Articles | Volume 15, issue 7
Research article 09 Apr 2018
Research article | 09 Apr 2018
Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient
Wenqiang Zhao et al.
No articles found.
Matthew L. Trumper, Daniel Griffin, Sarah E. Hobbie, Ian M. Howard, David M. Nelson, Peter B. Reich, and Kendra K. McLauchlan
Biogeosciences, 17, 4509–4522,Short summary
We developed century-scale records of wood nitrogen isotopes (δ15N) from 16 trees across a long-term savanna fire experiment. Results show similar long-term trajectories in three out of four burn treatments. Lack of evidence to support our hypotheses underscores the complexity of nitrogen dynamics inferred from wood δ15N. This is the first study to our knowledge to investigate multi-decadal effects of fire at different return intervals on wood δ15N, a potential proxy of nitrogen availability.
Deborah A. Clark, Shinichi Asao, Rosie Fisher, Sasha Reed, Peter B. Reich, Michael G. Ryan, Tana E. Wood, and Xiaojuan Yang
Biogeosciences, 14, 4663–4690,Short summary
Improved modeling of tropical-forest carbon cycling is urgently needed to project future climate and to guide global policy for greenhouse gases. Tropical forests store and process immense amounts of carbon, and their carbon cycling may be responding to climate change. Our goal with this paper, a multidisciplinary collaboration between modelers and field ecologists, is to identify reference-level field data from tropical forests that can be used to guide the models for these key ecosystems.
Related subject area
Biogeochemistry: LandImplementation of nitrogen cycle in the CLASSIC land modelCombined effects of ozone and drought stress on the emission of biogenic volatile organic compounds from Quercus robur L.A bottom-up quantification of foliar mercury uptake fluxes across EuropeLagged effects regulate the inter-annual variability of the tropical carbon balanceSpatial variations in terrestrial net ecosystem productivity and its local indicatorsReviews and Syntheses: Impacts of plant silica – herbivore interactions on terrestrial biogeochemical cyclingNitrogen cycling in CMIP6 land surface models: progress and limitationsDecomposing reflectance spectra to track gross primary production in a subalpine evergreen forestThe rising productivity of alpine grassland under warming, drought and N-deposition treatmentsExamining the sensitivity of the terrestrial carbon cycle to the expression of El NiñoSensitivity of 21st century simulated ecosystem indicators to model parameters, prescribed climate drivers, RCP scenarios and forest management actions for two Finnish boreal forest sitesSummarizing the state of the terrestrial biosphere in few dimensionsPatterns and trends of the dominant environmental controls of net biome productivityLocalized basal area affects soil respiration temperature sensitivity in a coastal deciduous forestDissolved organic carbon mobilized from organic horizons of mature and harvested black spruce plots in a mesic boreal regionIdeas and perspectives: Proposed best practices for collaboration at cross-disciplinary observatoriesEffects of leaf length and development stage on the triple oxygen isotope signature of grass leaf water and phytoliths: insights for a proxy of continental atmospheric humidityResponse of simulated burned area to historical changes in environmental and anthropogenic factors: a comparison of seven fire modelsEstimation of coarse dead wood stocks in intact and degraded forests in the Brazilian Amazon using airborne lidarTheoretical uncertainties for global satellite-derived burned area estimatesEstimating global gross primary productivity using chlorophyll fluorescence and a data assimilation system with the BETHY-SCOPE modelHow representative are FLUXNET measurements of surface fluxes during temperature extremes?Stable carbon and nitrogen isotopic composition of leaves, litter, and soils of various ecosystems along an elevational and land-use gradient at Mount Kilimanjaro, TanzaniaComparison of CO2 and O2 fluxes demonstrate retention of respired CO2 in tree stems from a range of tree speciesTropical climate–vegetation–fire relationships: multivariate evaluation of the land surface model JSBACHA global spatially contiguous solar-induced fluorescence (CSIF) dataset using neural networksTechnical note: A simple theoretical model framework to describe plant stomatal “sluggishness” in response to elevated ozone concentrationsWater-stress-induced breakdown of carbon–water relations: indicators from diurnal FLUXNET patternsEstimation of gross land-use change and its uncertainty using a Bayesian data assimilation approachSmaller global and regional carbon emissions from gross land use change when considering sub-grid secondary land cohorts in a global dynamic vegetation modelNitrogen isotopic composition of plants and soil in an arid