scholarly journals Fire as carbon sink? The global biome-dependent wildfire carbon balance

2020 ◽  
Author(s):  
Simon Bowring ◽  
Matthew Jones ◽  
Philippe Ciais ◽  
Bertrand Guenet ◽  
Samuel Abiven
Keyword(s):  
Forest Fires ◽  
Fire Regime ◽  
Carbon Sink ◽  
Global Scale ◽  
Vegetation Coverage ◽  
Tropical Regions ◽  
Scale Theory ◽  
C Balance ◽  
Gains And Losses ◽  
Soil Accumulation

Abstract Wildfires generally result in biospheric recovery approximating the pre-disturbance state. However legacy carbon(C) gains and losses that have until now been overlooked in global-scale theory and modelling indicate that post-fire C gains through pyrogenic carbon (PyC) production, and losses via fire regime shifts, post-fire mortality, topsoil loss and inland water export, may be central to whether 20th century fires have imposed a net terrestrial C source or sink. Here, we integrate PyC production and soil accumulation into a global terrestrial model (ORCHIDEE-MICT) and estimate wildfire C-gains and losses over 1901-2010, quantifying the fire-C balance at global, regional and vegetation scales. Excluding the effect of PyC mineralisation, fires provide a land storage of +177 TgC yr-1 (63% PyC production), dominated by grasslands. The global balance is nuanced, with forest fires resulting in strong terrestrial net C loss:gain ratios (>-2:1) that are greatest in tropical regions (>-3:1). Frequent tropical grassland fires are responsible for the bulk of the land PyC sink and its environmental persistence, whose theoretical minimum mean residence time we quantify at 2760yrs. We highlight the dependency of the global fire-C balance on vegetation coverage and the potential role of preserving grasslands, particularly those in the tropics, in that regard.

scholarly journals Global assessment and mapping of ecological vulnerability to wildfires

2021 ◽  
Author(s):  
Fátima Arrogante-Funes ◽  
Inmaculada Aguado ◽  
Emilio Chuvieco
Keyword(s):  
Forest Fires ◽  
Fire Regime ◽  
Conservation Status ◽  
Critical Role ◽  
Fire Regimes ◽  
Global Scale ◽  
Natural Phenomenon ◽  
Ecological Value ◽  
Ecological Vulnerability ◽  
The Face

Abstract. Fire is a natural phenomenon that has played a critical role in transforming the environment and maintaining biodiversity at a global scale. However, the plants in some habitats have not developed strategies for recovery from fire or have not adapted to the changes taking place in their fire regimes. Maps showing ecological vulnerability to fires could contribute to environmental management policies in the face of global change scenarios. The main objective of this study is to assess and map ecological vulnerability to fires on a global scale. To this end, we created ecological value and post-fire regeneration delay indices on the basis of existing global databases. Two ecological value indices were identified: biological distinction and conservation status. For the post-fire regeneration delay index, various factors were taken into account, including the type of fire regime, the increase in the frequency and intensity of forest fires and the potential soil erosion they can cause. These indices were combined by means of a qualitative cross-tabulation to create a new index evaluating ecological vulnerability to fire. The results showed that global ecological value could be reduced by as much as 50 %, due to fire perturbation of ecosystems that are poorly adapted to it. The terrestrial biomes most affected are the tropical and subtropical moist broadleaf forest; tundra; mangroves; tropical and subtropical coniferous forests; and tropical and subtropical dry broadleaf forests.

scholarly journals Global pattern of ecosystem respiration tendencies and its implications on terrestrial carbon sink potential

2021 ◽  
Author(s):  
Peixin Yu ◽  
Tao Zhou ◽  
Hui Luo ◽  
Xia Liu ◽  
Peijun Shi ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Carbon Export ◽  
Growth Trend ◽  
Global Pattern ◽  
Tropical Regions ◽  
Sink Capacity ◽  
Terrestrial Carbon Sink

Abstract As the largest component of carbon export from terrestrial ecosystems, ecosystem respiration (RECO) determines the carbon stock changes in terrestrial ecosystems. It is essential to accurately simulate the response of RECO to climate change. In this study, by constructing an optimal deep learning model for simulating global-scale RECO, we found that there is a 1–2 years' lagged response of RECO to changes in water conditions and an inconsistency in carbon input (NPP) and output (RECO) trends. The NPP growth trend in global terrestrial ecosystems is greater than that of RECO, with a trend showing increasing carbon sinks, particularly in the northern extra-tropics; while the carbon sink capacity of tropical regions has gradually saturated, showing that the changing trend of RECO is close to that of NPP, which poses a potential risk to the sustainable carbon sink capacity of global ecosystems in the future.

