- Salmonberry community structure was examined in alder-dominated
riparian buffer strips in the Oregon Coast Range. Salmonberry growing on slopes
was found to respond differently, to both characteristics of the buffer strips and
to environmental factors, than salmonberry growing on terraces.
Salmonberry, as measured by total height, number of ramets or sprouting
centers, cover, and estimated biomass, was found to increase with increasing light
on the slopes. Salmonberry cover, height and number of ramers were all found
to be greater on slopes within buffer strips, than on slopes in undisturbed riparian
stands, where the adjacent stand had not been cut and no buffer created. The
greater dominance of salmonberry within buffer strips was attributed to increased
sidelight into the riparian area, due to the hest of the adjacent stand. None of
the four salmonberry characteristics were found to be related to light on the
terraces. Salmonberry height, cover, number of ramets, and biomass on terraces
did, however, all increase with increasing age of the buffer strip.
There did not appear to be any clear edge effect on salmonberry within the
buffer strips. An index of herbaceous vegetation was developed, through
ordination, to examine the effects of unquantified environmental factors on
salmonberry. Disturbance appeared to play a role in the variation seen in the
Salmonberry's aerial stem diameter distribution, both within buffer strips
and in undisturbed stands, resembled an uneven-aged distribution. Sairnonberry
stem distribution followed the same pattern whether on slopes or terraces. This
suggests persistent, self-replacing salmonberry stands in these alder-dominated
Salmonberry was found to be negatively correlated with herb, vine maple,
and swordfern cover, and also with herbaceous species abundance. There was
no relationship between salmonberry and elderberry cover. Tree regeneration
was found to be extremely sparse. Only one alder seedling per hectare was found
in the undisturbed riparian stands. There were 29 seedlings per hectare found
within the buffer strips, 22 of which were conifers.
The four salmonberry community variables increased in response to buffer
strip creation when growing on both slopes and terraces. Salmonberry was shown
to have a self-replacing canopy, and to dominate other shrubs and herbs in the
riparian community. These factors, along with the lack of tree regeneration in these alder-dominated riparian areas, all suggest that without silvicultural
intervention salmonberry could eventually dominate the riparian community.