Performance of red alder seed sources in France

Abstract

We report on a series of 7- and 8-year-old genetic trials of red alder (Alnusrubra Bong.) planted in France as an initial exploration of its growth potential and genetic needs. Red alder is native to the Pacific Northwest coast of North America. Seed for the French plantings was collected in four Pacific Northwest river drainages (Santiam, Nisqually, Nooksack, and Hoh), which cover a wide latitudinal and elevational range.Of the four sites at which the red alder seed was planted, the best growth was observed at Rouvray in northwestern France, a site with deep sandy soil and adequate summer precipitation. Growth here was above average for red alder in its native habitat. Poor soil drainage at the other three test sites resulted in much poorer performance. Trees from Santiam River seed sources were generally the poorest performers at all test sites; the source river(s) for the best performing trees, however, varied by test site. Comparing performance of trees from the same source drainage, elevation of seed collection location correlated at best only weakly with growth; the level of nonsys-tematic variation was high. Regression on principal components derived from seed collection location environmental variables indicated that the best growth performance was associated with seed sources from warmer areas with low moisture demands. In general, this combination of climate conditions exists in low-elevation coastal areas; in this study, all seed collection locations fitting this description were in northwestern Washington state.