Towards a nudging of stratospheric overshoots in the 3D mesoscale BRAMS model

2021 ◽  
Author(s):  
Justine Pichon ◽  
Emmanuel Riviere ◽  
Abhinna Behera ◽  
Jeremie Burgalat
Keyword(s):  
Mesoscale Model ◽  
Water Concentration ◽  
Global Scale ◽  
Satellite Measurement ◽  
Model Categories ◽  
Tropical Regions ◽  
Water Ice ◽  
Convective Clouds ◽  
Starting Point ◽  
Ice Water

<p>Water repartition in the stratosphere is a key compound in the atmospheric chemical and<br>radiative equilibrium. Since the 80’s, an increase of the water concentration in the<br>stratosphere has been observed.This presence in the stratosphere can be explained by the<br>slow ascent of air mass above convective clouds in tropical regions. The amount of water<br>vapor entering in the stratosphere depends on the coldest temperature and countered<br>during this slow ascent because it can lead to ice cristal formation that sediment and<br>dehydrate the air masses. But some other processes may contribute to the stratospheric<br>water budget, especially to explain the increase of water vapor. Stratospheric overshoots<br>phenomenon can take part in the stratospheric hydratation, by injecting directly water ice in<br>the stratosphere. Injected ice water, by sublimation, will hydrate stratosphere locally. The<br>local role of overshoots is better known but their contributions at the global scale steal need<br>to be quantified. In order to estimate this contribution, previous studies have used the 3D<br>simulation mesoscale model BRAMS to show overshoot impact in the upper Tropical<br>Tropopause Layer (TTL). These studies are the starting point of our study.</p><p>The aim of this paper is to present the new development inside BRAMS to nudge<br>stratospheric ice injection by overshoots. It uses an overshoot occurrence climatology from<br>MHS (Microwave Humidity Sounder) satellite measurement. Ice injection in the model is<br>made according to ice model categories previously shown to be present in the overshoot<br>plumes with ratios already diagnosed in previous studies. Ice injection is made between two<br>layers of TTL’s stratospheric part: between 380 and 385K and between 385 et 400K. Nudging<br>is triggered only if, in the grid mesh (20 x 20 km) where MHS has detected an overshoot,<br>BRAMS computes a cumulonimbus with a top above 13.5km. For the layer above 385 K<br>isentrope, a subgrid box of 2 km x 2 km is considered for the computation of ice injection.<br>Sensibility test of this nudging scheme will be presented in this presentation. </p>

scholarly journals Forest Fire Regime in a Mediterranean Ecosystem: Unraveling the Mutual Interrelations between Rainfall Seasonality, Soil Moisture, Drought Persistence, and Biomass Dynamics

Fire ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 49
Author(s):  
Nunzio Romano ◽  
Nadia Ursino
Keyword(s):  
Climate Change ◽  
Soil Water ◽  
Forest Fires ◽  
Fire Regime ◽  
Fire Regimes ◽  
Mediterranean Ecosystem ◽  
Water Retention Capacity ◽  
Soil Water Retention ◽  
Retention Capacity ◽  
Rainfall Frequency

Frequent and severe droughts typically intensify wildfires provided that there is enough fuel in situ. The extent to which climate change may influence the fire regime and long time-scale hydrological processes may soften the effect of inter-annual climate change and, more specifically, whether soil-water retention capacity can alleviate the harsh conditions resulting from droughts and affect fire regimes, are still largely unexplored matters. The research presented in this paper is a development of a previous investigation and shows in what way, and to what extent, rainfall frequency, dry season length, and hydraulic response of different soil types drive forest fires toward different regimes while taking into consideration the typical seasonality of the Mediterranean climate. The soil-water holding capacity, which facilitates biomass growth in between fire events and hence favors fuel production, may worsen the fire regime as long dry summers become more frequent, such that the ecosystem’s resilience to climate shifts may eventually be undermined.

