Six-year growth of Douglas-fir saplings after manual or herbicide release from coastal shrub competition.

Abstract

This publication reports research involving pesticides. It does not contain recommendations for specific uses, nor does it imply that the uses reported on currently are registered. All uses of pesticides must be registered by appropriate State and Federal agencies before they can be recommended. CAUTION: Pesticides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife-if they are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the disposal of surplus pesticides and pesticide containers. Pesticide Statement WILLIAM I. STEIN is a principal plant ecologist (emeritus), Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331. Author Stein, William I. 1999. Six-year growth of Douglas-fir saplings after manual or herbicide release from coastal shrub competition. Res. Pap. PNW-RP-500. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 55 p.Survival and growth of planted Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) saplings and associated shrubs were observed after seven release treatments had been installed side by side in a large-scale experiment replicated on four areas in the Coast Ranges of Oregon. After 6 years, total height, stem diameter, and crown radius of Douglas-fir were greater in treated areas than in untreated areas. Four times as much Douglas-fir volume as in the control was produced by one manual cutting of competing brush, which also represented the best economic return. Trees subjected to a second and third manual treatment did not grow as much as those with one manual treatment nor did those released with glyphosate or fosamine herbicide or a combination manual plus fosamine treatment. Survival averaged 95.9 percent during the 6-year period.Six years after treatment, shrub cover was significantly greater around trees in untreated than in treated areas but did not differ significantly in average height. Dominant competitors in untreated areas averaged nearly two-thirds of tree height, those in treated areas only one-third. Effects of herbicide treatment were most visible on red alder (Alnus rubra Bong.), salmonberry (Rubus spectabilis Pursh), and red elder (Sambucus callicarpa Greene). Diversity of competing species temporarily increased after release treatments.In the highly productive forests of the Pacific Coast Ranges, competition from fastgrowing shrubs can reduce the survival and slow the growth of planted Douglas-fir (Pseudotsuga menziesii (Mirb) Franco). 1 Overtopping by competitors and concurrent setbacks from animal damage can be major impediments to development of fastgrowing, well-stocked stands. Though release effects of some herbicides were well known when the study was started, results achievable with newer selective herbicides and by manual methods were fragmentary, and these release methods had not been compared directly. This cooperative endeavor, initiated in 1980-81 between the Siuslaw National Forest and the Pacifi...

Harvest residue and competing vegetation affect soil moisture, soil temperature, N availability, and Douglas-fir seedling growth

“…Numerous studies have demonstrated that Douglasfir seedlings are capable of responding positively to reductions in cover or biomass of competing vegetation (Gratkowsi and Lauterback, 1974;Preest, 1977;Dimock et al, 1983;Miller and Obermeyer, 1996;Stein, 1999). Relatively few, however, have explicitly correlated growth responses to changes in site resource availability.…”

Natural tree regeneration and coarse woody debris dynamics after a forest fire in the western Cascade Range

“…A different postfire study, from northern California, shows steady ongoing establishment over more than a decade (Shatford et al 2007 simultaneous regeneration of shrubs alongside seedlings can hinder survival and growth of planted seedlings (e.g., Stein 1999). However, Shatford et al (2007) found no interference.…”

“…Whereas experimental work in harvested areas has demonstrated that mechanical removal of shrubs can increase the growth of planted P. menziesii seedlings (Stein 1999), in a more natural setting encroaching and even overtopping vegetation may provide a measure of heat and moisture protection for seedlings and saplings (Irvine et al 2009), allowing them to survive until they overtop the shrub canopy.…”

The Fall River Long-Term Site Productivity study in coastal Washington: site characteristics, methods, and biomass and carbon and nitrogen stores before and after harvest.

“…Positive effects of competition control on seedling growth have been associated with increased soil water availability (Flint and Childs 1987, Newton and Preest 1988, Watt et al 2003, nutrients Nambiar 1995, Zutter et al 1999), or both (Elliott andWhite 1987, Powers andReynolds 1999). Douglas-fir seedlings responded positively to reductions in cover or biomass of competing vegetation (Dimock et al 1983, Miller and Obermeyer 1996, Roberts et al 2005, Stein 1999), but few studies have correlated growth responses to changes in resource availability or uptake. Average increases of 16 percent in bole diameter of Douglas-fir seedlings were recorded after 2 years of chemical release from shrub competition on a loamy-skeletal Typic Xerochrept in a dry site in southwest Oregon (Flint and Childs 1987).…”