Methodology.- Open top chambers for exposing plant canopies to elevated CO2 concentration and for measuring net gas exchange.- Free air carbon dioxide enrichment: development, progress, results.- Analysing the responses of photosynthetic CO2 assimilation to long-term elevation of atmospheric CO2 concentration.- Plant water relations and the effects of elevated CO2: a review and suggestions for future research.- Ecophysiological and ecosystem responses: effects of CO2 enrichment on growth and production.- Effects of increasing atmospheric CO2 on vegetation.- Interspecific variation in the growth response of plants to an elevated ambient CO2 concentration.- Root growth and functioning under atmospheric CO2 enrichment.- Crop responses to CO2 enrichment.- Interactions between C3 and C4 salt marsh plant species during four years of exposure to elevated atmospheric CO2.- Plant responses to past concentrations of CO2.- Increasing CO2 and plant-plant interactions: effects on natural vegetation.- Response to CO2 enrichment: interaction with soil and atmospheric conditions.- Plant responses to atmospheric carbon dioxide enrichment: interactions with some soil and atmospheric conditions.- Responses of plants to CO2 under water limited conditions.- Interaction between elevated atmospheric concentration of CO2 and humidity on plant growth: comparison between cotton and radish.- The greenhouse effect: the impacts of carbon dioxide (CO2), ultraviolet-B (UV-B) radiation and ozone (O3) on vegetation (crops).- Contrasting crop species responses to CO2 and temperature: rice, soybean and citrus.- Indirect responses to CO2 enrichment: interactions with soil organisms and soil processes.- Rising CO2, secondary plant metabolism, plant-herbivore interactions and litter decomposition Theoretical considerations.- The influence of plant carbon dioxide and nutrient supply on susceptibility to insect herbivores.- Implications of increased carbon dioxide levels for carbon input and turnover in soils.- CO2 enrichment: biosphere-atmosphere exchange.- Response of the terrestrial biosphere to global climate change and human perturbation.- Impact of CO2 enrichment on the regional evapotranspiration of agroecosystems, a theoretical and numerical modelling study.- The need for micrometeorological research of the response of the energy balance of vegetated surfaces to CO2 enrichment.- Interaction of ocean and biosphere in their transient responses to increasing atmospheric CO2.- CO2 and plants: revisited.- Environmental policy and the greenhouse effect.- Case studies.- Assimilation, respiration and allocation of carbon in Plantago major as affected by atmospheric CO2 levels A case study.- Interactive effects of atmospheric CO2 enrichment, salinity and flooding on growth of C3 (Elymus athericus) and C4 (Spartina anglica) salt marsh species.- Studying the effect of elevated CO2 in the open in a naturally enriched environment in Central Italy.- Elevated CO2 and the mineral content of herbaceous and woody plants.- Effects of elevated CO2 on growth, photosynthesis and respiration of sweet chestnut (Castanea sativa Mill.).- Effects of long-term elevated atmospheric carbon dioxide on Loliurn perenne and Trifolium repens, using a simple photosynthesis model.- The combined effects of elevated CO2 levels and UV-B radiation on growth characteristics of Elymus athericus (=E. pycnanathus) 433.- Photosynthetic acclimation in tomato plants grown in high CO2.- Posters.- Description of branch bags and a system to control the CO2 concentration within them.- Effects of elevated CO2 on birch.- Acclimation of Lolium temulentum to enhanced carbon dioxide.- Effects of elevated CO2 on mature Sitka spruce.- Effects of elevated CO2 on Sitka spruce seedlings.- Interaction of CO2 and temperature in the growth and yield of winter wheat: test of ARCWHEAT model.- The effect of CO2 concentration on barley.- Interactive effects of CO2 and O3 on growth of radish (Raphanus sativus L.).- Growth response to CO2 and NO3-: experimentation and modelling on waterhyacinth.- Characteristics of an UV-B transmitting open top chamber.