surface layer of the entire fjord and adjacent shelf, creating a high annual uptake of 65gCm-2yr-1.
Biogeosciences, 12, 2347-2363, doi:10.5194/bg-12-2347-2015, 2015
Predicting the denitrification capacity of sandy aquifers from in situ measurements using push–pull 15N tracer tests
Biogeosciences, 12, 2327-2346, doi:10.5194/bg-12-2327-2015, 2015
On the use of the post-closure methods uncertainty band to evaluate the performance of land surface models against eddy covariance flux data
Summary: The energy balance of eddy covariance (EC) flux data is normally not closed. Therefore, EC flux data are usually post-closed, i.e. the measured turbulent fluxes are adjusted so as to close the energy balance. We propose to use in model evaluation the post-closure method uncertainty band (PUB) to account for the uncertainty in EC data originating from lacking energy balance closure. Working with only a single post-closing method might result in severe misinterpretations in model-data comparison.
Biogeosciences, 12, 2311-2326, doi:10.5194/bg-12-2311-2015, 2015
Fossilized bioelectric wire – the trace fossil Trichichnus
Biogeosciences, 12, 2301-2309, doi:10.5194/bg-12-2301-2015, 2015
Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands
Summary: Carbon dioxide exchange (NEE) between the atmosphere and forested subtropical wetlands is quantified at three locations for 2 years. Each forested wetland showed net carbon uptake (retained in the soil and biomass or transported laterally via overland flow) from the atmosphere both monthly and annually. Changes in NEE were clearly a function of seasonality in solar insolation, air temperature and flooding, which suppressed heterotrophic soil respiration.
Biogeosciences, 12, 2285-2300, doi:10.5194/bg-12-2285-2015, 2015
Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part 2: Lignin-derived phenol compositions
Biogeosciences, 12, 2261-2283, doi:10.5194/bg-12-2261-2015, 2015
Effects of CO2 and iron availability on rbcL gene expression in Bering Sea diatoms
Biogeosciences, 12, 2247-2259, doi:10.5194/bg-12-2247-2015, 2015
Organic-matter quality of deep permafrost carbon – a study from Arctic Siberia
Summary: Climatic warming is affecting permafrost, including decomposition of organic matter (OM). However, quantitative data for the quality of OM and its availability for decomposition is limited. We analyzed the quality of OM in late Pleistocene (Yedoma) and Holocene (thermokarst) deposits. A lack of depth trends reveals a constant quality of OM showing that permafrost acts like a freezer, preserving OM quality. This OM will be susceptible to decomposition under climatic warming.
Biogeosciences, 12, 2227-2245, doi:10.5194/bg-12-2227-2015, 2015
Global analysis of seasonality in the shell flux of extant planktonic Foraminifera
Biogeosciences, 12, 2207-2226, doi:10.5194/bg-12-2207-2015, 2015