Variation in the foliar nutrient status of several Douglas-fir provenances

Graduation date: 1978From a preliminary 1969 foliar analysis, eight provenances were chosen from the sixteen included in a region-wide, reciprocal Doulgas-fir provenance study for further study of variation in foliar nutrition. In the fall of 1969 separate foliar samples were collected from ten\ud trees per provenance at each of ten plantations ranging from south-central\ud Oregon to northern Vancouver Island, British Columbia. Sixteen composite soil samples were collected from each plantation. Three of\ud the same seed sources, growing in three Oregon plantations, were also sampled at three dates during the 1971 growing season and at bi-weekly intervals (ten to twelve sampling dates) during the 1972 season. Finally, progeny grown from 23 open-pollinated trees from a west-east\ud transect in Oregon and from 7, full-sib crosses made among 5 of these parents were sampled at an arboretum located near Corvallis, Oregon. All foliar samples were analyzed for N, P, K. Ca and Mg; Mn and Zn\ud data were also collected for the 1972 growing season samples. Several physical foliage parameters were also measured. Soils were analyzed for pH and macronutrients, except S. Provenance effects were highly significant for all nutrients analyzed, indicating the presence of relatively strong, genetically controlled geographic variation in Douglas-fir foliar nutrient status. A fairly weak trend of increasing nutrient concentration with increasing\ud latitude of the provenances was apparent; Vancouver Island, British Columbia sources tended to rank high, whereas Medford, Oregon, the most southerly provenance, ranked last for all nutrients. Foliage weight\ud was also under strong genetic control and tended to result in reversed provenance rankings when nutrient contents were expressed as mg/lOO needles. Transformation of data to mg/lateral shoot generally restored initial rankings. Implications of these results were discussed for foliar analysis interpretations and for future nutritional research. Analysis of variance, correlation coefficients and multiple regression analyses of soil and foliar chemical data and field observations were used to characterize the marked differences in soil fertility and productivity of the ten plantations. Variability within test sites was also documented and discussed.\ud Growing season sampling revealed considerable variation in nutrient level patterns with time among the three provenances and three plantations studied. A pre-bud break decline and recovery in foliar N levels could not be explained by dry weight changes alone. A more complicated\ud theory was proposed. Stability of foliar N values varied unpredictably during the growing season. The timing of maximum height growth-foliar N concentration correlations varied between sampling years and among the test sites. Sampling during both the dormant and active seasons was recommended. Growing season collections should be related to specific phenological events rather than to calendar dates. Half-sib families from the west-east Oregon transect exhibited few\ud significant correlations between foliar nutrient values and physiographic variables. Partitioning the transect into segments defined by foliar N homogeneity generally paralleled variation in phenology