Black spruce needle nitrogen concentration from 5 stands in 1999

We collected black spruce needle from several sites located near Fairbanks Ak, and Delta, Ak in August 1999 (Sites designated here as S1, S2, and S3) were located in Fairbanks (64o40?N, 148o15?W), Alaska (S1: 64o52.164? N, 147o51.462? W; S2: 64o52.058? N, 147o51.378? W; S3: 64o51.603? N, 147o52.789? W) with 2 additional sites (S4, S5) in Delta, Alaska (64010? N, 145030? W). In each stand, 30 trees were randomly selected for sampling. Within each tree, five shoots were collected from the southern aspect of the mid-canopy height from each of the following age classes: 0-, 1-, 4-, 9-, and 19-years old. In two of the Fairbanks stands (S2, S3), 19-year old needles were not present. A total of 690 samples over the five stands include 150 samples per stand in three stands (S1, S4, S5) and 120 samples per stand in the other two stands (S2, S3). Needles were returned to the lab and nitrogen content was determined. We used a three-factor nested analysis of variance (ANOVA) to evaluate differences in needle N concentration among the ages of needles on a tree, among trees nested within a stand, and among stands. Ages and stands were treated as fixed factors and tree was treated as a random factor. The ANOVA and means testing for these differences used Proc GLM in the SAS statistical package with needle N content as the dependent variable and needle age, tree, and stand as independent variables. The GLM procedure handled the problem of missing treatment combinations within the ANOVA. Type III sum of squares was used to test the effects of factors without interactions