INFLUENCE OF CLIMATE ON RADIAL GROWTH AND CONE PRODUCTION IN SUB-ALPINE FIR (ABIES-LASIOCARPA) AND MOUNTAIN HEMLOCK (TSUGA-MERTENSIANA)

Thirty years of cone production records for subalpine fir (Abies lasio carpa (Hook.) Nutt.) and mountain hemlock (Tsuga mertensiana (Bong.) C aff.) (two sites each) in the Cascade Mountains of Washington and Oreg on were compared with basal area increment and weather records to dete rmine relationships among weather, radial growth, and cone crop. Resul ts show that the size of subalpine fir cone crops was negatively relat ed to large crops and positively related to radial growth in the previ ous 2 years. Mountain hemlock cone crops were negatively related to a large cone crop and positively related to July or August temperature i n the previous year. Radial growth in heavy cone years was inhibited m ore for subalpine fir than for mountain hemlock. Results are explained by differences in the location of cone production between species. It is concluded that global climate warming could result in fewer and mo re irregular cone crops for these species.