Amazonia comprises a mosaic of contrasting habitats, with wide environmental heterogeneity at local and regional scales. In central Amazonia, upland forest (terra firme) is the predominant forest type and seasonally flooded forests inundated by white- and black-water rivers (várzea and igapó, respectively) represent around 20% of the forested areas. In this work, we took advantage of a natural spatial arrangement of the main vegetation types in central Amazonia to investigate butterfly assemblage structure in terra firme, várzea and igapó forests at the local scale. We sampled in the low- and high-water seasons, combining active and passive sampling with traps placed in both the understory and canopy. Terra firme supported the highest number of butterfly species, whereas várzea forest provided the highest number of butterfly captures. The high species richness in terra firme may reflect that this forest type is floristically richer than várzea and igapó. Várzea is a very productive environment and may thus support a higher number of butterfly individuals than terra firme and igapó. Most butterfly species (80.2%) were unique to a single forest type and 17 can be considered forest type indicator species in this landscape. Floodplain forest environments are therefore an important complement to terra firme in terms of butterfly species richness and conservation in Amazonia.

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The composition of communities of fruit‐feeding butterflies in the Brazilian Atlantic forest changes in response to landscape fragmentation and can be used as an indicator of habitat quality. Landscape fragmentation, aridity, and early signs of global warming at the northernmost distribution of this biome may impose extra challenges for species persistence. We aim to clarify the drivers of fruit‐feeding butterflies' metacommunity structure in the northernmost portion of the Brazilian Atlantic Forest. We propose to disentangle consequences of habitat loss from fragmentation per se by using both habitat amount and patch scale metrics. We sampled fruit‐feeding butterflies in 15 forest fragments of up to ~30 ha during 1 year. We used fragment size, shape, distance to nearest perennial stream, Euclidean distance to nearest neighbour, forest habitat amount, proximity index, and the percentage of sugarcane within a buffer to elucidate patterns of species richness, abundance, and beta diversity. A configuration metric, stream distance, was the only variable predicting metacommunity total abundance and richness: fragments farther from water had fewer species and individuals. However, forest habitat amount and sugar cane were important to rarefied richness and species replacement between fragments. Our findings suggest that streams and associated riparian zones provide source populations for the butterfly metacommunities in this landscape, which fits the mass effect model. We also emphasise that small forest patches have high conservation value for persistence of butterfly populations, because each fragment preserves a substantial portion of the total species pool.

The seasonal flood pulse in Amazonia can be considered a primary driver of community structure in floodplain environments. Although this natural periodic disturbance is part of the landscape dynamics, the seasonal inundation presents a considerable challenge to organisms that inhabit floodplain forests. The present study investigated the effect of seasonal flooding on fruit‐feeding butterfly assemblages in different forest types and strata in central Amazonia. We sampled fruit‐feeding butterflies in the canopy and the understory using baited traps in adjacent upland (unflooded forests—terra firme), white and blackwater floodplain forests (várzea and igapó, respectively) during the low‐ and high‐water seasons. Butterfly abundance decreased in the high‐water season, especially of dominant species in várzea, but the number of species was similar between seasons in the three forest types. Species composition differed between strata in all forest types. However, the flood pulse only affected butterfly assemblages in várzea forest. The β‐diversity components also differed only in várzea. Species replacement (turnover) dominated the spatial β‐diversity in igapó and terra firme in both seasons and várzea in the high‐water season. Nonetheless, nestedness was relatively higher in várzea forests during the low‐water season, mainly due to the effect of dominant species. These results emphasize the importance of seasonal flooding to structure butterfly assemblages in floodplain forests and reveal the idiosyncrasy of butterfly community responses to flooding in different forest types. Our results also suggest that any major and rapid changes to the hydrological regime could severely affect floodplain communities adapted to this natural seasonal hydrological cycle, threatening the existence of these unique environments.