mountainous terrain: south slope versus north slopeLand-use and land-cover change carbon emissions between 1901 and 2012 constrained by biomass observationsImpacts of temperature extremes on European vegetation during the growing seasonAn assessment of geographical distribution of different plant functional types over North America simulated using the CLASS–CTEM modelling frameworkVariability in above- and belowground carbon stocks in a Siberian larch watershedPrecipitation–fire linkages in Indonesia (1997–2015)Fire-regime variability impacts forest carbon dynamics for centuries to millenniaChanging patterns of fire occurrence in proximity to forest edges, roads and rivers between NW Amazonian countriesReviews and syntheses: Flying the satellite into your model: on the role of observation operators in constraining models of the Earth system and the carbon cycleMapping the reduction in gross primary productivity in subarctic birch forests due to insect outbreaksTechnical note: Dynamic INtegrated Gap-filling and partitioning for OzFlux (DINGO)Nitrogen mineralization, not N2 fixation, alleviates progressive nitrogen limitation – Comment on “Processes regulating progressive nitrogen limitation under elevated carbon dioxide: a meta-analysis” by Liang et al. (2016)Transient dynamics of terrestrial carbon storage: mathematical foundation and its applicationsDevelopment and evaluation of an ozone deposition scheme for coupling to a terrestrial biosphere modelVariations of leaf N and P concentrations in shrubland biomes across northern China: phylogeny, climate, and soilSpatial and seasonal variations of leaf area index (LAI) in subtropical secondary forests related to floristic composition and stand charactersBiomass burning fuel consumption dynamics in the tropics and subtropics assessed from satelliteThe status and challenge of global fire modellingParametrization consequences of constraining soil organic matter models by total carbon and radiocarbon using long-term field dataProcesses regulating progressive nitrogen limitation under elevated carbon dioxide: a meta-analysis
Ali Asaadi and Vivek K. Arora
Biogeosciences, 18, 669–706,Short summary
More than a quarter of the current anthropogenic CO2 emissions are taken up by land, reducing the atmospheric CO2 growth rate. This is because of the CO2 fertilization effect which benefits 80 % of global vegetation. However, if nitrogen and phosphorus nutrients cannot keep up with increasing atmospheric CO2, the magnitude of this terrestrial ecosystem service may reduce in future. This paper implements nitrogen constraints on photosynthesis in a model to understand the mechanisms involved.
Arianna Peron, Lisa Kaser, Anne Charlott Fitzky, Martin Graus, Heidi Halbwirth, Jürgen Greiner, Georg Wohlfahrt, Boris Rewald, Hans Sandén, and Thomas Karl
Biogeosciences, 18, 535–556,Short summary
Drought events are expected to become more frequent with climate change. Along with these events atmospheric ozone is also expected to increase. Both can stress plants. Here we investigate to what extent these factors modulate the emission of volatile organic compounds (VOCs) from oak plants. We find an antagonistic effect between drought stress and ozone, impacting the emission of different BVOCs, which is indirectly controlled by stomatal opening, allowing plants to control their water budget.
Lena Wohlgemuth, Stefan Osterwalder, Carl Joseph, Ansgar Kahmen, Günter Hoch, Christine Alewell, and Martin Jiskra
Biogeosciences, 17, 6441–6456,Short summary
Mercury uptake by trees from the air represents an important but poorly quantified pathway in the global mercury cycle. We determined mercury uptake fluxes by leaves and needles at 10 European forests which were 4 times larger than mercury deposition via rainfall. The amount of mercury taken up by leaves and needles depends on their age and growing height on the tree. Scaling up our measurements to the forest area of Europe, we estimate that each year 20 t of mercury is taken up by trees.
A. Anthony Bloom, Kevin W. Bowman, Junjie Liu, Alexandra G. Konings, John R. Worden, Nicholas C. Parazoo, Victoria Meyer, John T. Reager, Helen M. Worden, Zhe Jiang, Gregory R. Quetin, T. Luke Smallman, Jean-François Exbrayat, Yi Yin, Sassan S. Saatchi, Mathew Williams, and David S. Schimel
Biogeosciences, 17, 6393–6422,Short summary
We use a model of the 2001–2015 tropical land carbon cycle, with satellite measurements of land and atmospheric carbon, to disentangle lagged and concurrent effects (due to past and concurrent meteorological events, respectively) on annual land–atmosphere carbon exchanges. The variability of lagged effects explains most 2001–2015 inter-annual carbon flux variations. We conclude that concurrent and lagged effects need to be accurately resolved to better predict the world's land carbon sink.
