关键词: 沙漠化, 沙质草原, 共有种群, 抗氧化酶

Abstract: In last 40 years (1960-2005), the spring phenology of Shenyang urban forest was affected by global warming. The mean annual air temperature of Shenyang had an overall increase, with the increment being 0.96 ℃. Before 1982, it was relative cold and the maximal of the decrease was 1.95 ℃;while after 1982, it was relative warm and the maximal increment was 1.60 ℃. The air temperature was increased in the whole year, with the maximal increment in winter (2.3 ℃) and spring (1.35 ℃). The spring phenological phase of main tree species in Shenyang urban forest presented itself later in relatively cold period, but in advance in the relatively warm period. The dates of the beginning and ending of the spring phenological phase had a close synchronous relationship, and correlated negatively with the length of the seasonal rhythm of phenology. There was a significant negative correlation between the date of budding and the air temperature in winter and early spring. The higher the air temperature in winter and early spring, the earlier the tree budded. The date of sprouting new leaves was mainly affected by the air temperature in spring and had less correlation with the temperature in winter, while that of early flowering was mainly affected by the air temperature 20-80 days (especially 20-40 days) before early flowering.Coldness index (CI) had significant positive correlations with the dates of budding and sprouting new leaves, but less correlation with the date of early flowering. It was predicted that under the conditions of elevated CO₂ concentration and air temperature, the dates of budding, sprouting new leaves, and early flowering of the main tree species in Shenyang urban forest would be advanced for 40.41, 43.08, and 24.13 days, respectively.

Key words: Desertification, Sandy grassland, Common plant population, Anti-oxidative enzymes