Сarbon fluxes intensity from substrates and phototrophic consortiums of the photic zones in Montenegro caves

2020 ◽  
Vol 34 ◽  
pp. 20-33
Author(s):  
Svetlana E. Mazina ◽  
Ekaterina V. Kozlova ◽  
Sofiia M. Turchinskaya ◽  
Elizaveta K. Pichugina ◽  
Akhmed K. Yuzbekov ◽  
...  
Keyword(s):  
Primary Production ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Isotopic Analysis ◽  
Closed Chamber ◽  
Clay Deposits ◽  
Composition And Structure ◽  
Pleurocarpous Mosses ◽  
Negative Balance ◽  
First Time

Сarbon dioxide fluxes from substrates and consortiums were estimated for the first time in the photic zones of seven caves of Montenegro. The dependence of consortiums productivity with their species composition and structure, as well as determination of the priority source of carbon dioxide for the primary producers of trophic chains of the photic zones were revealed.Five consortiums were distinguished in the fouling communities of the photic zones of seven karst caves of Montenegro: with the dominance of acrocarpous mosses, pleurocarpous mosses, green algae, cyanobacteria biofilms and sheath-forming cyanobacteria on various substrates. The closed chamber technique was used to calculate carbon fluxes. The net carbon flux, gross respiration of substrates and consortiums, and gross primary production of consortiums in the summer and winter were determined. The biomass of the phototrophic and heterotrophic components of the consortiums was estimated. Isotopic analysis of clay deposits and phytomass of bryophytes in the consotriums as well as on the surface was carried out. All of the investigated consortiums function as a carbon sink in both seasons, providing a negative balance to the atmosphere. Consortiums with the dominance of bryophytes possessed the greatest biomass, spores of micromycetes dominated in the heterotrophic component. The respiration of substrates was maximized on clay deposits, the respiration rate increased in winter. Phototrophic respiration and gross primary production were maximal in the consortiums of acrocarpous mosses and case-forming cyanobacteria in terms of dry phytomass. Increased content of the light carbon isotope 12C in the bryophytes phytomass in the photic zones compared to the bryophytes phytomass on the surface was established.

scholarly journals Eddy covariance carbon flux in a scrub in the Mexican highland

2020 ◽  
Author(s):  
Aurelio Guevara-Escobar ◽  
Enrique González-Sosa ◽  
Mónica Cervantes-Jiménez ◽  
Humberto Suzán-Azpiri ◽  
Mónica Elisa Queijeiro-Bolaños ◽  
...  
Keyword(s):  
Primary Production ◽  
Eddy Covariance ◽  
Vegetation Index ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Net Ecosystem Exchange ◽  
R Package ◽  
Dark Cycle ◽  
Remote Sensors

Abstract. Vegetation fixes C in its biomass through photosynthesis or might release it into the atmosphere through respiration. Measurements of these fluxes would help us understand ecosystem functioning. The eddy covariance technique (EC) is widely used to measure the net ecosystem exchange of C (NEE) which is the balance between gross primary production (GPP) and ecosystem respiration (Reco). Orbital satellites such as MODIS can also provide estimates of GPP. In this study, we measured NEE with the EC in a scrub at Bernal in Mexico, and then partitioned into gross primary production (GPP-EC) and Reco using the recent R package Reddyproc. Measurements of GPP-EC were related to the estimates from the MODIS satellite provided in product MOD17A2H, which contains data of the gross primary productivity (GPP-MODIS). The Bernal site was a carbon sink despite it was an overgrazed site, the average NEE during fifteen months of 2017 and 2018 was −0.78 g C m−2 d−1 and the flux was negative in all measured months. The GPP-MODIS underestimated the ground data when representing the relation with a Theil-Sen regression: GPP-EC = 1.866 + 1.861 GPP-MODIS; an ordinary less squares regression had similar coefficients and the R2 was 0.6. Although cacti (CAM), legume shrubs (C3) and herbs (C3) had a similar vegetation index, the nighttime flux was characterized by positive NEE suggesting that the photosynthetic dark-cycle flux of cacti was lower than Reco. The discrepancy among the GPP flux estimates stresses the need to understand the limitations of EC and remote sensors, while incorporating complementary monitoring and modelling schemes of nighttime Reco, particularly in the presence of species with different photosynthetic cycles.

