Consumption of residual pyrogenic carbon by wildfire

2013 ◽  
Vol 22 (8) ◽  
pp. 1072 ◽  
Author(s):  
C. Santín ◽  
S. H. Doerr ◽  
C. Preston ◽  
R. Bryant
Keyword(s):  
Forest Floor ◽  
Global Carbon Cycle ◽  
Stainless Steel Mesh ◽  
Major Mechanism ◽  
Pyrogenic Carbon ◽  
Mass Losses ◽  
Mesh Bags ◽  
The Subject ◽  
Global Carbon

Pyrogenic carbon (PyC) produced during vegetation fires represents one of the most degradation resistant organic carbon pools and has important implications for the global carbon cycle. Its long-term fate in the environment and the processes leading to its degradation are the subject of much debate. Its consumption in subsequent fires is considered a potential major mechanism of abiotic PyC degradation; however, no quantitative data supporting this removal pathway have been published to date. To address this gap, we quantified consumption of residual PyC at the forest floor during an experimental fire, representative of a typical boreal wildfire, complemented by exploratory laboratory heating experiments. Labelled PyC (pinewood charcoal from a slash pile burn), in granular form contained in stainless steel mesh bags and as individual pieces, were placed at ~2-cm depth within the forest floor. The median mass loss of granular charcoal was 6.6%, with 75% of the samples losing <15%, and of individual pieces 15.1% with 75% of the samples losing <25%. The mass losses under laboratory conditions, although somewhat higher than in the field, confirm an overall low consumption of PyC. The limited losses of PyC found here do not support the widely held notion that wildfire is a major cause of loss for residual PyC.

scholarly journals Causes and timing of future biosphere extinctions

2006 ◽  
Vol 3 (1) ◽  
pp. 85-92 ◽  
Author(s):  
S. Franck ◽  
C. Bounama ◽  
W. von Bloh
Keyword(s):  
Global Carbon Cycle ◽  
Temperature Tolerance ◽  
Cambrian Explosion ◽  
Strong Decrease ◽  
The Earth ◽  
Reverse Sequence ◽  
Different Types ◽  
Global Surface ◽  
Global Carbon

Abstract. We present a minimal model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the combined ocean and atmosphere reservoir. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. During the entire existence of the biosphere procaryotes are always present. 2 Gyr ago eucaryotic life first appears. The emergence of complex multicellular life is connected with an explosive increase in biomass and a strong decrease in Cambrian global surface temperature at about 0.54 Gyr ago. In the long-term future the three types of biosphere will die out in reverse sequence of their appearance. We show that there is no evidence for an implosion-like extinction in contrast to the Cambrian explosion. In dependence of their temperature tolerance complex multicellular life and eucaryotes become extinct in about 0.8–1.2 Gyr and 1.3–1.5 Gyr, respectively. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr.

scholarly journals Long-term evolution of the global carbon cycle: historic minimum of global surface temperature at presen

Tellus B ◽  
2002 ◽  
Vol 54 (4) ◽  
pp. 325-343 ◽  
Author(s):  
Siegfried Franck ◽  
Konrad J. Kossacki ◽  
Werner Von Bloth ◽  
Christine Bounama
Keyword(s):  
Carbon Cycle ◽  
Surface Temperature ◽  
Global Carbon Cycle ◽  
Long Term Evolution ◽  
Global Surface Temperature ◽  
Term Evolution ◽  
Global Surface ◽  
Global Carbon

scholarly journals Lower oceanic 𝛿<sup>13</sup>C during the Last Interglacial compared to the Holocene

2020 ◽  
Author(s):  
Shannon A. Bengtson ◽  
Laurie C. Menviel ◽  
Katrin J. Meissner ◽  
Lise Missiaen ◽  
Carlye D. Peterson ◽  
...  
Keyword(s):  
North Atlantic ◽  
Global Carbon Cycle ◽  
Oceanic Circulation ◽  
Last Interglacial ◽  
The Holocene ◽  
Time Period ◽  
Significant Difference ◽  
Depth Extent ◽  
Global Carbon

