Effects of Phosphorus Additions on Growth, Mineral Nutrition, and Gas Exchange of Red Alder (Alnus rubra) Seedlings Grown in Outdoor Sandbeds

Abstract

Abstract The growth of young red alder on Vancouver Island may increase with phosphorus (P) availability. In order to better interpret growth responses in field fertilization trials, this study examined the effects of P additions (10, 100, 200, or 400 kg P/ha) on the growth and nutrient uptake of red alder seedlings grown in outdoor sandbeds for one growing season. Height did not increase with P supply. Stem growth and whole-plant mass increased with P rate from 10 to 100 kg/ha, but did not increase further at greater rates of P addition. Stem volumes, averaged across the P100, P200 and P400 treatments, were 37% greater than in the P10 treatment. Volume and mass did not increase as foliar P concentrations exceeded 2.2 g P/kg. These responses were consistent with data from field trials. Reduced growth in the P10 treatment was not accompanied by significantly reduced foliar P concentrations. Increases in stem volume with P supply were associated with increases in the amount of branching and foliage borne on branches but not with shifts in allocation of dry matter from roots to shoots. West. J. Appl. For. 17(4):209–215.