Document: KIR-3-37-6

Moss mediation of site occupation in two monkeyflowers.

KIRKPATRICK, H.E.* and J.W.S.BARNES

University of Puget Sound, Tacoma, WA, U.S.A. 1

Abstract:
Mimulus lewisii and M. tilingii occur together along streams at moderate to high elevations on the west side of the Washington Cascades. Most commonly, M. lewisii occupies the streambanks whereas M. tilingii occupies the streambeds, usually associated with a thick layer of emergent moss. We investigated the role of moss as a potential mediator of this microhabitat separation of the two species. To test the effects of moss on germination and early establishment of each monkeyflower species, we scattered field-collected seeds of either M. tilingii or M. lewisii over 4 trays of potting soil, then covered one tray of each species with field-collected moss 1 in deep. After 10 weeks, we counted the number of emergent seedlings in each tray. Moss cover decreased seedling establishment for M. lewisii much more drastically than for M. tilingii (X2, P<0.0001). Moreover, many plants of M. tilingii established in the M. lewisii trays despite no intentional planting of M. tilingii in these trays. To test effects of moss on growth of established monkeyflower seedlings, individual seedlings of each species, in separate pots, were surrounded with field collected moss and growth was compared to seedlings in the same conditions but without moss (n=15 per treatment combination). After 4 mo growth, both species had gained more biomass with moss present than absent, although this difference was significant only for M. lewisii (ANOVA, P=0.0014 and P=0.1501). These results suggest that moss acts as a seed bank for M. tilingii but not for M. lewisii, and that the presence of moss might be responsible for the general exclusion of M. lewisii from, and contribute to the success of M. tilingii in, the streambeds. The mechanism that excludes M. tilingii from the streambanks is still under investigation.

Keywords: moss, Mimulus, microdistribution

 Abstracts by Session: Symposia, Oral, Poster
Abstracts Listed by Title/Reference Number
Schedule of Sessions in Chronological Order
Sr. Author and Co-Authors
Information updates, contact source
Snowbird 2000 Program Web Site
Snowbird Page on the ESA Web Site

This abstract is being presented at: 10:30 AM in session:
PLANT DEMOGRAPHY