Impacts of long-term elevation of atmospheric carbon dioxide concentration and temperature on the establishment, growth and mortality of boreal Scots pine branches

Abstract

The aim of this study was to investigate the impacts of elevated carbon dioxide (CO₂) and temperature on the establishment, growth and mortality of the branches of Scots pine (Pinus sylvestris L). In 1997, 16 young trees were individually enclosed in chambers, in eastern Finland, for a period of 5 years (1997–2001), in an environment that simulated the future climate for the region. There were four replicates of each treatment, including combinations of ambient and elevated CO₂ and temperature. Measurements were carried out on the establishment of new branches, branch diameter growth and branch mortality. Elevated temperature and elevated CO₂ had no positive effect on the number of branches that established each year or branch diameter growth. They were, instead, related to tree height growth and stem diameter growth, respectively. However, elevated CO₂ and temperature caused an increase in branch mortality.

Keywords:

• Branch diameter
• branch mortality
• branching
• climate change
• crown dynamics
• Pinus sylvestris

This work was carried out as a part of the Finnish Centre of Excellence Programme (2000–2005), under the Centre of Excellence for Forest Ecology and Management (project no. 64308) co-ordinated by Professor Seppo Kellomäki, Faculty of Forestry, University of Joensuu. Funding from the Academy of Finland, the National Technology Agency (Tekes) and the University of Joensuu is gratefully acknowledged. We would like to thank Mr Malcolm Hicks for revising the English of the manuscript.