The influence of elevated CO2 concentration on growth of seven grasses and one clover species in a cool maritime climate

The effect of elevated CO2 concentration on the growth of eight common species and cultivars in Norwegian meadows-Festuca pratensis ''Salten'' and ''Fure'', Festuca rubra ''Koket'' and ''Leik'', Festuca arundinaceae ''Vantage'' Festuca duruiscula ''Barfina'', Poa pratensis ''Lavang'', Agrostis capillar is ''Aros'', Dactylis glomerata ''Apelsvoll'', and Trifolium repens ''Grasslands Huia''-was studied during 11 weeks (April 26-early July). The study was performed in ten 9 m(2) large field chamber units in a cool (11.3 degrees C) maritime climate under long days (15.1-18.1 h), on the south-west coast of Norway (59 degrees N, 6 degrees E). The different species responded differently to elevated CO2 with respect to tillering, which was enhanced in A. capillaris (81%), D. glomerata (23%) and F. pratensis (36%), but was not significantly affected in the other species. The sward length was significantly decreased by high CO2 concentration, by 20% in P. pratensis, 36% in A. capillaris, 29% in D. glomerata, 26% in F. duruiscula, 36% in F. pratensis and 16% in F. rubra, but was not affected in F. arundinacea, F. pratensis ''Salten'' and T. repens. The dry matter was decreased at elevated CO2 concentration in A. capillaris (14%), increased in F. rubra (10%) and not significantly affected in the other plants. The results are discussed in relation to climate and interspecific responses.