Plant ecophysiology is an experimental science that seeks to describe the physiological mechanisms underlying ecological observations. In other words, ecophysiologists, or physiological ecologists, address ecological questions about the controls over the growth, reproduction, survival, abundance, and geographical distribution of plants, as these processes are affected by interactions between plants with their physical, chemical, and biotic environment. These ecophysiological patterns and mechanisms can help us understand the functional significance of specific plant traits and their evolutionary heritage. The questions addressed by ecophysiologists are derived from a higher level of integration, i.e. from “ecology” in its broadest sense, including questions originating from agriculture, horticulture, forestry, and environmental sciences. However, the ecophysiological explanations often require mechanistic understanding at a lower level of integration (physiology, biochemistry, biophysics, molecular biology). It is, therefore, quintessential for an ecophysiologist to have an appreciation of both ecological questions and biophysical, biochemical, and molecular methods and processes. In addition, many societal issues, often pertaining to agriculture, environmental change, or nature conservation, benefit from an ecophysiological perspective. A modern ecophysiologist thus requires a good understanding of both the molecular aspects of plant processes and the functioning of the intact plant in its environmental context.
In many cases, animals are able to escape unfavourable and changing environmental factors such as heat, cold, drought, or floods, while generally plants are unable to move away and therefor must endure the adverse conditions or perish. Some plants have an impressive array of genes which aid in adapting to changing conditions. It is hypothesized that this large number of genes can be partly explained by plant species' need to adapt to a wider range of conditions.