Abstract:
General outcomes of this study show that early growth of planted red alder is often slowed in the presence of neighboring vegetation, and overwhelmingly by salmonberry, a common associate in disturbed Oregon Coast Range habitats. Additionally, young red alder plantations located in
riparian areas may be highly susceptible to frost injury or death and animal damage, particularly by beavers and mountain beavers.
Growth analysis of two- and three-year old red alder planted at seventeen planting densities in a type 1a Nelder design are represented in this study. Each density is also analyzed in the presence and absence of salmonberry-dominated "weedy" vegetation native to the Oregon Coast Range. Red alder volume growth was reduced with increasing
density of planted seedlings when salmonberry was not present, but intraspecific competition was eliminated in the presence of salmonberry. Red alder seedlings grew less in volume with salmonberry competition than at the highest
weed-free planting densities. Although salmonberry presence played a significantly
larger role in decreasing early growth of young alder than intraspecific competition among experimentally-induced planting densities, competition between individual red alder seedlings began at plantation age two, where alders were weed free and grew large enough to compete with other alders. Indications show that density competition between trees will increase as the stand develops. Drought stress did not significantly affect young red alder growth on these generally mesic sites. Among growth parameters, diameter and volume increment
and height:diameter ratios were the most sensitive indicators of planting density and shrub and herbaceous competition among young red alders. Therefore, these measurements may be used to best predict early competitive
stress in tree seedlings. Conversely, early height growth was too variable to be of significant predictive value for density and salmonberry competition effects. Study results imply that the successful establishment of red alder in Oregon Coast Range habitats may benefit from proper spacing of planted seedlings and minimizing the potential for salmonberry invasion, animal browsing and frost injury to trees in the initial years of stand development.
