scholarly journals After trees die: quantities and determinants of necromass across Amazonia

2009 ◽  
Vol 6 (8) ◽  
pp. 1615-1626 ◽  
Author(s):  
K.-J. Chao ◽  
O. L. Phillips ◽  
T. R. Baker ◽  
J. Peacock ◽  
G. Lopez-Gonzalez ◽  
...  
Keyword(s):  
Wood Density ◽  
Forest Structure ◽  
Forest Dynamics ◽  
Amazon Basin ◽  
Mortality Rates ◽  
Permanent Plots ◽  
Mortality Data ◽  
Terra Firma ◽  
Amazonian Forests ◽  
Stem Mortality

Abstract. The Amazon basin, one of the most substantial biomass carbon pools on earth, is characterised by strong macroecological gradients in biomass, mortality rates, and wood density from west to east. These gradients could affect necromass stocks, but this has not yet been tested. This study aims to assess the stocks and determinants of necromass across Amazonian forests. Field-based and literature data were used to find relationships between necromass and possible determinants. Furthermore, a simple model was applied to estimate and extrapolate necromass stocks across terra firma Amazonian forests. In eight northwestern and three northeastern Amazonian permanent plots, volumes of coarse woody debris (≥10 cm diameter) were measured in the field and the density of each decay class was estimated. Forest structure and historical mortality data were used to determine the factors controlling necromass. Necromass is greater in forests with low stem mortality rates (northeast) rather than in forests with high stem mortality rates (northwest) (58.5±10.6 and 27.3±3.2 Mg ha−1, respectively). Using all published necromass values, we find that necromass across terra firma forests in Amazonia is positively related to both forest dynamics (mortality mass inputs and a surrogate for decomposition rate (average wood density of living trees)) and forest structure (biomass), but is better explained by forest dynamics. We propose an improved method to estimate necromass for plots where necromass has not been measured. The estimates, together with other actual measurements of necromass, were scaled-up to project a total Amazonian necromass of 9.6±1.0 Pg C. The ratio of necromass (on average weighted by forest region) to coarse aboveground biomass is 0.127. Overall, we find (1) a strong spatial trend in necromass in parallel with other macroecological gradients and (2) that necromass is a substantial component of the carbon pool in the Amazon.

scholarly journals After trees die: quantities and determinants of necromass across Amazonia

2009 ◽  
Vol 6 (1) ◽  
pp. 1979-2006 ◽  
Author(s):  
K.-J. Chao ◽  
O. L. Phillips ◽  
T. R. Baker ◽  
J. Peacock ◽  
G. Lopez-Gonzalez ◽  
...  
Keyword(s):  
Wood Density ◽  
Amazon Basin ◽  
Woody Debris ◽  
Mortality Rates ◽  
Permanent Plots ◽  
Mortality Data ◽  
Regression Result ◽  
Terra Firma ◽  
Amazonian Forests ◽  
Stem Mortality

Abstract. The Amazon basin, one of the most substantial biomass carbon pools on earth, is characterised by strong macroecological gradients in biomass, mortality rates, and wood density from the west to the east. These gradients could affect necromass stocks, but this has not yet been tested. This study aims to assess the stocks and determinants of necromass patterns across Amazonian forests. Field-based and literature data were used to find relationships between necromass and possible determinants. The final regression result was used to estimate and extrapolate the necromass stocks across terra firma Amazonian forests. In eight northwestern and three northeastern Amazonian permanent plots, volumes of coarse woody debris (≥10 cm diameter) were measured in the field and density of each decay class was estimated. Forest structure and historical mortality data were used to determine controlling factors of necromass. Necromass is greater in forests with low stem mortality rates (northeast) rather than forest with high stem mortality rates (northwest) (58.5±10.6 and 27.3±3.2 Mg ha−1, respectively). After integrating all published necromass values, we find that necromass across terra firma forests in Amazonia is positively related to stand biomass, mortality mass input, and average wood density of live trees (ρBA j). We applied these relationships to estimate necromass for plots where necromass has not been measured. The estimates, together with other actual measurements of necromass, were scaled-up to project a total Amazonian necromass of 9.6±1.0 Pg C. The ratio of necromass (on average weighted by forest region) to coarse aboveground biomass is 0.127. Overall, we find (1) a strong spatial trend in necromass in parallel with other macroecological gradients and (2) that necromass is a substantial component of the carbon pool in the Amazon.