scholarly journals Analysis of Four Years of Global XCO2 Anomalies as Seen by Orbiting Carbon Observatory-2

2019 ◽  
Vol 11 (7) ◽  
pp. 850 ◽  
Author(s):  
Janne Hakkarainen ◽  
Iolanda Ialongo ◽  
Shamil Maksyutov ◽  
David Crisp
Keyword(s):  
South Africa ◽  
Biomass Burning ◽  
Fossil Fuel ◽  
Global Scale ◽  
Complex Model ◽  
Fuel Combustion ◽  
Local Concentration ◽  
Fossil Fuel Combustion ◽  
Tropical Regions ◽  
Model Based

NASA’s carbon dioxide mission, Orbiting Carbon Observatory-2, began operating in September 2014. In this paper, we analyze four years (2015–2018) of global (60°S–60°N) XCO2 anomalies and their annual variations and seasonal patterns. We show that the anomaly patterns in the column-averaged CO2 dry air mole fraction, XCO2, are robust and consistent from year-to-year. We evaluate the method by comparing the anomalies to fluxes from anthropogenic, biospheric, and biomass burning and to model-simulated local concentration enhancements. We find that, despite the simplicity of the method, the anomalies describe the spatio-temporal variability of XCO2 (including anthropogenic emissions and seasonal variability related to vegetation and biomass burning) consistently with more complex model-based approaches. We see, for example, that positive anomalies correspond to fossil fuel combustion over the major industrial areas (e.g., China, eastern USA, central Europe, India, and the Highveld region in South Africa), shown as large positive XCO2 enhancements in the model simulations. We also find corresponding positive anomalies and fluxes over biomass burning areas during different fire seasons. On the other hand, the largest negative anomalies correspond to the growing season in the northern middle latitudes, characterized by negative XCO2 enhancements from simulations and high solar-induced chlorophyll fluorescence (SIF) values (indicating the occurrence of photosynthesis). The largest discrepancies between the anomaly patterns and the model-based results are observed in the tropical regions, where OCO-2 shows persistent positive anomalies over every season of every year included in this study. Finally, we demonstrate how XCO2 anomalies enable the detection of anthropogenic signatures for several local scale case studies, both in the Northern and Southern Hemisphere. In particular, we analyze the XCO2 anomalies collocated with the recent TROPOspheric Monitoring Instrument NO2 observations (used as indicator of anthropogenic fossil fuel combustion) over the Highveld region in South Africa. The results highlight the capability of satellite-based observations to monitor natural and man-made CO2 signatures on global scale.

Inferring non-steady-state terrestrial vegetation carbon turnover times from multi-decadal space-borne observations on global scale

2020 ◽  
Author(s):  
Naixin Fan ◽  
Simon Besnard ◽  
Maurizio Santoro ◽  
Oliver Cartus ◽  
Nuno Carvalhais
Keyword(s):  
Climate Change ◽  
Steady State ◽  
Carbon Fixation ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Turnover Time ◽  
Terrestrial Vegetation ◽  
Time Step

<p>The global biomass is determined by the vegetation turnover times (τ) and carbon fixation through photosynthesis. Vegetation turnover time is a central parameter that not only partially determines the terrestrial carbon sink but also the response of terrestrial vegetation to the future changes in climate. However, the change of magnitude, spatial patterns and uncertainties in τ as well as the sensitivity of these processes to climate change is not well understood due to lack of observations on global scale. In this study, we explore a new dataset of annual above-ground biomass (AGB) change from 1993 to 2018 from spaceborne scatterometer observations. Using the long-term, spatial-explicit global dynamic dataset, we investigated how τ change over almost three decades including the uncertainties. Previous estimations of τ under steady-state assumption can now be challenged acknowledging that terrestrial ecosystems are, for the most of cases, not in balance. In this study, we explore this new dataset to derive global maps of τ in non-steady-state for different periods of time. We used a non-steady-state carbon model in which the change of AGB is a function of Gross Primary Production (GPP) and τ (ΔAGB = α*GPP-AGB/ τ). The parameter α represents the percentage of incorporation of carbon from GPP to biomass. By exploring the AGB change in 5 to 10 years of time step, we were able to infer τ and α from the observations of AGB and GPP change by solving the linear equation. We show how τ changes after potential disturbances in the early 2000s in comparison to the previous decade. We also show the spatial distributions of α from the change of AGB. By accessing the change in biomass, τ and α as well as their associated uncertainties, we provide a comprehensive diagnostic on the vegetation dynamics and the potential response of biomass to disturbance and to climate change.   </p><p></p><p></p><p></p><p></p><p></p><p></p>

