Browsing by Autor "Anthony Di Fiore"

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Do species traits determine patterns of wood production in Amazonian forests?
(Copernicus Publications, 2009) Timothy R. Baker; Oliver L. Phillips; William F. Laurance; Nigel C. A. Pitman; S. Almeida; Luzmila Arroyo; Anthony Di Fiore; T. Erwin; Níro Higuchi; Timothy J. Killeen
Abstract. Understanding the relationships between plant traits and ecosystem properties at large spatial scales is important for predicting how compositional change will affect carbon cycling in tropical forests. In this study, we examine the relationships between species wood density, maximum height and above-ground, coarse wood production of trees ≥10 cm diameter (CWP) for 60 Amazonian forest plots. Average species maximum height and wood density are lower in Western than Eastern Amazonia and are negatively correlated with CWP. To test the hypothesis that variation in these traits causes the variation in CWP, we generate plot-level estimates of CWP by resampling the full distribution of tree biomass growth rates whilst maintaining the appropriate tree-diameter and functional-trait distributions for each plot. These estimates are then compared with the observed values. Overall, the estimates do not predict the observed, regional-scale pattern of CWP, suggesting that the variation in community-level trait values does not determine variation in coarse wood productivity in Amazonian forests. Instead, the regional gradient in CWP is caused by higher biomass growth rates across all tree types in Western Amazonia. Therefore, the regional gradient in CWP is driven primarily by environmental factors, rather than the particular functional composition of each stand. These results contrast with previous findings for forest biomass, where variation in wood density, associated with variation in species composition, is an important driver of regional-scale patterns in above-ground biomass. Therefore, in tropical forests, above-ground wood productivity may be less sensitive than biomass to compositional change that alters community-level averages of these plant traits.
Increased folivory in brown spider monkeys Ateles hybridus living in a fragmented forest in Colombia
(Inter-Research, 2016) Ana Gabriela de Luna; Alissa R. Link; Ana Lucía Sánchez Montes; F. Alfonso; Luz Enith Guerrero Mendieta; Anthony Di Fiore
Brown spider monkeys Ateles hybridus are one of the most threatened primates in the Neotropics. Most of the remaining populations of this species already live either in forest fragments or in areas that face imminent anthropogenic disturbance. Understanding how these animals cope with the challenge of living in small fragments, while at the same time being a large, frugivorous mammal is crucial to design effective conservation and management strategies. We studied the diet of wild A. hybridus and measured forest productivity in a small (~65 ha) fragment in the Magdalena Region of northern Colombia over a period of 26 mo. Spider monkeys at this site spent far less time feeding on fruits than reported in previous studies of Ateles spp. living in less fragmented sites. Moreover, we registered a high consumption of leaves in every month (on average 37% of their feeding time) as well as the consistent inclusion of decayed wood in the diet. Ficus trees can be considered staple feeding items, as they were present in high proportions in the monkeys' diet throughout the study. Although wild populations of spider monkeys can have flexible diets that include large proportions of leaves over long periods of time, they may also be exposed to a suboptimal diet which may have negative implications for their reproduction and well-being in the long run, further compromising the viability of wild populations living in disturbed habitats.
Increasing biomass in Amazonian forest plots
(Royal Society, 2004) Timothy R. Baker; Oliver L. Phillips; Yadvinder Malhi; Samuel Almeida; Luzmila Arroyo; Anthony Di Fiore; Terry L. Erwin; Níro Higuchi; Timothy J. Killeen; Susan G. W. Laurance
A previous study by Phillips et al. of changes in the biomass of permanent sample plots in Amazonian forests was used to infer the presence of a regional carbon sink. However, these results generated a vigorous debate about sampling and methodological issues. Therefore we present a new analysis of biomass change in old-growth Amazonian forest plots using updated inventory data. We find that across 59 sites, the above-ground dry biomass in trees that are more than 10 cm in diameter (AGB) has increased since plot establishment by 1.22 +/- 0.43 Mg per hectare per year (ha(-1) yr(-1), where 1 ha = 10(4) m2), or 0.98 +/- 0.38 Mg ha(-1) yr(-1) if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is neither confounded by spatial or temporal variation in wood specific gravity, nor dependent on the allometric equation used to estimate AGB. The conclusion is also robust to uncertainty about diameter measurements for problematic trees: for 34 plots in western Amazon forests a significant increase in AGB is found even with a conservative assumption of zero growth for all trees where diameter measurements were made using optical methods and/or growth rates needed to be estimated following fieldwork. Overall, our results suggest a slightly greater rate of net stand-level change than was reported by Phillips et al. Considering the spatial and temporal scale of sampling and associated studies showing increases in forest growth and stem turnover, the results presented here suggest that the total biomass of these plots has on average increased and that there has been a regional-scale carbon sink in old-growth Amazonian forests during the previous two decades.
