Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Excavations at the Lower Palaeolithic site at East Farm, Barnham, Suffolk 1989-92

Preliminary results are presented from three seasons' work at the Lower Palaeolithic site at Barnham. The complex stratigraphy is described and a provisional interpretation given, which suggests that the archaeological deposits date to a warm phase after the Anglian (Middle Pleistocene) cold stage. A fauna1 assemblage from the deposits is described, providing an environmental and biostratigraphic context for the site. Further geochronological control is provided by amino acid ratios on shells from the sequence. Two flint assemblages have been excavated, the first consisting of flakes and cores, and the second including bifaces. These assemblages and their position in the British sequence are considered in terms of their stratigraphic context and their relationship to other Lower Palaeolithic assemblages in the British Isles