Erqian Cui, Chenyu Bian, Yiqi Luo, Shuli Niu, Yingping Wang, and Jianyang Xia
Biogeosciences, 17, 6237–6246,Short summary
Mean annual net ecosystem productivity (NEP) is related to the magnitude of the carbon sink of a specific ecosystem, while its inter-annual variation (IAVNEP) characterizes the stability of such a carbon sink. Thus, a better understanding of the co-varying NEP and IAVNEP is critical for locating the major and stable carbon sinks on land. Based on daily NEP observations from eddy-covariance sites, we found local indicators for the spatially varying NEP and IAVNEP, respectively.
Bernice C. Hwang and Daniel B. Metcalfe
Revised manuscript accepted for BGShort summary
Despite growing recognition of herbivores as important ecosystem engineers, many major gaps remain in our understanding of how silicon and herbivory interact to shape biogeochemical processes. We highlight the need for more research particularly in natural settings as well as on the potential effects of herbivory on terrestrial silicon cycling to understand potentially critical animal-plant-soil feedbacks.
Taraka Davies-Barnard, Johannes Meyerholt, Sönke Zaehle, Pierre Friedlingstein, Victor Brovkin, Yuanchao Fan, Rosie A. Fisher, Chris D. Jones, Hanna Lee, Daniele Peano, Benjamin Smith, David Wårlind, and Andy J. Wiltshire
Biogeosciences, 17, 5129–5148,
Rui Cheng, Troy S. Magney, Debsunder Dutta, David R. Bowling, Barry A. Logan, Sean P. Burns, Peter D. Blanken, Katja Grossmann, Sophia Lopez, Andrew D. Richardson, Jochen Stutz, and Christian Frankenberg
Biogeosciences, 17, 4523–4544,Short summary
We measured reflected sunlight from an evergreen canopy for a year to detect changes in pigments that play an important role in regulating the seasonality of photosynthesis. Results show a strong mechanistic link between spectral reflectance features and pigment content, which is validated using a biophysical model. Our results show spectrally where, why, and when spectral features change over the course of the season and show promise for estimating photosynthesis remotely.
Matthias Volk, Matthias Suter, Anne-Lena Wahl, and Seraina Bassin
Revised manuscript accepted for BGShort summary
In a multi-year field study alpine grassland growth increased with 1.3 °C warming. Even at the maximum warming of 2.4 °C the yield was larger than at the reference site. At the same time −1.7 °C cooling did not reduce growth. Thus, alpine grassland growth has likely not increased during the past century, but, despite growing soil moisture deficits, will do so with continued warming in the near future. Ecosystem services (eg. fodder production, erosion control) will benefit from moderate warming.
Lina Teckentrup, Martin G. De Kauwe, Andrew J. Pitman, and Benjamin Smith
Revised manuscript accepted for BGShort summary
The El Niño‐Southern Oscillation (ENSO) describes changes in the sea surface temperature patterns of the Pacific Ocean. This influences the global weather, impacting vegetation on land. There are two types of El Niño: Central–Pacific (CP) and Eastern–Pacific (EP). In this study, we explored the long-term impacts on the carbon balance on land linked to the two El Niño types. Using a dynamic vegetation model, we simulated what would happen if only either CP or EP El Niño events had occurred.
Jarmo Mäkelä, Francesco Minunno, Tuula Aalto, Annikki Mäkelä, Tiina Markkanen, and Mikko Peltoniemi
Biogeosciences, 17, 2681–2700,Short summary
We assess the relative magnitude of uncertainty sources on ecosystem indicators of the 21st century climate change on two boreal forest sites. In addition to RCP and climate model uncertainties, we included the overlooked model parameter uncertainty and management actions in our analysis. Management was the dominant uncertainty factor for the more verdant southern site, followed by RCP, climate and parameter uncertainties. The uncertainties were estimated with canonical correlation analysis.
Guido Kraemer, Gustau Camps-Valls, Markus Reichstein, and Miguel D. Mahecha
Biogeosciences, 17, 2397–2424,Short summary
To closely monitor the state of our planet, we require systems that can monitor the observation of many different properties at the same time. We create indicators that resemble the behavior of many different simultaneous observations. We apply the method to create indicators representing the Earth's biosphere. The indicators show a productivity gradient and a water gradient. The resulting indicators can detect a large number of changes and extremes in the Earth system.
Barbara Marcolla, Mirco Migliavacca, Christian Rödenbeck, and Alessandro Cescatti
Biogeosciences, 17, 2365–2379,Short summary
This work investigates the sensitivity of terrestrial CO2 fluxes to climate drivers. We observed that CO2 flux is mostly controlled by temperature during the growing season and by radiation off season. We also observe that radiation importance is increasing over time while sensitivity to temperature is decreasing in Eurasia. Ultimately this analysis shows that ecosystem response to climate is changing, with potential repercussions for future terrestrial sink and land role in climate mitigation.
Stephanie C. Pennington, Nate G. McDowell, J. Patrick Megonigal, James C. Stegen, and Ben Bond-Lamberty
Biogeosciences, 17, 771–780,Short summary
Soil respiration (Rs) is the flow of CO2 from the soil surface to the atmosphere and is one of the largest carbon fluxes on land. This study examined the effect of local basal area (tree area) on Rs in a coastal forest in eastern Maryland, USA. Rs measurements were taken as well as distance from soil collar, diameter, and species of each tree within a 15 m radius. We found that trees within 5 m of our sampling points had a positive effect on how sensitive soil respiration was to temperature.
Keri L. Bowering, Kate A. Edwards, Karen Prestegaard, Xinbiao Zhu, and Susan E. Ziegler
Biogeosciences, 17, 581–595,Short summary
We examined the effects of season and tree harvesting on the flow of water and the organic carbon (OC) it carries from boreal forest soils. We found that more OC was lost from the harvested forest because more precipitation reached the soil surface but that during periods of flushing in autumn and snowmelt a limit on the amount of water-extractable OC is reached. These results contribute to an increased understanding of carbon loss from boreal forest soils.
Jason Philip Kaye, Susan L. Brantley, Jennifer Zan Williams, and the SSHCZO team
Biogeosciences, 16, 4661–4669,Short summary
Interdisciplinary teams can only capitalize on innovative ideas if members work well together through collegial and efficient use of field sites, instrumentation, samples, data, and model code. Thus, biogeoscience teams may benefit from developing a set of best practices for collaboration. We present one such example from a the Susquehanna Shale Hills critical zone observatory. Many of the themes from our example are universal, and they offer insights useful to other biogeoscience teams.
Anne Alexandre, Elizabeth Webb, Amaelle Landais, Clément Piel, Sébastien Devidal, Corinne Sonzogni, Martine Couapel, Jean-Charles Mazur, Monique Pierre, Frédéric Prié, Christine Vallet-Coulomb, Clément Outrequin, and Jacques Roy
Biogeosciences, 16, 4613–4625,Short summary
This calibration study shows that despite isotope heterogeneity along grass leaves, the triple oxygen isotope composition of bulk leaf phytoliths can be estimated from the Craig and Gordon model, a mixing equation and a mean leaf water–phytolith fractionation exponent (lambda) of 0.521. The results strengthen the reliability of the 17O–excess of phytoliths to be used as a proxy of atmospheric relative humidity and open tracks for its use as an imprint of leaf water 17O–excess.
Lina Teckentrup, Sandy P. Harrison, Stijn Hantson, Angelika Heil, Joe R. Melton, Matthew Forrest, Fang Li, Chao Yue, Almut Arneth, Thomas Hickler, Stephen Sitch, and Gitta Lasslop
Biogeosciences, 16, 3883–3910,Short summary
This study compares simulated burned area of seven global vegetation models provided by the Fire Model Intercomparison Project (FireMIP) since 1900. We investigate the influence of five forcing factors: atmospheric CO2, population density, land–use change, lightning and climate. We find that the anthropogenic factors lead to the largest spread between models. Trends due to climate are mostly not significant but climate strongly influences the inter-annual variability of burned area.
Marcos A. S. Scaranello, Michael Keller, Marcos Longo, Maiza N. dos-Santos, Veronika Leitold, Douglas C. Morton, Ekena R. Pinagé, and Fernando Del Bon Espírito-Santo
Biogeosciences, 16, 3457–3474,Short summary
The coarse dead wood component of the tropical forest carbon pool is rarely measured. For the first time, we developed models for predicting coarse dead wood in Amazonian forests by using airborne laser scanning data. Our models produced site-based estimates similar to independent field estimates found in the literature. Our study provides an approach for estimating coarse dead wood pools from remotely sensed data and mapping those pools over large scales in intact and degraded forests.
James Brennan, Jose L. Gómez-Dans, Mathias Disney, and Philip Lewis
Biogeosciences, 16, 3147–3164,Short summary
We estimate the uncertainties associated with three global satellite-derived burned area estimates. The method provides unique uncertainties for the three estimates at the global scale for 2001–2013. We find uncertainties of 4 %–5.5 % in global burned area and uncertainties of 8 %–10 % in the frequently burning regions of Africa and Australia.