scholarly journals Forest loss and fragmentation in the Amazon: implications for wildlife conservation

Oryx ◽  
2000 ◽  
Vol 34 (1) ◽  
pp. 39-45 ◽  
Author(s):  
William F. Laurance ◽  
Heraldo L. Vasconcelos ◽  
Thomas E. Lovejoy
Keyword(s):  
Forest Dynamics ◽  
Amazon Basin ◽  
Wildlife Conservation ◽  
Animal Species ◽  
Global Climate ◽  
Forest Loss ◽  
Fragmented Landscapes ◽  
Regional Hydrology ◽  
Wildlife Populations ◽  
Amazonian Forests

AbstractAmazonian forests are experiencing rapid, unprecedented changes that are having major impacts on wildlife, regional hydrology and the global climate. Rates of deforestation and logging have accelerated in recent years and patterns of forest loss are changing, with extensive new highways providing conduits for settlers and loggers into the heart of the Amazon basin. These myriad changes are causing widespread fragmentation of forests. Fragmented landscapes in the Amazon experience diverse changes in forest dynamics, structure, composition and microclimate, and are highly vulnerable to droughts and fires—alterations that negatively affect a wide variety of animal species. In human-dominated lands intensive hunting may interact synergistically with fragmentation to further threaten wildlife populations.

scholarly journals Forest Diversity and Structure in the Amazonian Mountain Ranges of Southeastern Ecuador

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 196 ◽  
Author(s):  
Wilson Quizhpe ◽  
Ángel Benítez ◽  
Klever Cuenca ◽  
Hernán Uvidia ◽  
Isau Huamantupa ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Annual Rainfall ◽  
Permanent Plots ◽  
Scaling Analysis ◽  
Terra Firme ◽  
Forest Diversity ◽  
Mountain Ranges ◽  
Average Temperature ◽  
Diameter Structure ◽  
Amazonian Forests

We analyze the structure of diameter, richness, and diversity of the forests in the upper limit of the great Amazon basin located in the Ecuadorian territory of the Cordilleras del Cóndor and Cutucú. Our hypothesis was that the forests of the eastern mountain ranges are not homogeneous, but rather present differences in their structure, richness, and floristic diversity. Our main objective was to classify the types of forests based on the characteristics of the diameter structure and the species composition of the Amazonian forests of the eastern mountain ranges in southern Ecuador, and we determined the influence of critical edaphic, environmental, and geomorphological factors, For this we installed eight permanent plots of one hectare in homogeneous and well preserved forest stands, four plots in the province of Zamora Chinchipe and four in the province of Morona Santiago. We identified and measured all trees >10 cm at chest height and for each plot, soil samples, as well as environmental and slope data were taken. We performed an non-metric multidimensional scaling analysis (NMDS) analysis to evaluate changes in climatic and geomorphological gradients, and used the CCA analysis to assess the relationship between the composition of the species at the plot level and the edapho-climatic variables. Finally, we modeled the change in diversity ad species (Fisher’s alpha) in relation to climatic, altitudinal, and geomorphological gradients using a GLM. We determined the existence of two different types of forest, the first called Terra Firme, characterized by the presence of a greater number of species and individuals per plot as compared to the second type of forest called Tepuy or Sandstone forest. Species richness was negatively correlated with the phosphorus content of the soil and the pH, annual average temperature, annual rainfall, and altitude. Terra Firme forests, settled in more stable and nutrient-rich climatic areas, were more diverse and Sandstone forests are poor in nutrients and develop in areas with greater seasonality.

Pyrogenic carbon and forest dynamics during drought in Amazonian forests

2021 ◽  
Author(s):  
Laura Vedovato ◽  
Lidiany Carvalho ◽  
Luiz Aragão ◽  
Ted Feldpausch
Keyword(s):  
Forest Dynamics ◽  
Amazon Basin ◽  
Fire History ◽  
T Test ◽  
Extreme Drought ◽  
Amazon Forest ◽  
Carbon Loss ◽  
Pyrogenic Carbon ◽  
Significant Difference ◽  
Amazonian Forests

<p>During extreme drought events, aboveground biomass (AGB) dynamics in Amazonian forests are altered through reduced productivity and increased tree mortality and carbon loss. Tree adaptations developed in response to historical drought may reduce the severity of carbon loss. Past droughts were likely associated with fire, which produced Pyrogenic Carbon (PyC), a form of carbon formed by the incomplete combustion of biomass burn and fossil fuel. PyC has specific properties that improve soil fertility and water holding capacity and decrease aluminium toxicity, among others. PyC can be found in different concentrations across the Amazon Basin, since it can be produced by local fires and aerosol deposition. It is unknown whether PyC could explain tree adaptations or contributes to Amazon forest dynamics, especially for extreme drought events. We hypothesize that PyC in soil can serve as a proxy of fire history and fire/drought adaptations and also support the forest during drought events because of its properties, decreasing mortality rates and maintaining rates of AGB gain equivalent to a non-extreme drought year. To evaluate this hypothesis, we used a dataset with more than 70 plots with repeat censuses distributed across the Amazon Basin and classified extreme drought events using maximum cumulative water deficit (MCWD) analysis. Soil samples were collected from the same plots during an intensive fieldwork campaign and PyC was quantified by hydrogen pyrolysis (HyPy). Forest plots were classified into high and low PyC based on the median across the whole dataset. Our preliminary results show that during extreme drought events, plots that have a greater concentration of PyC had significantly higher rates of AGB gain when compared with plots with lower concentrations of PyC (t-test, p < 0.05). During non-extreme drought years there was no significant difference in rates of AGB gain between plots with different concentrations of PyC. When we focus on plots with lower concentrations of PyC there is a significant decrease in rates of AGB gain during drought years compared to non-extreme drought years (t-test, p < 0.05). However, in plots with high concentrations of PyC there is no significant difference in rates of AGB gain, showing trees are able to maintain normal forest dynamics during extreme drought years. We conclude that PyC has an important role in mediating drought resistance and productivity in Amazonian forests.</p>

scholarly journals Forest response to increased disturbance in the central Amazon and comparison to western Amazonian forests

2014 ◽  
Vol 11 (20) ◽  
pp. 5773-5794 ◽  
Author(s):  
J. A. Holm ◽  
J. Q. Chambers ◽  
W. D. Collins ◽  
N. Higuchi
Keyword(s):  
Wood Density ◽  
Empirical Data ◽  
Amazon Basin ◽  
Basal Area ◽  
Surface Model ◽  
Disturbance Regime ◽  
Earth System ◽  
Data Set ◽  
Central Amazon ◽  
Amazonian Forests

Abstract. Uncertainties surrounding vegetation response to increased disturbance rates associated with climate change remains a major global change issue for Amazonian forests. Additionally, turnover rates computed as the average of mortality and recruitment rates in the western Amazon basin are doubled when compared to the central Amazon, and notable gradients currently exist in specific wood density and aboveground biomass (AGB) between these two regions. This study investigates the extent to which the variation in disturbance regimes contributes to these regional gradients. To address this issue, we evaluated disturbance–recovery processes in a central Amazonian forest under two scenarios of increased disturbance rates using first ZELIG-TROP, a dynamic vegetation gap model which we calibrated using long-term inventory data, and second using the Community Land Model (CLM), a global land surface model that is part of the Community Earth System Model (CESM). Upon doubling the mortality rate in the central Amazon to mirror the natural disturbance regime in the western Amazon of ∼2% mortality, the two regions continued to differ in multiple forest processes. With the inclusion of elevated natural disturbances, at steady state, AGB significantly decreased by 41.9% with no significant difference between modeled AGB and empirical AGB from the western Amazon data sets (104 vs. 107 Mg C ha−1, respectively). However, different processes were responsible for the reductions in AGB between the models and empirical data set. The empirical data set suggests that a decrease in wood density is a driver leading to the reduction in AGB. While decreased stand basal area was the driver of AGB loss in ZELIG-TROP, a forest attribute that does not significantly vary across the Amazon Basin. Further comparisons found that stem density, specific wood density, and basal area growth rates differed between the two Amazonian regions. Last, to help quantify the impacts of increased disturbances on the climate and earth system, we evaluated the fidelity of tree mortality and disturbance in CLM. Similar to ZELIG-TROP, CLM predicted a net carbon loss of 49.9%, with an insignificant effect on aboveground net primary productivity (ANPP). Decreased leaf area index (LAI) was the driver of AGB loss in CLM, another forest attribute that does not significantly vary across the Amazon Basin, and the temporal variability in carbon stock and fluxes was not replicated in CLM. Our results suggest that (1) the variability between regions cannot be entirely explained by the variability in disturbance regime, but rather potentially sensitive to intrinsic environmental factors; or (2) the models are not accurately simulating all tropical forest characteristics in response to increased disturbances.

