Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth’s land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m⁻² y⁻¹, storage: 55, 113 and 38 g m⁻², on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas.

This study showed that the main impact on Odonata species of removal of riparian vegetation for road building was on community composition, since species richness remained unaltered. This result, most evident in damselflies, was probably driven by the entry of generalist species that replaced specialist species after the impact. We collected adult odonates in forested and deforested streams in the surroundings of Manaus, Amazonas, northern Brazil. We collected 380 specimens belonging to 32 odonate species. Erythrodiplax fusca and Argia sp. 1 could be used in biomonitoring programs, since they were significantly associated with deforested streams. Using odonate community composition and key species appears to be more efficient in biomonitoring programs than simply using species richness. Em nosso estudo mostramos que o principal impacto sobre as espécies de Odonata causado pela retirada da vegetação ciliar para a construção de estradas é a modificação na composição da comunidade, uma vez que a riqueza de espécies continua praticamente constante. Possivelmente, devido à entrada de espécies mais generalistas em detrimento das especialistas, que são extintas localmente após o impacto, e isso é mais evidente em Zygoptera. Coletamos em 100 m de igarapés localizados em áreas sem vegetação e em fragmentos florestais na região de Manaus-AM. Foram coletados 380 espécimes, distribuídos em 32 espécies. Dessas, Erytrhodiplax fusca e Argia sp. 1 podem ser utilizadas em programas de biomonitoramento pois mostraram uma associação com ambientes sem vegetação marginal. Nossos resultados indicam que a composição da comunidade de Odonata e o uso de espécies chaves são mais eficientes que a simples medida de riqueza para avaliar os impactos causados a esse grupo.