Modeling Aboveground Biomass in Tropical Forests Using Multi-Frequency SAR Data—A Comparison of Methods

ABSTRACTOne of the major uncertainties concerning the role of tropical forests in the global carbon cycle is the lack of adequate data on the carbon content of all their components. The goal of this study was to contribute to filling this data gap by estimating the quantity of carbon in the biomass, soil and necromass for 23 long-term permanent forest plots in five life zones of Venezuela to determine how C was partitioned among these components across a range of environments. Aboveground biomass C ranged from 70 to 179 Mg ha−1 and soil C from 125 to 257 Mg ha−1, and they represented the two largest C components in all plots. The C in fine litter (2.4 to 5.2 Mg ha−1), dead wood (2.4 to 21.2 Mg ha−1) and roots (23.6 to 38.0 Mg ha−1) accounted for less than 13% of the total C. The total amount of C among life zones ranged from 302 to 488 Mg ha−1, and showed no clear trend with life zone. In three of the five life zones, more C was found in the dead (soil, litter, dead wood) than in the live (biomass) components (dead to live ratios of 1.3 to 2.3); the lowland moist and moist transition to dry life zones had dead to live ratios of less than one. Results from this research suggest that for most life zones, an amount equivalent to between 20 and 58% of the aboveground biomass is located in necromass and roots. These percentages coupled with reliable estimates of aboveground biomass from forest inventories enable a more complete estimation of the C content of tropical forests to be made.

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Effects of large aboveground biomass loss events on the deadwood and litter mass dynamics of seasonal tropical forests in Cambodia

Tropics ◽

10.3759/tropics.ms18-05 ◽

2018 ◽

Vol 27 (2) ◽

pp. 33-48

Author(s):

Yoshiyuki Kiyono ◽

Eriko Ito ◽

Yukako Monda ◽

Jumpei Toriyama ◽

Thy Sum

Keyword(s):

Tropical Forests ◽

Aboveground Biomass ◽

Litter Mass ◽

Biomass Loss

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Individual Plant Allometric Equations for Estimating Aboveground Biomass and Its Components for a Common Bamboo Species (Bambusa procera A. Chev. and A. Camus) in Tropical Forests

Forests ◽

10.3390/f10040316 ◽

2019 ◽

Vol 10 (4) ◽

pp. 316 ◽

Cited By ~ 1

Author(s):

Bao Huy ◽

Giang Thanh ◽

Krishna Poudel ◽

Hailemariam Temesgen

Keyword(s):

Tropical Forests ◽

Aboveground Biomass ◽

Nonlinear Models ◽

Generalized Least Squares ◽

Forest Degradation ◽

Seemingly Unrelated Regression ◽

Simultaneous Estimation ◽

Individual Plant ◽

Bamboo Species ◽

Species Specific

Bamboo forests play an important role in achieving the objectives of the United Nations program on Reducing Emission from Deforestation and Forest Degradation. We developed and validated a modeling system that simultaneously estimate aboveground biomass and its components for a common bamboo species (Bambusa procera A. Chev. and A. Camus) in tropical forests. Eighty-three bamboo culms were destructively sampled from seventeen 100 m2 sample plots located in different parts of the Central Highlands in Viet Nam to obtain total plant aboveground biomass (AGB) and its components. We examined the performance of weighted nonlinear models fit by maximum likelihood and weighted nonlinear seemingly unrelated regression fit by generalized least squares for predicting bamboo biomass. The simultaneous estimation of AGB and its components produced higher reliability than the models of components and total developed separately. With a large number of bamboo species, it may not be feasible to develop species- specific biomass models, hence genus-specific allometric models may be considered.

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Effect of species grouping and site variables on aboveground biomass models for lowland tropical forests of the Indo-Malay region

Annals of Forest Science ◽

10.1007/s13595-017-0618-1 ◽

2017 ◽

Vol 74 (1) ◽

Cited By ~ 4

Author(s):

Solichin Manuri ◽

Cris Brack ◽

Teddy Rusolono ◽

Fatmi Noor’an ◽

Louis Verchot ◽

...

Keyword(s):

Tropical Forests ◽

Aboveground Biomass ◽

Biomass Models ◽

Species Grouping

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Ground and Volume Decomposition as a Proxy for AGB from P-Band SAR Data

Remote Sensing ◽

10.3390/rs12020240 ◽

2020 ◽

Vol 12 (2) ◽

pp. 240 ◽

Cited By ~ 2

Author(s):

Francesco Banda ◽

Mauro Mariotti d’Alessandro ◽

Stefano Tebaldini

Keyword(s):

Tropical Forests ◽

Forest Structure ◽

Synthetic Aperture ◽

Above Ground Biomass ◽

Volume Scattering ◽

Interferometric Phase ◽

Volume Decomposition ◽

Sar Data

In this work, the role of volume scattering obtained from ground and volume decomposition of P-band synthetic aperture radar (SAR) data as a proxy for biomass is investigated. The analysis here presented originates from the BIOMASS L2 activities, part of which were focused on strengthening the physical foundations of the SAR-based retrieval of forest above-ground biomass (AGB). A critical analysis of the observed strong correlation between tomographic intensity and AGB is done in order to propose simplified AGB proxies to be used during the interferometric phase of BIOMASS. In particular, the aim is to discuss whether, and to what extent, volume scattering obtained from ground/volume decomposition can provide a reasonable alternative to tomography. To do this, both are tested on P-band data collected at Paracou during the TropiSAR campaign and cross-validated against in-situ AGB measurements. Results indicate that volume backscattered power as obtained by ground/volume decomposition is weakly correlated to AGB, notwithstanding different solutions for volume scattering are tested, and support the conclusion that forest structure actually plays a non-negligible role in AGB retrieval in dense tropical forests.

