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.

scholarly journals Importance of succession in estimating biomass loss: Combining remote sensing and individual-based forest models

2020 ◽  
Author(s):  
Ulrike Hiltner ◽  
Andreas Huth ◽  
Rico Fischer
Keyword(s):  
Primary Production ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Tree Mortality ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Mortality Rates ◽  
Area Index ◽  
Forest Height ◽  
Biomass Loss

Abstract. Disturbances can have strong impacts on the dynamics and structure of tropical forests. They often lead to increased tree mortality and affect their behaviour as carbon sinks. In the future, the intensity of disturbances, such as extreme weather events, fires, floods, and biotic agents, will probably even increase, with more serious consequences for tropical forests than we have already observed. However, impacts of altering disturbances on rates of forest biomass loss through tree mortality (hereinafter: biomass mortality) have been little described yet. This complicates progress in quantifying the effects of climate change on forests globally. This study aims to analyse the consequences of elevated tree mortality on forest dynamics and to provide a methodology that can reduce uncertainties in estimating biomass mortality rates at local and country level. We achieved this by linking benefits of individual-based forest model-ling, statistical linear regression, and remote sensing. We applied an individual-based forest model to investigate the impact of varying disturbance regimes on the succession dynamic of a humid Terra Firma forest at the Paracou study site in French Guiana. By simulating increased tree mortality rates, we were able to investigate their influence on several forest attributes, namely biomass, leaf area index, forest height, gross primary production, net primary production, and biomass mortality. Based on simulations of leaf area index and forest height, we developed a linear multivariate regression model to project biomass mortality. Our findings demonstrate that severe disturbances altered the succession pattern of the forests in favour of fast-growing species, which changed gross primary production, but net primary production remained stable. We also observed a strong influence on biomass mortality rates as well as observed complex relationships between these rates and single forest attributes (leaf area index, forest height, and biomass). By combining leaf area index and forest height we obtained relationships that allow an estimation of the biomass mortality. Based on these findings, we mapped the biomass mortality for whole French Guiana. We found a nation-wide biomass mortality of 3 % per year (standard deviation = 1.4 % per year). The approach we describe here, provides a novel methodology for quantifying the spatial-temporal distribution of biomass loss, which has recently been identified as particularly critical for monitoring mortality hot spots. Quantifying biomass mortality rates may help reducing uncertainties in the terrestrial component of the global carbon cycle.

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 Controls over aboveground forest carbon density on Barro Colorado Island, Panama

2011 ◽  
Vol 8 (6) ◽  
pp. 1615-1629 ◽  
Author(s):  
J. Mascaro ◽  
G. P. Asner ◽  
H. C. Muller-Landau ◽  
M. van Breugel ◽  
J. Hall ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Tropical Forests ◽  
Slope Angle ◽  
Global Carbon Cycle ◽  
Barro Colorado Island ◽  
Satellite Monitoring ◽  
Secondary Forests ◽  
Carbon Density ◽  
Site Factors ◽  
Global Carbon

Abstract. Despite the importance of tropical forests to the global carbon cycle, ecological controls over landscape-level variation in live aboveground carbon density (ACD) in tropical forests are poorly understood. Here, we conducted a spatially comprehensive analysis of ACD variation for a continental tropical forest – Barro Colorado Island, Panama (BCI) – and tested site factors that may control such variation. We mapped ACD over 1256 ha of BCI using airborne Light Detection and Ranging (LiDAR), which was well-correlated with ground-based measurements of ACD in Panamanian forests of various ages (r2 = 0.84, RMSE = 17 Mg C ha−1, P < 0.0001). We used multiple regression to examine controls over LiDAR-derived ACD, including slope angle, forest age, bedrock, and soil texture. Collectively, these variables explained 14 % of the variation in ACD at 30-m resolution, and explained 33 % at 100-m resolution. At all resolutions, slope (linked to underlying bedrock variation) was the strongest driving factor; standing carbon stocks were generally higher on steeper slopes. This result suggests that physiography may be more important in controlling ACD variation in Neotropical forests than currently thought. Although BCI has been largely undisturbed by humans for a century, past land-use over approximately half of the island still influences ACD variation, with younger forests (80–130 years old) averaging ~15 % less carbon storage than old-growth forests (>400 years old). If other regions of relatively old tropical secondary forests also store less carbon aboveground than primary forests, the effects on the global carbon cycle could be substantial and difficult to detect with traditional satellite monitoring.

Tropical Forests and the Global Carbon Cycle

Science ◽  
1988 ◽  
Vol 239 (4835) ◽  
pp. 42-47 ◽  
Author(s):  
R. P. DETWILER ◽  
C. A. S. HALL
Keyword(s):  
Carbon Cycle ◽  
Tropical Forests ◽  
Global Carbon Cycle ◽  
Global Carbon

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

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.

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