Jc. Tappeiner et al., Salmonberry and salal annual aerial stem production: the maintenance of shrub cover in forest stands, CAN J FORES, 31(9), 2001, pp. 1629-1638
Citations number
37
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
Annual sprouting of aerial stems and ramets enables populations of salmonbe
rry (Rubus spectabilis Pursh), salal (Gaultheria shallon Pursh), and probab
ly other forest shrubs to maintain dense covers (> 20 000 stems/ha). We stu
died annual stem production of salmonberry on cut (all stems cut within 15
cm of the ground) and uncut (stems were not treated) plots for 8 years and
salal for 5 years in the understories of Douglas-fir (Pseudotsuga menziesii
(Mirb.) Franco), alder, and riparian stands, as well as clearcuts, which a
re all common stand types in western Oregon. Mean salmonberry stem producti
on on uncut plots ranged from 4.7 stems.m(-2).year(-1) (95% CI 2.9-7.4) in
alder stands and clearcuts to 1.6 stems.m(-2).year(-1) (95% CI 1.0-2.6) in
conifer stands. Mean salal production was greater, ranging from 58 stems.m(
-2).year(-1) (95% CI 25-135) to 8.6 stems.m(-2).year(-1) (95% CI 3.7-20.1)
on uncut plots in clearcuts and unthinned Douglas-fir stands, respectively.
Annual production of both species was somewhat greater on cut plots. Most
stems produced in early spring die by December, but enough are recruited to
replace mortality of older stems. Stem density was maintained for 8 years
for salmonberry and 5 years for salal on both cut and uncut plots. Based on
length of rhizomes and bud density we estimate that only 1-5% of the buds
in the rhizomes are needed to support this annual stem production. Although
these species sprout vigorously after their aerial stems are killed, distu
rbance is not necessary for maintaining a dense cover. It appears that, onc
e established, salal, salmonberry, and probably other clonal forest shrubs
can maintain a dense cover that can interfere with establishment of trees a
nd other shrubs in canopy gaps or other openings.