Title: EFFECTS OF THERMOPERIOD ON THE EARLY GROWTH OF RED ALDER FROM DIFFERENT ELEVATIONS AND GEOGRAPHIC SOURCES Abstract approved: Signature redacted for privacy.

This study was designed to help elucidate what differences, if any, exist within the species Alnus rubra Bong., grown naturally at various elevations and locations throughout the Pacific Northwest and coastal Alaska. Increasing importance of the species, including both economic and silviculture values, prompted the investigation into the early growth of red alder, an area in which detailed information is lacking. Two areas of investigation that were established included, first, an elevational transect from Newport toMarys Peak in the Coast Range of Oregon and, second, a study of ten geographic sources located throughout the range of Alnus rubra, Both phases of this investigation were conducted under three growth regimes involving the use of a 16 hour photoperiod and three thermoperiods (day-night temperatures are: 21°, 16°C; 10 10°C and 21°, 21°C). The Transect Study showed differences between red alder cone