Abstract. The last time in Earth’s history when the high latitudes were warmer than during pre-industrial times was the last interglacial (LIG, 129–116 ka BP). Since the LIG is the most recent and best documented warm time period, it can provide insights into climate processes in a warmer world. However, some key features of the LIG are not well constrained, notably the oceanic circulation and the global carbon cycle. Here, we use a new database of LIG benthic 𝛿13C to investigate these two aspects. We find that the oceanic mean 𝛿13C was ~ 0.2 ‰ lower during the LIG (here defined as 125–120 ka BP) when compared to the mid-Holocene (7–4 ka BP). As the LIG was slightly warmer than the Holocene, it is possible that terrestrial carbon was lower, which would have led to both a lower oceanic 𝛿13C and atmospheric 𝛿13CO2 as observed in paleo-records. However, given the multi-millennial timescale, the lower oceanic 𝛿13C most likely reflects a long-term imbalance between weathering and burial of carbon. The 𝛿13C distribution in the Atlantic Ocean suggests no significant difference in the latitudinal and depth extent of North Atlantic Deep Water (NADW) between the LIG and the mid-Holocene. Furthermore, the data suggests that the multi-millennial mean NADW transport was similar between these two time periods.

scholarly journals Importance of the forest state in estimating biomass losses from tropical forests: combining dynamic forest models and remote sensing

2021 ◽  
Author(s):  
Ulrike Hiltner ◽  
Andreas Huth ◽  
Rico Fischer
Keyword(s):  
Tropical Forests ◽  
French Guiana ◽  
Strong Influence ◽  
Tree Mortality ◽  
Global Carbon Cycle ◽  
Mortality Rates ◽  
Forest Height ◽  
Biomass Loss ◽  
Global Carbon

Abstract. Disturbances, such as extreme weather events, fires, floods, and biotic agents, can have strong impacts on the dynamics and structures of tropical forests. In the future, the intensity of disturbances will likely further increase, which may have more serious consequences for tropical forests than those we have already observed. Thus, quantifying aboveground biomass loss of forest stands due to tree mortality (hereafter biomass loss) is important for the estimation of the role of tropical forests in the global carbon cycle. So far, the long-term impacts of altered tree mortality on rates of biomass loss have been described little. This study aims to analyse the consequences of long-term elevated tree mortality rates on forest dynamics and biomass loss. We applied an individual-based forest model and investigated the impacts of permanently increased tree mortality rates on the growth dynamics of humid, terra firme forests in French Guiana. Here, we focused on biomass, leaf area index (LAI), forest height, productivity, forest age, quadratic mean stem diameter, and biomass loss. Based on the simulations, we developed a multiple linear regression model to estimate biomass losses of forests in different successional states from the various forest attributes. The findings of our simulation study indicated that increased tree mortality altered the succession patterns of forests in favour of fast-growing species, which changed the forests’ gross primary production, though net primary production remained stable. Tree mortality intensity had a strong influence on the functional species composition and tree size distribution, which led to lower values in LAI, biomass, and forest height at the ecosystem level. We observed a strong influence of a change in tree mortality on biomass loss. Assuming a doubling of tree mortality, biomass loss increased (from 3.2 % y−1 to 4.5 % y−1). We also obtained a multidimensional relationship that allowed for the estimation of biomass loss from forest height and LAI. Via an example, we applied this relationship to remote sensing data of LAI and forest height and mapped biomass loss for French Guiana. We estimated a mean biomass loss rate of 3.2 % per year. The approach described here provides a novel methodology for quantifying biomass loss, taking the successional state of tropical forests into account. Quantifying biomass loss rates may help to reduce uncertainties in the analysis of the global carbon cycle.

Soil carbon: A measure of ecosystem response in a changing world?

2005 ◽  
Vol 85 (Special Issue) ◽  
pp. 467-480 ◽  
Author(s):  
H. H. Janzen
Keyword(s):  
Agricultural Soils ◽  
Global Carbon Cycle ◽  
Ecosystem Response ◽  
Soil C ◽  
Four Dimensions ◽  
C Storage ◽  
C Dynamics ◽  
C Cycle ◽  
Global Carbon

The global carbon (C) cycle is changing, as evident from abrupt increases in atmospheric CO2. These changes have sparked interest in agricultural soils as potential repositories for excess atmospheric C. Our perspective on soil C, therefore, has shifted: once, we focused mainly on how soil C affected productivity within agroecosystems; now we see also how C dynamics in agricultural soils exert influences far beyond the farm. We have long used soil C as an indicator of soil quality; now we may want to use soil C also as a broader indicator of ecosystem response. To prompt further discussion, I offer some tentative thoughts about how we might use soil C as an indicator on a changing earth. They include: using soil C to measure changes across time, not only across space; devising more sensitive measures of soil C change; quantifying soil C across four dimensions; measuring the nature of C, as well as its amount; using soil C alongside other indicators; finding better ways of admitting our uncertainty; establishing long-term sites for our successors to measure soil C change; and following flows of C past the farm fences. Recent worries about global warming have focused our attention on “sequestering” soil C to remove atmospheric CO2. That aim may be worthy, but perhaps too narrow; a broader goal might be to ensure the productivity, permanence, and health of our agroecosystems and adjacent environments – and use C storage as a measure of progress toward that goal. Key words: Soil organic matter, global carbon cycle, carbon sequestration, global change

scholarly journals Decomposition rates of surface and buried forest-floor material

