Phenology and seasonality of woody plants: An unappreciated element in global change research?

Abstract

It is regrettable, but not surprising, that phenology has received relatively little attention from ecologists. Phenological data are hard won, accumulating only slowly through careful, daily observations not well suited to the demands of a thesis project or a grant cycle. Organizing coordinated and standardized observations over many sites and many years is a daunting task not much in keeping with the priorities of most granting agencies. Until very recently, it was impractical to simulate realistic diurnal and seasonal climate regimes as a basis for controlled phenological experiments (Wang et al. 1994). Despite these difficulties work on the phenology of woody plants has continued and invites incorporation into a variety of ecological analyses. We convened a symposium at the XVth International Botanical Congress to highlight contemporary work on the phenology of woody species in the hope that this topic would gain wider recognition and support. The papers that follow include most of those presented at the symposium. Helmut Lieth, who has long appreciated the importance of phenological studies (1974), provided an excellent introduction to the symposium. He reported on the long tradition of phenological observation, including contemporary efforts like the International Phenological Gardens that include clonal plantings at sites throughout Europe (Polte-Rudolf 1993). He emphasized the availability of long-term historical records of phenological observations (Lieth 1974; Polte-Rudolf 1993), which provide a basis and reference for current work. Martin Lechowicz drew on some of these historical records to explore the interrelationships among reproductive events and foliar phenology in eastern North American deciduous trees. Kihachiro Kikuzawa presented an overview of his models for foliar phenology, including an outline of their recent extension to questions of coordination between canopy architecture, leaf physiology, and leaf phenology. Takayoshi Koike reports an experimental study that followed the phenological as well as physiological responses of tree seedlings to ele-