Margaret Bornyasz
M.S. 2003
(co-advised by Michael Allen, Director, Center for Conservation Biology, UCR)
Thesis Title:
- Distribution of coast live oak woodland mycorrhizae in a soil-weathered bedrock regolith.
Currently:
- Plant Ecologist/Soil Scientist, M.J. Klinefelter, GIS and Environmental Consulting, Temecula, CA.
Publications from Thesis Research:
- Bornyasz, M.A., R.C. Graham, and M.F. Allen. 2005. Ectomycorrhizae in a soil-weathered granitic bedrock regolith: Linking matrix resources to plants. Geoderma 126:141-160.
Synopsis:
- Margaret studied the spatial distribution of coast live oak (Quercus agrifolia) mycorrhizae and fungal hyphae in thin soils and underlying deeply weathered granitic bedrock at Santa Margarita Ecological Reserve in southern California. Within the bedrock, roots are confined to fractures, but water is held throughout the porous matrix of the weathered rock. Mycorrhizal hyphae have been shown to act as water conduits and can transport water to the host roots. They are also of sufficiently small diameter that they can penetrate the micropores in the weathered bedrock. For an evergreen mycorrhizal obligate such as Q. agrifolia, the existence of deep mycorrhizae may be essential for meeting annual water requirements, especially in this dry Mediterranean-type ecosystem.
Map of southern California showing coast live oak habitat range, distribution of granitic terrain, and the study site location northeast of San Diego.
A cross-section was exposed, gridded, key features were logged, and the materials sampled.
(a) Photomosaic of the study profile and (b) scaled diagram showing the soil (gray) and weathered bedrock (white) areas with major fracture-features (solid lines), selected faint fracture-features (dashed lines), sampled weathering profiles (1-11), and sample locations for soil moisture (solid circles), sample locations for intact cores (open circles), roots (capital letters). Dashed white lines in photomosaic delineate parent material boundaries.
Margaret collecting samples for mycorrhizal analysis.
Margaret examining roots for evidence of mycorrhizal infection.
Comparison of hyphal length density values in the fractures and in the matrix of the different lithologies. Hyphal length density was greatest in the soil, but hyphae were also found in both the fractures and matrix of the underlying weathered bedrock.
The formation of mycorrhizae in weathered bedrock fractures, and hyphal extension into the matrix, provides a critical link for transporting water from the rock matrix and the plant.