scholarly journals Constraining uncertainty in projected gross primary production with machine learning

2020 ◽  
Author(s):  
Manuel Schlund ◽  
Veronika Eyring ◽  
Gustau Camps-Valls ◽  
Pierre Friedlingstein ◽  
Pierre Gentine ◽  
...  
Keyword(s):  
Machine Learning ◽  
Carbon Cycle ◽  
Primary Production ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Boosted Regression Trees ◽  
Supervised Machine Learning ◽  
Climate Projections ◽  
Intergovernmental Panel ◽  
The Future

<p>By absorbing about one quarter of the total anthropogenic CO<sub>2</sub> emissions, the terrestrial biosphere is an important carbon sink of Earth’s carbon cycle. A key metric of this process is the terrestrial gross primary production (GPP), which describes the biogeochemical production of energy by photosynthesis. Elevated atmospheric CO<sub>2</sub> concentrations will increase GPP in the future (CO<sub>2</sub> fertilization effect). However, projections from different Earth system models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) show a large spread in carbon cycle related quantities. In this study, we present a new supervised machine learning approach to constrain multi-model climate projections using observation-driven data. Our method based on Gradient Boosted Regression Trees handles multiple predictor variables of the present-day climate and accounts for non-linear dependencies. Applied to GPP in the representative concentration pathway RCP 8.5 at the end of the 21st century (2081–2100), the new approach reduces the “likely” range (as defined by the Intergovernmental Panel on Climate Change) of the CMIP5 multi-model projection of GPP to 161–203 GtC yr<sup>-1</sup>. Compared to the unweighted multi-model mean (148–224 GtC yr<sup>-1</sup>), this is an uncertainty reduction of 45%. Our new method is not limited to projections of the future carbon cycle, but can be applied to any target variable where suitable gridded data is available.</p>

scholarly journals Impacts of droughts and extreme temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zones

2017 ◽  
Author(s):  
Jannis von Buttlar ◽  
Jakob Zscheischler ◽  
Anja Rammig ◽  
Sebastian Sippel ◽  
Markus Reichstein ◽  
...  
Keyword(s):  
Heat Stress ◽  
Primary Production ◽  
Extreme Events ◽  
Extreme Event ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Extreme Temperature ◽  
Initial Increase ◽  
Climate Zones

Abstract. Extreme climatic events, such as droughts and heat stress induce anomalies in ecosystem-atmosphere CO2 fluxes, such as gross primary production (GPP) and ecosystem respiration (Reco), and, hence, can change the net ecosystem carbon balance. However, despite our increasing understanding of the underlying mechanisms, the magnitudes of the impacts of different types of extremes on GPP and Reco within and between ecosystems remain poorly predicted. Here we aim to identify the major factors controlling the amplitude of extreme event impacts on GPP, Reco, and the resulting net ecosystem production (NEP). We focus on the impacts of heat and drought and their combination. We identified hydrometeorological extreme events in consistently downscaled water availability and temperature measurements over a 30 year time period. We then used FLUXNET eddy-covariance flux measurements to estimate the CO2 flux anomalies during these extreme events across dominant vegetation types and climate zones. Overall, our results indicate that short-term heat extremes increased respiration more strongly than they down-regulated GPP, resulting in a moderate reduction of the ecosystem’s carbon sink potential. In the absence of heat stress, droughts tended to have smaller and similarly dampening effects on both GPP and Reco, and, hence, often resulted in neutral NEP responses. The combination of drought and heat typically led to a strong decrease in GPP, whereas heat and drought impacts on respiration partially offset each other. Taken together, compound heat and drought events led to the strongest C sink reduction compared to any single-factor extreme. A key insight of this paper, however, is that duration matters most: for heat stress during droughts, the magnitude of impacts systematically increased with duration, whereas under heat stress without drought, the response of Reco over time turned from an initial increase to a down-regulation after about two weeks. This confirms earlier theories that not only the magnitude but also the duration of an extreme event determines its impact. Our study corroborates the results of several local site-level case studies, but as a novelty generalizes these findings at the global scale. Specifically, we find that the different response functions of the two antipodal land-atmosphere fluxes GPP and Reco can also result in increasing NEP during certain extreme conditions. Apparently counterintuitive findings of this kind bear great potential for scrutinizing the mechanisms implemented in state-of-the-art terrestrial biosphere models and provide a benchmark for future model development and testing.

A new global Gross Primary Production (GPP) dataset based on microwave Vegetation Optical Depth Climate Archive (VODCA)

2020 ◽  
Author(s):  
Benjamin Wild ◽  
Irene Teubner ◽  
Leander Moesinger ◽  
Wouter Dorigo
Keyword(s):  
Carbon Source ◽  
Primary Production ◽  
Optical Depth ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Operation Time ◽  
Ecosystem Dynamics ◽  
Single Frequency ◽  
Model Input ◽  
Single Sensor

<p>Gross Primary Production (GPP) describes the uptake of C0<sub>2</sub> by plants through photosynthesis and is essential to monitor and analyze ecosystem dynamics. Teubner et al.<sup>1</sup> developed a carbon sink-driven approach to estimate GPP on a global scale using Vegetation Optical Depth (VOD), derived from active and passive microwave observations. This allows to analyze GPP variability, complementing existing optical GPP products which are more affected by weather conditions. The short operation time of the individual microwave sensors and the bias between them prohibit analyzing GPP variability. This issue can potentially be overcome by using the Vegetation Optical Depth Climate Archive (VODCA) developed by Moesinger et al.<sup>2</sup>, which merges multiple VOD products into a single data record. However, the use of a long-running VOD composite for estimating global GPP is challenging because the implications of the VOD aggregation process on the modelling of GPP are difficult to identify a priori.</p><p>Here, we present the results of applying the carbon sink-driven GPP estimation approach on the VODCA datasets. As model input for each pixel we used raw VOD from VODCA as well as changes in VOD and median VOD, the latter serves as proxy for vegetation cover. In order to analyze the performance of the carbon sink-driven approach when using VODCA as input, the model is cross-validated against single-sensor (AMSR-E) VOD estimates and commonly used carbon source-driven estimates (MODIS/FLUXCOM). We assessed the ability to model GPP based on single-frequency VODCA (C-, X- and Ku-band) as well as using multiple frequencies as model input.</p><p>Overall, the results show that single-band as well as multi-band VODCA performs slightly better in predicting GPP than single-sensor based VOD. Especially in the tropical regions multi-frequency VODCA GPP outperforms single-sensor based estimates. Compared to source-driven approaches, VOD based GPP estimates are higher than FLUXCOM and MODIS GPP. The spatial patterns, however, show good correspondence with the carbon source-driven GPP products, confirming that VODCA can be used to extend the GPP estimates to the past three decades.</p><p><sup>1</sup>Teubner, I., Forkel, M., Camps-Valls, G., Jung, M., Miralles, Diego, Tramontana, G., van der Schalie, R., Vreugdenhil, M., Moesinger, L., Dorigo, W.:A carbon sink-driven approach to estimate gross primary production from microwave satellite observations, 2019. Remote Sensing of Environment. 229. 100-113. 10.1016/j.rse.2019.04.022.</p><p><sup>2</sup>Moesinger, L., Dorigo, W., de Jeu, R., van der Schalie, R., Scanlon, T., Teubner, I., and Forkel, M.: The Global Long-term Microwave Vegetation Optical Depth Climate Archive VODCA, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2019-42, in review, 2019.</p>

Moisture and heat advection as drivers of global ecosystem productivity

2020 ◽  
Author(s):  
Dominik L. Schumacher ◽  
Jessica Keune ◽  
Diego G. Miralles
Keyword(s):  
Primary Production ◽  
Interannual Variability ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Ecosystem Productivity ◽  
Climate Conditions ◽  
Source Regions ◽  
Heat And Moisture ◽  
The Impact

