Evidence for older carbon loss with lowered water tables and changing plant functional groups in peatlands.

A small imbalance in plant productivity and decomposition accounts for the carbon (C) accumulation capacity of peatlands. As climate changes, the continuity of peatland net C storage relies on rising primary production to offset increasing ecosystem respiration (ER) along with the persistence of older C in waterlogged peat. A lowering in the water table position in peatlands often increases decomposition rates, but concurrent plant community shifts can interactively alter ER and plant productivity responses.

The relationship of C and N stable isotopes to high-latitude moss-associated N fixation.

Moss-associated N fixation by epiphytic microbes is a key biogeochemical process in nutrient-limited high-latitude ecosystems. Abiotic drivers, such as temperature and moisture, and the identity of host mosses are critical sources of variation in N fixation rates. An understanding of the potential interaction between these factors is essential for predicting N inputs as moss communities change with the climate.

The bacterial communities of Alaskan mosses and their contributions to N-fixation.

Background: Mosses in high-latitude ecosystems harbor diverse bacterial taxa, including N-fixers which are key contributors to nitrogen dynamics in these systems. Yet the relative importance of moss host species, and environmental factors, in structuring these microbial communities and their N-fixing potential remains unclear. We studied 26 boreal and tundra moss species across 24 sites in Alaska, USA, from 61 to 69° N.