Abstract:
I surveyed epiphytic macrolichens and bryophytes in six stands in each of
seven riparian stand types in the Oregon Coast Range. This study (Chapter 2)
describes the association of epiphytes with stand types and the corresponding
potential of forest canopy conversions to affect epiphyte communities. Species
composition, diversity, and representation of functional groups differed among
stand types. Epiphyte communities changed along a valley continuum, from higher
elevation, older, conifer-dominated stands along constrained stream reaches
bounded closely by slopes, to lower elevation, hardwood-dominated stands on
broad floodplains along unconstrained rivers or streams. Epiphyte communities
also appear to be affected by bark pH. We conclude that riparian canopy
conversions in the Oregon Coast Range have great potential to affect epiphyte
communities.
A transplant study (Chapter 3) examined whether canopy environment is
important in determining associations between lichen species and canopy type in
Oregon Coast Range riparian forests. The growth of four lichen species was
compared beneath three canopy types. If canopy environment is important in
determining the distribution of individual transplant species, then transplant species
should show growth response patterns under the different canopy treatments that
correspond to their known habitat preferences. We found that the survival, health
and growth of individual transplant species did not differ by canopy type, though,
as a group, lichen transplants were less healthy and did not survive as often under
bigleaf maple canopies. Hypogymnia inactiva grew less well and was less healthy
than the other three lichen species, though its survival rate was similar to that of the
other transplant species.
Chapter 4 supplements data presented in Chapter 2 by, (1) describing where
and with what abundance ROD-listed epiphyte species were found, (2) reporting
species found to be rare and, (3) reporting absent species that we had expected to
find. Of the nine ROD-listed "riparian" lichens, five were encountered in our
surveys. Sixteen additional ROD-listed lichen and 2 bryophyte species were
encountered during surveys. Of all the ROD-listed riparian species that were
encountered more than once, none were restricted to a specific stand type. Many
rare species (present in less than 5% of sampled stands) are more common on other
substrates or in nearby habitats. Though suitable habitat was available, we found
some lichen and bryophyte species less often than expected; these species may be
more rare than has been previously recognized. This information improves our
understanding of the habitat requirements of riparian epiphyte species and allows
us to assess their rarity within the Oregon Coast Range.
