Riparian zone as a main determinant of the structure of lizard assemblages in upland Amazonian forests

The use of lizards as model organisms in ecological studies is based on their success in occupying a great diversity of habitats, and some species are closely tied to the environment, which is disadvantaged by the legislation of several countries concerning land use. Our aim was to relate lizard species distribution patterns in rainforest environments to variation in environmental gradients, and provide ecologically based metrics for establishing buffer zones around streams. Lizards were sampled three times in 41 standardised transects near Manaus, Brazil, only in dry season, with Time Limited Visual Search associated with raking through leaf litter. We recorded 20 species from 10 families and used non‐metric multidimensional scaling to reduce the dimensionality of quantitative and qualitative compositions of species. Multiple linear regression models indicated that the environmental gradients distance to nearest stream, extent of canopy openness, vegetation density and slope did not significantly influence assemblage species distribution, with an indication of effect of litter depth. By means of piecewise linear regression, the use of riparian zone was estimated at ~190 m from quantitative species composition and ~211 m from qualitative species composition. Five species occurred only in the riparian zone. Our results suggest that conservation of the entire riparian lizard assemblage in Amazonian rainforest is likely to require protection of at least a 211 m buffer on either side of streams. Resumo O uso de lagartos como organismos modelo em estudos ecológicos é baseado em seu sucesso em ocupar uma grande diversidade de habitats e algumas espécies estão intimamente ligadas ao ambiente, o qual é prejudicado pela legislação de vários países sobre o uso da terra. Nosso objetivo foi relacionar padrões de distribuição de espécies de lagartos em ambientes de floresta tropical a variações em gradientes ambientais e fornecer métricas ecológicas para o estabelecimento de áreas de proteção em torno de corpos d’água. Lagartos foram amostrados três vezes em 41 transectos padronizados perto de Manaus, Brasil, apenas na estação seca, por meio de Busca Visual Limitada por Tempo (TLVS) associada à busca na serapilheira. Registramos 20 espécies de 10 famílias e usamos escalonamento multidimensional não‐métrico (nMDS) para reduzir a dimensionalidade das composições quantitativa e qualitativa de espécies. Modelos de regressão linear múltipla indicaram que os gradientes ambie