Vegetation dynamics like growth, reproduction, winter rest, competition for nutrients, water, and light are strongly influenced and determined by climate variables. A change in climate will result in a change of these dynamics. A scientific discipline, which is able to link vegetation dynamics with climate variables, is phenology. Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate. Examples include flowering, budburst, insect hatching, bird nesting, fruit ripening, and leaf fall (so called phenophases). Numerous studies have already provided insight into the relationship between climate variables and the timing of these phenophases. In the context of climate change, phenology also provides indicators for ecosystem responses and has clearly shown that plants and animals are already responding to observed increases in global mean temperature. The climate-induced changes in vegetation dynamics will have an impact on all kinds of species-species interactions and eventually on ecosystem composition and structure. Thus, biodiversity will change in response. The theory is that expected future changes in climate will continue to change vegetation dynamics and biodiversity. In order to effectively assess regional changes in biodiversity, extensive multi-species inventories across climatic gradients are required.