scholarly journals Phylogenetic homogenization of amphibian assemblages in human-altered habitats across the globe

2018 ◽  
Vol 115 (15) ◽  
pp. E3454-E3462 ◽  
Author(s):  
A. Justin Nowakowski ◽  
Luke O. Frishkoff ◽  
Michelle E. Thompson ◽  
Tatiana M. Smith ◽  
Brian D. Todd
Keyword(s):  
Evolutionary History ◽  
Phylogenetic Diversity ◽  
Biodiversity Loss ◽  
Global Scale ◽  
Large Species ◽  
Tropical Regions ◽  
Habitat Conversion ◽  
Average Loss ◽  
Species Responses ◽  
Landscape Scales

Habitat conversion is driving biodiversity loss and restructuring species assemblages across the globe. Responses to habitat conversion vary widely, however, and little is known about the degree to which shared evolutionary history underlies changes in species richness and composition. We analyzed data from 48 studies, comprising 438 species on five continents, to understand how taxonomic and phylogenetic diversity of amphibian assemblages shifts in response to habitat conversion. We found that evolutionary history explains the majority of variation in species’ responses to habitat conversion, with specific clades scattered across the amphibian tree of life being favored by human land uses. Habitat conversion led to an average loss of 139 million years of amphibian evolutionary history within assemblages, high species and lineage turnover at landscape scales, and phylogenetic homogenization at the global scale (despite minimal taxonomic homogenization). Lineage turnover across habitats was greatest in lowland tropical regions where large species pools and stable climates have perhaps given rise to many microclimatically specialized species. Together, our results indicate that strong phylogenetic clustering of species’ responses to habitat conversion mediates nonrandom structuring of local assemblages and loss of global phylogenetic diversity. In an age of rapid global change, identifying clades that are most sensitive to habitat conversion will help prioritize use of limited conservation resources.

scholarly journals Current and future estimates for the fire frequency and the fire rotation period in the main woodland types of peninsular Spain: a case-study approach

2015 ◽  
Vol 24 (2) ◽  
pp. e031 ◽  
Author(s):  
Antonio Vázquez ◽  
José M. Climent ◽  
Luis Casais ◽  
José R. Quintana
Keyword(s):  
Forest Fires ◽  
Fire Regime ◽  
Rotation Period ◽  
Fire Frequency ◽  
Large Variability ◽  
Rotation Periods ◽  
In Fire ◽  
Climatic Scenario ◽  
Peninsular Spain ◽  
Reference Areas

<p><em>Aim of study</em>. Fire regimes are frequently dynamic and change as a function of the interactions between the three main fire drivers: fuels, ignitions and climatic conditions. We characterized the recent period (1974-2005) and performed estimates for the future fire regime</p><p><em>Area of study</em>. We have considered five pine and another four woodland types by means of the analyses of 100 reference areas in peninsular Spain.</p><p><em>Material and methods</em>. The estimates of the expected alterations in fire frequency and the fire rotation period were based on models previously developed for the climatic scenarios SRES A2 and B2.</p><p><em>Main results</em>. The results point to the large variability in fire frequency and rotation periods between the woodland types as defined, and also among the reference areas delimited for each of them. Fire frequencies will increase for all woodland types while very relevant shortenings of the fire rotation periods are expected. For the 32 yr period analysed, rotation periods longer than 500 yr were obtained in 54% of the reference areas while this percentage would decrease to 31% in the B2 and to 29% in the A2 climatic scenario. In the most affected woodland type, <em>P. pinaster</em>, from a median rotation period of 83 yr it would decrease to 26 yr in the B2 and to 20 yr in the A2 climatic scenario.</p><p><em>Research highlights</em>. We conclude that the predicted increases in fire activity will have adverse effects on some of the main Spanish woodland types due to the expected future disruptions in the fire regime.  </p><p><strong>Keywords: </strong>Forest fires; fire regime; fire frequency; fire rotation period; climatic change.</p><p><strong>Abbreviations used: </strong>SRES: Special Report on Emissions Scenarios; IPCC: Intergovernmental Panel on Climate Change; RA: Reference Areas.</p>

