Abstract: Selecting fourteen public green spaces in Lanzhou downtown as the sampling sites, leaves and xylems of four greening plants Platycladus orientalis, Buxus megistophylla, Sophora japonica, and Forsythia suspensa were collected. Combined with the monitoring data of the automatic meteorological station on New Campus of Northwest Normal University supported by Bureau of Meteorology in Lanzhou City, the variations of temporal and spatial differences of stable hydrogen and oxygen isotopes in leaf and xylem water of the four plants were analyzed, and their correlations with temperature, wind speed, relative humidity, and air pressure were discussed. The results indicated that δ¹⁸O of deciduous plants was more enriched than that of evergreen plants, while δ¹⁸O of xylem water of deciduous and evergreen plants changed slightly in sampling period and was similar to that of leaf water. The variation of d in leaf water of the four plants was opposite to the variation of δ¹⁸O. The slope and intercept of transpiration line for plant leaves were far from those of the precipitation line equation, and the slope of transpiration line for leaf and xylem water of B. megistophylla was the lowest. The δ¹⁸O and d of leaf water in evergreen and deciduous plants were correlated with meteorological elements. However, the response of leaf water to meteorological elements was in contrast with d, and there were good correlations of δ¹⁸O and d with wind speed and air pressure.

Key words: controlled release urea, nitrification inhibitor, paddy field., annual greenhouse gas emission