Variations in growth and architecture in the range limit of Salix humboldtiana, the native willow from South America

The conditions faced by edge populations of a tree species may affect the architecture of individual trees. The latitudinally broad range of Salix humboldtiana encompasses tropical to cold-temperate climatic regions, with its southernmost population in central Patagonia. We expected S. humboldtiana trees from the southern-edge population to develop smaller shoots and a lower level of axis differentiation than trees of this species from a more northerly population, and expected edge trees to outperform non-edge trees when growing in common-garden at an intermediate latitude. For juvenile individuals of S. humboldtiana from edge and non-edge natural populations, trunk diameter, height, branching angle, and the length, number of nodes, diameter, leaf area and specific leaf area of main branch and trunk annual shoots were measured. The size and extension rates of shoots developed by trees of both origins in a common-garden were also evaluated. In natural populations, shoot leaf area and specific leaf area were higher for the edge population than for non-edge population. In common garden, shoot extension period and length were higher for non-edge plants than for edge plants. Growth-period differences between populations in the common garden may support the hypothesis of stress adaptation in the southernmost S. humboldtiana trees.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author