Alexander J. Norton, Peter J. Rayner, Ernest N. Koffi, Marko Scholze, Jeremy D. Silver, and Ying-Ping Wang
Biogeosciences, 16, 3069–3093,Short summary
This study presents an estimate of global terrestrial photosynthesis. We make use of satellite chlorophyll fluorescence measurements, a visible indicator of photosynthesis, to optimize model parameters and estimate photosynthetic carbon uptake. This new framework incorporates nonlinear, process-based understanding of the link between fluorescence and photosynthesis, an advance on past approaches. This will aid in the utility of fluorescence to quantify terrestrial carbon cycle feedbacks.
Sophie V. J. van der Horst, Andrew J. Pitman, Martin G. De Kauwe, Anna Ukkola, Gab Abramowitz, and Peter Isaac
Biogeosciences, 16, 1829–1844,Short summary
Measurements of surface fluxes are taken around the world and are extremely valuable for understanding how the land and atmopshere interact, and how the land can amplify temerature extremes. However, do these measurements sample extreme temperatures, or are they biased to the average? We examine this question and highlight data that do measure surface fluxes under extreme conditions. This provides a way forward to help model developers improve their models.
Friederike Gerschlauer, Gustavo Saiz, David Schellenberger Costa, Michael Kleyer, Michael Dannenmann, and Ralf Kiese
Biogeosciences, 16, 409–424,Short summary
Mount Kilimanjaro is an iconic environmental asset under serious threat due to increasing human pressures and climate change constraints. We studied variations in the stable isotopic composition of carbon and nitrogen in plant, litter, and soil material sampled along a strong land-use and altitudinal gradient. Our results show that, besides management, increasing temperatures in a changing climate may promote carbon and nitrogen losses, thus altering the stability of Kilimanjaro ecosystems.
Boaz Hilman, Jan Muhr, Susan E. Trumbore, Norbert Kunert, Mariah S. Carbone, Päivi Yuval, S. Joseph Wright, Gerardo Moreno, Oscar Pérez-Priego, Mirco Migliavacca, Arnaud Carrara, José M. Grünzweig, Yagil Osem, Tal Weiner, and Alon Angert
Biogeosciences, 16, 177–191,Short summary
Combined measurement of CO2 / O2 fluxes in tree stems suggested that on average 41 % of the respired CO2 was not emitted locally to the atmosphere. This finding strengthens the recognition that CO2 efflux from tree stems is not an accurate measure of respiration. The CO2 / O2 fluxes did not vary as expected if CO2 dissolution in the xylem sap was the main driver for the CO2 retention. We suggest the examination of refixation of respired CO2 as a possible mechanism for CO2 retention.
Gitta Lasslop, Thomas Moeller, Donatella D'Onofrio, Stijn Hantson, and Silvia Kloster
Biogeosciences, 15, 5969–5989,Short summary
We apply a multivariate model evaluation to the relationship between climate, vegetation and fire in the tropics using the JSBACH land surface model and two remote-sensing data sets, with the aim to identify the potential for model improvement. The overestimation of tree cover for low precipitation and a very strong relationship between tree cover and burned area indicates opportunities in the improvement of drought effects and the impact of fire on tree cover or the adaptation of trees to fire.
Yao Zhang, Joanna Joiner, Seyed Hamed Alemohammad, Sha Zhou, and Pierre Gentine
Biogeosciences, 15, 5779–5800,Short summary
Using satellite reflectance measurements and a machine learning algorithm, we generated a new solar-induced chlorophyll fluorescence (SIF) dataset that is closely linked to plant photosynthesis. This new dataset has higher spatial and temporal resolutions, and lower uncertainty compared to the existing satellite retrievals. We also demonstrated its application in monitoring drought and improving the understanding of the SIF–photosynthesis relationship.
Chris Huntingford, Rebecca J. Oliver, Lina M. Mercado, and Stephen Sitch
Biogeosciences, 15, 5415–5422,Short summary
Raised ozone levels impact plant stomatal opening and thus photosynthesis. Most models describe this as a suppression of stomata opening. Field evidence suggests more complexity, as ozone damage may make stomatal response
sluggish. In some circumstances, this causes stomata to be more open – a concern during drought conditions – by increasing transpiration. To guide interpretation and modelling of field measurements, we present an equation for sluggish effects, via a single tau parameter.
Jacob A. Nelson, Nuno Carvalhais, Mirco Migliavacca, Markus Reichstein, and Martin Jung
Biogeosciences, 15, 2433–2447,Short summary
Plants have typical daily carbon uptake and water loss cycles. However, these cycles may change under periods of duress, such as water limitation. Here we identify two types of patterns in response to water limitations: a tendency to lose more water in the morning than afternoon and a decoupling of the carbon and water cycles. The findings show differences in responses by trees and grasses and suggest that morning shifts may be more efficient at gaining carbon per unit water used.
