With the increasing scarcity of timber, forest managers need to know how much they can increase forest volume and value yield from intensive forestry practices, which include thinning, pruning, and fertilization. Many studies have looked at fertilization of Douglas-fir stands in the commercial-thinning size and age range. A few studies have looked at pruning Douglas-fir. It is well known that fertilization can profitably be combined with proper thinning regimes, but no studies in the Oregon Coast Range have investigated the combined effects of pruning and fertilization on young, precommercially thinned Douglas-fir stands.
The practice of fertilizing Douglas-fir is well founded. Trials established by the Pacific Northwest Stand Management Cooperative research program at the University of Washington have demonstrated its efficacy, and forest fertilization is practiced operationally on thousands of acres each year. The most cost-effective programs fertilize thinned stands that can be harvested or thinned again in 6-10 years. This approach minimizes the length of time between investment and return.
Recent studies by the PNW Research Station have demonstrated that trees pruned 20-30 years ago will produce enough value when they are properly milled to more than pay for the investment in pruning. Moreover, pruned stands could eventually provide high-quality, clear wood--a commodity that has become scarce as old-growth and mature forests have been logged off or put into reserves. Internationally, forestry enterprises have already begun investing heavily in pruning; New Zealand is a good example.
Our objectives in this study are to determine the efficacy of fertilizing young, precommercially thinned Douglas-fir stands and young, pruned, precommercially thinned Douglas-fir stands; and to quantify the growth, form, and branch size of trees in fertilized and unfertilized plots in stands that have: 1) had no treatment, 2) been precommercially thinned, and 3) been precommercially thinned and pruned. Our approach is to investigate the earliest possible opportunity to capitalize on the well-known growth response produced by fertilizing thinned stands; i.e., at the time of the first commercial thinning. The study will be conducted on Menasha Corporation lands near Coos Bay. The area is located within a 15-minute drive from Coos Bay and is adjacent to the Menasha Demonstration Forest.
This year, we laid out study plots, randomly assigning six treatments in three replications. All plots are within a few miles of one another. We installed precommercial thinning, pruning, and fertilization treatments, collected and summarized data on initial post-treatment conditions, and made a site-coordination visit. Still to be done this year is the writing of an establishment report.
This study complements other COPE studies that address intermediate stand treatments, an area of concern that emerged in 1992.
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