scholarly journals Historical CO<sub>2</sub> emissions from land-use and land-cover change and their uncertainty

2020 ◽  
Author(s):  
Thomas Gasser ◽  
Léa Crepin ◽  
Yann Quilcaille ◽  
Richard A. Houghton ◽  
Philippe Ciais ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Carbon Sink ◽  
Data Sets ◽  
Tropical Regions ◽  
Dynamic Global Vegetation Models ◽  
Vegetation Models ◽  
Global Vegetation ◽  
Global Carbon

Abstract. Emissions from land-use and land-cover change are a key component of the global carbon cycle. Models are required to disentangle these emissions and the land carbon sink, however, because only the sum of both can be physically observed. Their assessment within the yearly community-wide effort known as the Global Carbon Budget remains a major difficulty, because it combines two lines of evidence that are inherently inconsistent: bookkeeping models and dynamic global vegetation models. Here, we propose a unifying approach relying on a bookkeeping model that embeds processes and parameters calibrated on dynamic global vegetation models, and the use of an empirical constraint. We estimate global CO2 emissions from land-use and land-cover change were 1.36 ± 0.42 Pg C yr−1 (1-σ range) on average over 2009–2018, and 206 ± 57 Pg C cumulated over 1750–2018. We also estimate that land-cover change induced a global loss of additional sink capacity – that is, a foregone carbon removal, not part of the emissions – of 0.68 ± 0.57 Pg C yr−1 and 32 ± 23 Pg C over the same periods, respectively. Additionally, we provide a breakdown of our results' uncertainty following aspects that include the land-use and land-cover change data sets used as input, and the model's biogeochemical parameters. We find the biogeochemical uncertainty dominates our global and regional estimates, with the exception of tropical regions in which the input data dominates. Our analysis further identifies key sources of uncertainty, and suggests ways to strengthen the robustness of future Global Carbon Budgets.

scholarly journals Mapping and Inventory of Forest Fires in Andhra Pradesh, India: Current Status and Conservation Needs

ISRN Forestry ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
C. Sudhakar Reddy ◽  
P. Hari Krishna ◽  
K. Anitha ◽  
Shijo Joseph
Keyword(s):  
Remote Sensing ◽  
Protected Areas ◽  
Forest Fires ◽  
Andhra Pradesh ◽  
Forest Cover ◽  
Fire Regime ◽  
Spatial Extent ◽  
Current Status ◽  
Wide Field ◽  
Tiger Reserve

Analyzing the spatial extent and distribution of forest fires is essential for sustainable forest management. The present study appraises the distribution of forest fires in one of the largest states in India, Andhra Pradesh, using satellite remote sensing. Advanced Wide Field Sensor (AWiFS) onboard on Indian Remote Sensing Satellite (IRS P6) was used for mapping and analyzing the spatial extent of burnt areas. Comparative analysis was carried out with respect to different forest types, protected areas and across elevation zones to demarcate and identify the fire-affected areas. The results show that about 19% (8594 km2) of forest area were burnt in the state during 2009. Burnt area statistics for Protected Areas reveal that 24% of forest cover was affected by fire. Nagarjunasagar Srisailam Tiger Reserve, the largest tiger reserve of the country, shows an area of 793 km2 (22%) under forest fire. Higher elevation areas which are predominantly dominated by savannah and woodlands experienced higher fire occurrence in comparison with lower elevation areas. Similarly, fires were prevalent near edges compared to core forest. Results of the study suggested that forests of Andhra Pradesh are prone to high fire occurrences and current fire regime poses a severe conservation threat to biodiversity both within and outside the Protected Areas.

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