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The impact of long dry periods on the aboveground biomass in tropical forests: 20 years of monitoring

10.21203/rs.2.22656/v1 ◽

2020 ◽

Author(s):

Milton Serpa de Meira-Junior ◽

José Roberto Rodrigues Pinto ◽

Natália Oliveira Ramos ◽

Eder Pereira Miguel ◽

Ricardo de Oliveira Gaspar ◽

...

Keyword(s):

Tropical Forests ◽

Aboveground Biomass ◽

Carbon Stocks ◽

Stem Density ◽

Biomass Carbon ◽

Neotropical Forests ◽

Aboveground Carbon ◽

Large Trees ◽

The Impact

Abstract Background Long-term studies of community and population dynamics indicate that abrupt disturbances often catalyse changes in vegetation and carbon stocks. These disturbances include the opening of clearings, flooding, rainfall seasonality, and drought, as well as fire and direct human disturbance. Such events may be super-imposed on longer-term trends in disturbance, such as those associated with climate change (heating, drying), as well as resources. Intact neotropical forests have recently experienced increased drought frequency and fire, on top of pervasive increases in atmospheric CO2 concentrations, but we lack long-term records of responses to such changes especially in the critical transitional areas at the interface of forest and savanna biomes. Here, we present results from 20 years monitoring a valley forest (moist tropical forest outlier) in central Brazil. The forest has experienced multiple drought events and includes plots which have and which have not experienced fire. We focus on how forest structure (stem density and aboveground biomass carbon) and dynamics (stem and biomass mortality and recruitment) have responded to these disturbance regimes. ResultsOverall, the biomass carbon stock increased due to the growth of the trees already present in the forest, without any increase in the overall number of tree stems. Over time, both recruitment and especially mortality of trees tended to increase, and periods of prolonged drought in particular resulted in increased mortality rates of larger trees. This increased mortality was in turn responsible for a decline in aboveground carbon toward the end of the monitoring period. Fire in 2010, which occurred in only some of our plots, tended to exacerbate the trends of increasing mortality and losses of biomass carbon. Conclusion Prolonged droughts influence the mortality of large trees, leading to a decline in aboveground carbon stocks. Here, and in other neotropical forests, recent droughts are capable of shutting down and reversing biomass carbon sinks. These new results add to evidence that anthropogenic climate changes are already adversely impacting tropical forests.

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Influence of tree size, taxonomy, and edaphic conditions on heart rot in mixed-dipterocarp Bornean rainforests: implications for aboveground biomass estimates

Biogeosciences Discussions ◽

10.5194/bgd-12-6821-2015 ◽

2015 ◽

Vol 12 (9) ◽

pp. 6821-6861 ◽

Cited By ~ 4

Author(s):

K. D. Heineman ◽

S. E. Russo ◽

I. C. Baillie ◽

J. D. Mamit ◽

P. P.-K. Chai ◽

...

Keyword(s):

Tropical Forests ◽

Wood Density ◽

Aboveground Biomass ◽

Tree Size ◽

Stem Volume ◽

Mixed Effect ◽

Edaphic Conditions ◽

Environmental Controls ◽

Dipterocarp Forests ◽

Source Of Error

Abstract. Fungal decay of heartwood creates hollows and areas of reduced wood density within the stems of living trees known as heart rot. Although heart rot is acknowledged as a source of error in forest aboveground biomass estimates, there are few datasets available to evaluate the environmental controls over heart rot infection and severity in tropical forests. Using legacy and recent data from drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of heart rot, and used generalized linear mixed effect models to characterize the association of heart rot with tree size, wood density, taxonomy, and edaphic conditions. Heart rot was detected in 55% of felled stems > 30 cm DBH, while the detection frequency was lower for stems of the same size evaluated by non-destructive drilling (45%) and coring (23%) methods. Heart rot severity, defined as the percent stem volume lost in infected stems, ranged widely from 0.1–82.8%. Tree taxonomy explained the greatest proportion of variance in heart rot frequency and severity among the fixed and random effects evaluated in our models. Heart rot frequency, but not severity, increased sharply with tree diameter, ranging from 56% infection across all datasets in stems > 50 cm DBH to 11% in trees 10–30 cm DBH. The frequency and severity of heart rot increased significantly in soils with low pH and cation concentrations in topsoil, and heart rot was more common in tree species associated with dystrophic sandy soils than with nutrient-rich clays. When scaled to forest stands, the percent of stem biomass lost to heart rot varied significantly with soil properties, and we estimate that 7% of the forest biomass is in some stage of heart rot decay. This study demonstrates not only that heart rot is a significant source of error in forest carbon estimates, but also that it strongly covaries with soil resources, underscoring the need to account for edaphic variation in estimating carbon storage in tropical forests.

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