Global patterns of vascular plant alpha diversity.

Global patterns of regional (gamma) plant diversity are relatively well known, but whether these patterns hold for local communities, and the dependence on spatial grain, remain controversial. Using data on 170,272 georeferenced local plant assemblages, we created global maps of alpha diversity (local species richness) for vascular plants at three different spatial grains, for forests and non-forests. We show that alpha diversity is consistently high across grains in some regions (for example, Andean-Amazonian foothills), but regional 'scaling anomalies' (deviations from the positive correlation) exist elsewhere, particularly in Eurasian temperate forests with disproportionally higher fine-grained richness and many African tropical forests with disproportionally higher coarse-grained richness. The influence of different climatic, topographic and biogeographical variables on alpha diversity also varies across grains. Our multi-grain maps return a nuanced understanding of vascular plant biodiversity patterns that complements classic maps of biodiversity hotspots and will improve predictions of global change effects on biodiversity.

Dominant tree species drive beta diversity patterns in western Amazonia.

The forests of western Amazonia are among the most diverse tree communities on Earth, yet this exceptional diversity is distributed highly unevenly within and among communities. In particular, a small number of dominant species account for the majority of individuals, whereas the large majority of species are locally and regionally extremely scarce. By definition, dominant species contribute little to local species richness (alpha diversity), yet the importance of dominant species in structuring patterns of spatial floristic turnover (beta diversity) has not been investigated. Here, using a network of 207 forest inventory plots, we explore the role of dominant species in determining regional patterns of beta diversity (community-level floristic turnover and distance-decay relationships) across a range of habitat types in northern lowland Peru. Of the 2,031 recorded species in our data set, only 99 of them accounted for 50% of individuals. Using these 99 species, it was possible to reconstruct the overall features of regional beta diversity patterns, including the location and dispersion of habitat types in multivariate space, and distance-decay relationships. In fact, our analysis demonstrated that regional patterns of beta diversity were better maintained by the 99 dominant species than by the 1,932 others, whether quantified using species-abundance data or species presence-absence data. Our results reveal that dominant species are normally common only in a single forest type. Therefore, dominant species play a key role in structuring western Amazonian tree communities, which in turn has important implications, both practically for designing effective protected areas, and more generally for understanding the determinants of beta diversity patterns.

Diversity and Abundance of Plants with Flowers and Fruits from October 2001 to September 2002 in Paucarillo Reserve, Northeastern Amazon, Peru

En el presente trabajo damos a conocer la diversidad de floración y fructificación observada durante un año de estudio fenológico en la Reserva de Paucarillo (noroeste de la Amazonía Peruana 3°41’ S, 72°24’ W). Registramos un total de 270 especies en 59 familias, de las cuales el 57 por ciento son representadas solamente por 1 individuo. Las Arecaceae y Rubiaceae fueron las familias dominantes en este sitio.

We recorded the diversity of flowering and fruiting plants during one year of phenological study at Paucarillo Reserve located in the northeastern part of the Peruvian Amazon (3°41’ S, 72°24’ W). A total of 270 species from 59 families were recorded, of which 57 per cent were represented by only one individual plant. Arecaceae and Rubiaceae were the dominant families in this site.

Una nueva especie de Neosprucea (Salicaceae/Flacourtiaceae) de Perú y Colombia / A new species of Neosprucea (Salicaceae/Flacourtiaceae) from Peru and Colombia

Se describe e ilustra una nueva especie de Neosprucea (Salicaceae / Flacourtiaceae: Prockieae), Neosprucea rimachii McDaniel ex Alford, Grández, & Vásquez, procedente de la cuenca amazónica del Perú y Colombia. Es caracterizada por la forma y nervadura de las hojas, el color de los pétalos, el largo de las anteras, y la pubescencia del fruto. Se presenta una discusión de relaciones con otras especies y una clave para distinguirlas.

A new species of Neosprucea (Salicaceae / Flacourtiaceae: Prockieae), Neosprucea rimachii McDaniel ex Alford, Grandez, & Vasquez, is described from the Amazon basin of Peru and Colombia. The new species differs from other Neosprucea in leaf shape, leaf venation, petal color, anther length, and fruit pubescence. A discussion of its relationships to the other species and a key to separate them are also presented.

Increasing dominance of large lianas in Amazonian forests.

Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7-4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests.