Plant physiological ecology: An essential link for integrating across disciplines and scales in plant ecology

A sizeable number of scientists and funding organisations are of the opinion that the relevance of plant physiological ecology as an important discipline has declined to the point that it is no longer considered as one of the important topics of ecological research. Plant physiological ecology is typically associated with the autecological plant research conducted during the latter portion of the 20th century or, even worse, simply with gas exchange measurements. However, taking a closer look, it becomes obvious that, by focusing on the intermediate integration levels (individuals, populations), this discipline represents an essential link between the high integration levels (communities, ecosystems, biosphere) and the disciplines at the bottom of the complexity hierarchy (physiology, molecular biology). In this paper we show that the principal question of all ongoing community and ecosystem level research – What is the mechanistic background of vegetation composition, biodiversity structure and dynamics and how is this linked to fluxes of matter at the community and higher levels of organisation? – can only be answered if the mechanism of interactions between the relevant organisms are understood. In consequence, the classical discipline of plant physiological ecology will continuously develop into a truly interdisciplinary experimental ecology of interactions and its importance will rather increase than diminish. Promising activities of this kind are already underway. Scientists needed for this new direction should have a rather broad scientific perspective, including knowledge and experience in fields outside of typical ecological research, instead of being specialists for single ecophysiological aspects.