From its origins as a small sub-discipline of ecology, plant physiological ecology has become a dynamic, highly experimental field focusing on questions of both basic scientific importance and deep social concern. A comprehensive understanding of organismal function remains central, but physiological ecology now provides the underpinnings for the emerging field of ecosystem physiology (Mooney et al. 2000) on the one hand and organismal adaptation on the other (Ackerly et al. 2000). Moreover, physiological ecology is embracing advances in molecular biology to gain new insight into the adaptive significance of physiological and morphological traits, thus strengthening its connection to population genetics and evolutionary biology. A symposium at the 2000 meeting of the Ecological Society of America provided an opportunity for introspection and the expression of a new vision for discipline. Here we report some emerging themes from this symposium.
A solid foundation for physiological ecology took shape in 1987 with the publication of a seminal series of articles, leading with Plant Physiological Ecology Today (Mooney et al. 1987). These articles defined the core of physiological ecology and brought integration to its various avenues of inquiry. The study of physiological and morphological responses of plants to variation in the physical world, the "adaptive value" of these responses, and their contribution to our understanding of the factors defining the distribution of individual species were the central themes of the discipline (Fig. 1). Theories of resource optimization, matter and energy exchange, and mathematical growth modeling provided a conceptual framework; evolutionary inferences were drawn largely from comparative measurements. Thirteen years later, new methodologies are bringing a renewed experimental approach to organismal research and entirely new avenues of inquiry have opened at the molecular and ecosystem scales.