Allometric regressions for improved estimate of secondary forest biomass in the central Amazon

Nelson, Bruce; Mesquita, Rita; Pereira, Jorge Luís Gavina; Souza, Silas Garcia Aquino de; Batista, Getúlio Teixeira; Couto, Luciana Bovino

doi:10.1016/s0378-1127(98)00475-7

Cited by 327 publications

(313 citation statements)

References 9 publications

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“…Errors for individual trees using the off-site allometric equations were on the order of 30-40%, but much of this error was comprised of bias; errors for the total aboveground biomass were as great as 33%. Contrary to expectations, the best performer among the off-site allometric equations was Model 2 of Nelson et al (1999), which uses DBH alone. Its error of 17% for plotlevel aboveground biomass estimates might still be judged unacceptable in some situations.…”

Section: Resultsmentioning

confidence: 58%

“…A graphic comparison between the best mixed-species equations in this study, and the comparable equations of Uhl et al (1988) and Nelson et al (1999), is shown in Figure 3. Model 6 of Nelson et al, which requires specific gravity, tended to overpredict in relation to Model 2 of this study.…”

Section: Resultsmentioning

confidence: 98%

“…To compare the selected models with this study with those from previously published studies Nelson et al, 1999), we estimated the aboveground biomass for each sampled tree using the equations developed here and the previously published equations. Differences were assessed graphically, and the models were also compared for median percent error and median absolute error for each tree.…”

Section: Discussionmentioning

confidence: 99%

“…Most studies on biomass or carbon increment in Amazonian forest regrowth rely on mixed-species equations (such as those developed by Uhl et al, 1988;Saldarriaga et al, 1988, andHonzák et al, 1996 using data from Brown et al, 1989). However, Nelson et al (1999) report considerable discrepancies between the predictions of these equations, suggesting considerable error may remain when using existing mixed-species regressions in new sites.…”

Section: Introductionmentioning

confidence: 99%

“…However, few species-specific allometric equations have been published Saldarriaga et al, 1988;Nelson et al, 1999). Most studies on biomass or carbon increment in Amazonian forest regrowth rely on mixed-species equations (such as those developed by Uhl et al, 1988;Saldarriaga et al, 1988, andHonzák et al, 1996 using data from Brown et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

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Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling

Ducey

Zarin²,

Vasconcelos

et al. 2009

Acta Amaz.

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Forest regrowth occupies an extensive and increasing area in the Amazon basin, but accurate assessment of the impact of regrowth on carbon and nutrient cycles has been hampered by a paucity of available allometric equations. We develop pooled and species-specific equations for total aboveground biomass for a study site in the eastern Amazon that had been abandoned for 15 years. Field work was conducted using randomized branch sampling, a rapid technique that has seen little use in tropical forests. High consistency of sample paths in randomized branch sampling, as measured by the standard error of individual paths (14%), suggests the method may provide substantial efficiencies when compared to traditional procedures. The best fitting equations in this study used the traditional form Y=a×DBH b , where Y is biomass, DBH is diameter at breast height, and a and b are both species-specific parameters. Species-specific equations of the form Y=a(BA×H), where Y is biomass, BA is tree basal area, H is tree height, and a is a species-specific parameter, fit almost as well. Comparison with previously published equations indicated errors from -33% to +29% would have occurred using off-site relationships. We also present equations for stemwood, twigs, and foliage as biomass components.KEY WORDS: Allometry, Allometric equations, Secondary growth, Tropical forest Equações alométricas para estimativa de biomassa de floresta secundária na Amazônia Oriental usando amostragem aleatória de ramos RESUMO Florestas secundárias ocupam uma área extensa e crescente na bacia Amazônica, porém determinações acuradas do impacto dessas florestas nos ciclos de carbono e nutrientes têm sido dificultadas pelo número reduzido de equações alométricas. Neste estudo, nós desenvolvemos equações em nível de comunidade e espécies individuais para estimar a biomassa total da parte aérea de uma floresta secundária com 15 anos de idade na Amazônia oriental. O trabalho de campo utilizou amostragem aleatória de ramos, que é uma técnica rápida, porém pouco utilizada em florestas tropicais. Baseada no erro padrão da série de segmentos individuais (14%), a consistência da série de segmentos totais amostrados foi considerada elevada, sugerindo que o método pode ser eficiente em comparação com procedimentos tradicionais. Os melhores ajustes foram obtidos com a equação tradicional Y=a×DBH b , onde Y é a biomassa, DBH é o diâmetro à altura do peito, e a e b são parâmetros para cada espécie arbórea. Ajustes razoáveis também foram alcançados com equações da forma Y=a(BA×H), onde Y é a biomassa, BA é a área basal, H é a altura e a é um parâmetro específico para cada espécie arbórea. Comparações com equações disponíveis na literatura indicaram uma faixa de erro provável de -33% a +29% usando-se relações desenvolvidas para outros sítios. Nós também apresentamos equações para os seguintes componentes da biomassa da parte aérea: tronco, ramos e folhas.

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Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling

Ducey

Zarin²,

Vasconcelos

et al. 2009

Acta Amaz.

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Prediction intervals: Placing real bounds on regression‐based allometric estimates of biomass

Ward

2015

Biometrical J

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Biomass allometry studies routinely assume that regression models can be applied across species and sites, and that goodness of fit of a regression model to its derivation dataset indicates both the relevance of the model to a new dataset and the likely error. Assuming that a model is relevant for a new sample, a prediction interval is a useful error measure for stand mass. Prediction coverage tests whether the model and hence the interval are appropriate in the new sample. Data for three similar shrubby species from four similar sites were combined in various ways to test the impact of varying levels of biodiverse heterogeneity on the performance of the four models most commonly used in published biomass studies. No one model performed consistently well predicting new data, and validation checks were not good indicators of prediction coverage. The highly variable results suggest that the common models might contain insufficient variables. Euclidean distance was used to quantify the relative similarity of samples as a possible means of estimating prediction coverage; it proved unsuccessful with these data.

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Smallholders at a Crossroad: Intensify or Fall behind? Exploring Alternative Livelihood Strategies in a Globalized World

et al. 2018

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The chocolate market is experiencing a wave of market differentiation thanks to the emergence of the bean‐to‐bar movement. Cacao is seeing both a rise in demand for mass markets and a process of market bifurcation into more specialized, high‐quality products for wealthy urban consumers. For the specialized market, the quality and origin of the beans are important attributes. Direct trading between chocolate makers and famers seeks to promote the conservation of rare cultivars and traditional agroforestry systems, while lifting farmers out of poverty. Here we assess whether these alternative configurations of the global value chain truly offer smallholders new opportunities, beyond the traditional intensification or marginalization pathways that are generally offered to them. We conducted detailed socio‐economic and biophysical surveys with a sample of farms in three of the largest cacao producing provinces of Ecuador. Our results show that, even though smallholders lack the assets needed to join mainstream commodity markets, they have been able to capitalize on the qualities of their traditional varieties to access niche markets. Through strong cooperatives, the knowledge held by buyers about what constitutes a high‐quality bean has been transferred to farmers. A unique natural capital may provide smallholders with rewarding pathways to develop their agriculture, exploiting new market opportunities offered by globalization. Copyright © 2018 John Wiley & Sons, Ltd and ERP Environment

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Allometric regressions for improved estimate of secondary forest biomass in the central Amazon

Cited by 327 publications

References 9 publications

Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling

Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling

Prediction intervals: Placing real bounds on regression‐based allometric estimates of biomass

Smallholders at a Crossroad: Intensify or Fall behind? Exploring Alternative Livelihood Strategies in a Globalized World

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