Abstract Detail

Bryological and Lichenological Section/ABLS

Glime, Janice [1].

Do Rare Geothermal Habitats Have Rare Bryophyte Communities?.

Some taxa of bryophytes are common inhabitants of thermal fields throughout the world. In high latitudes, thermal areas maintain perennially unfrozen soil and maintain species as disjuncts from regions that have warmer climates. In Japan bryophytes restricted to heated soils in Hokkaido are found in non-vent areas on more southern islands. In Greenland, bryophytes associated with geothermal fields are often far north of their usual northern limits. Yet, in New Zealand, Marchantia berteroana appeared in scattered small patches on a geothermal field within three months of a minor eruption that covered the area with fresh ash. In Japan, Trematodon is common in front of vent openings. This is a genus that is intolerant of other vegetation and as a colonizer it soon disappears when other plants arrive. But near the vents, where the 15 cm soil temperature is above 50C, cryptogams dominate. Lichens, common slightly farther from the vent, are tolerant of low pH and high temperatures, but intolerant of continuous high humidity. In Iceland, 66% of the geothermal taxa are cryptogams, whereas heathlands have only 40%. Is disturbance an important component that maintains some rare species?
Based on the foregoing observations, I hypothesize that several factors contribute to the success of many bryophytes in geothermal areas on a worldwide scale: 1. Little competition is provided by tracheophytes, thus permitting the length of time needed for long-distance dispersal and establishment. 2. Conditions are sufficiently warm to permit the bryophytes to prosper and grow. 3. Prolific spores can contribute to the arrival of some and vegetative propagules for others, whereas vegetative fragments can contribute to new establishments locally. 4. Success of vegetative reproduction from small fragments and subsequent growth are facilitated by the humidity provided by the vents.

1 - Michigan Technological University, Department of Biological Sciences, 1400 Townsend Dr., Houghton, Michigan, 49931-1295, USA

Keywords:
bryophyte
Community-based Conservation
geographical distribution
lichens
temperature
rarity
disturbance.

Presentation Type: Paper
Session: 47-7
Location: Magpie (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 10:30 AM
Abstract ID:165