2017 ◽  
Vol 47 (8) ◽  
pp. 1140-1144 ◽  
Author(s):  
Cindy E. Prescott ◽  
Anya Reid ◽  
Shu Yao Wu ◽  
Marie-Charlotte Nilsson
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Site Preparation ◽  
Soil C ◽  
Mechanical Site Preparation ◽  
C Stocks ◽  
Mesh Bags ◽  
Regional Climates ◽  
Floor Material

Mechanical site preparation is assumed to reduce soil C stocks by increasing the rate at which the displaced organic material decomposes, but the evidence is equivocal. We measured rates of C loss of forest-floor material in mesh bags either placed on the surface or buried in the mineral soil at four sites in different regional climates in British Columbia. During the 3-year incubation, buried forest-floor material lost between 5% and 15% more C mass than material on the surface, with the greatest difference occurring at the site with the lowest annual precipitation. Studies of the long-term fate of buried and surface humus are needed to understand the net effects of site preparation on soil C stocks.

scholarly journals Two aspects of decadal ENSO variability modulating the long-term global carbon cycle

2020 ◽  
Author(s):  
So-won Park ◽  
Jin-Soo Kim ◽  
Jong-Seong Kug ◽  
Malte F. Stuecker ◽  
In-Won Kim ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Flux ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Terrestrial Ecosystem ◽  
Global Carbon Cycle ◽  
Terrestrial Carbon ◽  
Enso Variability ◽  
Global Carbon

&lt;p&gt;El Ni&amp;#241;o-Southern Oscillation (ENSO) is the primary cause of interannual variations in the global carbon cycle because ENSO-driven extensive teleconnection over continents affects the terrestrial ecosystem process. ENSO is an interannual phenomenon, but it also has decadal variability. The ENSO-like SST pattern and ENSO characteristic, e.g. ENSO amplitude, change on decadal timescales. However, the influence of decadal ENSO variability on global carbon cycle has not yet been fully examined. Here we examined the impacts of decadal ENSO variability on decadal variation of terrestrial carbon flux by analyzing fully coupled pre-industrial control simulation of the Community Earth System Model 1 large ensemble (CESM1-LE). Considerable decadal variability of atmosphere-to-land carbon flux exists and this terrestiral carbon flux is mainly modulated by the tropical biosphere on decadal timescales as well as on interannual timescales. We found that there are two different pathways, which can explain about 36% of the decadal variations in terrestrial carbon flux. First, long-term climate change over tropics induced by decadal tropical Pacific SST variability regulates the terrestrial productivity and hence atmospheric CO&lt;sub&gt;2&lt;/sub&gt; on decadal time scale. Second, decadal changes in asymmetric terrestrial ecosystem&amp;#8217;s response to ENSO events, resulted from decadal modulation of ENSO amplitude, generate decadal variability of terrestrial carbon flux.&lt;/p&gt;&lt;p&gt;Key words: Global Carbon Cycle, El Ni&amp;#241;o-Southern Oscillation (ENSO), Pacific Decadal Variability, ENSO asymmetry, Decadal NBP variability&lt;/p&gt;

scholarly journals Causes and timing of future biosphere extinction

2005 ◽  
Vol 2 (6) ◽  
pp. 1665-1679 ◽  
Author(s):  
S. Franck ◽  
C. Bounama ◽  
W. von Bloh
Keyword(s):  
Minimal Model ◽  
Global Carbon Cycle ◽  
Cambrian Explosion ◽  
Strong Decrease ◽  
The Earth ◽  
Reverse Sequence ◽  
Different Types ◽  
Global Surface ◽  
Global Carbon

Abstract. We present a minimal model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the aggregated reservoir ocean and atmosphere. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. We find that from the Archaean to the future a procaryotic biosphere always exists. 2 Gyr ago eucaryotic life first appears. The emergence of complex multicellular life is connected with an explosive increase in biomass and a strong decrease in Cambrian global surface temperature at about 0.54 Gyr ago. In the long-term future the three types of biosphere will die out in reverse sequence of their appearance. We show that there is no evidence for an implosion-like extinction in contrast to the Cambrian explosion. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr.

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