A Study On Response Of Dominant Plants To Global Climate Change In Maowusu Sandland

Maowusu sandland is a classical semi梔ry one in China. The dry ecosystem has the much sensitive response 40 water梙eat pattern of global change there. The distribution pattern, productivity and water balance of terrestrial ecosystem are greatly affected by future global climate change, such as temperature and precipitation change. Therefore the dissertation is to investigate the response of dominant plants of Maowusu sandland to the global precipitation and temperature change by artificially controlling water supply at four levels of 157. 5mm, 315. 0mm, 472. 5mm and 630. 0mm and two temperature treatments of 25/20 0C and 28/230C (day and night). We have investigated the response of water balance to precipitation change in global change by creating an artificial control of four levels of water supply treating seedlings of Artemisia ordosica Krasch., Sa]ix psammophi]a C. Wang et Ch. Y. Yang and Hea~vsarwn mongo]icum Turcz.. The results show that sandland water storage and its variation, moisture, evaporation and transpiration increased with the increase of water supply. Plant sandland treated by 157.5mm and 315.0mm water supply appeared water deficit. The sandland water storage and moisture of IL mongo]icum sandland was larger than that of S. psa,nmnophi]a sandland, that of which was in turn higher than that of A. ordosica sandland in the same water supply treatment. But the transpiration of A. ordosica was larger than that ?IV - Abstract of S. psammophila, that of which was in turn higher that of ILL mongolicum in the same water supply treatment. It is investigated for the response of gas exchange processes of S. psammophyi]a and A. ordosica seedlings to precipitation change in global change by artificially controlling four water supply levels. The results show that the increase of water supply significantly enhanced the photosynthetic rate, transpiration rate, stomatal conductance and light use efficiency, but decreased leaf temperature of S. psamznophyi]a and A~ ordo.sica. Photosynthetic rate and transpiration rate of the two plants showed str~ongly midday depression in 157. 5mm water supply, but not or a little in full water supply. It is investigated for the response of chlorophyll fluorescence of seedlings of 8. psammophyi]a, HLmongo]icum, A.ordosica and Caragana interrnedia Kuanget H. C. Fu to precipitation ch&ige in global change by artificially controlling four water supply levels. The results show that the different water supply obviously affected the initial fluorescence, maximal fluorescence, variable fluorescence and PSII photochemical efficiency of the four plants. ~There were photoinhibition in the four plants treated by 157. 5mm water supply and in C intermedia treated by 630. 0mm water supply. It is investigated for the response of growth of seedlings of 8. psammophyi]a, IL mongo]icum, A. ordosica and C intermedia to precipitation change in global change by artificiallycontrolling four water supply levels. The results show that there were the positive effects of increasing water supply on morphology of branch and leaf and biomass of S. psammophyi]a, H. mongo]icum and A. ordosica, but the passive effects on the growth of C. interznedia treated by 157.5mm and 630. 0mm water supply. In addition, the root/shoot bidmass weight gradually decreased with the increase of water supply for...