Late twentieth-century trends in the biomass of Amazonian forest plots
(2005) Timothy R. Baker; Oliver L. Phillips; Yadvinder Malhi; Samuel Almeida; Luzmila Arroyo; Anthony Di Fiore; Terry L. Erwin; Níro Higuchi; Timothy J. Killeen; Susan G. W. Laurance
Abstract This chapter discusses a previous study by Phillips et al. (1998) on biomass changes in Amazonian permanent sample plots which has been used to infer the presence of a regional carbon sink, generating vigorous debate about sampling and methodological issues. A new analysis of biomass change in old-growth Amazonian forest plots is presented here using new inventory data. It has been found that across fifty-nine sites, the above-ground dry biomass in trees of more than 10 cm in diameter has increased since plot establishment by about 1.22 Mg per hectare per year, or about 0.98 Mg per hectare per year if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is not confounded by spatial or temporal variation in wood specific gravity, nor does it depend on the allometric equation used to estimate biomass. Overall, these results suggest a slightly greater rate of net stand-level change than reported in 1998, and indicate the presence of a significant regional-scale carbon sink in old-growth Amazonian forests during the past two decades.
Phylogeography of the Critically Endangered Brown Spider Monkey (Ateles hybridus): Testing the Riverine Barrier Hypothesis
(Springer Science+Business Media, 2015) Andrés Link; Lina M. Valencia; Laura N. Céspedes; Liz Diana Duque; Carlos Daniel Cadena; Anthony Di Fiore
The above‐ground coarse wood productivity of 104 Neotropical forest plots
(Wiley, 2004) Yadvinder Malhi; Timothy R. Baker; Oliver L. Phillips; Samuel Almeida; Esteban Álvarez‐Dávila; Luzmilla Arroyo; Jérôme Chave; C. I. Czimczik; Anthony Di Fiore; Níro Higuchi
Abstract The net primary production of tropical forests and its partitioning between long‐lived carbon pools (wood) and shorter‐lived pools (leaves, fine roots) are of considerable importance in the global carbon cycle. However, these terms have only been studied at a handful of field sites, and with no consistent calculation methodology. Here we calculate above‐ground coarse wood carbon productivity for 104 forest plots in lowland New World humid tropical forests, using a consistent calculation methodology that incorporates corrections for spatial variations in tree‐size distributions and wood density, and for census interval length. Mean wood density is found to be lower in more productive forests. We estimate that above‐ground coarse wood productivity varies by more than a factor of three (between 1.5 and 5.5 Mg C ha −1 a −1 ) across the Neotropical plots, with a mean value of 3.1 Mg C ha −1 a −1 . There appear to be no obvious relationships between wood productivity and rainfall, dry season length or sunshine, but there is some hint of increased productivity at lower temperatures. There is, however, also strong evidence for a positive relationship between wood productivity and soil fertility. Fertile soils tend to become more common towards the Andes and at slightly higher than average elevations, so the apparent temperature/productivity relationship is probably not a direct one. Coarse wood productivity accounts for only a fraction of overall tropical forest net primary productivity, but the available data indicate that it is approximately proportional to total above‐ground productivity. We speculate that the large variation in wood productivity is unlikely to directly imply an equivalent variation in gross primary production. Instead a shifting balance in carbon allocation between respiration, wood carbon and fine root production seems the more likely explanation.
Variation in wood density determines spatial patterns inAmazonian forest biomass
(Wiley, 2004) Timothy R. Baker; Oliver L. Phillips; Yadvinder Malhi; Samuel Almeida; Luzmila Arroyo; Anthony Di Fiore; Terry L. Erwin; Timothy J. Killeen; Susan G. W. Laurance; William F. Laurance
Abstract Uncertainty in biomass estimates is one of the greatest limitations to models of carbon flux in tropical forests. Previous comparisons of field‐based estimates of the aboveground biomass (AGB) of trees greater than 10 cm diameter within Amazonia have been limited by the paucity of data for western Amazon forests, and the use of site‐specific methods to estimate biomass from inventory data. In addition, the role of regional variation in stand‐level wood specific gravity has not previously been considered. Using data from 56 mature forest plots across Amazonia, we consider the relative roles of species composition (wood specific gravity) and forest structure (basal area) in determining variation in AGB. Mean stand‐level wood specific gravity, on a per stem basis, is 15.8% higher in forests in central and eastern, compared with northwestern Amazonia. This pattern is due to the higher diversity and abundance of taxa with high specific gravity values in central and eastern Amazonia, and the greater diversity and abundance of taxa with low specific gravity values in western Amazonia. For two estimates of AGB derived using different allometric equations, basal area explains 51.7% and 63.4%, and stand‐level specific gravity 45.4% and 29.7%, of the total variation in AGB. The variation in specific gravity is important because it determines the regional scale, spatial pattern of AGB. When weighting by specific gravity is included, central and eastern Amazon forests have significantly higher AGB than stands in northwest or southwest Amazonia. The regional‐scale pattern of species composition therefore defines a broad gradient of AGB across Amazonia.