Climate change will deeply modify the ecophysiological functioning of plants, by creating a set of conditions which could be more favourable (in the sense of biomass production) or not. Among the first, the increase of atmospheric CO2 will stimulate the photosynthesis (with levels depending upon plants and conditions), with a result of a potential increase in biomass up to 20 % in some cases. Warmer temperatures will also generally be favourable to most of the physiological processes, up to an optimum above which the risk of detrimental or lethal values exists. The (almost) generalized advance in phenology (calendar of development stages) will also have various effects: sometimes increase the risk of spring frost or bad setting for fruit trees, a reduced duration cycle for annual plants but an increased active vegetation season for perennial species (advance in spring occurrence, delay for autumn), positive or negative feedback in terms of the active temperature for the vegetal. Above all, the availability of water will be the key factor for modulating the changes in potential production. The changes in individual behaviour will evidently affect plant communities, which however will also to face changes in their geographical zones of potentialities. They can be approached in terms of potential shift by considering their bioclimatic envelope, but there is a large controversy on this approach in regard of possible biotic interactions. It would be also necessary to consider other components of continental ecosystems like insects and pests, or animals in the case of natural ecosystems, as well as future interactions with human intervention. These general notions will be mainly illustrated by examples in crop and forestry productions, with some complementary details about natural ecosystems.