In this study I assessed the potentials of selected,
established perennial grasses to maintain site occupancy in
the foothills ecosystem of the Rogue River Valley of
southwest Oregon which is currently dominated by a variety
of annual plants.
The first evaluation compared growth curves of the
perennial grasses and contrasted them to growth patterns of
residual annual plants. Periods of growth varied among the
perennial grasses studied. Of the perennial grasses, Idaho
fescue (Festuca idahoensis), a native, and Berber
orchardgrass (Dactylis glomerata var. 'Berber'),
introduced, most closely emulated the growth patterns of
the majority of the annual plants. Relative to the other
perenial grasses tested, they initiated growth earlier,
continued some growth through the winter and matured
earlier. Once established, they should be able to
effectively compete with the resident annuals for resources
and maintain their populatiOhs.
To assess the potential for competition for available
moisture, the second evaluation considered timing and
extent of soil moisture extraction by the perennial grasses
and the resident annual community through the periods of
active growth. This verified growth analysis results.
Idaho fescue and Berber orchardgrass extracted moisture
earlier than the other perennial grasses. Perennial grass
plots and plots dominated by yellow starthistle (Centaurea
solstitialis) end of season residual soil moisture levels
were similar. Resident annual grasses left considerably
more soil moisture. In years with an early summer drought,
the earlier growing perennial grasses should be able to
satisfy growth requirements and persist.
An assessment was also made of the abilities of
several selected established perennial grasses to resist
reinvasion by resident annual plants. Earlier growing
perennial grasses such as Berber orchardgrass and Idaho
fescue suppressed the annuals more effectively than the
later growing perennial grasses.
Of the perennial grasses studied, those emulating the
growth patterns of the annuals have been the Most
competitive and have maintained the most vigorous stands. / Graduation date: 1990
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/38135 |
| Date | 13 June 1989 |
| Creators | Borman, Michael M. |
| Contributors | Krueger, William C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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