El mecanismo de neutralidad propone que la diversidad beta es controlada por limitaciones de dispersión y que la similitud florística está correlacionada con la distancia geográfica. En este trabajo se evaluó dicha hipótesis y se comparó la riqueza de bosques subandinos de la Orinoquía con otras vertientes en Colombia, Ecuador y Perú. Se usó una prueba de Mantel para evaluar la correlación entre distancia y similitud florística en 19 parcelas de 0.1 ha y una prueba de Mann-Whitney para el análisis comparativo de riqueza. Se encontró que la distancia fue buen predictor de la similitud florística, sugiriendo que las limitaciones de dispersión son un mecanismo importante para explicar el recambio. La riqueza hallada (47–84 especies) fue significativamente más baja que en las vertientes Amazonía y Pacífico de los Andes, pero similar a la reportada en la vertiente Magdalena. La composición florística estuvo de acuerdo con el patrón reportado previamente para Orinoquía.

We describe four new species of Piper from the Amazonian slopes of the northern Andes. Piper hoyoscardozii is distinguished from similar climbing species, P. dryadum and P. flagellicuspe, by its longer peduncles. The Amazonian species Piper indiwasii is distinguished from P. scutilimbum from Panama and northern Colombia by the narrowly spatulate leaf base extension. Piper nokaidoyitau is characterised by the presence of larger leaves and longer spikes than similar species, P. anonifolium and P. hostmannianum. Finally, P. velae is characterised by cordulate leaf bases in all nodes, petioles 0.8–1.5 cm long and pubescent fruits, which easily distinguish it from the related species, P. holdridgeanum.

Quantification of multivariate trait spectra (or axes of specialization) make the definition of plant strategies more operational, which promotes trait-based theory of community assembly and the understanding of dynamics and functioning of ecosystems. We used field-quantified soil data to explore trait-environment relationships across palm communities in western Amazonia. We collected data from 116 palm species in 458 transects across four distinct forest types. We combined these data with trait records to relate local plant community trait composition to broad gradients in soil variables and forest types. There were significant trait-environment relationships across western Amazonia. Palms with large leaves and fruits, and palms with both growth forms (acaulescent/erect) were associated with fertile soils, while palms with unarmed leaves and stems were associated with non-inundated environments. These results suggest that the functional traits of palms vary consistently along soil gradients on a regional scale. This variation could be explained by the soil fertility and acidity + aluminum gradients, suggesting environmental filters related to resource availability and stressful environments, such as acid soils and soils with high aluminum content.

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Functional traits play a key role in driving plant community effects on ecosystem function. We examined nine functional traits in various palm (Arecaceae) species and their relationships with moisture, tree-fall gaps, slope, and forest type at 29 transects (500×5 m) in the northeastern region of the Colombian Amazon. Redundancy analysis of mean trait values of species within a plot weighted by their abundance and Pearson correlations were used to evaluate the relationships between traits and environmental factors. The community trait composition was correlated with local environmental factors, which explained 23% of the trait variance. We detected functional dominance of the tallest palms in soils with high moisture and in floodplain forests (p ≤0.05). Palms with relatively long leaves were dominant in the flooded forests. Acaulescent and small palms were dominant on high slopes, and in terra firme forests, long-petioled palms were dominant in forest gaps. The number of seeds per fruit was not correlated with any environmental variable. Thus, hydrology is one of the main drivers of the functional composition of neotropical palm communities at the local scale, segregating tall palms with competitive and evasive strategies from small understory palms, which are mainly stress tolerant.