Variations of leaf traits of an alpine shrub Sieversia pentapetala along an altitudinal gradient and under a simulated environmental change

Abstract

We investigated intraspecific variations of leaf traits such as number of leaves, leaf size, leaf mass per shoot, leaf mass per area (LMA) and leaf nitrogen concentration (leaf N), in a deciduous alpine dwarf shrub Sieversia pentapetala (L.) Greene (Rosaceae), along an altitudinal gradient in the Tateyama Range, Toyama Prefecture, central Japan. We also observed the change in leaf traits under simulated environmental amelioration using an open-top chamber (OTC). Three study sites were established at different altitudes (1900-2800m a. s. l.) and the OTC was installed at the highest elevation site. Snow-free duration and foliage period decreased with altitude. The number of compound leaves per shoot and individual leaf size (compound leaf area) significantly decreased, resulting in reduction of leaf mass per shoot with altitude. LMA decreased, while leaf N increased significantly with altitude. Under simulated environmental amelioration (increased temperature), number of leaves, individual leaf size, and leaf mass per shoot increased significantly. LMA showed significantly higher values and leaf N lower values in the OTC manipulated shoots compared with controls. In other words, leaf mass and LMA decrease and leaf N increases under harsh conditions. These variations and changes in leaf traits seemed to be adaptive responses to severe growth conditions to maintain positive carbon balance