Browsing by Autor "Emanuel Gloor"

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Amazon forest response to repeated droughts
(Wiley, 2016) Ted R. Feldpausch; Oliver L. Phillips; Roel Brienen; Emanuel Gloor; Jon Lloyd; Gabriela López‐González; Abel Monteagudo‐Mendoza; Yadvinder Malhi; Alejandro Alarcón; Esteban Álvarez‐Dávila
Abstract The Amazon Basin has experienced more variable climate over the last decade, with a severe and widespread drought in 2005 causing large basin‐wide losses of biomass. A drought of similar climatological magnitude occurred again in 2010; however, there has been no basin‐wide ground‐based evaluation of effects on vegetation. We examine to what extent the 2010 drought affected forest dynamics using ground‐based observations of mortality and growth from an extensive forest plot network. We find that during the 2010 drought interval, forests did not gain biomass (net change: −0.43 Mg ha −1 , confidence interval (CI): −1.11, 0.19, n = 97), regardless of whether forests experienced precipitation deficit anomalies. This contrasted with a long‐term biomass sink during the baseline pre‐2010 drought period (1998 to pre‐2010) of 1.33 Mg ha −1 yr −1 (CI: 0.90, 1.74, p < 0.01). The resulting net impact of the 2010 drought (i.e., reversal of the baseline net sink) was −1.95 Mg ha −1 yr −1 (CI:−2.77, −1.18; p < 0.001). This net biomass impact was driven by an increase in biomass mortality (1.45 Mg ha −1 yr −1 CI: 0.66, 2.25, p < 0.001) and a decline in biomass productivity (−0.50 Mg ha −1 yr −1 , CI:−0.78, −0.31; p < 0.001). Surprisingly, the magnitude of the losses through tree mortality was unrelated to estimated local precipitation anomalies and was independent of estimated local pre‐2010 drought history. Thus, there was no evidence that pre‐2010 droughts compounded the effects of the 2010 drought. We detected a systematic basin‐wide impact of the 2010 drought on tree growth rates across Amazonia, which was related to the strength of the moisture deficit. This impact differed from the drought event in 2005 which did not affect productivity. Based on these ground data, live biomass in trees and corresponding estimates of live biomass in lianas and roots, we estimate that intact forests in Amazonia were carbon neutral in 2010 (−0.07 Pg C yr −1 CI:−0.42, 0.23), consistent with results from an independent analysis of airborne estimates of land‐atmospheric fluxes during 2010. Relative to the long‐term mean, the 2010 drought resulted in a reduction in biomass carbon uptake of 1.1 Pg C, compared to 1.6 Pg C for the 2005 event.
Author Correction: Tree mode of death and mortality risk factors across Amazon forests
(Nature Portfolio, 2021) Adriane Esquivel‐Muelbert; Oliver L. Phillips; Roel Brienen; Sophie Fauset; Martin J. P. Sullivan; Timothy R. Baker; Kuo‐Jung Chao; Ted R. Feldpausch; Emanuel Gloor; Níro Higuchi
Detecting evidence for CO<sub>2</sub> fertilization from tree ring studies: The potential role of sampling biases
(Wiley, 2012) Roel Brienen; Emanuel Gloor; Pieter A. Zuidema
Tree ring analysis allows reconstructing historical growth rates over long periods. Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO 2 concentration. However, these trends may also have been caused by sampling biases. Here we describe two biases and evaluate their magnitude. (1) The slow ‐ grower survivorship bias is caused by differences in tree longevity of fast‐ and slow‐growing trees within a population. If fast‐growing trees live shorter, they are underrepresented in the ancient portion of the tree ring data set. As a result, reconstructed growth rates in the distant past are biased toward slower growth. (2) The big ‐ tree selection bias is caused by sampling only the biggest trees in a population. As a result, slow‐growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter. We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata . Tree growth rates used as input in our models were kept constant over time. By mimicking a standard tree ring sampling approach and selecting only big living trees, we show that both biases lead to apparent increases in historical growth rates. Increases for the slow‐grower survivorship bias were relatively small and depended strongly on assumptions about tree mortality. The big‐tree selection bias resulted in strong historical increases, with a doubling in growth rates over recent decades. A literature review suggests that historical growth increases reported in many tree ring studies may have been partially due to the big‐tree sampling bias. We call for great caution in the interpretation of historical growth trends from tree ring analyses and recommend that such studies include individuals of all sizes.
