Herbaceous plants are often under-studied in tropical forests, despite their high density and diversity, and little is known about the factors that influence their distribution at microscales. In a 25-ha plot in lowland Amazonian rain forest in Yasuní National Park, Ecuador, we censused six species of Heliconia (Heliconiaceae) in a stratified random manner across three topographic habitat types. We observed distribution patterns consistent with habitat filtering. Overall, more individuals occurred in the valley (N = 979) and slope (N = 847) compared with the ridge (N = 571) habitat. At the species level, Heliconia stricta (N = 1135), H. spathocircinata (N = 309) and H. ortotricha (N = 36) all had higher abundance in the valley and slope than ridge. Further, H. vellerigera (N = 20) was completely absent from the ridge. Conversely, H. velutina (N = 903) was most common in the drier ridge habitat. The two most common species (H. stricta and H. velutina) had a reciprocal or negative co-occurrence pattern and occurred preferentially in valley versus ridge habitats. These results suggest that taxa within this family have different adaptations to the wetter valley versus the drier ridge and that habitat partitioning contributes to coexistence.

The process by which solitary animals evolve to live in groups is a central question in biology. Conspecifics that compete for patchy resources may evolve incipient social behaviours such as group formation and conspecific tolerance when persistent aggressive interactions reduce resource access. In this investigation, a facultative group living species of whip spider was studied to understand the microhabitat resources that support group formation. Although most species of whip spider are solitary and oftentimes cannibalistic, Heterophrynus batesii sometimes aggregate in small groups at the bases of tree trunks. Twenty-five groups of whip spiders and associated tree buttress microhabitats were surveyed at Tiputini Biodiversity Station bordering Yasuní National Park in Eastern Amazonian Ecuador. Tree buttress complexity, surface area and other microhabitat variables were recorded. Heterophrynus batesii aggregated in groups of 2–8 animals and used large, buttressing, complex trees with more leaf litter relative to those available in the environment. This study showed that large groups of whip spiders require more complex microhabitats than smaller groups that were associated with more variable microhabitat parameters. These microhabitats act as patches of limited resources important for the species, and may have led to the evolution of tolerance and facultative group living.

Spatial and temporal variation in seedling dynamics was assessed using records of community-wide seedling demography collected with identical monitoring methods at four tropical lowland forests in Panama, Malaysia, Ecuador and French Guiana for periods of between 3 and 10 y. At each site, the fates of between 8617 and 391 777 seedlings were followed through annual censuses of the 370–1008 1-m2 seedling plots. Within-site spatial and inter-annual variation in density, recruitment, growth and mortality was compared with among-site variability using Bayesian hierarchical modelling to determine the generality of each site's patterns and potential for meaningful comparisons among sites. The Malaysian forest, which experiences community-wide masting, was the most variable in both seedling density and recruitment. However, density varied year-to-year at all sites (CVamong years at site = 8–43%), driven largely by high variability in recruitment rates (CV = 40–117%). At all sites, recruitment was more variable than mortality (CV = 5–64%) or growth (CV = 12–51%). Increases in mortality rates lagged 1 y behind large recruitment events. Within-site spatial variation and inter-annual differences were greater than differences among site averages in all rates, emphasizing the value of long-term comparative studies when generalizing how spatial and temporal variation drive patterns of recruitment in tropical forests.