scholarly journals Forest Diversity and Structure in the Amazonian Mountains Ranges of Southeastern Ecuador

2019 ◽  
Author(s):  
Wilson Quizhpe ◽  
Angel Benítez ◽  
Jesus Muñoz ◽  
Klever Cuenca ◽  
Hernán Uvidia ◽  
...  
Keyword(s):  
Species Composition ◽  
Amazon Basin ◽  
Size Structure ◽  
Soil Phosphorus ◽  
Permanent Plots ◽  
Mean Annual Temperature ◽  
Amazon Forest ◽  
Terra Firme ◽  
Forest Diversity ◽  
Amazonian Forests

1) Background: We analyzed the size structure, richness and diversity in eight permanent forest plots in the upper limit of the great Amazon basin located in the Ecuadorian parts of Cordilleras del Cóndor and Cutucú. Our hypothesis was that not all the forests of the eastern mountain ranges are homogeneous in characteristics, but rather present differences in their structure, richness and floristic diversity. In order to test this, our main objective was to classify the types of forests based on characteristics in diametric structure and species composition of the Amazonian forests of the eastern cordilleras in southern Ecuador, and also to determine the influence of critical edaphic-environmental and geomorphological factors. 2) Methods: Eight one-hectare permanent plots were installed in homogeneous and well-conserved forest stands. Four plots were located in the province of Zamora Chinchipe and four in the province of Morona Santiago. We identified and measured all trees> 10 cm at diameter breast height. For each plot, soil samples were taken, along with environmental and slope data. The multidimensional non-metric adjusted scaling (NMDS) was used to evaluate changes in climatic and geomorphological gradients. The relationship between the composition of the species at the plot level and the edaphoclimatic variables was tested using a canonical correspondence analysis (CCA). Finally, we modeled the change in species diversity (Fisher's alpha) in relation to the climatic gradients, altitudinal and geomorphological using a GLMM. 3) Results: Overall, we identified 517 species belonging to 76 families. We determined the existence of two different types of forest, the first one named Terra Firme, characterized by the presence of a larger number of species and individuals per plot, compared to the second type of forest, called Tepuy or Sandstones forest. Species richness was negatively correlated with soil phosphorus content and pH, mean annual temperature, annual precipitation and altitude. The CCA analysis showed differences in the species composition between the Terra Firme and Sandstone forests. The climatic seasonality and the concentration of cations in the soil influence the diversity of the Amazon forest communities of the southeastern cordilleras. The forests of Terra Firme, which are settled in more stable and nutrient-rich climatic areas, were more diverse. Sandstone forests are poor in nutrients and develop in areas with stronger seasonality

scholarly journals Persistent fire effect on forest dynamics and species composition of an old-growth tropical forest

2021 ◽  
Vol 30 (3) ◽  
pp. e009-e009
Author(s):  
Dárlison Fernandes-Carvalho-de-Andrade ◽  
Keyword(s):  
Species Composition ◽  
Tropical Forest ◽  
Forest Dynamics ◽  
Mortality Rates ◽  
Permanent Plots ◽  
Linear Mixed Effect Model ◽  
Ecological Groups ◽  
Pioneer Species ◽  
Old Growth ◽  
Mixed Effect

