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Of bogs, mosses, and spruce trees:
Early results from the Frost Phytotron

Hikers in the Colorado foothills are unlikely to run across a peat bog--that is, unless they venture into the Frost Phytotron at NCAR's Mesa Laboratory. Here, for two years, a team of ecologists has been studying the effects of changes in the atmosphere on ten tiny peat bogs and a group of potted oak, spruce, and pine trees.

The phytotron, funded by a grant from the Frost Foundation of Denver, offers a controlled environment in which to study how changes in the composition of the atmosphere affect the biosphere. Temperature, humidity, and light in the greenhouse-like facility can be very tightly regulated to maintain required experimental conditions.

Besides its initial grant, the Frost Foundation has also paid for a photosynthesis measurement system for the lab, which was installed last year, and a mini-rhizotron, which measures root growth and biomass. The mini-rhizotron arrived in November.

Two years is not a long time for a study of plant growth, especially of trees. However, several ongoing projects have produced results--in one case, more results than the investigator was ready for.

Lee Klinger in the Frost Phytotron. (Photo by Carlye Calvin)

Lee Klinger of NCAR's Atmospheric Chemistry Division was preparing an experiment on the role of mosses in forest decline. In the field, Klinger had found that flourishing moss growth around trees, especially in regions with acid precipitation, accompanies dead "feeder" tree roots. To prepare for the experiment, Klinger brought 30 healthy red spruce trees into the phytotron. As Klinger tells it, "Moss spores from the bogs quickly invaded the soils around all the potted trees. Before I was able to take baseline growth data, the mosses invaded the trees, and many nearly died.

"In a way it was great news, because it was the kind of phenomenon we expected and we wanted to study," he says optimistically. "But it's nothing you could publish." The pre-experiment took a turn for the better, however, when Klinger tried adding mineral pellets around the trees. These succeeded in inhibiting moss growth, and every treated tree is now growing again. With the mini-rhizotron, the controlled experiment can now begin.

For further information on this and other phytotron projects, contact Klinger at 303-497-1474 or klinger@ucar.edu.

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Edited by Carol Rasmussen, carolr@ucar.edu
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Last revised: Tue Apr 4 10:18:15 MDT 2000