Size of Douglas-fir trees in relation to distance from a mixed red alder - Douglas-fir stand

Abstract

Variation in diameter, height, and stem volume of 57-year-old Douglas-fir(Pseudotsuga menziesii var. menziesii (Mirb.) Franco) was related to distance of these trees from a 27 m wide strip in the same Douglas-fir plantation that had been interplanted with red alder (Alnus rubra Bong.). Within the interplanted strip and despite its greater total stand density, bole volume of dominant and codominant Douglas-fir averaged 1.27 m 3 compared with 0.55, 0.45, 0.46, or 0.49 m 3 in trees 15, 30, 45, or 60 m, respectively, from the edge of the mixed stand. Some positive influence of nitrogen-fixing red alder apparently extended about 15 m beyond the edge of the mixed stand at this poor quality site in southwest Washington. We infer that similar ribbon-like distributions of naturally regenerated red alder could be retained to improve growth of nearby conifers on nitrogen-deficient sites.

Citation

Miller, R.E.; Reukema, D.L.; Max, T.A. 1993. Size of Douglas-fir trees in relation to distance from a mixed red alder - Douglas-fir stand. Canadian Journal of Forest Research. 23: 2413-2418