Hydrogenotrophic methanogenesis is the dominant methanogenic pathway in neotropical tank bromeliad wetlands.

Several thousands of tank bromeliads per hectare of neotropical forest create a unique wetland ecosystem that emits substantial amounts of CH . Tank bromeliads growing in the forest canopy (functional type-II tank bromeliads) were found to emit more CH than tank bromeliads growing on the forest floor (functional type-I tank bromeliads) but the reasons for this difference and the underlying microbial CH -cycling processes have not been studied. Therefore, we characterized archaeal communities in bromeliad tanks of the two different functional types in a neotropical montane forest of southern Ecuador using terminal-restriction fragment length polymorphism (T-RFLP) and performed tank-slurry incubations to measure CH production potential, stable carbon isotope fractionation and pathway of CH formation.

Potential NO Emissions from the Tanks of Bromeliads Suggest an Additional Source of NO in the Neotropics.

We studied the propensity of the tank bromeliad Werauhia gladioliflora to emit the greenhouse gas nitrous oxide (NO) at current and at increased N deposition levels in the range of predicted future scenarios. Potential production rates and net accumulation of NO from tank substrate corresponded to N availability. NO was produced in excess at all N levels due to a low level of NO reductase activity which agreed well with a low abundance of NO reducers compared to nitrite reducers.

Drying effects on archaeal community composition and methanogenesis in bromeliad tanks.

Tank bromeliads are highly abundant epiphytes in neotropical forests and form a unique canopy wetland ecosystem which is involved in the global methane cycle. Although the tropical climate is characterized by high annual precipitation, the plants can face periods of restricted water. Thus, we hypothesized that water is an important controller of the archaeal community composition and the pathway of methane formation in tank bromeliads.

Tropical Andean forests are highly susceptible to nutrient inputs--rapid effects of experimental N and P addition to an Ecuadorian montane forest.

Tropical regions are facing increasing atmospheric inputs of nutrients, which will have unknown consequences for the structure and functioning of these systems. Here, we show that Neotropical montane rainforests respond rapidly to moderate additions of N (50 kg ha(-1) yr(-1)) and P (10 kg ha(-1) yr(-1)). Monitoring of nutrient fluxes demonstrated that the majority of added nutrients remained in the system, in either soil or vegetation.