Post-fire moss colonization and rehabilitation in forests of the Southwestern USA

With wildfires increasing in extent and severity in the Southwestern USA, practitioners need new tools to rehabilitate recently burned ecosystems. Fire mosses consist of three species, Ceratodon purpureus, Funaria hygrometrica, and Bryum argenteum, that naturally colonize burned landscapes, aggregate soils, and can be grown rapidly in the greenhouse. We explored the efficacy of fire moss as a passive and active postfire rehabilitation tool. First, we conducted a natural survey of moss colonization and function on 10 severely burned areas in the Southwestern USA. We tested 11 landscape scale predictors of fire moss cover and found that it is most strongly influenced by insolation, pre-fire vegetation type, soil organic carbon, and time since fire. We also found that, when compared to bare soils, fire mosses increase infiltration by 50% on average and soil stability by more than 100%. Using this information, we selected two study sites on which to inoculate greenhouse grown fire moss. Directly after a wildfire near Flagstaff, Arizona we added sieved moss, finely ground moss, and moss combined with diatomaceous earth and rolled into pellets (n=15). After two years of growth, B. argenteum was the only successful species and no treatment had attained more than 1% cover on average, pellet treated plots had higher moss colonization (p <.001).

Four months after a wildfire in the Jemez Mountains of New Mexico, we added greenhouse cultivated moss that was sieved as well as high and low cover of pellets (n= 12). After 1.5 years of growth, we found increased B. argenteum cover with a mean of 10.5% on plots that received high cover of pellets compared to 5.1% cover for controls (p= .02). Currently we are analyzing data to determine if this cover influenced point scale erosion and infiltration metrics. Our results indicate that fire mosses are functionally important colonizers of north facing severely burned hillslopes, however more research is necessary to develop them as an active rehabilitation tool.