Total number of trees 3.9×10^11: median tree density 565 trees/ha: ~16,000 tree species
||ter Steege H et al. Hyperdominance in the Amazonian tree flora. Science. 2013 Oct 18 342(6156):1243092. doi: 10.1126/science.1243092. p.326 right column 3rd paragraphPubMed ID24136971
||P.325 2nd paragraph: "The ~6-million-km^2 Amazonian lowlands were divided into 1° cells, and mean tree density was estimated for each cell by using a loess regression model that included no environmental data but had its basis exclusively in the geographic location of tree plots. A similar model, allied with a bootstrapping exercise to quantify sampling error, was used to generate estimated Amazon-wide abundances of the 4962 valid species in the data set. [Investigators] estimated the total number of tree species in the Amazon by fitting the mean rank-abundance data to Fisher’s log-series distribution."
||P.1243092-1 right column 3rd paragraph: "First, it [The rank-abundance distribution (RAD) of [spatial model]] provides the most precise estimates yet of two numbers that have been debated for decades: How many trees and how many tree species occur in the ~6-million-km^2 landscape of Amazonia (refs 1, 3–5). [Investigators'] estimate of tree density yielded a total of 3.9×10^11 individual trees and a median tree density of 565 trees/ha (fig. S4). Assuming that [their] population size estimates for the common species are reasonable (fig. S5) and that Fisher’s log-series model fits [their] data (table S2 and figs. S6 and S7) (ref 1), [they] estimated the total number of tree species in the Amazon to be about 16,000 (Fig. 2). A second estimate based on the Fisher’s alpha scores of all plots yielded a similar figure: 15,182 species (fig. S8)."