Fast demographic traits promote high diversification rates of Amazonian trees
(Wiley, 2014) Timothy R. Baker; R. Toby Pennington; Susana Magallón; Emanuel Gloor; Susan G. W. Laurance; Miguel N. Alexiades; Esteban Álvarez‐Dávila; Alejandro Araújo; E.J.M.M. Arets; Gerardo A. Aymard C.
The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits--short turnover times--are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests.
Increasing tree size across Amazonia
(Nature Portfolio, 2025) Adriane Esquivel‐Muelbert; Rebecca Banbury Morgan; Roel Brienen; Emanuel Gloor; Simon L. Lewis; Aurora Levesley; Gabriela López‐González; Edmar Almeida de Oliveira; Esteban Álvarez‐Dávila; Joey Talbot
Long-term decline of the Amazon carbon sink
(Nature Portfolio, 2015) Roel Brienen; Oliver L. Phillips; Ted R. Feldpausch; Emanuel Gloor; Timothy R. Baker; Jon Lloyd; Gabriela López‐González; Abel Monteagudo‐Mendoza; Yadvinder Malhi; Simon L. Lewis
Tree height integrated into pan-tropical forest biomass estimates
(2012) Ted R. Feldpausch; Jon Lloyd; Simon L. Lewis; Roel Brienen; Emanuel Gloor; Abel Monteagudo Mendoza; Gabriela López‐González; Lindsay F. Banin; Kamariah Abu Salim; Kofi Affum‐Baffoe
Abstract. Above-ground tropical tree biomass and carbon storage estimates commonly ignore tree height. We estimate the effect of incorporating height (H) on forest biomass estimates using 37 625 concomitant H and diameter measurements (n = 327 plots) and 1816 harvested trees (n = 21 plots) tropics-wide to answer the following questions: 1. For trees of known biomass (from destructive harvests) which H-model form and geographic scale (plot, region, and continent) most reduces biomass estimate uncertainty? 2. How much does including H relationship estimates derived in (1) reduce uncertainty in biomass estimates across 327 plots spanning four continents? 3. What effect does the inclusion of H in biomass estimates have on plot- and continental-scale forest biomass estimates? The mean relative error in biomass estimates of the destructively harvested trees was half (mean 0.06) when including H, compared to excluding H (mean 0.13). The power- and Weibull-H asymptotic model provided the greatest reduction in uncertainty, with the regional Weibull-H model preferred because it reduces uncertainty in smaller-diameter classes that contain the bulk of biomass per hectare in most forests. Propagating the relationships from destructively harvested tree biomass to each of the 327 plots from across the tropics shows errors are reduced from 41.8 Mg ha−1 (range 6.6 to 112.4) to 8.0 Mg ha−1 (−2.5 to 23.0) when including $H$. For all plots, above-ground live biomass was 52.2±17.3 Mg ha−1 lower when including H estimates (13%), with the greatest reductions in estimated biomass in Brazilian Shield forests and relatively no change in the Guyana Shield, central Africa and southeast Asia. We show fundamentally different stand structure across the four forested tropical continents, which affects biomass reductions due to $H$. African forests store a greater portion of total biomass in large-diameter trees and trees are on average larger in diameter. This contrasts to forests on all other continents where smaller-diameter trees contain the greatest fractions of total biomass. After accounting for variation in $H$, total biomass per hectare is greatest in Australia, the Guyana Shield, and Asia and lowest in W. Africa, W. Amazonia, and the Brazilian Shield (descending order). Thus, if closed canopy tropical forests span 1668 million km2 and store 285 Pg C, then the overestimate is 35 Pg C if H is ignored, and the sampled plots are an unbiased statistical representation of all tropical forest in terms of biomass and height factors. Our results show that tree $H$ is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of pantropical carbon stocks and emissions due to deforestation.
Tree mode of death and mortality risk factors across Amazon forests
(Nature Portfolio, 2020) Adriane Esquivel‐Muelbert; Oliver L. Phillips; Roel Brienen; Sophie Fauset; Martin J. P. Sullivan; Timothy R. Baker; Kuo‐Jung Chao; Ted R. Feldpausch; Emanuel Gloor; Níro Higuchi