Aim of the study: To assess structure, recruitment and mortality rates of tree species over almost three decades, 14 years before and 15 years after a forest fire. Material and methods: All trees ≥ 5 cm in DBH were identified and measured in 12 permanent plots (50 m x 50 m), in 1983, 1987, 1989, 1995, 2008, and 2012 of a dense ombrophilous forest in Eastern Amazon, Brazil. The analyses were carried out including all sampled species and their ecological groups: shade-tolerant, light-demanding, and pioneer species. Treatments were compared through a Linear Mixed Effect Model. Main results: The 15-year post-fire period is not enough for the old-growth tropical forest to recover its pre-fire conditions of recruitment and mortality rates. The post-fire recruitment and mortality rates increased, mainly the recruitment of pioneer species (p-value < 0.05). Research highlights: In a period of 15 years after the occurrence of a surface fire, the old-growth tropical forest still has high recruitment rates of shade-tolerant and light-demanding species and high incidence of pioneer species, confirming the persistent fire effects on forest dynamics and species composition in this ecosystem.

scholarly journals Drought-induced Amazonian wildfires instigate a decadal-scale disruption of forest carbon dynamics

2018 ◽  
Vol 373 (1760) ◽  
pp. 20180043 ◽  
Author(s):  
Camila V. J. Silva ◽  
Luiz E. O. C. Aragão ◽  
Jos Barlow ◽  
Fernando Espirito-Santo ◽  
Paul J. Young ◽  
...  
Keyword(s):  
Wood Density ◽  
Large Scale ◽  
Forest Biomass ◽  
Mortality Rates ◽  
Fire Disturbance ◽  
Decadal Scale ◽  
Time Required ◽  
The Impact ◽  
Stem Mortality

Drought-induced wildfires have increased in frequency and extent over the tropics. Yet, the long-term (greater than 10 years) responses of Amazonian lowland forests to fire disturbance are poorly known. To understand post-fire forest biomass dynamics, and to assess the time required for fire-affected forests to recover to pre-disturbance levels, we combined 16 single with 182 multiple forest census into a unique large-scale and long-term dataset across the Brazilian Amazonia. We quantified biomass, mortality and wood productivity of burned plots along a chronosequence of up to 31 years post-fire and compared to surrounding unburned plots measured simultaneously. Stem mortality and growth were assessed among functional groups. At the plot level, we found that fire-affected forests have biomass levels 24.8 ± 6.9% below the biomass value of unburned control plots after 31 years. This lower biomass state results from the elevated levels of biomass loss through mortality, which is not sufficiently compensated for by wood productivity (incremental growth + recruitment). At the stem level, we found major changes in mortality and growth rates up to 11 years post-fire. The post-fire stem mortality rates exceeded unburned control plots by 680% (i.e. greater than 40 cm diameter at breast height (DBH); 5–8 years since last fire) and 315% (i.e. greater than 0.7 g cm −3 wood density; 0.75–4 years since last fire). Our findings indicate that wildfires in humid tropical forests can significantly reduce forest biomass for decades by enhancing mortality rates of all trees, including large and high wood density trees, which store the largest amount of biomass in old-growth forests. This assessment of stem dynamics, therefore, demonstrates that wildfires slow down or stall the post-fire recovery of Amazonian forests. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

scholarly journals Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

2016 ◽  
Vol 22 (12) ◽  
pp. 3996-4013 ◽  
Author(s):  
Michelle O. Johnson ◽  
David Galbraith ◽  
Manuel Gloor ◽  
Hannes De Deurwaerder ◽  
Matthieu Guimberteau ◽  
...  
Keyword(s):  
Mortality Rates ◽  
Above Ground Biomass ◽  
Ground Biomass ◽  
Dynamic Global Vegetation Models ◽  
Vegetation Models ◽  
Global Vegetation ◽  
Amazonian Forests ◽  
Stem Mortality

scholarly journals Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate

2012 ◽  
Vol 9 (6) ◽  
pp. 2203-2246 ◽  
Author(s):  
C. A. Quesada ◽  
O. L. Phillips ◽  
M. Schwarz ◽  
C. I. Czimczik ◽  
T. R. Baker ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Physical Properties ◽  
Wood Density ◽  
Forest Structure ◽  
Amazon Basin ◽  
Soil Phosphorus ◽  
Amazon Forest ◽  
Turnover Rates ◽  
Wood Production ◽  
Structure And Dynamics

Abstract. Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the interacting effects of soil physical and chemical properties with climate. A hypothesis of self-maintaining forest dynamic feedback mechanisms initiated by edaphic conditions is proposed. It is further suggested that this is a major factor determining endogenous disturbance levels, species composition, and forest productivity across the Amazon Basin.

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