<p>Terrestrial ecosystems play a key role in climate by dampening the increasing atmospheric CO<sub>2</sub> concentrations primarily caused by anthropogenic fossil fuel emissions. The capability of the land biosphere to act as a carbon sink largely depends on climate conditions, which determine the energy and water availability required by plants to grow. Even though only a small part of the global land area is covered by vegetation, the impact of extreme dry and wet seasons has been shown to largely drive the global interannual variability of gross primary production. The climate in a certain area can be seen as the balance of different heat and moisture fluxes: local surface–atmosphere fluxes from below, entrainment of heat and moisture from aloft, and ‘horizontal’ advection of heat and moisture from upwind regions. The latter provides a mechanism for remote regions to impact gross primary production downwind, and has received less scientific attention. Here, advection is inferred from a bird’s eye perspective, focussing on the five ecoregions with the largest interannual variability in peak productivity around the globe. Employing the atmospheric Lagrangian trajectory model FLEXPART, driven by ERA-Interim reanalysis data, we track the air residing over ecoregions back in time to deduce the origins of heat and moisture that affect ecosystem gross primary production. Utilizing the evaporative source regions supplying water for precipitation to these ecosystems, as well as the analogous source regions of advected heat, we estimate the contribution of advection to gross primary production. Our findings show that source regions of heat and moisture are not congruent: upwind land surfaces typically supply most of the advected heat, whereas upwind oceans tend to provide more moisture. Moreover, low gross primary production in heat-stressed and water-limited ecosystems is often accompanied by enhanced heat and reduced moisture advection from land regions, exacerbated by upwind land–atmosphere feedbacks. These results demonstrate that anomalies in atmospheric advection can cause ecosystem productivity extremes. Particularly in light of ongoing climate change, we emphasize the potentially detrimental effects of upwind areas that may cause long-lasting impacts on the terrestrial carbon budget, thereby further affecting the climate.</p>

Sensitivity of global gross primary production to environmental drivers

2020 ◽  
Author(s):  
Wenjia Cai ◽  
Iain Colin Prentice
Keyword(s):  
Primary Production ◽  
Vegetation Cover ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Vapour Pressure Deficit ◽  
Terrestrial Ecosystems ◽  
Environmental Drivers ◽  
Generic Model ◽  
Terrestrial Plants ◽  
Green Vegetation

<p>Terrestrial Gross Primary Production (GPP), the total amount of carbon taken up by terrestrial plants, is one of the largest fluxes in the global carbon cycle – and a key process governing the capacity of terrestrial ecosystems to partly offset continuing anthropogenic CO<sub>2</sub> emissions. Accurate simulation of land carbon uptake and its response to environmental change is therefore essential for reliable future projections of the terrestrial carbon sink. However, there are still large uncertainties in the sensitivity of global GPP to environmental drivers. Here we use a recently developed and extensively tested generic model of GPP (the ‘P-model’), which uses satellite-derived green vegetation cover as an input, to simulate (a) trends in site-level GPP, as observed at eddy-covariance flux sites; (b) trends in global GPP, for comparison with independent geophysical estimates; and (c) quantitative spatial patterns of the sensitivity of grid-based GPP to green vegetation cover, vapour pressure deficit, temperature, solar radiation, soil moisture and atmospheric CO<sub>2.</sub></p>

scholarly journals Linkage between the temporal and spatial variability of dissolved organic matter and whole stream metabolism

2012 ◽  
Vol 9 (12) ◽  
pp. 18253-18293 ◽  
Author(s):  
S. Halbedel ◽  
O. Büttner ◽  
M. Weitere
Keyword(s):  
Molecular Weight ◽  
Land Use ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Primary Production ◽  
Gross Primary Production ◽  
Low Molecular Weight ◽  
Stream Metabolism ◽  
First Time ◽  
Dom Composition

Abstract. Dissolved organic matter (DOM) is an important resource for microbes, thus affecting the whole stream metabolism. The factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. We hypothesized that the whole stream metabolism itself can affect the DOM composition and that the coupling of both is influenced by seasonality and different land use forms. We tested this hypothesis in a comparative study on two pristine forestry streams and on two non-forestry streams. The investigated streams were located in the Harz Mountains (Central Europe, Germany). The whole stream metabolism was measured with a classical two station oxygen change technique and the variability of DOM with fluorescence spectroscopy. We take also into account the geochemical and geophysical characteristic of each stream. All streams were clearly net heterotrophic, whereby the non-forestry streams showed a higher primary production in general, which was correlated with irradiance and with the total phosphorus concentration. The whole stream metabolism but also the chromophoric DOM (CDOM) showed distinct seasonal patterns. We detected three CDOM component groups (C1, C2, C3) by the use of the parallel-factor-analysis (PARAFAC) and found temporarily variable, typical component fingerprints (C1:C2, C1:C3, C3:C2) for CDOM originated from forestry streams and from non-forestry streams. Based on comparative literature studies and correlation analysis with different indices, we demonstrate that two of the components are clearly from terrigenous sources (C1, C3) and one is rather autochthonously (C2) derived. The whole CDOM matrix was dominated by humic like, high molecular-weight substances, followed by humic like, fulfic acids, low molecular-weight substances, and with minor amounts of amino-acids and proteins. We showed for the first time a correlation between the gross primary production (GPP) and the autochthonously derived, low molecular weight DOM. The amount of autochthonously produced DOM increased overall with increasing GPP, as indicated by a tight, positive correlation between the fluorescence index (FI, R2 = 0.84) or C2 (R2= 0.48) and the ratio of GPP and the daily community respiration (CR24). This study showed for the first time the linkage between whole stream metabolism and DOM composition, based on a new integrated approach. We demonstrated that this relationship is influenced by seasonality and different land use forms. These complex mechanisms lead to typical DOM fingerprints for streams pass through the different land use forms.

scholarly journals Carbon cycle uncertainty in the Alaskan Arctic

2014 ◽  
Vol 11 (2) ◽  
pp. 2887-2932 ◽  
Author(s):  
J. B. Fisher ◽  
M. Sikka ◽  
W. C. Oechel ◽  
D. N. Huntzinger ◽  
J. R. Melton ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Primary Production ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
The Arctic ◽  
Regional Patterns ◽  
Alaskan Arctic

Abstract. Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for Alaska, we provide a baseline of terrestrial carbon cycle structural and parametric uncertainty, defined as the multi-model standard deviation (σ) against the mean (x) for each quantity. Mean annual uncertainty (σ/x) was largest for net ecosystem exchange (NEE) (−0.01± 0.19 kg C m−2 yr−1), then net primary production (NPP) (0.14 ± 0.33 kg C m−2 yr−1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m−2 yr−1), gross primary production (GPP) (0.22 ± 0.50 kg C m−2 yr−1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m−2 yr−1), CH4 flux (2.52 ± 4.02 g CH4 m−2 yr−1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m−2 yr−1), and soil carbon (14.0± 9.2 kg C m−2). The spatial patterns in regional carbon stocks and fluxes varied widely with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Additionally, a feedback (i.e., sensitivity) analysis was conducted of 20th century NEE to CO2 fertilization (β) and climate (γ), which showed that uncertainty in γ was 2x larger than that of β, with neither indicating that the Alaskan Arctic is shifting towards a certain net carbon sink or source. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic.

scholarly journals Carbon cycle uncertainty in the Alaskan Arctic

2014 ◽  
Vol 11 (15) ◽  
pp. 4271-4288 ◽  
Author(s):  
J. B. Fisher ◽  
M. Sikka ◽  
W. C. Oechel ◽  
D. N. Huntzinger ◽  
J. R. Melton ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Primary Production ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
The Arctic ◽  
Regional Patterns ◽  
Alaskan Arctic

Abstract. Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for the Alaskan Arctic from four recent model intercomparison projects – NACP (North American Carbon Program) site and regional syntheses, TRENDY (Trends in net land atmosphere carbon exchanges), and WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) – we provide a baseline of terrestrial carbon cycle uncertainty, defined as the multi-model standard deviation (σ) for each quantity that follows. Mean annual absolute uncertainty was largest for soil carbon (14.0 ± 9.2 kg C m−2), then gross primary production (GPP) (0.22 ± 0.50 kg C m−2 yr−1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m−2 yr−1), net primary production (NPP) (0.14 ± 0.33 kg C m−2 yr−1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m−2 yr−1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m−2 yr−1), net ecosystem exchange (NEE) (−0.01 ± 0.19 kg C m−2 yr−1), and CH4 flux (2.52 ± 4.02 g CH4 m−2 yr−1). There were no consistent spatial patterns in the larger Alaskan Arctic and boreal regional carbon stocks and fluxes, with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic and larger boreal region.

scholarly journals A carbon sink-driven approach to estimate gross primary production from microwave satellite observations

2019 ◽  
Vol 229 ◽  
pp. 100-113 ◽  
Author(s):  
Irene E. Teubner ◽  
Matthias Forkel ◽  
Gustau Camps-Valls ◽  
Martin Jung ◽  
Diego G. Miralles ◽  
...  
Keyword(s):  
Primary Production ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Satellite Observations
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