Branch xylem density variations across Amazonia

Abstract

Abstract. Measurements of branch xylem density, Dx, were made for 1466 trees representing 503 species, sampled from 80 sites across the Amazon basin. Measured values ranged from 240 kg m−3 for a Brosimum parinarioides from Tapajos in West Pará, Brazil to 1130 kg m−3 for an Aiouea sp. from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average Dx across the sample plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that geographic location and plot accounted for 33% of the variation with species identity accounting for an additional 27%; the remaining "residual" 40% of the variance accounted for by tree to tree (within species) variation. Variations in plot means, were, however, hardly accountable at all by differences in species composition. Rather, it would seem that variations of xylem density at plot level must be explained by the effects of soils and/or climate. This conclusion is supported by the observation that the xylem density of the more widely distributed species varied systematically from plot to plot. Thus, as well as having a genetic component branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing and in a predictable manner. Exceptions to this general rule may be some pioneers belonging to Pourouma and Miconia and some species within the genera Brosimum, Rinorea and Trichillia which seem to be more constrained in terms of this plasticity than most species sampled as part of this study.

Functional trait variation and sampling strategies in species‐rich plant communities

“…2008). This result is concordant with recent Amazon‐wide estimates for tree xylem density, where local environmental factors explained up to 22% of variability in sapwood density (Patiño et al. 2009).…”

“…We chose the threshold values to provide the greatest discrimination among the sampling designs we simulated; the larger threshold for trait variance reflects the inherent variation in these plant functional traits (Wright et al. 2004; Patiño et al. 2009).…”

Seasonal variations in stem CO2 efflux in the Neotropical rainforest of French Guiana

“…In the Terra Firme forest (TFF), under both non-limiting and limiting soil water conditions (wet season/dry season), a large variability in stem CO 2 efflux was observed among trees (Table 3); the range of E s values was similar to previous observations made in tropical rainforest ecosystems (Cavaleri et al 2006;Chambers et al 2004;Meir and Grace 2002;Nepstad et al 2002;Ryan et al 1994;Zach et al 2008Zach et al , 2010b and confirmed the large variability in functional characteristics observed to date for Neotropical rainforest species at the stem level (e.g., wood density- Patiño et al 2008, bark thickness-Paine et al 2010. In a study on functional explanations for variation in bark thickness in Neotropical trees, Paine et al (2010) concluded there was no significant relationship between bark thickness and E s .…”

Towards a worldwide wood economics spectrum

“…2004; ter Steege et al. 2006; Patiño et al. 2008), as does a positive but weaker relationship between wood density and temperature.…”

“…Heartwood xylem lacks functional conduits and parenchyma. Foresters typically measure heartwood density, yet sapwood (xylem containing functional conduits and parenchyma) densities are often significantly lower than heartwood densities (Woodcock & Shier 2002;Patiño et al 2008). This pattern has been attributed to the structural support required at different ontogenetic stages or changes in chemical deposition in heartwood.…”