Bryological and Lichenological Section/ABLS
Deines, Lynell , Barkes, Tara , Rosentreter, Roger , Serpe, Marcelo .
Germination and seed water status of two annual grasses on lichen-dominated biological soil crusts.
BIOLOGICAL soil crusts dominated by lichens are commonly found throughout arid and semiarid steppe communities of the Great Basin of North America. We conducted growth chamber experiments to investigate the effect of these crusts on seed germination of Bromus tectorum and Vulpia microstachys. For these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one dominated by the lichen Diploschistes muscorum (lichen crust) and the other comprised of various lichens and mosses (mixed crust). On the lichen crust, the germination percentage was about a third of that on soil. Furthermore, the mean germination time was three to four days longer on the lichen crust than on soil. In contrast to the lichen crust, the mixed crust did not reduce germination or increase the mean germination time. Similar results were observed in the two species studied. To investigate the mechanism by which lichen-dominated crusts affected germination, we analyzed the water status of seeds on soil and biological soil crusts. Five days after seeding, the water content of seeds on soil was approximately three to four times higher than that of seeds on the lichen crust. Similarly, the water potential of seeds on soil was significantly higher than that of seeds on the lichen crust. The low water status of seeds on the lichen crust was related to a rapid rate of drying of the lichen surface. Twenty four to 48 h after watering the water potential of the lichen crust was significantly lower than that of the soil and mixed crust surfaces. Our results indicate that biological soil crusts with dissimilar composition can have different effects on seed germination. Moreover, a biological soil crust dominated by the lichen Diploschistes muscorum had a negative effect on seed water status and significantly reduced seed germination.
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1 - Boise State University, Department of Biology, 1910 University Drive, Boise, Idaho, 83725-1515, USA
2 - USDI Bureau of Land Management, Boise, Idaho, 83709, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM