Ecological Bulletins 43: 64-75. Copenhagen 1994 Environmental influences on the phenology of pine

Phenology has been defined as the study of the timing of recurring biological events, the causes of their timing with regard to abiotic and biotic forces and the interrelation among phases of the same or different event (Reichle 1973, Leith 1974). The role of phenology in forest ecosystems has been discussed for several decades. Today, understanding how tree phenology is quantitatively related to environment is even more important because of anticipated global environmental change. One of the first steps in modeling tree growth is to define climatic conditions under which growth initiates and ceases. Increased ambient temperatures can be expected to change growth patterns through effects on plant processes such as dormancy deepening, cold hardiness and dormancy release. Modeling the phenology of pines under current and altered climates may not be easy because of their wide geographic and climatic range and the diversity of genotypes that have evolved. We have selected to review the phenology of six contrasting species of pine: Finns radiata D. Don (Monterey pine), P. taeda L. (loblolly pine), P. strobus L. (eastern white pine), P. elliottii Engelm. (slash pine), P. contorta Doug. ex. Loud, (lodgepole pine), and P. sylvestris L. (Scots pine). The specific emphasis is on interactions between environment and tree morphology, anatomy and physiology and how these interactions affect patterns of tree growth and stand productivity. The phenophases to be considered are: shoot growth, stem diameter growth, foliage and branch production and root growth. Comments on other phenophases will be made where they appear to have major, short duration impacts on the growth activities being considered.