The ectomycorrhizal fungi Cenococcum geophilum, Hebeloma
crustuliniforme and Laccaria laccata produced ethylene in vitro in
modified Melin-Norkrans liquid medium only if amended with 2.5 to
10 mM methionine; Pisolithus tinctorius failed to produce ethylene
unless the cultures were renewed with fresh methionine-amended
medium prior to ethylene assay. An additional 19...
Pollination ecology may play an important role in the maintenance of selfing in populations of self-compatible hermaphroditic plants where both selfing and outcrossing occur (mixed mating). Behavior and abundance of pollinators can influence the two major modes of selfing; autogamy (selfing within a flower) and geitonogamy (selfing between flowers on...
A new photosystem-II mutant of the green alga Scenedesmus
obliquus D₃, strain PS-28, has been shown to lack a-tocopherol
(vitamin E). The photosynthetic activity of dark grown samples of
PS-28 is about 20% of the wild-type control. Culturing the mutant
at low light intentisites (10⁴ ergs/sec-cm ²) stimulates photosynthetic
activity...
The vegetation of the Oregon coast is characterized by a
variety of stages of plant succession which are repeated widely
throughout the sand dune area. During the years from 1960 to 1963
the gradation of upland sand dune succession was studied on 48 plots
within a 150 mile section of...
The purpose of this study was to determine plant species composition, community structure, successional relationships, vegetational development and plant distributions in estuarine salt marshes on the Pacific Coast of Oregon.
Quadrat and transect samples of plant presence and cover, collected from April 1971 - June 1974, were subjected to phytosociological...
Alaska-cedar (Chamaecvparis nootkatensIs (D. Don) Spach) is a
valuable tree that is suffering from a serious decline and mortality of
unknown cause throughout southeast Alaska. Epidemiological and
pathological studies were initiated to determine if a pathogen is the
primary cause of this problem. By examining old aerial photographs and
by...
The Pacific Coast form of Douglas-fir in natural forest succession
is an intermediate species thriving in the Coast Range and
Cascade Mountains of the Pacific Northwest. This species constitutes
26 percent of the standing timber in the United States, and 24 percent
of the nation's annual timber harvest. Characteristics of...
The dynamics of stands in the mid-elevation old-growth
Douglas-fir (Pseudotsuga menziesii) forests of the central western
Oregon Cascade Range were investigated using stand structure
analysis. Trees with different growth rates were commonly present
in the same stand, which resulted often in a weak correlation
between tree diameter and age. Thus,...