Peter Levy, Marcel van Oijen, Gwen Buys, and Sam Tomlinson
Biogeosciences, 15, 1497–1513,Short summary
We present a new method for estimating land-use change using a Bayesian data assimilation approach. This allows us to constrain estimates of gross land-use change with reliable national-scale census data whilst retaining the information available from several other sources. This includes detailed spatial data; further data sources, such as new satellites, could easily be added in future. Uncertainty is propagated appropriately into the output.
Chao Yue, Philippe Ciais, and Wei Li
Biogeosciences, 15, 1185–1201,Short summary
Gross land use change such as shifting cultivation causes carbon emissions because carbon release in cleared forests is larger than absorption in regrowing ones. However, to appropriately account for this process, vegetation models have to represent sub-grid secondary forest dynamics. We found that gross land use emissions can be overestimated if sub-grid secondary forests are neglected in the model. Conversely, rotation lengths of shifting cultivation have a critical role.
Chongjuan Chen, Yufu Jia, Yuzhen Chen, Imran Mehmood, Yunting Fang, and Guoan Wang
Biogeosciences, 15, 369–377,Short summary
The south slope of Tian Shan differs from the north slope in environment. The study showed that leaf δ15N, soil δ15N and △δ15Nleaf-soil on the south slope were greater than those on the north slope. The significant influential factors of leaf and soil δ15N on the south slope were different from those on the north slope. The results suggested that the south slope has higher soil N transformation rates than the north slope and relationships between leaf and soil δ15N and environment are localized.
Wei Li, Philippe Ciais, Shushi Peng, Chao Yue, Yilong Wang, Martin Thurner, Sassan S. Saatchi, Almut Arneth, Valerio Avitabile, Nuno Carvalhais, Anna B. Harper, Etsushi Kato, Charles Koven, Yi Y. Liu, Julia E.M.S. Nabel, Yude Pan, Julia Pongratz, Benjamin Poulter, Thomas A. M. Pugh, Maurizio Santoro, Stephen Sitch, Benjamin D. Stocker, Nicolas Viovy, Andy Wiltshire, Rasoul Yousefpour, and Sönke Zaehle
Biogeosciences, 14, 5053–5067,Short summary
We used several observation-based biomass datasets to constrain the historical land-use change carbon emissions simulated by models. Compared to the range of the original modeled emissions (from 94 to 273 Pg C), the observationally constrained global cumulative emission estimate is 155 ± 50 Pg C (1σ Gaussian error) from 1901 to 2012. Our approach can also be applied to evaluate the LULCC impact of land-based climate mitigation policies.
Lukas Baumbach, Jonatan F. Siegmund, Magdalena Mittermeier, and Reik V. Donner
Biogeosciences, 14, 4891–4903,Short summary
Temperature extremes play a crucial role for vegetation growth and vitality in vast parts of the European continent. Here, we study the likelihood of simultaneous occurrences of extremes in daytime land surface temperatures and the normalized difference vegetation index (NDVI) for three main periods during the growing season. Our results reveal a particularly high vulnerability of croplands to temperature extremes, while other vegetation types are considerably less affected.
Rudra K. Shrestha, Vivek K. Arora, Joe R. Melton, and Laxmi Sushama
Biogeosciences, 14, 4733–4753,Short summary
Computer models of vegetation provide a tool to assess how future changes in climate may the affect geographical distribution of vegetation. However, such models must first be assessed for their ability to reproduce the present-day geographical distribution of vegetation. Here, we assess the ability of one such dynamic vegetation model. We find that while the model is broadly successful in reproducing the geographical distribution of trees and grasses in North America some limitations remain.
Elizabeth E. Webb, Kathryn Heard, Susan M. Natali, Andrew G. Bunn, Heather D. Alexander, Logan T. Berner, Alexander Kholodov, Michael M. Loranty, John D. Schade, Valentin Spektor, and Nikita Zimov
Biogeosciences, 14, 4279–4294,Short summary
Permafrost soils store massive amounts of C, yet estimates of soil C storage in this region are highly uncertain, primarily due to undersampling at all spatial scales; circumpolar soil C estimates lack sufficient continental spatial diversity, regional intensity, and replication at the field-site level. We aim to reduce the uncertainty of regional C estimates by providing a comprehensive assessment of vegetation, active-layer, and permafrost C stocks in a watershed in northeast Siberia, Russia.
