Record ID No. |
1857 |
Author(s) |
Prescott C.E., Sajedi T , 2008 |
Affiliation |
Univ British Columbia, Fac Forestry, Dept Forest Sci, 2005-2424 Main Mall, Vancouver, BC V6T 1Z4, CANADA |
Title |
The role of salal in forest regeneration problems in coastal British Columbia: problem or symptom? |
Source. Vol.(no):Page |
Forestry Chronicle.84(1):29-36p. |
Categories |
Mycorrhiza General |
Subjects |
Biochemistry |
Sub-subjects |
Miscellaneous |
Organism |
n.a. |
Country |
CANADA, Central America |
Abstracts |
The ericaceous shrub, salal (Gaultheria shallon Pursch) is associated with forest
regeneration problems on a variety of site types along the west coast of North America. On dry
sites, salal is a serious competitor for water; on wet (cedar-salal) sites, salal is thought to
limit nutrient availability to trees by competing, interfering with mycorrhizae and
''short-circuiting'' the nitrogen cycle through production of phenolic compounds. Short-term
field experiments and laboratory and greenhouse studies provided some evidence of each of these
effects. However, long-term results from a suite of silvicultural trials and associated
ecological studies indicated that salal is not the fundamental problem for regenerating conifers
on cedar-salal sites. Fertilization of cedar-salal sites caused a large and sustained response in
tree growth regardless of the presence of salal, and growth responses to salal removal were much
smaller than fertilization responses. Greenhouse experiments indicated that salal does not have
allelopathic effects on germination or growth of conifer seedlings. In laboratory studies, salal
did not demonstrate a greater capacity to take up organic N forms than the conifers, and
molecular studies uncovered a vast diversity of mycorrhizal fungi associated with salal and
hemlock roots. Together these findings indicate that the nutrient ''short-circuiting''
hypothesis, based on assumptions about ericoid versus non-ericoid mycorrhizal plants does not
adequately describe the nutrition of plants in these ecosystems. We conclude that salal should be
viewed as a symptom of the underlying problem of poor nutrient supply on cedar-salal sites, and
that fertilization, rather than salal control, is the optimal solution for improving forest
regeneration on thesesites. |