关键词: 毛乌素沙地, 臭柏, 天然更新, 幼苗动态, 气象因子

Abstract:

For the purpose of understanding dynamics of sexual regeneration seedlings of Sabina vulgaris communities in Mu Us sandland,we had investigated continuously for six years. Results indicated that:The annual average increment rate of seedlings height and crown width was about 24.69% and 44.48% respectively. The trendline of seedlings height and crown width was ascendling. The dynamic variation rate of tolal numbers of seedling was 31%, death rate of marked seedlings was 8.88%, indicating that the increased rate was higher than death rate, showing regenerative condition was well. Three seedlings that height over 20 cm were dead within five year, about 7.89% of total tead seedlings. The death rate of seedlings declined gradually with increasing of seedlings height. The growth speed of seedlings that height over 20 cm reached 9.43 cm·a^-1, which was the most quick compared with that of other height levels. Direct ratio was revealed between growth speed and seedlings height. At the same time, linear correlative analysis was conducted on selecting meteorologic elements that might influence natural regeneration. The result showed there was the positive correlation between the average height of seedlings and winter (Nov.—Mar.) rainfall, and the negative correlation between the average height of seedlings and the summer (June—Aug.) temperature. The crown width of seedlings was negatively correlated with the summer temperature. There were the positive correlations between the dynamic variation rate of total seedlings and the precipitation in winter and in spring (Apr.—May). Whereas the death rate of marked seedlings was related with the annual mean temperature negatively.

Key words: Mu Us sandland, Sabina vulgaris, natural regeneration, seedling dynamics, meteorologic element