Resumo Pequenos roedores dependem da aquisição de recursos para sustentar a reprodução e a sobrevivência da ninhada. Uma vez que plantações podem servir como fonte complementar de alimento, nós avaliamos a influência da presença de plantações de milho na borda da floresta sobre a abundância e a reprodução de Oligoryzomys nigripes (Olfers, 1818). Constatamos que a abundância, a proporção de indivíduos reprodutivos, assim como o número de juvenis foram maiores nas bordas dos campos de milharal, sem sazonalidade, um padrão divergente da reprodução sazonal descrita para a espécie. Nossos resultados suportam a hipótese de que as plantações de milho beneficiam a abundância e a atividade reprodutiva de O. nigripes.

Abstract Small rodents rely on resource gathering during the breeding season to support their reproductive output and offspring survival. Since croplands may provide complementary food sources, we evaluated the influence of the presence of cornfield on the forest edge in Oligoryzomys nigripes (Olfers, 1818) abundance and breeding. We found that abundance, proportion of reproductive females and males, as well as the number of juveniles were higher in the cornfield-forest edges, with no seasonality, a pattern divergent from the seasonal reproduction described for the species. Therefore, our results supported the hypothesis of cornfields benefiting O. nigripes abundance and breeding success.

Although Merostachys fischeriana is very abundant in the Brazilian Atlantic Rainforest, little attention has been paid to the biological interactions with other animals. The present study describes some of the interactions between ants and this bamboo species. The experiment was carried out in a fragment of a montane tropical forest in the Parque Estadual do Itacolomi, near Ouro Preto, MG, Brazil. Thirty culms of bamboo were randomly collected. The ants were obtained by direct collection from nodes and internodes. Morphometric variables of the bamboo were recorded for characterization of potential ant habitat. Merostachys fischeriana grows in rosettes as a thin bamboo (average = 1,0 cm; se = 0,27; n = 20) and is tall enough to reach the upper canopy of this low forest (average = 9,1 m; se = 2,72; n = 20). Fifteen ant species were sampled. Brachymyrmex heeri Forel was the most abundant in the nodes, while Camponotus crassus Mayr (Hymenoptera: Formicidae) was the most abundant in the internodes. The composition of the species that inhabit the internodes was different from the composition in the node (Q-test: Q = 3,76; P = 0,05). The level of occupation was defined by the number of holes (F = 10,33; P < 0,01), the number of internodes in the canopy (F = 6,84; P = 0,01) and the length of the culm (F = 7,52; P = 0,01). The plant's morphology allowed the occurrence of additional species of ants in the canopy and influenced the composition of the entire ant assemblage.