Elevated CO2 accelerates net assimilation rate and enhance growth of dominant shrub species in a sand dune in central Inner Mongolia
Rimmington, Glyn M.
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Zheng, Y., Xie, Z., Rimmington, G.M., Yu, Y., Gao, Y., Zhou, G., An, P., Li, X., Tsuji, W., and Shimizu, H., 2010, Elevated CO2 accelerates net assimilation rate and enhance growth of dominant shrub species in a sand dune in central Inner Mongolia: Environmental and Experimental Botany v. 68, no. 1, p. 31-36, doi: 10.1016/j.envexpbot.2009.11.005.
It has been reported that elevated CO2 can enhance plant growth and water use, and that desert plants in particular will show the strongest response to rising atmospheric CO2 due to the strong water stress on these plants. In this study experiments were conducted to understand the responses of seedlings from four species, which are dominant in different successional stages in the semi-arid sandy grassland of central Inner Mongolia, to rising temperature and elevated CO2. Seedlings of the four species were grown for 8 weeks at two air temperatures and two CO2 concentration regimes in growth chambers. It was found that for the two Artemisia species and Hedysarum laeve elevated CO2 level resulted in increased relative growth rates (RGR) (6-12%), height increments (24-106%), net assimilation rates (20-45%) and water use efficiencies (WUE) (43-105%), and decreased transpiration (16-55%). For Caragana korshinskii, the elevated CO2 significantly increased the ratio of below ground to above ground biomass (16-23%), height increment (31-65%) and WUE (79-84%). At elevated CO2 level and the higher temperature, the two Artemisia species showed decreased RGR and height increments, while for, C. korshinskii and H. laeve increased RGR and height increments were observed. For A. sphaerocephala the higher temperature also resulted in increased WUE, but decreased WUE for the other three species. Obvious differences were observed between the two Artemisia species and C. korshinskii, with the Artemisia species characterized by higher RGR, lower ratio of below ground to above ground biomass and lower WUE. These findings should be applicable to similar shrub species located in other arid and semi-arid environments.
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