VARIATION OF PIPERIDINE ALKALOIDS IN PONDEROSA (PINUS-PONDEROSA) AND LODGEPOLE PINE (P-CONTORTA) FOLIAGE FROM CENTRAL OREGON

We quantified 2,6-disubstituted piperidine alkaloids in Pinus ponderos a and P. contorta needles from three forest sites in April, June, Augu st, and December. Alkaloids were detected on at least one date in 71% of the ponderosa pine and in 29% of the lodgepole pine trees sampled. Pinidine was the major alkaloid constituent of ponderosa pine, while e uphococcinine was the predominant compound in lodgepole pine. For pond erosa pine, total alkaloid concentrations were very low at two sites o n all dates. At the third site, concentrations were variable but signi ficantly higher on all dates. Total alkaloid concentrations in previou s-year foliage from this site were highest in April, then significantl y lower from June through December. Current-year foliage collected in August and December had significantly higher alkaloid concentrations t han previous-year foliage on the same dates. Variation in foliar nitro gen concentrations accounted for some of the alkaloid variation in cur rent-year foliage sampled in August.