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

Abstract

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.

Unearthing the hidden world of roots: Root biomass and architecture differ among species within the same guild

“…Our study evaluated belowground and aboveground biomass of native species planted in the tropics. Unsurprisingly, BD and DBH were the strongest predictors of total biomass when compared to height, BD*height, DBH*height [32,34,66]. We also show AGB can predict TB, a potentially important finding for scaling AGB estimates of forests to TB and C stock estimates (Fig 3).…”

Allometric models for estimating aboveground biomass and carbon stock for <i>Diospyros mespiliformis</i> in West Africa

“…Actually, the previously published models of Brown et al (1989), Chave et al (2005), Chave et al (2014), andJucker et al (2017) are not wrong; they are simply not right for this species or the study sites. Ducey et al (2009) made similar observation in the eastern Amazon and found errors from -33% to +29% that occurred when using off-site relationships, indicating that site-and species specific allometric models differ with species, tree status, climate and soil (Zianis and Mencuccini 2004), and are generally preferred over generic allometric models (Montagu et al 2005). Kim et al (2011), in their study, emphasize that the site-specific allometric models are more accurate in predicting the forest biomass estimates on the local level as they take into account the site effects.…”

Aboveground net primary productivity in tropical forest regrowth increases following wetter dry-seasons

“…To estimate AGB, we used site-specific mixed-species and species-specific allometric equations based on diameter measurements (Ducey et al, 2009); estimated AGB refers to the sum of stemwood, branches, twigs, and foliage biomass. Within each measurement subplot, we measured DBH of every tree with DBH P 1 cm on an annual basis (every first week of July).…”

“…Stem diameter and height measures are usually used to estimate aboveground biomass (AGB) through allometric equations (e.g., Ducey et al, 2009). Despite several reports on AGB for tropical forest regrowth (Saldarriaga et al, 1988;Zarin et al, 2001;Gehring et al, 2005), repeated measures of AGB and litterfall are rare and calculations of ANPP for these forests are therefore lacking.…”