The research of the Plant Ecology & Biodiversity group focuses on the functional analysis of plant strategies against the background of a vegetation structure which changes during the growth cycle of the plant. The idea behind this is, that plants are adapted to the possibilities offered by their habitat. Adaptation consists of a combination of population biological, morphological, and physiological traits, which together and in interaction determine the degree of adaptation and, consequently, its fitness. An important part of plant adaptation is its plasticity in response to environmental signals. We call a set of coherent traits that determine the functioning of a plant in its environment a plant strategy. A plant in its habitat is not a fixed, stationary entity: plants grow up and mature; together they form a changing vegetation structure. The question now is, which sets of traits optimize the chance that a plant or population exploits its habitat successfully. In other words, how does the mechanism of this adaptation work? The answer to this question contributes to the answers to the focal questions in our research programme: 1) How does a plant tune its response to spatial and temporal variation in its surroundings? 2) How can plants coexist, or in other words, how is diversity regulated? These questions require investigations at the levels of the individual plant, the population, and the community. They also require a combination of field observations, experiments in the field, garden, greenhouse, or growth chamber, and modelling. We carry out this research in the temperate zone, in the tropics and in the subtropics, in close and extensive collaboration with foreign colleagues and institutes.