|Red alder has long been considered an undesirable competitor with its coniferous associates. More recently, management for red alder has been encouraged, in view of its potentially fast juvenile growth rates, ability to fix substantial quantities of atmospheric nitrogen (N2), immunity to laminated root rot, Phellinus weirii, a serious pathogen of coastal Douglas-fir forests, suitability as a source of valuable wood products, and contribution to habitat diversity in a conifer-dominated landscape. Recognition of alder’s value is reflected in consistently increasing prices for alder logs in British Columbia, Oregon, and Washington, with log prices exceeding those of second-growth Douglas-fir in Oregon and Washington and of hemlock in coastal B.C. Market demand for alder lumber is high within and outside of North America (Mason 2006). Increased harvest of mature alder has led to concerns that the current inventory of red alder will not meet projected demands (Weyerhaeuser BC Coastal Group 2005). Long-term research in progress across the range of the species (Courtin et al. 2002; Bluhm and Hibbs 2006) demonstrate that maximum log quality and value depend on density management and pruning beginning early in plantation development. Recent studies have shown that growth of young red alder in coastal British Columbia may be limited by deficiencies of phosphorus (P) even in soils classified as rich to very rich (Brown and Courtin 2003a,b; Brown and Courtin 2006). Seedlings fertilized with phosphorus within a year of planting exhibited three year increases in volume of 45-96% in single-tree plot experiments and comparable increases in more-recently established multi-tree plot experiments. P additions increased foliar P concentrations, but also increased foliar N concentrations, suggesting that P additions increased N2 fixation or soil N uptake. Adding elements other than N and P also increased growth and foliar concentrations of N (and some other elements), but increases were smaller and less consistent across sites than when P was added (Brown and Courtin, in press). The potential for fertilization at planting to reduce the time required to reach free to grow status has stimulated operational fertilization at planting experiments by licensees in coastal B.C. The longer-term effects of P additions on alder growth are unknown. Effects of P additions on growth of conifer plantations in P-deficient soils have been reported to persist through an entire rotation (Turner et al. 2002) and effects of P fertilization of hybrid poplars on eastern Vancouver Island were detectable 10 years after fertilization. Given the increasing demand for alder logs and the short (25-40 year) rotations envisioned for alder under intensified management (Bluhm and Hibbs 2006), it is important to determine the long-term effects of P additions on growth of red alder. In this project, we propose to re-measure stem growth from three sets of alder fertilization experiments, consisting of: 1. 5 single-tree plot fertilization experiments, established in 1998-9 in plantations across a range of soil moisture and nutrient regimes between Fanny Bay and Campbell River 2. 1 multi-tree plot fertilization experiment established in 2001 and located on a moderately dry site near Bowser 3. 3 multi-tree experiments established in 2004 near Powell River and in 2005 near Campbell River and Sayward on moist and rich sites We propose a 3 year study, with re-measurement of trees in all experiments in year 1 and re-measurements of experiments 2 and 3 in years 2 and 3 of the study. Frequent re-measurements of fast-growing species such as alder are critical early in stand development in order to document changes in growth and mortality with variation in soil moisture and increases in tree size. Experiments in group 1 received P at rates ranging from 0 – 30g P per tree, with or without a blended fertilizer containing other elements, within a year of planting. Responses have been reported for 3 years following fertilization (Brown and Courtin in press). Experiment 2 has received P (only) in multiple additions since 2001, and responses have been reported through 4 years (Brown and Courtin 2006). Group 3 experiments received 0, 30, or 60 g of P per tree immediately after planting. Significant responses have been documented through 2 growing seasons. The existence of these experiments and documentation of early growth responses provides an excellent opportunity to assess how long P fertilization effects persist. |
References: Bluhm and Hibbs, 2006. In Red alder: a state of knowledge. USDA GTR-669; Brown and Courtin 2003. Can J For Res 33:2089-2096; Brown and Courtin 2003. BCMOF Vancouver Reg. EN-019; Brown and Courtin 2006. In Red alder: a state of knowledge. USDA GTR-669; Brown and Courtin, West. J. Appl. For., in press; Courtin, Brown and Harper 2002. BC MOF Vancouver Reg EN-008; Mason, 2006. In Red alder: a state of knowledge. USDA GTR-699. Turner et al. 2002. For Sci 48:556-568.