Two objectives of this research were to identify fungi which are
mycorrhizal with western hemlock and to examine the ecology of hemlock
mycorrhizal fungi indigenous to outplanting sites. Another objective
was to evaluate the effectiveness of mycorrhizal inoculation in
improving the performance of outplanted hemlock seedlings.
A list of over 100 mycorrhizal fungi associated with hemlock in
the field was compiled. Many of these were tested in pure culture
synthesis showing that 18 of them were indeed capable of mycorrhiza
formation with hemlock. Due to the frequency with which mycorrhizal
hemlock seedlings are found on rotten wood, an additional 18 wood
inhabiting fungi were tested with hemlock in pure culture synthesis.
Five of these proved to be capable of mycorrhiza formation. Field
observations indicate that four more are mycorrhizal with hemlock
growing in rotten wood.
Nonmycorrhizal western hemlock seedlings planted on two clearcuts
in western Oregon were readily colonized by indigenous mycorrhizal
fungi. Examination of excavated seedlings every two weeks showed a
gradual increase in the proportion of short roots colonized by mycorrhizal
fungi through the season. The first mycorrhizae appeared two months after planting.
Another experiment showed that nonmycorrhizal containerized
hemlock seedlings survived and grew well on both rotten wood and
mineral soil. Mycorrhizal colonization took place at the same rate
and in the same total numbers in rotten wood and mineral soil.
Finally, two outplanting studies were done to compare the
performance of mycorrhizal and uninoculated hemlock seedlings. The
first of these compared the survival and top growth of two year old
containerized western hemlock seedlings outplanted on three plots in
each of two areas. Mycorrhizal inoculation significantly improved
seedling top growth for two years after planting in both of the areas.
Survival was not improved in either area by mycorrhizal inoculation.
The second study compared survival, root growth and top growth for
outplanted mycorrhizal and uninoculated seedlings on both mineral
soil and rotten wood. No growth or survival differences between
mycorrhizal and uninoculated seedlings were seen on either substrate
the first season after planting.
Two additional experiments testing rotten wood as mycorrhizal
inoculum were done to support the above observations. They demonstrated
that rotten wood can indeed serve as a habitat for mycorrhizal
fungi