Thierry Fanin and Guido R. van der Werf
Biogeosciences, 14, 3995–4008,Short summary
Using night fire detection and rainfall datasets during 1997–2015, we found that the number of night fires detected in 1997 was 2.2 times higher than in 2015, but with a higher fraction of peatland burned in 2015. We also confirmed the non-linearity of rainfall accumulation prior to a fire to indicate a high fire year. The influence of rainfall on the number of yearly fires varies across Indonesia. Southern Sumatra and Kalimantan need 120 days of observations, while northern Sumatra only 30.
Tara W. Hudiburg, Philip E. Higuera, and Jeffrey A. Hicke
Biogeosciences, 14, 3873–3882,Short summary
Wildfire is a dominant disturbance agent in forest ecosystems, shaping important processes including net carbon (C) balance. Our results imply that fire-regime variability is a major driver of C trajectories in stand-replacing fire regimes. Predicting carbon balance in these systems, therefore, will depend strongly on the ability of ecosystem models to represent a realistic range of fire-regime variability over the past several centuries to millennia.
Dolors Armenteras, Joan Sebastian Barreto, Karyn Tabor, Roberto Molowny-Horas, and Javier Retana
Biogeosciences, 14, 2755–2765,Short summary
Tropical forests are highly threatened by the expansion of the agricultural frontier, use of fire and subsequent deforestation. NW Amazonia is the wettest part of the basin and the role of fire is still largely unknown in this subregion. In this study, we compared fire regimes in five countries sharing this tropical biome (Venezuela, Colombia, Ecuador, Peru and Brazil). We studied fire activity in relation to proximity to roads and rivers and how fire occurs in relation to forest fragmentation.
Thomas Kaminski and Pierre-Philippe Mathieu
Biogeosciences, 14, 2343–2357,Short summary
This paper provides the formalism and examples of how observation operators can be used, in combination with data assimilation or retrieval techniques, to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models.
Per-Ola Olsson, Michal Heliasz, Hongxiao Jin, and Lars Eklundh
Biogeosciences, 14, 1703–1719,
Jason Beringer, Ian McHugh, Lindsay B. Hutley, Peter Isaac, and Natascha Kljun
Biogeosciences, 14, 1457–1460,Short summary
Standardised, quality-controlled and robust data from flux networks underpin the understanding of ecosystem processes and tools to manage our natural resources. The Dynamic INtegrated Gap-filling and partitioning for OzFlux (DINGO) system enables gap-filling and partitioning of fluxes and subsequently provides diagnostics and results. Quality data from robust systems like DINGO ensure the utility and uptake of flux data and facilitates synergies between flux, remote sensing and modelling.
Biogeosciences, 14, 751–754,Short summary
The response of ecosystems to elevated atmospheric CO2 is affected by nitrogen (N) availability. It has been hypothesized that N limitation becomes progressively stronger (progressive N limitation, PNL). Most long-term free air CO2 enrichment studies did not see a PNL. This paper shows that enhanced biological N2 fixation only prevents PNL in plant communities with symbiotic N2 fixation. In most ecosystems a stimulation of gross N mineralization prevents the development of a PNL.
Yiqi Luo, Zheng Shi, Xingjie Lu, Jianyang Xia, Junyi Liang, Jiang Jiang, Ying Wang, Matthew J. Smith, Lifen Jiang, Anders Ahlström, Benito Chen, Oleksandra Hararuk, Alan Hastings, Forrest Hoffman, Belinda Medlyn, Shuli Niu, Martin Rasmussen, Katherine Todd-Brown, and Ying-Ping Wang
Biogeosciences, 14, 145–161,Short summary
Climate change is strongly regulated by land carbon cycle. However, we lack the ability to predict future land carbon sequestration. Here, we develop a novel framework for understanding what determines the direction and rate of future change in land carbon storage. The framework offers a suite of new approaches to revolutionize land carbon model evaluation and improvement.
Martina Franz, David Simpson, Almut Arneth, and Sönke Zaehle
Biogeosciences, 14, 45–71,Short summary
Ozone is a toxic air pollutant that can damage plant leaves and impact their carbon uptake from the atmosphere. We extend a terrestrial biosphere model to account for ozone damage of plants and investigate the impact on the terrestrial carbon cycle. Our approach accounts for ozone transport from the free troposphere to leaf level. We find that this substantially affects simulated ozone uptake into the plants. Simulations indicate that ozone damages plants less than expected from previous studies
Xian Yang, Xiulian Chi, Chengjun Ji, Hongyan Liu, Wenhong Ma, Anwar Mohhammat, Zhaoyong Shi, Xiangping Wang, Shunli Yu, Ming Yue, and Zhiyao Tang
Biogeosciences, 13, 4429–4438,Short summary
Leaf chemical concentrations are key traits in ecosystem functioning. Previous studies were biased for trees and grasses. Here, we explored the patterns of leaf N and P concentrations in relation to climate, soil, and evolutionary history in northern China. We found that climate influenced the community chemical traits through the shift in species composition, whereas soil directly influenced the community chemical traits.
Wenjuan Zhu, Wenhua Xiang, Qiong Pan, Yelin Zeng, Shuai Ouyang, Pifeng Lei, Xiangwen Deng, Xi Fang, and Changhui Peng
Biogeosciences, 13, 3819–3831,Short summary
We used hemispherical photography to measure LAI values in three subtropical forests from April 2014 to January 2015. Spatial heterogeneity of LAI and its controlling factors were analysed using geostatistical methods and the generalised additive models (GAMs), respectively. Our results showed that LAI values differed greatly in three forests and their seasonal variations were consistent with plant phenology. Stand characters significantly affected the spatial variations in LAI values.
Niels Andela, Guido R. van der Werf, Johannes W. Kaiser, Thijs T. van Leeuwen, Martin J. Wooster, and Caroline E. R. Lehmann
Biogeosciences, 13, 3717–3734,Short summary
Landscape fires occur on a large scale in savannas and grasslands, affecting ecosystems and air quality. We combined two satellite-derived datasets to derive fuel consumption per unit of area burned for savannas and grasslands in the (sub)tropics. Fire return periods, vegetation productivity, vegetation type and human land management were all important drivers of its spatial distribution. The results can be used to improve fire emission modelling and management or to detect ecosystem degradation.
Stijn Hantson, Almut Arneth, Sandy P. Harrison, Douglas I. Kelley, I. Colin Prentice, Sam S. Rabin, Sally Archibald, Florent Mouillot, Steve R. Arnold, Paulo Artaxo, Dominique Bachelet, Philippe Ciais, Matthew Forrest, Pierre Friedlingstein, Thomas Hickler, Jed O. Kaplan, Silvia Kloster, Wolfgang Knorr, Gitta Lasslop, Fang Li, Stephane Mangeon, Joe R. Melton, Andrea Meyn, Stephen Sitch, Allan Spessa, Guido R. van der Werf, Apostolos Voulgarakis, and Chao Yue
Biogeosciences, 13, 3359–3375,Short summary
Our ability to predict the magnitude and geographic pattern of past and future fire impacts rests on our ability to model fire regimes. A large variety of models exist, and it is unclear which type of model or degree of complexity is required to model fire adequately at regional to global scales. In this paper we summarize the current state of the art in fire-regime modelling and model evaluation, and outline what lessons may be learned from the Fire Model Intercomparison Project – FireMIP.
Lorenzo Menichetti, Thomas Kätterer, and Jens Leifeld
Biogeosciences, 13, 3003–3019,Short summary
Soil organic carbon dynamics are crucial for the global greenhouse gas balance, but their complexity is difficult to model and understand. We therefore often rely on radiocarbon measurements for calibrating models, but their effect on our understanding of the processes is still unclear. We calibrated five model structures on data from a long-term Swiss field experiment in a Bayesian framework to assess the effect of radiocarbon on the parameter and structural uncertainty of a soil carbon model.
Junyi Liang, Xuan Qi, Lara Souza, and Yiqi Luo
Biogeosciences, 13, 2689–2699,Short summary
It is unclear how the nitrogen (N) cycle regulates climate change through influencing carbon sequestration. By using meta-analysis, we tested a popular hypothesis, progressive N limitation (PNL), which postulates that greater N sequestration in organisms leads to declining N availability for further plant growth under elevated CO2. Our analyses suggest that extra nitrogen supply by increased biological N fixation and decreased leaching may potentially alleviate PNL.
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We found larger shrub leaf C, C : N and lower leaf N, N : P levels compared to other terrestrial ecosystems. Alpine shrubs exhibited the greatest leaf C at low temperatures, whereas the largest leaf N and P occurred in valley deciduous shrubs. The large heterogeneity in nutrient uptake and physiological adaptation of shrub types to environments explained the largest fraction of leaf C : N : P variations, while climate indirectly affected leaf C : N : P via its interactive effects on shrub type or soil.
We found larger shrub leaf C, C : N and lower leaf N, N : P levels compared to other terrestrial...