Secondary metabolite concentrations and terpene emissions of Scots pine xylem after long-term forest fertilization.

Secondary compounds are known to be associated with the resistance of conifer xylem against insects and fungi. The effects of long-term forest fertilization with nitrogen (N) or with N, calcium (Ca), and phosphorus (P) on secondary compounds in the xylem of 50-yr-old Scots pine (Pinus sylvestris L.) trees were examined. Xylem samples were collected from trees growing in three locations in southern Finland: Vilppula, Padasjoki, and Punkaharju. Forests were fertilized every fifth (Vilppula and Padasjoki) or tenth (Punkaharju) year since the 1950s. We compared concentrations of individual and total monoterpenes and resin acids in the heartwood and sapwood of Scots pine. Terpene emissions were analyzed from the sapwood and total phenolics from the heartwood. Fertilization did not have any significant effect on the concentrations and emissions of xylem monoterpenes. Concentrations of several individual terpenes in sapwood were positively correlated with the corresponding terpene emission. The concentrations of individual resin acids (i.e., abietic and dehydroabietic) decreased significantly in Punkaharju, but increased in the sapwood of N-fertilized trees compared with control ones at Padasjoki and Vilppula. The concentrations of resin acids in the heartwood were not significantly affected by fertilization. Both fertilization treatments decreased the total phenolic concentrations in the heartwood of trees growing in Padasjoki. There was a significant positive correlation between the total phenolics and total resin acid concentration. Overall, resin acids and phenolics seemed be more responsive than monoterpenes to N treatment. These results suggest that forest fertilization might cause slight changes in secondary compound concentrations of xylem, and thus might have significance in the decay resistance of wood.

The effect of genotype and cultivation method on the total salicylate yield of dark-leaved willows (Salix myrsinifolia).

Ten clones of dark-leaved willows ( Salix myrsinifolia Salisb.) were grown for two years on two different sites, Luikonlahti and Punkaharju, using various combinations of soil cultivation, fertilization and mulch treatments, with the objective of comparing the effect of different cultivation methods on the growth and total salicylate yield. In cultivated soil, the total salicylate yield ranged from 20 to 220 kg/ha, depending on the clone and cultivation method. The use of black polythene mulch and the addition of mineral fertilizer reduced the total salicylate concentrations of several clones. On the other hand, polythene mulch noticeably increased the hectare yield of total salicylates by promoting biomass accumulation.