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Termites play important roles in tropical ecosystem functioning, and their evolutionary success has been linked to their defense mechanisms. However, microhabitat overlap with potential aggressors may constrain their distribution and thus, their environmental impacts on an ecological timescale. We investigated a possible negative effect of abundant generalist ants (Azteca sp.) on the termite Neocapritermes braziliensis. Both taxa frequently build their nests attached to trees. We determined the densities of their active nests in 10 plots (250 × 10 m) systematically distributed over 5 km2 in central Amazonia, Brazil, and recorded their co-occurrence in individual trees. Using generalized nonlinear modeling in a Bayesian framework, we found good support for a negative effect of Azteca's nest density on N. braziliensis. This effect conformed to a power law, and accounted for more than half of the variation in the termite s nest density (r2 = 0.56). Additionally, of all counted N. braziliensis mounds, only 1.08 percent was attached to trees also hosting Azteca. Such patterns may have arisen due to N. braziliensis'inability to establish new nests within Azteca territories, or predation by ants on established colonies of the termite. We suggest that even non-strictly termitophagous ant species may have important impacts on termite populations and, consequently, on their roles in nutrient cycling and ecosystem engineering.

O pulso de inundação dos rios amazônicos impõe anualmente aos organismos que habitam as áreas alagáveis a alternância entre uma fase aquática e uma fase terrestre. Em resposta a inundação periódica as plantas desenvolveram adaptações e padrões específicos de crescimento. Montrichardia arborescens (L.) Schott é uma herbácea aquática de ocorrência nas áreas alagáveis por águas pobres em nutrientes (igapós), e Montrichardia linifera (Arruda) Schott ocorre em áreas ricas em nutrientes (várzeas). Este trabalho objetivou comparar ambas as espécies, ao longo de um ciclo hidrológico, quanto às taxas de crescimento, densidade dos talos, a biomassa, a fenologia, e quantidade de clorofila. Foi medida a concentração de macronutrientes (Ma) e micronutrientes (Mi) das espécies nas fases de cheia e seca. O estudo foi realizado no Curari, no rio Solimões (S 03°17’38,5”; W 059°55’47,9”), e na Praia Grande no rio Negro (S 03°02’18,9”; W 060°32’47,7”). Em oito pontos em cada ambiente foram marcados cinco talos com folhas (CF) e brotos sem folha (SF), para medir a altura e o número de folhas durante 11 meses. Na fase terrestre foram coletados todos os indivíduos das duas espécies presentes em 1m2 (n=10), para a determinação da biomassa seca. A densidade dos talos foi obtida pela diferença entre o peso fresco e peso seco de cinco talos de cada ponto (n = 50). Para a determinação de Ma e Mi nos tecidos das plantas, 10 plantas de cada espécie foram coletadas e feitas amostras compostas. Os talos CF de M. arborescens apresentaram maior taxa de crescimento em relação a M. linifera (F = 4,85; p < 0,05), porém, a taxa de crescimento dos brotos não diferiu entre as espécies (F = 3,22 p > 0,05). A biomassa entre as espécies tampouco diferiu significativamente (F = 0,22; p > 0,05). A densidade dos talos foi maior em M. arborescens (0.10g/m3) do que em M. linifera (0,05g/m3). A floração e frutificação ocorrem em dois picos, um na fase aquática e outro na terrestre. Durante a inundação a concentração de nutrientes sofreu redução de até 23% (Ma) e 27% (Mi) em M. arborescens; e de 14,21% (Ma) e 32,72% (Mi) em M. linifera; houve também redução na clorofila nas folhas das espécies (menos de 10%). Os resultados indicam que a espécie M. arborescens não apresenta restrições de crescimento no igapó. Investigações detalhadas sobre a evolução e genética dessas duas espécies são necessárias para poder elucidar sua distribuição diferencial nas áreas alagáveis amazônicas. The flood pulse of Amazonian rivers imposes on organisms that inhabit the floodplains, the alternation between a water phase and a terrestrial phase. In response to periodic flooding, plants have developed adaptations and specific growth patterns. Montrichardia arborescens (L.) Schott is an aquatic herb occurring in nutrient-poor floodplain (igapós), while Montrichardia linifera (Arruda) Schott occurs in nutrient-rich- floodplain (várzeas). This study aimed to compare the two species over a hydrological cycle, the growth rates, density of stems, biomass, phenology, and chlorophyll content. It was measure the macronutrient (Ma) and micronutrients (Mi) of the species in aquatic and terrestrial phases. The study was conducted in Curari, in the Solimões River (S 03 ° 17'38, 5 "W 059 ° 55'47, 9"), and Praia Grande on the Rio Negro (03 ° 02'18 S, 9 "; W 060 ° 32'47, 7 "). At eight points in each environment were scored five steams with leaves (CF) and shoots without leaves (SF) to measure the height and number of leaves during 11 months. In the terrestrial phase were collected all individuals of two species in 1m2 (n = 10) for the determination of dry biomass. The density of stems was established by the difference between fresh height and dry height of five stems at each point. (n = 50). For the determination of Ma and Mi in tissues plants, 10 plants of each species were collected and made composite samples. The stems of M. arborescens showed higher growth rate comparing to M. linifera (F = 4.85, p 0.05). The biomass among species was not significantly different (F = 0.22, p> 0.05). The stem density was higher in M. arborescens (0.10g/m3) than in M. linifera (0.05 g/m3). Flowering and fruiting occur in two peaks, one in phase aquatic and another in the terrestrial phase. There was little reduction in chlorophyll (less than 10%) in the species during flooding. There was also a reduction in nutrient concentrations of 23% (Ma) and 27% (Mi) in M. arborescens, and 14.21% (Ma) and 32.72% (Mi) in M. linifera. There were differences in the pattern of growth and size structure. The results indicate that the species M. arborescens has no restrictions for growth in igapó. Detailed investigations on the evolution and genetics of these two species are required which may elucidate its differential distribution in Amazonian floodplains.