Bryophyte reproductive response to long-term elevated CO2 flux on Horseshoe Lake at Mammoth Mountain, CA

Background/Question/Methods

A constant efflux of ground carbon dioxide has characterized Horseshoe Lake at
Mammoth Mountain CA since a group of earthquakes occurred underneath Mammoth Mountain
in 1989. The current constant ground leakage of carbon dioxide has been linked to a small body
of magma that rose through a fissure underneath Mammoth Mountain subsequent to the series of
1989 earthquakes and is the cause of decaying roots, dead trees, and the absence of vegetation on
over 100 acres near Horseshoe Lake. Bryophytes, specifically mosses, benefit from high
ambient carbon dioxide concentrations and use it to compensate for carbon dioxide lost through
respiration. Mosses have no means of storing carbon dioxide and can only utilize carbon dioxide
uptake for direct photosynthesis. Mosses are primary producers that can be used as preliminary
indicators of climate change, because they can assimilate carbon at a range of temperatures in a
damp or wet environment. In this study, we ask if an efflux of ground carbon dioxide can impact
reproductive traits in moss genera such as Polytrichum, Mnium, and Grimmia found on boulders,
streambeds, tree bark, and the ground.

Results/Conclusions

Specifically, we test whether these genera of mosses can
assimilate the elevated levels of carbon dioxide at a beneficial rate to photosynthesize and
reproduce across the three sections of the study area, the tree kill (dead) zone, the transitionary
zone, and the control (normal) zone. An initial objective is to quantify male and female
gametangia, the gamete producing structures on moss, to decipher if gametangial formation
variation occurs across the three abiotically and biotically differing sections of the study area.
From this study we expect to further research the effects of long-term elevated CO2 exposure on
mosses and decipher if they show any variance in reproductive potential and persistence. One of
the ultimate goals of research at Horseshoe Lake is to characterize the biotic and geochemical
effects of escaped ground CO2, as this escape of CO2 gas could be a consequence of future
attempts to sequester excess greenhouse gasses underground.